Glossary
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A
- A1
- See primary auditory cortex.
- A2
- See secondary auditory cortex.
- abulia
- A symptom of brain damage, often to the frontal lobes, that manifests as flat affect, limited willpower, and reduced motivation. [23]
- accommodation
- A stage of child development in which the child learns to react to novel entities by modifying their scheme of thought. Compare assimilation. [27]
- acquired sociopathy
- A personality change, often following focal damage to the frontal lobes, in which a person’s behavior becomes sociopathic. [23]
- action potential
- The electrical signal conducted along neuronal axons by which information is conveyed from one place to another in the nervous system. [1, Appendix]
- acuity
- The ability of a sensory system to accurately discriminate spatial detail; usually tested by the ability to spatially discriminate two points, as in the Snellen eye chart exam for vision. Applies to all the sensory systems, but most obviously to vision and somatic sensation. [4]
- adaptation
- The adjustment of sensory receptors or other elements in a sensory system to different levels of stimulus intensity; allows sensory systems to operate over a wide range of stimulus intensities. [4,26]
- ADHD
- See attention deficit hyperactivity disorder.
- aerial perspective
- The diminution of contrast (i.e., the increasing haziness of contour boundaries) as a function of distance from the observer; occurs as a result of the imperfect transmittance of the atmosphere, and is a monocular cue to depth. [5]
- affect
- The outward display of emotion, which typically reflects a subjective feeling (often used synonymously with emotion). Compare temperament. [17]
- affect intensity
- See arousal (definition 2).
- affective neuroscience
- The study of the neurobiological basis of emotions. [17,18]
- afferent neuron
- An axon that conducts action potentials from the periphery to more central parts of the nervous system. Compare efferent neuron. [1]
- affirming the consequent
- An error in deductive logic caused by reversing the direction of inference (e.g., “If P, then Q. Q is true. Therefore, P.”) Compare denying the antecedent. [25]
- aftereffect
- The influence on visual perception that arises from looking at any sort of repetitive stimulus, such as a continuous motion stimulus. The classic example is the waterfall effect: the apparent upward movement seen after staring at falling water. [5]
- afterimage
- The altered image that follows the presentation and removal of a visual stimulus—for example, the residual image after a flash, or after looking for many seconds at a chromatic stimulus (in which case a complementary-color afterimage is seen). [4,5]
- agonist
- A neuropharmacological agent that mimics the action of a neurotransmitter. Compare antagonist. [3]
- AI
- See artificial intelligence.
- alexithymia
- A clinical condition marked by a lack of words to describe one’s own emotions.
- algorithm
- A set of rules or procedures set down in logical notation, and typically (but not necessarily) carried out by a computer.
- allometry
- The study of differential growth rates. [26]
- alpha motor neurons
- Spinal cord neurons that innervate skeletal muscle fibers. Compare gamma motor neurons. [8]
- amblyopia
- Diminished visual acuity arising from a failure to establish appropriate visual cortical connections in early life as a result of visual deprivation. [27]
- amnesia
- The pathological inability to remember or to establish memories. See also anterograde amnesia and retrograde amnesia. [13]
- amygdala
- A nuclear complex in the temporal lobe that forms part of the limbic system; its major functions concern autonomic, emotional, and sexual behavior. [1,17,18]
- analog magnitude system
- A cognitive system that represents the number of elements in a set in a continuous or analog fashion as opposed to a digital or discrete fashion. [22]
- analytical
- Derived according to a set of principles, such as the features of an image. Compare empirical.
- antagonist
- A neuropharmacological agent that opposes or interferes with the action of a neurotransmitter. Compare agonist. [3]
- anterior
- In front of. [1]
- anterior cingulate cortex
- A cortical structure in the midline frontal lobe, usually considered to be part of the limbic cortex; its dorsal regions are associated with the detection of conflicting information or stimuli and with the attentional control invoked to resolve such conflict. [23]
- anterior commissure
- A small midline fiber tract that lies at the anterior end of the corpus callosum; like the callosum, it connects the two hemispheres. [1]
- anterior horn
- See ventral horn.
- anterograde amnesia
- The inability to lay down new memories. Compare retrograde amnesia. [13]
- anthropoid primates
- Non-human primates that have characteristics especially similar to those of humans; generally refers to monkeys and great apes. [26]
- aperture problem
- The challenge of determining the speed and direction of a moving line when its ends are obscured by an opening such as a circular hole or a vertical rectangle. [5]
- aphasias
- Language deficits that arise from damage to one of the cortical language areas, typically in the left hemisphere. [21]
- apparent motion
- The sensation of motion elicited by presentation of a stimulus in two positions over a brief interval. [5]
- appendicular ataxia
- Uncoordinated, jerky movements of the limbs, typically associated with damage to the cerebellum. [9]
- aprosodia
- The inability to inflect speech with the usual emotional color that typically arises from the contribution of the right hemisphere to language. Results in a monotonic or “robotic” speech pattern. [21]
- area LIP
- See lateral intraparietal area.
- arousal
- 1. A global state of the brain (or the body) reflecting an overall level of responsiveness. Compare attention. [2,10] 2. Also known as affect intensity. The degree of intensity of an emotion. [17]
- artificial intelligence (AI)
- A computational approach to mimicking brain function that generally depends on the analytical solving of problems. [2, 28]
- artificial neural network
- A computer architecture for solving problems by feedback from trial and error, rather than by a predetermined algorithmic solution. [28]
- ascending pathway
- A pathway that extends from a more peripheral processing station to a higher one, typically in a sensory system. Compare descending pathway.
- assimilation
- A developmental stage in which young children deal with novel entities by encompassing them into their preexisting thought schemes (for example, assuming any woman who seems to be the child’s mother’s age is also a mother). Compare accommodation. [27]
- association
- An approach employed in cognitive neuroscience in which experimental evidence is used to show that a particular cognitive function is associated with a specific brain area or brain activity. Compare dissociation. [3]
- association cortices
- See cortical association areas.
- associativity
- In the hippocampus, the enhancement of a weakly activated group of synapses when a nearby group is strongly activated. [13]
- attention
- The marshalling of cognitive processing resources on a particular aspect of the external or internal environment, or on internal processes such as thoughts or memories. Compare arousal (definition 1). [10]
- attention deficit hyperactivity disorder (ADHD)
- A childhood disorder of unknown cause characterized by impulsiveness, short attention span, and continual activity. [23]
- attentional blink
- A cognitive phenomenon, typically observed in a rapidly presented stream of stimuli, in which the ability to successfully report a second target stimulus occurring within 100 to 300 milliseconds of a successfully reported first target in the stream is decreased. [10]
- attentional orienting
- The process by which attentional resources are directed toward specific aspects of the environment. [11,12]
- attentional stream paradigm
- A paradigm used in attention research in which two or more segregated series of stimuli are presented and subjects selectively attend to one of the series to perform a task. [11]
- auditory N1
- Also called N100 wave. The first major negative ERP wave elicited by an auditory stimulus, arising from secondary auditory cortex and peaking at about 100 milliseconds after the stimulus; can be strongly modulated by auditory spatial attention. [11]
- auditory nerve
- The eighth cranial nerve, which carries information from the inner ear and vestibular system centrally to the cochlear nuclei and other processing stations in the brainstem. [6]
- auditory system
- The peripheral and central neural apparatus for hearing. [6]
- autism
- A childhood disorder of unknown cause, characterized by social disengagement that varies greatly in severity. [27]
- autobiographical memory
- Memory of one’s personal experience. [14]
- autonomic ganglia
- Collections of autonomic motor neurons outside the central nervous system that innervate visceral smooth muscles, cardiac muscle, and glands. [1]
- autonomic motor system
- Also called visceral motor system. The very large component of the nervous system that is dedicated to proper functioning of the viscera (all the organs that maintain the well-being of the body and brain). [1,8]
- autonomic nervous system
- Also called the visceral nervous system. All of the neural apparatus that controls visceral behavior; includes the sympathetic, parasympathetic, and enteric systems. [1,8,17]
- availability heuristic
- A simplified rule for gauging the frequency or importance of an event by the ease with which it can be accessed in memory. [24]
- awareness
- The subjective aspects of consciousness. [28]
- axial section
- See horizontal section.
- axon
- The extension of a neuron that carries the action potential from the nerve cell body to a target. Compare dendrite. [1, Appendix]
- axon hillock
- The initial portion of an axon, closest to the cell body; the point where action potentials are typically initiated. [1]
- axon terminal
- The presynaptic ending of an axon; the point at which an action potential affects the postsynaptic target cell. [Appendix]
B
- background
- In visual perception, pertaining to the part or parts of a scene that are farther away from an observer and/or less salient. [5]
- backtracking
- In problem solving, moving temporarily farther from the end goal in order to set up a path to the solution. [2,25]
- Baddeley model
- A model, proposed by Alan Baddeley, positing that working memory consists of three memory buffers that briefly maintain information (the phonological loop, the visuospatial sketchpad, and the episodic buffer) and a central executive that allocates attentional resources to the buffers. [16]
- Balint’s syndrome
- A neurological syndrome, caused by bilateral damage to the posterior parietal and lateral occipital cortex, that has three hallmark symptoms: simultanagnosia, optic ataxia, and oculomotor apraxia. Simultanagnosia is the sign most closely associated with the syndrome, and the one most studied from a cognitive neuroscience standpoint. [12]
- bandwidth
- A frequency range within a spectrum; a measure of stimulus duration. [3,6]
- basal forebrain nuclei
- Also called septal forebrain nuclei. A complex of primarily cholinergic nuclei that lies between the hypothalamus in the diencephalon and the orbital cortex of the frontal lobes; concerned with alertness and memory, among other functions. [1]
- basal ganglia
- A group of nuclei lying deep in the subcortical white matter of the frontal lobes that organize motor behavior. The caudate, putamen, and globus pallidus are major components of the basal ganglia; the subthalamic nucleus and substantia nigra are often included. [1,9,23]
- basic emotions
- Emotions that are innate, pan-cultural, evolutionarily old, shared with other species, and expressed by particular physiological patterns and facial configurations. Compare complex emotions. [17, 26]
- basilar membrane
- The membranous sheet in the cochlea of the inner ear that contains the receptor cells (hair cells) that initiate audition. [6]
- behavioral LTP
- A change in synaptic efficacy similar to LTP that follows an actual learning experience. [13]
- behavioral facilitation
- The phenomenon in an exogenously cued spatial attention paradigm of faster behavioral response to a target stimulus presented at the (validly) cued location earlier than 300 milliseconds after the cue. Compare inhibition of return. [10]
- behaviorism
- A perspective in cognitive psychology that holds that only directly observable behavior, and not internal mental states, can be studied scientifically. [2]
- belt area
- See secondary auditory cortex.
- BER
- See brainstem-evoked response.
- beta
- A measure of a processing system’s response bias in the performance of a discrimination or detection (i.e., being more or less likely to press the response button even when very unsure versus only when very sure). Compare d-prime. [10]
- bi-stable figures
- Visual stimuli that elicit perceptual changes that fluctuate back and forth between the perception one of two different objects (e.g., between seeing a face and a vase in Figure 28.3A). [28]
- binding
- 1. The postulated mechanisms by which the various features and qualities of an object are bound together to bring about a holistic perception of the object. [4,10] 2. The attachment of a biochemical molecule such as an odorant, tastant, or neurotransmitter to a protein in the cell membrane. [7, Appendix]
- binocular
- Pertaining to both eyes. Compare monocular. [5]
- binocular disparity
- The geometric difference between the view of the left and right eyes in animals with frontal eyes and stereoscopic depth perception. [5, 27]
- binocular rivalry
- The bi-stable visual experience that occurs when the right and left eye are presented with incompatible or conflicting images. [5,28]
- bipolar cells
- Cells in the vertebrate retina that receive input from the photoreceptors and communicate that input directly or indirectly to retinal ganglion cells. [4]
- blastocyst
- A stage of embryonic development intermediate between the zygote (fertilized egg) and the embryo; differentiates into the three layers that make up the gastrula. [27]
- blind spot
- The region of visual space that falls on the optic disk in the view generated by each eye; because photoreceptors are lacking in this part of the retina, objects that lie completely within the blind spot are not perceived in monocular view. [4,28]
- blindsight
- The ability of people who are blind, usually because of damage to their cortex, to identify the properties of simple visual stimuli when forced to guess. [18,28]
- block design
- An experimental design in which the integrated brain activity over an extended period in one experimental condition (a block) is measured; the experimental block can then be compared to the integrated brain activity recorded during a block with a different experimental or a control condition. [3]
- blood oxygenation level-dependent (BOLD)
- Pertaining to the signal typically measured with fMRI to measure brain activity; based on the local variations of the blood concentration of deoxygenated hemoglobin that result from the changes in blood flow induced by neural activity. [3]
- bottom-up processing
- Peripheral sensory processing; or, more generally, processing that occurs in the lower stations of a sensory system. Compare top-down processing.
- bounded rationality
- The idea that biological limitations on cognitive processing prevent people from making decisions or reasoning in a fully rational manner. [24]
- brain
- The cerebral hemispheres and brainstem. [1]
- brain activity
- The physiological processes that occur in the brain. Recent technologies that allow us to noninvasively measure brain activity in humans has revolutionized studies of how such activity may underlie cognitive functions (and behavior in general). [3]
- brain lesion
- A localized region of brain damage.
- brainstem
- The portion of the brain that lies between the diencephalon and the spinal cord; comprises the midbrain, pons, and medulla. [1,8]
- brainstem-evoked response (BER)
- A small electrical brain wave elicited during the first 10 milliseconds after onset of a brief auditory stimulus that can be detected at the scalp; BERs reflect activity in the auditory brainstem nuclei as the sound stimulus information reaches them in sequence via the auditory afferent pathway. [11]
- brainstem nucleus
- A collection of anatomically identifiable neurons in the brainstem that carries out specific functions.
- brightness
- Technically, the apparent intensity of a source of light; more generally, a sense of the effective overall intensity of a light stimulus. Compare lightness, hue, and saturation. [5]
- Broca’s aphasia
- Also called expressive aphasia, motor aphasia, or production aphasia. A language deficit arising from damage to Broca’s area in the frontal lobe and characterized by difficulty in the production of speech. Compare Wernicke’s aphasia. [21]
- Broca’s area
- Cytoarchitectonic areas 44 and 45 in the ventral posterior region of the frontal lobe in the left hemisphere; named after the nineteenth-century anatomist and neurologist Paul Broca. Compare Wernicke’s area. [1,21,26]
- Brodmann areas
- Approximately 50 anatomically distinct subdivisions of the cerebral cortex identified in the early twentieth century by Korbinian Brodmann. [1]
- Brodmann area 17
- See primary visual cortex.
C
- CA
- Abbreviation for cornus Ammon (“horn of Ammon”), an area of the hippocampus. Subregions CA1, CA2, and CA3 are important in memory processing. [13]
- calcarine sulcus
- The major sulcus on the medial aspect of the human occipital lobe; the primary visual cortex lies largely within this sulcus. [1]
- Cannon-Bard theory
- A theory of emotion, developed by Walter Cannon and Philip Bard, that emphasized the role of the hypothalamus and related parallel processing routes for emotional expression and emotional experience. [17]
- categorical theories
- Theories of emotion positing that emotions are organized into discrete categories. Compare dimensional theories. [17]
- caudal
- Posterior, or “tailward” (toward the back of the head when speaking of the brain). Compare rostral. [1]
- caudate
- A nucleus that, together with the putamen, serves as the input structure for the globus pallidus. Damage to the caudate nucleus leads to hyperkinetic movement disorders such as Huntington’s disease. [1]
- cell
- The basic biological unit of life, defined by a membrane or wall that encloses cytoplasm and, in eukaryote organisms (including all plants and animals), a nucleus.
- cell body
- Also called soma. The portion of a neuron that houses the cell’s nucleus; axons and dendrites typically extend from the neuronal cell body. [1]
- central nervous system
- The brain and spinal cord of vertebrates (by analogy, the central nerve cord and ganglia of invertebrates). Compare peripheral nervous system. [1]
- central pattern generator
- The oscillatory activity found in the spinal cord of vertebrates (or the central nerve cord of invertebrates) that generates specific patterns of motor activity. [8]
- central sulcus
- A major sulcus on the lateral aspect of the hemispheres that forms the boundary between the frontal and parietal lobes. Its anterior bank contains the primary motor cortex; the posterior bank contains the primary sensory cortex. [1]
- cerebellar cortex
- The superficial gray matter of the cerebellum. [1]
- cerebellum
- The prominent hindbrain structure that is concerned with motor coordination, posture, balance, and some cognitive processes; composed of a three-layered cortex and deep nuclei, and attached to the brainstem by the cerebellar peduncles. [1,9]
- cerebral achromatopsia
- Loss of color vision as a result of damage to the visual cortex. [5]
- cerebral aqueduct
- The portion of the ventricular system that connects the third and fourth ventricles. [1]
- cerebral cortex
- The superficial gray matter of the cerebral hemispheres. [1]
- cerebral hemispheres
- The two halves of the forebrain. [1]
- cerebral peduncles
- The major fiber bundles that connect the brainstem to the cerebral hemispheres. [1]
- cerebrocerebellum
- The part of the cerebellar cortex that receives input from the cerebral cortex via axons from the pontine relay nuclei. [9]
- cerebrospinal fluid
- A normally clear and cell-free fluid that fills the ventricular system of the central nervous system; produced by the choroid plexus in the lateral ventricles. [1]
- cerebrum
- The largest and most rostral part of the brain in humans and other mammals, consisting of the two cerebral hemispheres. [1]
- change blindness
- Also called inattentional blindness. The normal inability to see a particular alteration in a changing scene because the change is not noticed. [28]
- channel
- A protein in a cell membrane that creates a pore through which ions can pass [Appendix]
- channel capacity
- In information theory, the maximum number of bits that a communication channel can carry. [2]
- chiasm
- See optic chiasm.
- cholinergic nuclei of the pons-midbrain junction
- Nuclei that play a central role in the regulation of sleep and wakefulness. [28]
- chord
- In audition, a combination of two or more consonant tones sounded simultaneously (typically three simultaneously sounded notes, called a triad). [6]
- choreiform movement
- Uncontrollable, dancelike (“choreiform”) writhing or twisting movements associated with damage to the basal ganglia as occurs in disorders such as Huntington’s disease. [9]
- choroid plexus
- Specialized epithelium in the ventricular system that produces cerebrospinal fluid. [1]
- chromatic scale
- A 12-tone musical scale that divides octaves into 12 approximately equal parts . [6]
- chunking
- A method of increasing working memory capacity by packing more information into each remembered item. [2,16]
- cingulate gyrus
- The gyrus that surrounds the corpus callosum. [1,17]
- cingulate sulcus
- A sulcus on the medial aspect of the cerebral hemispheres defined by the cingulate gyrus. [1]
- circadian rhythm
- Periodic variations over the 24-hour cycle of light and darkness (i.e., a day). [22]
- circle of Willis
- A ring of arteries at the base of the midbrain; connects the posterior and anterior cerebral circulation. [1]
- circuitry
- The connections between neurons; usually used in reference to a particular neural function (as in visual circuitry; see Chapters 4 and 5; or a spinal reflex circuit; see Chapter 1).
- circumplex model
- A way to graphically represent the relationships among emotions by ordering them along the circumference of a circle formed by intersecting two orthogonal axes of valence and arousal at the circle’s center. Compare vector model. [17]
- classical conditioning
- Also called conditioned reflex. The modification of an innate reflex by associating its normal triggering stimulus with an unrelated stimulus. The unrelated stimulus comes to trigger the original response by virtue of this repeated association. [15]
- clinical-pathological correlation
- A method in which damage to the brain is correlated with behavioral signs and symptoms to draw conclusions about the nature of a patient’s problems and the function of the relevant brain area. [3]
- cochlea
- The portion of the inner ear specialized for transducing sound energy into neural signals. [6]
- cochlear nucleus
- The initial processing station in the brainstem for auditory nerve signals. [6]
- cocktail party effect
- An attentional phenomenon in which an individual can selectively focus attention on one particular speaker and tune out other simultaneously occurring conversations. [2,10]
- cognition
- “Higher-order” mental processes.
- cognitive map theory
- A theory positing that the hippocampus mediates memory for spatial relations among objects in the environment. [14]
- cognitive skill learning
- Gradual improvement in the performance of cognitive operations through practice. Compare perceptual skill learning. [15]
- coincidence detectors
- Neurons that detect simultaneous events, as in sound localization. [6]
- color
- The subjective sensations elicited in humans (and presumably many other animals) by different spectral distributions of light. [5]
- color-blind
- See color-deficient.
- color constancy
- The similar appearance of surfaces despite different spectral return from them; usually applied to the approximate maintenance of object appearances in different illuminants. Compare lightness constancy. [5]
- color contrast
- The different color appearance of surfaces despite similar spectral returns from them. [5]
- color-deficient
- Describing an individual who has abnormal color vision as a result of the absence of (or abnormalities in) one or more of the three types of human cone cells. [5]
- color space
- The depiction of a human color experience in diagrammatic form by a space with three axes representing the perceptual attributes of hue, saturation, and brightness. [5]
- coma
- A pathological state of profound and persistent unconsciousness. [28]
- competence
- The knowledge or cognitive capacity that an organism possesses. Compare performance. [2]
- complex emotions
- Emotions that are learned, socially and culturally shaped, evolutionarily new, and typically expressed by combinations of the response patterns that characterize basic emotions. Compare basic emotions. [17]
- component process theories of emotion
- Theories that attempt to classify emotions according to the extent to which they recruit similar cognitive appraisals of emotion-eliciting situations. [17]
- comprehension aphasia
- See Wernicke’s aphasia.
- computerized tomography (CT)
- An imaging method in which X-rays acquired at multiple angles are used to build a three-dimensional image of biological tissue. [3]
- conceptual priming
- A form of direct priming in which the test cue and the target are semantically related. Compare perceptual priming. [15]
- concrete operations stage
- In Jean Piaget’s theory of cognitive development, the stage from ages 7 to 12 years in which a child begins to reason about the world; precedes the formal operations stage. [27]
- conditioned reflex
- See classical conditioning.
- conditioned response (CR)
- In classical conditioning, the reflex (normally innate in response to a particular unconditioned stimulus) that is triggered by a novel stimulus by virtue of repeated association. Compare unconditioned response. [15]
- conditioned stimulus (CS)
- In classical conditioning, the novel stimulus that eventually comes to trigger the innate reflex by virtue of repeated association. Compare unconditioned stimulus. [15]
- conditioning
- The generation of a novel response that is gradually elicited by repeated pairing of a novel stimulus (the conditioned stimulus) with a stimulus that normally elicits the response being studied (the unconditioned stimulus). [13,15]
- cone opsins
- The three distinct photopigment proteins found in cones; the basis for color vision. [5]
- cones
- Photoreceptor cells (i.e., cells that respond to light energy signals) that are specialized for high visual acuity and the perception of color. Compare rods. [4,5]
- connectionist
- Pertaining to the connectivity of neural networks whose connection weights vary according to experience. [20]
- connectionist models
- Information-processing models based on neural networks, in which problems are solved by changing the “weights” of the network connections. [2]
- consciousness
- A contentious concept that includes the ideas of wakefulness, awareness of the world, and awareness of the self as an actor in the world. [28]
- conservation
- The understanding that some physical transformations preserve quantity despite changes in apparent size or shape. [27]
- consolidation
- The strengthening of memory traces following encoding. [2,13]
- consonance
- The pleasing quality of two notes sounded together. [6]
- content-based model of prefrontal organization
- A model of prefrontal cortex organization proposing that ventrolateral regions are involved primarily in object working memory, whereas dorsolateral regions are involved more in spatial working memory. Compare process-based model of prefrontal organization. [16]
- context
- The information provided by the surroundings of a “target.” The division of a scene into target and surround is useful, but arbitrary, since any part of a scene provides contextual information for any other part. [4,5]
- contextual fear conditioning
- A form of emotional learning in which fear responses are acquired in response to environments that predict the presence of an aversive stimulus. [18]
- continuity effect
- Also called filling in. The perceptual attribution of a property or properties to a region of visual space when the information from that space is either absent or physically different from what is actually seen. [2,20]
- continuous mental magnitudes
- A mental representation that is continuous in format, as opposed to discrete. [22]
- contralateral
- On the opposite side. Compare ipsilateral.
- contrast
- The difference, usually expressed as a percentage, between the luminance (or spectral distribution, in the case of color) of two surfaces.
- coronal section
- Also called frontal section. A brain section in the plane of the face; the term comes not from the concept of a crown but from a halo, which is classically depicted in that plane. Compare horizontal section, sagittal section. [1]
- cornus Ammon
- See CA.
- corpus callosum
- The large midline fiber bundle that connects the cortices of the two cerebral hemispheres. [1]
- correspondence problem
- The problem presented in a random dot stereogram (or any image for that matter) of matching a dot in the retinal image in one eye to the corresponding dot in the retinal image of the other eye.
- cortex
- The gray matter of the cerebral hemispheres and cerebellum, where most of the neurons in the brain are located.
- cortical association areas
- Also called association cortices. The regions of cerebral neocortex that are not involved in primary sensory or motor processing. [4]
- cortical columns
- See cortical modules.
- cortical magnification
- Also called magnification factor. The disproportionate representation of cortical space according to peripheral receptor density (such as occurs for the central representation of the fovea of the human eye). [4]
- cortical modules
- Also called cortical columns. Vertically organized groups of cortical neurons that process the same or similar information; examples are ocular dominance columns and orientation columns in the primary visual cortex. [4]
- cortisol
- A steroid hormone released by the adrenal gland that is involved in the stress response. Called corticosterone in rodents. [18]
- counting
- A serial enumeration process that results in a cardinal representation of the number of objects in a set. [22]
- covert attention
- The directing of visual attention without shifting the direction of gaze to the attended region. Can apply to other sensory modalities or to attentional paradigms. Compare overt attention. [10]
- Cowan model
- A model positing that working memory is organized in two embedded levels: (1) long-term memory representations in an activated state, and (2) activated representations that fall within the focus of attention. [16]
- CR
- See conditioned response.
- cranial motor nerves
- Nerves projecting from the cranial motor nuclei to muscles of the face, head, eyes, or neck. [1]
- cranial nerve ganglia
- The sensory or motor ganglia associated with the 12 cranial nerves. Compare dorsal root ganglia. [1]
- cranial nerves
- The 12 pairs of nerves arising from the brainstem that carry sensory information toward and motor information away from the central nervous system. [1]
- critical period
- Also called sensitive period. A restricted developmental period during which the nervous systems of humans and other mammals are particularly sensitive to the effects of experience. [20,27]
- crossed extension reflex
- A complex reflex arc that flexes a limb on one side of the body while simultaneously extending the limb on the opposite side of the body, thereby maintaining postural stability. Compare flexion reflex. [8]
- CS
- See conditioned stimulus.
- CT
- See computerized tomography.
- cue
- See retrieval cue.
- cutaneous withdrawal reflex
- A reflex initiated by a noxious stimulus that moves the affected body part away from the stimulus.
- cyclopean fusion
- The normal sense when looking at the world with both eyes that we see it as if with a single eye. [5]
D
- d-prime (d′)
- A measure of a processing system’s ability to discriminate or detect; developed from information theory, it is based on the numbers of correctly detected/discriminated targets (hits), missed targets (misses), and nontargets that were incorrectly identified as targets (false alarms). Compare beta. [10]
- dark adaptation
- Adjustment of the sensitivity of the visual system to scotopic conditions; based on the reactivation of bleached rhodopsin. Compare light adaptation. [4]
- dB
- See decibel.
- deactivations
- Regional decreases in brain activity measured in response to a cognitive task or event.
- decibel (dB)
- A logarithmic unit of sound stimulus intensity based on the threshold of human hearing. [6]
- declarative memory
- Also called explicit memory. Memory available to consciousness that can be expressed by language. Compare nondeclarative memory. [2,13]
- declarative memory theory
- A theory positing that the hippocampus mediates all declarative memories, regardless of whether they are spatial, nonspatial, relational, nonrelational, episodic or semantic. [14]
- deductive reasoning
- Deriving a logical inference by considering only a set of premises. Compare inductive reasoning. [2,25]
- deep tendon reflex
- See stretch reflex.
- default mode
- Brain processes that occur in the absence of active executive control; a pattern of brain activation that reflects a set of cognitive processes that are typically more engaged during passive experience. [19]
- default-mode network
- A network of the brain that includes the posterior cingulate cortex, the ventral anterior cingulate cortex, and the medial inferior prefrontal cortex and that has been proposed to be engaged when the brain is either “idling” or not engaged in any specific cognitive task. [12]
- degree
- A unit in terms of which visual space is measured; 1 degree is approximately the width of the thumbnail held at arm’s length and covers about 0.2 mm on the retina.
- delay conditioning
- A form of classical conditioning in which the conditioned stimulus is still ongoing when the unconditioned stimulus starts, and they both terminate at the same time. [15]
- delay lines
- The time delay generated by axons of different lengths—a mechanism important in coincidence detection. [6]
- delay phase
- The second of three phases of working memory, in which the information is maintained for several seconds. Compare encoding phase and response phase. [16]
- delayed match-to-sample task
- Also called delayed recognition task. A memory test, often used with monkeys, in which the subject must maintain memory for a single object over a delay and then, when given the option between that object and a new one, must select the new object. [16]
- delayed recognition task
- See delayed match-to-sample task.
- delayed response task
- A task in which the appropriate response is known during the delay phase. [16]
- dendrite
- The extension of a neuron that receives synaptic input; usually branches near the cell body. Compare axon. [1]
- dendritic field potential
- An electrical potential induced in the dendritic tree of a neuron by input from the axons of other neurons. Called local field potential (LFP) when recorded locally, this electrical activity can often also be detected at the scalp as an EEG or ERP. [3]
- dendritic spines
- Small extensions from the surfaces of dendrites that receive synapses. [13]
- denying the antecedent
- An error in deductive logic caused by reasoning from a false premise (e.g., “If P, then Q. P is false. Therefore, Q is false.”). Compare affirming the consequent. [25]
- deoxyglucose technique
- A method for marking neurons according to their level of activity by incorporating a radioactively tagged, nonmetabolized sugar.
- depolarization
- Changing the membrane potential of a neuron in the positive direction, which initiates an action potential if threshold is reached. Compare hyperpolarization. [1]
- depth perception
- The perception of distance from the observer (either monocular or stereoscopic).
- descending pathway
- A pathway that extends from the cerebral cortex to subcortical structures. Compare ascending pathway. [4]
- descriptive model
- A model that attempts to describe how things are, as opposed to how they should be. Compare normative model. [2]
- development
- See ontogeny.
- developmental amnesia
- Amnesia that is due to brain damage occurring early during childhood development and is characterized by a deficit in episodic memory but relatively normal semantic memory. [14]
- developmental dissociations
- Different rates of change during childhood and adult aging. [15]
- developmental dyscalculia
- A learning disability in children that is characterized by the inability to learn simple arithmetic. [22]
- dichotic listening
- A paradigm used in auditory attention research in which two different streams of auditory input are presented, one to each ear, and the subject is instructed to attend selectively to one of them. [18]
- dichromat
- A color-deficient human (or the majority of mammals) whose color vision depends on only two cone types. Compare monochromat and trichromat. [5]
- diencephalon
- The portion of the brain that lies just rostral to the brainstem; comprises the thalamus and hypothalamus. [1]
- difference-in-memory (Dm) effects
- Greater study-phase activity for items that are remembered than for items that are forgotten in a subsequent memory test. Regions showing Dm effects are assumed to mediate successful encoding operations. [14]
- differentiation
- The progressive specialization of developing cells. [27]
- digit-span task
- A working memory test in which the subject is asked to immediately recall a random string of numbers, which is gradually increased until recall fails. [13]
- dimensional theories
- Theories of emotion positing that emotions are organized according to two fundamental orthogonal axes of arousal and valence. Compare categorical theories. [17]
- direct pathway
- A neural circuit in the basal ganglia that releases movement from inhibition when activated. Compare indirect pathway. [9]
- direct priming
- The facilitation of recall in which the prime and the target are identical or have the same name. Compare indirect priming. [15]
- direction
- The trajectory taken by something (e.g., a point moving within a frame of reference); together with speed, defines velocity. [23]
- disinhibition
- The arranging of inhibitory and excitatory cells in a circuit that generates excitation by transiently inhibiting tonically active inhibitory neuron. [23]
- dissociation
- An method in which experimental evidence is used to show that a particular cognitive function is not associated with a specific brain area or brain activity. See also double dissociation. Compare association. [3]
- dissonance
- A combination of simultaneous sounds or notes heard by most people as suggesting tension or lack of resolution.
- distal
- Farther away from a point of reference. In anatomy, often refers to a position toward the extremities as opposed to the trunk of the body. Compare proximal.
- Dm effects
- See difference-in-memory effects.
- dopamine
- A catecholamine neurotransmitter involved in learning and reward evaluation, among other roles in the nervous system of humans and other animals. [24]
- dorsal
- When pertaining to the long body axis, refers to the back (as in dorsal columns). When pertaining to the brain, refers to the top (e.g., a “dorsal view” would be from the top of the head looking down). Compare ventral. [1]
- dorsal columns
- Major ascending tracts in the spinal cord that carry mechanosensory information from the spinal cord to the thalamus; comprise the cuneate and gracile nuclei. [1,8]
- dorsal horn
- The dorsal portion of the spinal cord gray matter, which contains neurons that process sensory information. Compare lateral horn and ventral horn. [1]
- dorsal lateral geniculate nucleus
- Usually called the lateral geniculate. The thalamic nucleus that relays information from the retina to the cerebral cortex. [5]
- dorsal root ganglia
- The segmental sensory ganglia of the spinal cord that contain the first-order sensory neurons whose axons project centrally via the dorsal column/medial lemniscus and spinothalamic pathways. Compare cranial nerve ganglia. [1]
- dorsal spinal roots
- The bundle of axons that runs from the dorsal root ganglia to the dorsal horn of the spinal cord, carrying sensory information from the periphery. Compare ventral spinal roots. [1,8]
- dorsal stream
- A partially segregated visual processing pathway passing from primary visual cortex through extrastriate areas to the higher-order association cortices of the parietal cortex; thought to be concerned primarily with spatial aspects of visual processing. Compare ventral stream. [4]
- dorsolateral prefrontal cortex
- Typically, the part of the lateral surface of frontal lobes that is anterior to motor cortex and the frontal eye fields. [23]
- dorsolateral prefrontal syndrome
- See frontal dysexecutive syndrome.
- double dissociation
- An approach in which one area of the brain is experimentally shown to be associated with a particular task or cognitive function, whereas another area is shown not to be involved in the same task or function. This demonstration thus distinguishes the cognitive roles of different regions in a more rigorous way than does simply showing that the two regions in question respond differently. [3]
- dyslexia
- A common disorder characterized by difficulty reading. [21]
E
- early selection
- A model of attention postulating that attentional mechanisms can selectively filter out or attenuate irrelevant sensory input at an early processing stage, before the completion of sensory and perceptual analysis. Compare late selection. [10]
- eccentricity
- The distance from the center; in vision, typically refers to the distance in degrees away from the line of sight. [5]
- EEG
- See electroencephalographic recording.
- efferent neuron
- An axon that conducts information away from the central nervous system. Compare afferent neuron. [1]
- electroencephalographic (EEG) recording
- A method of recording electrical brain activity, typically noninvasively from the scalp. EEG activity is thought to reflect mainly the currents produced in the dendritic trees of the large pyramidal cells in underlying cortex. [3]
- electromagnetic radiation
- The full spectrum of radiated energy found in the universe; includes light, X-rays, gamma rays, and so on.
- electrophysiological recording
- Referring to various methods of recording electrical activity in the nervous system. [1,3]
- embodiment
- A sense of physical location of the self within one’s own body. [19]
- emotion
- A set of physiological responses, action tendencies, and subjective feelings that adaptively engage humans and other animals to react to events of biological and/or individual significance. Compare affect and mood. [17]
- emotion family
- A group of emotions that share similar properties. [17]
- emotion regulation
- The voluntary or involuntary deployment of resources to gain control over emotional responses. [18]
- emotional perseveration
- The continuation of an emotional response to a stimulus after the emotional significance of the stimulus has changed and the response is no longer appropriate. [18]
- empathy
- The ability to share the same feelings expressed by another individual. Compare sympathy. [19]
- empirical
- Derived on the basis of past experience, effectively by trial and error. Compare analytical.
- encoding
- The incorporation of new information into a memory store, which requires the modification or creation of memory traces. Compare retrieval. [2,13]
- encoding phase
- The first of three phases of working memory, in which information is incorporated into memory. Compare delay phase and response phase. [16]
- endogenous attention
- A form of attention in which processing resources are directed voluntarily to specific aspects of the environment, typically based on experimental instructions or more normally on an individual’s goals, expectations, and/or knowledge. Compare exogenous attention. [2,10]
- engram
- Also called memory trace. The physical basis of a stored memory. [13]
- enteric division
- The division of the autonomic nervous system that is specifically concerned with regulating the behavior of the gut. [1]
- epiphenomenon
- An effect taken to be an incidental consequence of a more basic property or principle.
- episodic memory
- A component of declarative memory that refers to memory for personally experienced past events. Compare semantic memory. [2,13,14]
- episodic memory theory
- A theory positing that the hippocampus is critical for episodic memory but not for semantic memory. [14]
- episodic retrieval mode
- Also called simply retrieval mode. The mental state of episodic retrieval (the retrieval of episodic memories), which is assumed to be qualitatively different than the mental states of other cognitive abilities. [14]
- EPSP
- See excitatory postsynaptic potential.
- ERF
- See event-related magnetic-field response.
- EROS
- See event-related optical signals.
- ERP
- See event-related potential.
- error-related negativity (ERN)
- An electrophysiological marker that occurs when participants make errors in cognitive tasks. [19,23]
- ethology
- An approach to understanding behavior by determining its evolutionary origins, current function, developmental trajectory, and underlying physiological mechanisms. [26]
- event-related magnetic-field response (ERF)
- Magnetic-field fluctuations in an ongoing brain MEG recording that are triggered by sensory and cognitive events, reflecting the summed activity of neuronal populations specifically responding to those events. [3]
- event-related optical signals (EROS)
- A noninvasive optical imaging approach based on the fact that when brain tissue is illuminated, even through the skull, the amount of transmitted versus scattered light varies as a function of whether the neuronal tissue is electrically active. [3]
- event-related potential (ERP)
- Voltage fluctuations in an ongoing brain EEG that are triggered by sensory and/or cognitive events; the changes reflect the summed electrical activity of neuronal populations specifically responding to those events and are extracted from the ongoing EEG by time-locked averaging. [3]
- excitatory
- Pertaining to a synaptic effect that brings the membrane of the postsynaptic cell closer to threshold, thereby making firing of the postsynaptic cell more likely. Compare inhibitory. [1]
- excitatory postsynaptic potential
- Usually abbreviated EPSP. A synaptic potential that increases the likelihood of an action potential occurring in the postsynaptic (target) cell. Compare inhibitory postsynaptic potential, synaptic potential. [Appendix]
- executive control
- The cognitive function associated with altering thought and behavior in a goal-directed, context-dependent, and flexible manner. [23]
- executive processes
- The cognitive functions that allow flexible and goal-directed control. The major executive processes are initiation, inhibition, task switching, and monitoring. [2,23]
- exogenous attention
- Also called reflexive attention. A form of attention in which processing resources are directed to specific aspects of the environment as the result of a sudden stimulus change, such as a loud noise or sudden movement, that attracts attention automatically. Compare endogenous attention. [2,10]
- expected utility
- The personal value (i.e., utility) placed on the potential outcome of a decision. Compare expected value. [2,24]
- expected-utility theory
- A normative model for decision making in which individuals select the option that provides the greatest expected utility, regardless of other factors. Compare expected-value theory and prospect theory. [24]
- expected value
- The absolute value in a particular currency (e.g., dollars) of the potential outcome of a decision. Compare expected utility. [2,24]
- expected-value theory
- A normative model for decision making in which individuals select the option that provides the greatest expected value, regardless of other factors. Compare expected-utility theory. [24]
- explicit memory
- See declarative memory. [13]
- explicit memory test
- A memory test in which subjects are instructed to intentionally remember information from a particular past event. Compare implicit memory test. [2]
- expressive aphasia
- See Broca’s aphasia.
- external ear
- The cartilaginous elements of the visible ear (the pinna and concha). [6]
- extinction
- 1. The gradual disappearance of a conditioned response that is no longer being rewarded. [15] 2. A phenomenon, found in patients with hemispatial neglect, in which a stimulus on the right side of the body or right visual field (processed by the intact left hemisphere) dominates perception, “extinguishing” the ability to perceive the simultaneous stimulus on the left. [12]
- extrastriate visual cortical areas
- Regions of the visual cortex that lie outside the primary (striate) visual cortex; includes higher-order visual processing areas such as V4, MT, and MST. [4,5]
- eyeblink conditioning
- A paradigm in which a puff of air is repeatedly paired with a tone until the tone by itself elicits blinking. [15]
F
- face-in-a-crowd effect
- The phenomenon in visual search behavior in which it is easier to identify an angry face dispersed among many happy ones compared to a happy face dispersed among many angry ones. Compare snake-in-the-grass effect. [18]
- facial expressions of emotion
- Facial movements that express emotions including surprise, fear, disgust, anger, happiness, and sadness. [2]
- facilitation model of repetition suppression
- A model positing that suppression reflects faster processing of stimuli because of shorter latencies and/or shower duration of neural firing. Compare fatigue model of repetition suppression and sharpening model of repetition suppression. [15]
- false-belief task
- A task used to test whether a child comprehends that another person can hold a false belief. [27]
- familiarity
- The feeling that one has experienced an event at some point in the past, even though no specific associations or contextual detail come to mind. Compare recollection. [14]
- fatigue model of repetition suppression
- A model positing that when a stimulus is repeated, all initially responsive neurons show a proportionally equivalent reduction in their response. Compare facilitation model of repetition suppression and sharpening model of repetition suppression. [15]
- fear conditioning
- A form of emotional learning in which fear responses are acquired to cues that predict the occurrence of an aversive stimulus. See also contextual fear conditioning. Compare fear extinction. [18]
- fear extinction
- A form of emotional learning in which fear responses are reduced by repeated presentation of a feared stimulus without any unpleasant consequences. Compare fear conditioning. [18]
- feature detection
- The concept that sensory percepts entail the processing of physical features of the stimuli arising from objects in the world. [2]
- feature integration theory
- An attention model postulating that the visual perceptual system is organized as a set of feature maps, each providing information about the location(s) in the visual field of a particular feature. [10]
- feature similarity gain model
- A model in which the attentional modulation of the amplitude (gain) of a sensory neuron’s response depends on the similarity of the features of the currently relevant target and the feature preferences of that neuron. [11]
- feedback
- Information that is projected backward from a higher-order station to a lower one in a neural processing system. Compare feedforward. [4]
- feedforward
- Information that is projected forward from a lower-order station to a higher one in a neural processing system. Compare feedback. [4]
- FFA
- See fusiform face area.
- fight-or-flight response
- A rapid reaction to a threatening stimulus that causes engagement of the sympathetic branch of the autonomic nervous system in preparation for action. [18]
- filling in
- See continuity effect.
- fissure
- A deep cleft in the surface of the brain; can be between two lobes (e.g., the lateral fissure between the frontal and temporal lobes), or an especially deep sulcus (e.g., the calcarine fissure in the occipital lobe). [1]
- flanker task
- An attentional paradigm used to study stimulus-processing interference that arises when irrelevant flanking stimuli conflict on a particular dimension with the features of a task-relevant visual stimulus. [10]
- flashbulb memory
- The concept that traumatic memories are vividly and accurately represented in the brain as though the event were recorded through the flash of a camera. [18]
- flexion reflex
- A polysynaptic reflex mediating withdrawal from a painful stimulus. Compare crossed extension reflex. [8]
- fMRI
- See functional magnetic resonance imaging.
- FN400 effect
- In ERP studies of recognition memory, the greater negativity that is elicited by new items than by old items over midfrontal regions about 300 to 500 milliseconds after the stimulus. [14]
- folia
- The ridges and valleys that are apparent in the cerebellar cortex. [1]
- foraging hypothesis
- The proposal that the information-processing demands of finding scarce foods such as ripe fruit stimulated the evolution of enhanced cognition in some species of primates relative to others that feed on more evenly distributed foods, such as leaves or grass. [26]
- forebrain
- The anterior portion of the brain that includes the cerebral hemispheres (the telencephalon and diencephalon). [1]
- form
- The perception of object geometry or shape; one of the major visual perceptual qualities. [5]
- formal operations stage
- In Jean Piaget’s theory of cognitive development, the stage from 12 years old and beyond in which reasoning children become able to engage in abstract problem solving; follows the concrete operations stage. [27]
- formant
- One of several frequencies that represent the natural resonances of different components of the vocal tract. [20]
- fornix (pl. fornices)
- An axon tract, best seen from the medial surface of the divided brain, that interconnects the hypothalamus and hippocampus. [1]
- Fourier analysis
- A mathematical procedure for representing a function as the sum of a series of sinusoids. Based on Fourier’s theorem, the idea established by Jean-Baptiste-Joseph Fourier in the late eighteenth century, that any periodic function can be decomposed into a series of sine or cosine waves that are harmonically related (and thus that any spectrum can be represented as the sum of a series of appropriate sine waves). [6]
- fourth ventricle
- The ventricular space that lies between the pons and the cerebellum. [1]
- fovea
- The area of the human retina specialized for high acuity; contains a high density of cones and few rods. Most mammals do not have a well-defined fovea, although many have an area of central vision (called the area centralis) in which acuity is higher than in more eccentric retinal regions. [4]
- framing effect
- A mode of representing a decision-making scenario that changes the decisions that people make, even though the basic structure of the problem is left unchanged. [2,24]
- frequency
- How often something occurs in a unit of time and/or space.
- frequency band
- See bandwidth.
- frequency distribution
- A histogram or other graphical representation showing the relative frequency of occurrence of an event.
- frontal disinhibition syndrome
- A collection of behavioral signs and symptoms, typically caused by damage to the ventral prefrontal cortex; manifested by a loss of control, inappropriate outbursts, and a lack of inhibition in social settings. [23]
- frontal dysexecutive syndrome
- Also called dorsolateral prefrontal syndrome. A collection of behavioral signs and symptoms, typically caused by damage to the dorsolateral prefrontal cortex; manifested by an inability to change behavior willfully and flexibly according to context. [23]
- frontal eye fields
- A region of the prefrontal cortex in human and nonhuman primates, often associated with Brodmann area 8a, that plays a key role in voluntary visual orienting movements. [8]
- frontal lobe
- The lobe of the brain that includes all the cortex lying anterior to the central sulcus and superior to the lateral fissure. [1]
- frontal section
- See coronal section.
- frontomedian cortex
- The region of the superior and medial frontal lobe that is immediately anterior to supplementary motor cortex. [24]
- frontopolar cortex
- The most anterior part of the prefrontal cortex. [23]
- functional brain imaging
- A technique for imaging brain activity that depends on the metabolic activity of the relevant brain tissue to reveal the location of neural functions; major types include positron emission tomography (PET) and functional magnetic resonance imaging (fMRI). [3]
- functional dissociation
- Differential effects of experimental factors manipulated in the laboratory. For example, a functional dissociation between episodic memory and perceptual priming is that semantic processing during encoding enhances the former but not the latter. [15]
- functional fixedness
- Focusing on one reasonable, but incorrect, solution to a problem. [25]
- functional magnetic resonance imaging (fMRI)
- A noninvasive method for imaging brain activity that uses imaging pulse sequences generated by an MRI scanner; the signal measured is caused by hemoglobin-based changes in blood oxygenation and blood flow that are induced by local neural activity. [3]
- fundamental frequency (f0)
- The first harmonic in the harmonic series evident in the sound spectra generated by a vibrating string or column of air. Compare harmonic. [6,20]
- fusiform face area (FFA)
- A region of the fusiform gyrus that shows enhanced responses to faces relative to other objects. [19]
G
- game theory
- A subfield of behavioral economics that investigates how people make decisions in simple, well-controlled games. [2,24]
- gamma motor neurons
- Spinal motor neurons that are specifically concerned with the regulation of muscle spindle length; they innervate the intrafusal muscle fibers of the spindle. Compare alpha motor neurons. [8]
- ganglion (pl. ganglia)
- A structurally and functionally discrete collection of neurons (individually referred to as ganglion cells) in the periphery (i.e., outside the central nervous system). Not to be confused with the basal ganglia, a group of structures that lie within the brain (see Chapter 1). Compare nucleus. [1,8]
- gastrula
- A phase of embryonic development that follows the blastocyst phase and is characterized by three layers (endoderm, mesoderm, and ectoderm). [27]
- gating
- Allowing or permitting. The basal ganglia, for example, gate movement initiation. Channels through the neuronal membrane are often gated, allowing the access of certain ions under certain conditions. [9, Appendix]
- gaze-triggered shift of attention
- A shift of visual attention that is induced by viewing another individual’s gaze being directed to a location in space. [10]
- gene
- A hereditary unit located on a chromosome and defined in the simplest case by encoding the information for a particular protein; the genetic information is carried by linear sequences of nucleotides in DNA that code for corresponding sequences of amino acids.
- generator potential
- See receptor potential.
- genetic algorithms
- A computer-based scheme for simulating evolution using artificial neural networks. [28]
- genome
- The complete set of an animal’s genes.
- genotype
- The genetic makeup of an individual. Compare phenotype.
- geometric illusion
- A discrepancy between a visual stimulus and the resulting percept based on geometric measurements (measurements of length, angle, etc.). [5]
- geon
- An abbreviation for “geometric icon.” A hypothetical feature detector that is sensitive to simple three-dimensional shapes such as cylinders or cubes. [2]
- Gestalt laws
- Generalizations about the rules of perception as applied to stimulus categories; not widely accepted today but of historical interest. [2]
- Gestalt school
- An early-twentieth-century school of psychology promulgating the theory that the overall set of features of a scene determine its perception according to simple rules. (The German Gestalt means “an integrated perceptual whole.”) [2]
- glia
- See neuroglial cells.
- globus pallidus
- One of the three major nuclei that make up the basal ganglia in the cerebral hemispheres; relays information from the caudate and putamen to the thalamus. [1]
- glomeruli
- Characteristic collections of neurons in the olfactory bulb; formed by dendrites of mitral cells and terminals of olfactory receptor cells, as well as processes from local interneurons. [7]
- glottis
- The space or opening between the vocal cords. [20]
- goal state
- The solution to a problem. [24]
- G-protein-coupled receptors
- See metabotropic receptors.
- grammar
- The system of rules implicit in a language. [2,20]
- grandmother cell
- A hypothetical neuron whose activity would indicate the presence of a specific object in the environment (e.g., one’s grandmother). [28]
- grapheme
- A symbol used in the written representation of speech. The symbol may represent a whole word, a syllable, or a speech sound, as in the letters of an alphabet. [20]
- gray matter
- Regions of the central nervous system that are rich in neuronal cell bodies; includes the cerebral and cerebellar cortices, the nuclei of the brain, and the central portion of the spinal cord. Compare white matter. [1, 27]
- guided search
- An attention theory positing that top-down mechanisms based on behavioral goals can be used to set priorities and facilitate processing during visual search. [10]
- gustatory system
- Also called taste system. The peripheral and central components of the nervous system dedicated to processing and perceiving taste stimuli. [7]
- gyrification index
- A quantitative measure of the degree of neocortical folding. [26]
- gyrus
- A ridge in the folded cerebral cortex. Compare sulcus. [1]
H
- habituation
- The process by which a behavioral response to the same stimulus decreases in intensity, frequency, or duration when a stimulus is repeated over and over. Compare sensitization (definition 1). [13]
- hair cell
- The receptor cell in the inner ear for transducing sound stimuli (or other mechanical stimuli in the case of vestibular hair cells) into neural signals. [6]
- hardware
- The mechanical components (machinery) of a computer. Compare software. [28]
- harmonic
- Also called overtone. A natural frequency of resonant vibration in a harmonic series; always an integer multiple of the fundamental frequency of the vibrating object. Compare fundamental frequency. [20]
- harmonic series
- The series of vibratory modes evident in the spectra produced by resonating objects. [6]
- harmony
- The perceptual responses to presenting simultaneous tones that comprise consonant musical intervals. See chord. [6]
- Hebbian learning
- The idea, proposed by Donald Hebb in the late 1940s, that when presynaptic and postsynaptic neurons fire action potentials together, the strength of the synaptic connections between them is enhanced. Hebb’s rule is often state as “Cells that fire together wire together.” [2,13]
- hemiballismus
- A neurological disorder resulting from unilateral damage to the basal ganglia; manifested by flinging movements of the limbs contralateral to the lesion. [9]
- hertz (Hz)
- A measure of frequency; 1 hertz equals 1 cycle per second.
- heuristic
- A rule of procedure derived from past experience that can be used to solve a problem; in vision, heuristics are sometimes taken to determine perception. [2,24]
- heuristic process
- A process used for simple tasks or decisions that is based on a set of rules and a decision criterion. Compare systematic process. [14]
- hidden unit
- In connectionist models, the elements in the layer or layers of an artificial neural network between the input and the output. [2]
- hierarchy
- A system of interconnected higher and lower ranks. In vision, the idea that neurons in initial stations of the visual system determine the properties of higher-order neurons. [4]
- higher-order
- Pertaining to processes and/or areas taken to be further removed from the input stages of a system; in neuroscience, sometimes used as a synonym for cognitive.
- higher-order neurons
- Neurons that are relatively remote from peripheral sensory receptors or motor effectors; often refers to neurons in the cerebral cortex.
- hill climbing
- A strategy for solving a problem that entails choosing the action that brings one closest to the goal state, without backtracking. [2]
- hippocampal-perirhinal theory
- The idea that the hippocampus processes information relatively slowly and is associational and spatial, whereas the perirhinal cortex processes information more rapidly and is automatic and item-based. [14]
- hippocampus (pl. hippocampi)
- A specialized cortical structure located in the medial portion of the temporal lobe; in humans, concerned with short-term declarative memory, among many other functions. [1,17]
- homeostasis
- Pertaining to the steady maintenance at optimal levels of essential physiological processes such as heart rate, blood pressure, and breathing rate. Myriad feedback and feedforward loops in the nervous system serve to maintain homeostasis. [8]
- hominids
- The family of primates that includes humans and their bipedal ancestors but not great apes (although some taxonomists include all African apes, humans, and human ancestors within the hominid family). [26]
- Homo
- The genus of humans and their ancestors characterized by upright walking, a relatively large brain, certain advanced dental features, and toolmaking. [26]
- homologue
- A biological feature or trait shared by two organisms because it was inherited from a common ancestor. Homologous traits may differ in their function, but they derive from the same genetic and developmental programs. [26]
- homonyms
- Words that sound the same and have the same spelling but different meanings (e.g., bank). [20]
- homophones
- Words that sound the same but are spelled differently (e.g., kernel and colonel). [20]
- homunculus (pl. homunculi)
- Literally “little man” (Greek), often used in referring to the shape of a primary sensory or motor cortical map; also used to refer (often derisively) to the dualist notion of an “I” that stands above neural processing. [7,28]
- horizontal section
- Also called an axial section. Brain sections taken parallel to the rostral-caudal (i.e, nose to back of head) axis. Compare coronal section, sagittal section. [1]
- HPA axis
- See hypothalamic-pituitary-adrenal axis.
- hue
- The aspect of color sensation that pertains specifically to judgments about a color with respect to its redness, greenness, blueness, or yellowness. Compare brightness and saturation. [5]
- Huntington’s disease
- An autosomal dominant genetic disorder in which a single gene mutation results in damage to the basal ganglia that causes personality changes, progressive loss of the control of voluntary movement, and eventually death. [9]
- hyperpolarization
- Changing the membrane potential of a neuron in the negative direction, driving it away from threshold and making it less likely to initiate an action potential. Compare depolarization. [1]
- hyperscanning
- An fMRI technique that involves the simultaneous collection of data across more than one MRI scanner, often while individuals are playing a multiplayer game. [24]
- hypothalamic-pituitary-adrenal (HPA) axis
- The primary information-processing pathway for stress responses; connects the hypothalamus, pituitary gland, and adrenal gland. [18]
- hypothalamus
- A collection of small but critical nuclei in the diencephalon that lies just inferior to the thalamus; governs reproductive, homeostatic, and circadian functions. [1,17]
- Hz
- See hertz.
I
- illumination
- The light that falls on a scene or surface. [5]
- illusion
- A discrepancy between the physically measured properties of a stimulus and what is actually perceived.
- illusory conjunction
- A perceptual process in which sensory features from different objects in a scene are falsely perceived as being part of the same object. [10]
- image
- The representation in art, on the retina, or in perception, of an external form.
- imagery
- The mental representation of an image without the physical presence of sensory stimuli. [16]
- implicit memory
- See nondeclarative memory.
- implicit memory test
- A memory test in which subjects are asked to perform a task that is seemingly unrelated to the encoding event but nonetheless reveals memory for it. Compare explicit memory test. [2]
- in vitro
- Literally “in glass” (Latin). Pertaining to any biological process studied outside of the organism. Compare in vivo.
- in vivo
- Literally “in life” (Latin). Pertaining to any biological process studied in an intact living organism. Compare in vitro.
- inattentional blindness
- See change blindness.
- incidental learning
- Learning that occurs when participants do not know that they are encoding information. Compare intentional learning. [2]
- indirect pathway
- A neural circuit in the basal ganglia that inhibits movement when activated. Compare direct pathway. [9]
- indirect priming
- The facilitation of recall by an item (the prime) that is not directly related to the item. For example, the word winter may indirectly prime both summer and snow. Compare direct priming. [9]
- inductive reasoning
- Deriving an inference about a larger category by considering examples from within that category. Compare deductive reasoning. [2,25]
- infantile amnesia
- In adults, the inability to remember the early years of childhood. [27]
- inferior
- Below. [1]
- inferior colliculi
- Paired hillocks on the dorsal surface of the midbrain; concerned with auditory processing. Compare superior colliculi. [1,6]
- information
- The systematic arrangement of a parameter such that an observer (or a receiver) can, in principle, extract a signal from the background noise.
- information theory
- A theory of communication channel efficiency first elaborated by Claude Shannon in the late 1940s. [2]
- inhibition
- Also called inhibitory response. Any effect that leads to a decrease in neuronal signaling. [2,23]
- inhibition of return (IOR)
- A phenomenon in an exogenously cued spatial attention paradigm that is apparent as a slower behavioral response to a target stimulus presented at the (validly) cued location later than 300 milliseconds after the cue. Compare behavioral facilitation. [10]
- inhibitory postsynaptic potential
- Abbreviated IPSP. A synaptic potential that increases the likelihood of an action potential occurring in the postsynaptic (target) cell. Compare excitatory postsynaptic potential, synaptic potential. [Appendix]
- initiation
- The executive control process associated with starting a behavior. [2,23]
- inner ear
- The cochlea and semicircular canals. [6]
- innervate
- To establish synaptic contact with another neuron or target cell.
- innervation
- All the synaptic contacts made on a particular target.
- input
- The information supplied to a neural processing or other information-processing system.
- insight
- The experience felt when one suddenly perceives the solution of a problem. [2,25]
- insula
- Literally “island” (Latin). The portion of the cerebral cortex that is buried within the depths of the lateral fissure [1,4,19]
- insular cortex
- The hidden portion of the cerebrum formed by the conjunction of the frontal and temporal lobes. [24]
- intelligence quotient (IQ)
- A standardized but controversial measure of intelligence. [25]
- intention tremor
- A tremor that occurs during performance of a voluntary motor act. Characteristic of cerebellar pathology. [9]
- intentional learning
- Learning that occurs when participants know that their memory will be tested and hence try to encode the information efficiently. Compare incidental learning. [2]
- interaural intensity difference
- The difference in the intensity of a sound stimulus at the two ears, which contributes to sound localization. Compare interaural time difference. [6]
- interaural time difference
- The difference in the time of arrival of a sound stimulus at the two ears, which contributes to the ability to localize sounds. Compare interaural intensity difference. [6]
- intercellular communication
- Signaling interactions between cells; in neurons, typically by means of synaptic transmission. [1, Appendix]
- interleaved learning
- Learning in which a particular item is learned not all at once but through a series of presentations intermixed with exposure to other examples of the same general domain. [13]
- intermodal attention
- The ability to focus attention on the stimulus information in one modality and relatively tune out the stimulus information in the sensory input in another modality. Compare supramodal attention. [11]
- internal capsule
- A large white matter tract that lies between the diencephalon and the basal ganglia; contains, among others, sensory axons that run from the thalamus to the cortex and motor axons that run from the cortex to the brainstem and spinal cord. [1]
- interneuron
- Literally, a neuron in a circuit that lies between primary sensory and primary effecter neurons; more generally, a neuron that branches locally to innervate other neurons. [1]
- interval timing
- The postulated mechanisms that allow us and other animals to track durations over the range of seconds to minutes. [2]
- intracellular recording
- Recording the potential between the inside and outside of a neuron with a microelectrode. [1]
- invalidly cued
- Pertaining an attentional cuing paradigm in which the target following a cue occurs in a location different from the one in which it was cued. Compare validly cued. [10]
- inverse optics problem
- The impossibility of knowing the world directly by means of light stimuli; the problem arises because of the ambiguity of light patterns projected onto the retina. [5]
- investment game
- See trust game.
- ion
- An atom or group of atoms in which the number of electrons is either greater or less than the number of protons, resulting in an electrical charge on the atom. The primary ions of the nervous system are potassium (K+), sodium (Na+), calcium (Ca2+), and chloride (Cl–). Movement of ions across neuronal membranes in response to stimuli creates the electrical signals that result in action potentials and synaptic transmission. [Appendix]
- ion channel
- A membrane protein that uses the passive energy of concentration gradients (created by ion exchangers) to allow the passage of ions across the cell membrane. Compare ion exchanger. [1, Appendix]
- ion exchanger
- Also called ion pumps. A membrane protein that uses metabolic energy to create ion concentration gradients across neuronal membranes. Compare ion channel. [1, Appendix]
- ionotropic receptors
- Also called ligand-gated ion channels. Class of postsynaptic neurotransmitter receptors that link binding of neurotransmitter with the action of ion channels. Compare metabotropic receptors. [Appendix]
- IOR
- See inhibition of return.
- Iowa Gambling Task
- An experimental paradigm, developed by Antonio Damasio and colleagues at the University of Iowa, that tests subjects’ sensitivity to risk and reward; the test reveals that patients with damage to the inferior prefrontal cortex tend to make risk-seeking choices. [24]
- ipsilateral
- On the same side. Compare contralateral.
- IPSP
- See inhibitory postsynaptic potential.
- IQ
- See intelligence quotient.
- ischemia
- A paucity or complete lack of blood supply. A common cause of stroke. [1]
- isoluminance
- Also called equiluminance. The condition in which two surfaces have the same luminance. [5]
- item-in-context theory
- A theory positing that the perirhinal cortex and the associated lateral entorhinal cortex are concerned with memory for items, that the parahippocampal cortex and associated medial entorhinal cortex are involved in memory for context, and that the hippocampus interacts with both regions and is involved in memory for items in context. [14]
- item memory test
- An explicit memory test that asks participants to remember what happened during a particular event. Compare source memory test. [2]
J
- James-Lange theory
- A theory, developed by William James and Carl Lange, positing that emotions are determined by the pattern of feedback from the body periphery to the cerebral cortex. [17]
K
- Kennard principle
- The principle that cortical injuries in infancy are often less deleterious compared to the same injury in adulthood; named after Margaret Kennard. [27]
- Klüver-Bucy syndrome
- A rare behavioral syndrome following anterior temporal lobe damage that includes the lack of appreciation for the motivational significance of objects in the environment, hyperorality, and altered sexual behavior; named after Heinrich Klüver and Paul Bucy. [17]
L
- labyrinth
- The bony portion of the inner ear that contains the vestibular apparatus. [7]
- lamina
- A layer, typically one of the cell layers that characterize the neocortex, hippocampus, cerebellar cortex, spinal cord, or retina. [1,5]
- laminated
- Layered.
- language
- The system of communication used in the speech of any group of people. [2]
- larynx
- The upper part of the respiratory tract that lies between the trachea and the pharynx. [20]
- late selection
- A theory of attention postulating that all stimuli are processed through the completion of sensory and perceptual analysis before any selection or influence of attention occurs. Compare early selection. [10]
- lateral
- Located away from the midline. Compare medial. [1]
- lateral column
- The lateral regions of spinal cord white matter that convey motor information from the brain to the spinal cord. [1]
- lateral fissure
- Also called Sylvian fissure. The cleft on the lateral surface of the human brain that separates the temporal and frontal lobes. [1]
- lateral geniculate
- See dorsal lateral geniculate nucleus.
- lateral horn
- The lateral portion of the spinal cord gray matter, which mediates sympathetic motor responses. Compare dorsal horn and ventral horn. [1]
- lateral inhibition
- Inhibitory effects extending laterally in the plane of any neural tissue (e.g., the retina or the visual cortex).
- lateral intraparietal area
- Also called area LIP. Part of the inferior parietal lobule, typically associated with Brodmann area 7 in primates, which plays a key role in orienting attention and the eyes to a location in space. [23,24]
- lateral olfactory tract
- The projection from the olfactory bulbs to higher olfactory centers. [7]
- lateral ventricles
- The major ventricles in each cerebral hemisphere. [1]
- learning
- The acquisition of novel information and behavior through experience.
- left-brain interpreter
- A hypothesis postulating that the prefrontal cortex in the left hemisphere supports the construction of coherent mental narratives. [25]
- left-parietal effect
- In ERP studies of recognition memory, the phenomenon whereby old items elicit a greater positivity over parietal electrodes than do new items at about 400 to 800 milliseconds after the stimulus. Compare right-frontal effect. [14]
- levels of processing framework
- The idea that semantic processing leads to better retention than does nonsemantic (e.g., perceptual) processing. [2]
- lexeme
- The key word in a group of words that have the same basic meaning. For example, being, been, am, and is refer to the lexeme be. [2]
- ligand-gated ion channels
- See ionotropic receptors.
- light
- The wavelength range in the electromagnetic spectrum that elicits visual sensations in humans (photons having a wavelength of about 400 to 700 nanometers). [4,5]
- light adaptation
- Adjustment of the sensitivity of the visual system according to ambient light conditions. Compare dark adaptation. [4]
- lightness
- In vision, the apparent reflectance of a surface. Compare brightness. [5]
- lightness constancy
- The similar grayscale appearance of two surfaces, despite differences in their spectral return. Compare color constancy. [5]
- limbic system
- The cortical and subcortical structures concerned with the emotions that lie along the medial wall of the forebrain. [17]
- limbic system theory
- The theory that structures of the limbic forebrain constitute a system that generates emotions. [17]
- LIP
- See lateral intraparietal area.
- lobes
- The four major regions of the cerebral cortex: the frontal, parietal, occipital, and temporal lobes. [1]
- local circuit neuron
- A neuron whose local connections contribute to processing circuitry. [8]
- locus coeruleus
- A small adrenergic nucleus in the rostral brainstem that projects widely in the brain; it plays a role in the sleep-waking cycle, mediating alertness and perhaps attention. [28]
- long-term depression (LTD)
- A particular kind of diminishment of synaptic strength as a result of repetitive activity. Compare long-term potentiation. [13]
- long-term memory
- Memory that last days, weeks, months, years, or a lifetime. Compare short-term memory. [2,13]
- long-term potentiation (LTP)
- A particular kind of enhancement of synaptic strength as a result of repetitive activity. Compare long-term depression. [13]
- loudness
- The sensory quality elicited by the intensity of sound stimuli. [6]
- lower motor neuron
- Also called primary motor neuron or spinal motor neuron. A motor neuron that directly innervates muscle. Compare upper motor neuron. [8]
- lower motor neuron syndrome
- A clinical condition characterized by signs and symptoms arising from direct damage to motor neurons; includes paralysis or paresis, muscle atrophy, areflexia, and fibrillations. Compare upper motor neuron syndrome. [8]
- LTD
- See long-term depression.
- LTP
- See long-term potentiation.
- luminance
- The physical measure of light intensity. [5]
M
- Machiavellian intelligence hypothesis
- The proposal that the information-processing demands of navigating large, complex social groups are responsible for the evolution of enhanced cognition in primates relative to other mammals. [26]
- machine
- Any man-made device, or more broadly, any apparatus that accomplishes a purpose by the operation of a series of causally connected parts. In cognitive neuroscience, often refers to a digital computer. [28]
- macula
- Also called macula lutea. The central region of the retina that includes the fovea; distinguished by is pale appearance when the retina is viewed through an ophthalmoscope. [4]
- magnetic resonance imaging (MRI)
- A noninvasive imaging method based on the behavior of atomic nuclei (particularly hydrogen) within a strong magnetic field; provides excellent soft tissue contrast of brain anatomy, and can also be used to measure functional brain activity noninvasively. See also functional magnetic resonance imaging. [3]
- magnetoencephalographic (MEG) recording
- A method of recording electrical brain activity from the scalp based on the detection of magnetic fields. Like EEG, MEG activity is thought to reflect mainly the electrical currents produced in the dendritic trees of the large pyramidal cells in cortex, which in turn produce the magnetic effects. [3]
- magnification factor
- See cortical magnification.
- magnocellular system
- The component of the primary visual processing pathway that is specialized in part for the perception of motion and other aspects of stimulus change; so named because of the relatively large neurons involved. Compare parvocellular system. [5]
- mammal
- An animal whose embryos develop in a uterus, and whose young suckle at birth; technically, a member of the class Mammalia.
- mammillary bodies
- Small prominences on the ventral surface of the diencephalon; functionally, part of the caudal hypothalamus. [1]
- map
- A systematic arrangement of information in space. In neurobiology, the ordered projection of axons from one region of the nervous system to another, by which the organization of a relatively peripheral part of the body (e.g., the retina) is reflected in the organization of the nervous system (e.g., the primary visual cortex). [4]
- mapping
- The corresponding arrangement of the peripheral and central components of a sensory or motor system. [4]
- mask
- An interfering stimulus that follows shortly after a prime. [15]
- masked priming
- A technique in which conscious awareness of a prime is prevented by an interfering mask that follows shortly after the prime. [15]
- mass action principle
- A principle stating that when the brain is damaged, the ensuing reduction in learning ability is proportional to the amount of tissue destroyed. [13]
- McGurk effect
- The misperception of speech sounds due to conflicting visual stimuli. [20]
- medial
- Located nearer to the midline of an animal. Compare lateral. [1]
- medial geniculate nucleus
- The thalamic nucleus in the primary auditory pathway. [1,6]
- median section
- See sagittal section.
- medulla
- The caudal portion of the mammalian brainstem, extending from the pons to the spinal cord. [1]
- medullary pyramids
- Longitudinal bulges on the ventral aspect of the medulla that signify the corticospinal tracts at this level of the neuraxis. [8]
- MEG
- See magnetoencephalographic recording.
- melody
- A sequence of tones in a musical composition; typically structured in the diatonic scale for a given key. [6]
- memory load
- See working memory load.
- memory modulation hypothesis
- A hypothesis positing that the basolateral amygdala is important for modulating memory processing in other brain regions to enhance the retention of emotional events. [18]
- memory trace
- See engram.
- mental number line
- A spatially organized representation of numbers. [22]
- mentalizing
- See theory of mind.
- mesopic
- Pertaining to light levels at which both the rod and cone systems are active. [4]
- metabotropic receptors
- Also called G-protein-coupled receptors. Class of postsynaptic neurotransmitter receptors in which neurotransmitter binding activates G-proteins, triggering metabolic molecular cascades whose actions regulate the opening and closing of ion channels. Compare ionotropic receptors. [Appendix]
- metacognition
- Knowing that one knows something. [28]
- microelectrode
- A recording device (typically made of wire, or of a glass tube pulled to a point and filled with an electrolyte) used to monitor electrical potentials from individual or small groups of nerve cells. [1]
- midbrain
- The most rostral portion of the brainstem; identified by the superior and inferior colliculi on its dorsal surface, and the cerebral peduncles on its ventral aspect. [1,23]
- middle ear
- The portion of the ear between the eardrum and the oval window; contains the three small bones that amplify sound stimuli mechanically. [6]
- midlatency response
- The second major phase of the auditory ERP, 10 to 50 milliseconds following an auditory stimulus; it reflects early evoked activity in auditory cortex. [11]
- midsagittal section
- The midline; that plane that divides a structure into mirror-image halves. Compare sagittal section.
- mind
- The full spectrum of a person’s awareness (one aspect of consciousness) at any point in time, reflecting sensory percepts, as well as thoughts, feelings, goals, desires, and so on. [28]
- mind-body problem
- The age-old problem of understanding how the body (i.e., the brain) is related to the contents of consciousness (mind). [28]
- mirror neurons
- Neurons in the frontal and parietal cortices that show similar electrophysiological responses to actions executed oneself or to observation of the same actions being executed by another. [19]
- mirror test
- A test that supposedly determines whether a non-human animal sees its reflection in a mirror as an image of itself; taken as a measure of self-awareness. [28]
- mismatch negativity (MMN)
- A negative ERP wave peaking at about 150 to 200 milliseconds following a deviant stimulus in a stream of otherwise identical stimuli (usually sound stimuli). [11]
- missing fundamental
- Hearing the pitch of the fundamental frequency of a harmonic series when the energy of the fundamental has been removed. [6]
- MMN
- See mismatch negativity.
- modality
- A category of function; for example, vision, hearing, and touch are different sensory modalities.
- modality-specific
- Pertaining to a specific sensory modality; opposite of supramodal. [11]
- mode control model
- A model of nonverbal enumeration that results in an analog magnitude representation of number. Compare object file model. [22]
- modification theory of priming
- The theory proposing that priming reflects an alteration in preexisting memory representations. [15]
- modularity
- The principle of iterated (repeating) units. The anatomical organization of sensory cortices into iterated groups of neurons (modules, columns, or “blobs”) with similar functional properties. [4]
- modus ponens
- A form of valid logical reasoning in which the antecedent of a conditional relation is true (i.e., “If P, then Q. P is true. Therefore, Q.”) Compare modus tollens. [25]
- modus tollens
- A form of valid logical reasoning in which the consequent of a conditional relation is false (i.e., “If P, then Q. Q is false. Therefore, P is false.”) Compare modus ponens. [25]
- monitoring process
- A process during memory retrieval that evaluates the appropriateness and accuracy of answers generated by search during a memory test. [14]
- monochromat
- A color-deficient individual who has only one or no cone opsins, and therefore has no color vision. Compare dichromat and trichromat.
- monochromatic
- Referring to light comprising a single wavelength; in practice, often a narrow band of wavelengths generated by an interference filter [5]
- monocular
- Pertaining to one eye. Compare binocular. [5]
- mood
- A prolonged feeling state. Compare emotion. [17]
- mood regulation
- The long-term balance between emotional and attentional processing of emotions. When these processes become skewed, mood disorders such as depression can occur. [18]
- morpheme
- A linguistic unit that cannot be divided into smaller meaningful parts (e.g., dog). [2]
- Morris water maze
- A task used to test spatial memory, developed by Richard Morris, in which an animal is placed in water and required to swim to a hidden platform. [14]
- mosaic brain evolution
- The proposal that different functional parts of the brain, or modules, evolve at different rates in response to different selective pressures in the environment. [26]
- motion
- The changing position of an object defined by speed and direction within a frame of reference. [5]
- motion aftereffects
- The persistence of perceived motion in the opposite direction when a motion stimulus has ceased. [5]
- motion parallax
- The different degree of movement of near and far objects as a function of moving the head or body while observing a scene. [5]
- motivation
- The desire to attain a particular goal. [17]
- motives
- Basic needs or drives that influence goal-directed behavior.
- motor
- Pertaining to movement.
- motor aphasia
- See Broca’s aphasia.
- motor cortex
- In humans and other mammals, the region of the cerebral cortex anterior to the central sulcus that is concerned with motor behavior; includes the primary motor cortex in the precentral gyrus, and associated premotor cortical areas in the frontal lobe. [1,8]
- motor neuron
- A nerve cell that innervates skeletal or smooth muscle. [1,8]
- motor neuron pool
- The collection of motor neurons that innervates a single muscle. [8]
- motor program
- The plan to produce a particular motor action, such as writing one’s name, that occurs independently of the effectors used to carry out the movement. [8]
- motor system
- All the central and peripheral structures that support motor behavior. [1]
- motor unit
- A motor neuron and the skeletal muscle fibers that it innervates; more loosely, the collection of skeletal muscle fibers innervated by a single motor neuron. [8]
- MRI
- See magnetic resonance imaging.
- MST
- An extrastriate cortical region in primates that is in part specialized for motion processing. [4,5]
- MT
- In primates, an extrastriate cortical region related to the MST that is also in part specialized for motion processing. [4,5]
- MT+
- Also called V5. The more inclusive name given the MT area in humans because of its poor definition. [5]
- Müller-Lyer illusion
- A geometric effect, first described by the nineteenth-century German philosopher and sociologist F. D. Müller-Lyer, in which the length of a line terminated by arrowheads appears shorter than the same line terminated by arrow tails.
- multiple-trace theory
- A theory positing that episodic memories, consolidated or otherwise, always depend on the hippocampus. [13]
- multisensory integration
- The combining of sensory information from different sensory modalities. [4,11]
- muscle fibers
- The striated, smooth, or cardiac muscle cells that generate biological movements. [8]
- muscle spindles
- Specialized sensory organs found in most skeletal muscles that provide the central nervous system with information about muscle strength. [7,8]
- music
- Sounds produced by a wide variety of physical objects that are appreciated as pleasing to humans and that are implemented formally in the chromatic scale. [6]
- myelin
- The membranous wrapping of axons by certain classes of glial cells that makes brain regions with axonal pathways look whitish. See white matter. [1,27, Appendix]
- myelination
- The process by which glial cells wrap axons to form multiple layers of glial cell membrane that electrically insulate the axon, thereby speeding up the conduction of action potentials. [1,27, Appendix]
- myotatic reflex
- See stretch reflex.
N
- N-back tasks
- Tasks in which subjects must indicate whether each item in a continuous stream matches an item presented one, two, or more items “back” in the series. [16]
- N100 wave
- See auditory N1 and visual N1.
- N2pc wave
- An ERP component elicited by the detection of a feature pop-out target in a visual search array, thought to reflect either the shift of attention to the location of the pop-out or the filtering of the nearby distracter items. [12]
- Nash equilibrium
- In an interactive game, a set of decisions by the players of that game from which no player would deviate unilaterally (thus the game is at an equilibrium). [24]
- natural resonance frequency
- The fundamental frequency at which strings, air columns, or other objects tend to vibrate when mechanically perturbed. [6]
- Neanderthals
- A subspecies of Homo sapiens that lived between 200,000 and 30,000 years ago in the Middle East and Europe. [26]
- neglect syndrome
- A neurological syndrome due to damage to the right inferior parietal lobe that causes deficits in spatial attention to the left side of personal and extrapersonal space. [12]
- neocortex
- The six-layered cortex that covers the bulk of the cerebral hemispheres. [1,26]
- nerve
- A collection of peripheral axons that are bundled together and travel a common route. [1]
- nerve cell
- Also called neuron. A cell specialized for the conduction and transmission of electrical signals in the nervous system. [1]
- neural circuit
- A collection of interconnected neurons mediating a specific function. [1]
- neural network
- An artificial network of interconnected nodes whose connections change in strength as a means of solving problems. [20]
- neural plasticity
- The ability of the nervous system to change as a function of experience; typically applied to changes in the fully formed adult nervous system. [13]
- neural plate
- The thickened region of the dorsal ectoderm of a neurula that gives rise to the neural tube. [27]
- neural precursor cells
- Undifferentiated stem cells in the neural tube that will divide to produce more precursor cells and neuroblasts that develop into neurons. [27]
- neural processing
- All the operations carried out by neural circuitry.
- neural system
- A collection of peripheral and central neural circuits dedicated to a particular function (e.g., the visual system, the auditory system). [1]
- neural tube
- The primordium of the brain and spinal cord; derived from the neural ectoderm. [27]
- neuroblast
- A dividing cell, the progeny of which develop into neurons. [27]
- neuroeconomics
- An emerging discipline that combines theoretical perspectives from neuroscience and economics, as well as other of the social sciences, in the creation of mechanistic models for behavior. [24]
- neuroglial cells
- Also called neuroglia or glia. Any of several types of non-neural cells found in the peripheral and central nervous system that carry out a variety of functions that do not directly entail signaling. [1]
- neuromuscular junction
- The synapse made by a motor axon on a skeletal muscle fiber. [8, Appendix]
- neuron
- See nerve cell.
- neuronal receptive field
- See receptive field.
- neuroscience
- The study of the structure and function of the nervous system.
- neurotransmitter
- A chemical agent released at synapses that mediates signaling between nerve cells. [1, Appendix]
- neurotransmitter receptor
- A molecule embedded in the membrane of a postsynaptic cells that binds a neurotransmitter. Compare ionotropic receptors, metabotropic receptors. [1, Appendix]
- neurulation
- The process by which the neural plate folds to form the neural tube. [27]
- nociceptive system
- See pain system.
- nociceptor
- A cell that specifically responds to potentially harmful stimuli. [7]
- noise
- A signal that does not carry information. [6]
- nondeclarative memory
- Also called implicit memory. Memory expressed through performance; assumed to operate unconsciously. Compare declarative memory. [2,13]
- noradrenaline
- See norepinephrine.
- norepinephrine
- Also called noradrenaline. A catecholaminergic neurotransmitter released across synapses in postganglionic neurons of the sympathetic nervous system, in the adrenal medulla, and in some parts of the central nervous system. [18]
- normative model
- A model for a particular phenomenon that attempts to describe how things should be, as opposed to how they are. Compare descriptive model. [2,24]
- nucleus
- An anatomically discrete collection of neurons within the brain; typically serves a particular function. [1]
- nucleus accumbens
- A subdivision of the ventral striatum that contains neurons sensitive to the neurotransmitter dopamine and that contributes to learning and reward evaluation. [24]
- nucleus of the lateral lemniscus
- A brainstem nucleus in the primary auditory pathway. [6]
- nucleus of the solitary tract
- A brainstem nucleus that integrates gustatory and other information relevant to the autonomic control of the gut and other autonomic target organs. [7]
- numerical distance effect
- The greater ease of discriminating two numbers that differ significantly in magnitude compared to two numbers close in magnitude. Compare numerical size effect. [22]
- numerical size effect
- The greater ease of discriminating smaller values compared to larger values if numerical distance is held constant. Compare numerical distance effect. [22]
- numerons
- Nonverbal representations of number that are arbitrarily related to the value they represent, but are applied according to the counting principles offered by psychologists Rochel Gelman and Charles Gallistel. [22,27]
O
- object
- A physical entity that gives rise to a visual stimulus by reflecting illumination (or by emitting light if, as more rarely happens, it is itself a generator of light). [5]
- object file model
- A model of nonverbal enumeration that allows the representation of small sets of objects by the opening of an “object file” for each event or item; numerical equivalence is established through a process of one-to-one correspondence. Compare mode control model. [22]
- object permanence
- The awareness that objects continue to exist even when they are out of sight. [27]
- occipital cortex
- Part of the brain nearest the back of the head, containing mainly visual processing areas. [3,5]
- occipital lobe
- The most posterior lobe of the brain; devoted primarily to vision. [1,5]
- octave
- The frequency or pitch interval between any starting (or fundamental) frequency and its multiplication by two. [6]
- ocular dominance columns
- The segregated termination patterns of thalamic inputs representing the two eyes in the primary visual cortex of some species of primates and carnivores. [5]
- oculomotor apraxia
- Impairment of voluntarily directing gaze toward objects in the visual field by means of a saccade; seen in Balint’s patients, who have suffered bilateral damage in lateral parieto-occipital cortex. [12]
- odorant
- An airborne molecule in the environment that when bound to a receptor neuron in the olfactory epithelium elicits the sensation of a specific odor, or smell. [7]
- olfactory bulb
- The olfactory relay station that receives axons from the olfactory cranial nerve and transmits this information via the olfactory tract to higher centers. [1,7]
- olfactory epithelium
- Pseudostratified epithelium that contains olfactory receptor cells, supporting cells, and mucus-secreting glands in the nasal cavity. [7]
- olfactory nerve
- The first cranial nerve; runs from the olfactory mucosa to the olfactory bulb. [1]
- olfactory receptor neurons
- Bipolar neurons in olfactory epithelium that contain receptors for odorants. [7]
- olfactory system
- The sensory system that includes the olfactory epithelium of the nasal cavity, the olfactory tract and olfactory bulbs; mediates the perception of odors. [7]
- olfactory tract
- See lateral olfactory tract. [1]
- one-to-one correspondence principle
- A counting principle indicating that only one label must be applied to each item that is to be counted. [22]
- ontogeny
- Also called development. The developmental history of an individual animal. [26,27]
- operant conditioning
- The altered probability of a behavioral response engendered by associating responses with rewards (or punishments). [15]
- opponent colors
- Colors that appear to be perceptual opposites, (e.g., red and green, or blue and yellow), with no way to reach one from the other by gradual steps. [5]
- opsins
- Proteins (pigments) in photoreceptors that absorb light (in humans, rhodopsin and the three specialized cone opsins). [5]
- optic ataxia
- A neurological condition associated with damage to the dorsal parietal cortex and characterized by deficits in visually guided reaching. [9,12]
- optic chiasm
- The crossing of optic nerve axons from the nasal portions of the retinas in humans and other mammals such that the temporal visual fields are represented in the contralateral cerebral hemispheres. [1,4,5]
- optic nerve
- Cranial nerve II, containing the axons of retinal ganglion cells; extends from the eye to the optic chiasm. [4,5]
- optic radiation
- The portion of the internal capsule containing the axons from lateral geniculate neurons that carry visual information to the striate cortex. [4,5]
- optic tract
- The axons of retinal ganglion cells after they have passed through the region of the optic chiasm en route to the lateral geniculate nucleus of the thalamus. [4,5]
- optical axis
- See line of sight.
- optical brain imaging
- A set of methods based on the fact that active and inactive brain tissues absorb and transmit light differently, and that these differences can be picked up and imaged by optical recording devices. Optical brain imaging signals can derive from hemodynamic changes, voltage changes, or membrane-swelling changes induced by neural activity. [3]
- orbitofrontal cortex
- The division of the prefrontal cortex that lies above the orbits in the most rostral and ventral extension of the sagittal fissure; important in emotional processing and rational decision making. [17,23]
- organelle
- A subcellular component visible in a light or electron microscope (e.g., nucleus, ribosome, endoplasmic reticulum).
- orientation selectivity
- The propensity of certain neurons to respond selectively to edges presented over a relatively narrow range of stimulus orientations. [5]
- orientation tuning curve
- See tuning curve.
- oval window
- Site where the middle-ear bones transfer vibrational energy to the cochlea. [6]
- overt attention
- The directing of attention (typically visual) by voluntarily shifting gaze. Compare covert attention. [10]
- overtone
- See harmonic.
P
- P100 wave
- See visual P1.
- P20–50 attention effect
- An enhanced positive ERP wave 20 to 50 milliseconds after the stimulus elicited by attended relative to unattended auditory stimuli from. [11]
- P300
- A positive ERP wave peaking at about 300 to 500 milliseconds, elicited by stimuli that are infrequent or surprising, typically occurring within a stream of other sensory events. [19]
- pain
- The highly unpleasant percepts generated by stimuli that are potentially damaging. [7]
- pain system
- Also called nociceptive system. The mechanosensory system that mediates the perception of pain. [7]
- parahippocampal gyrus
- Cortical gyrus in the medial temporal lobe adjacent to the hippocampus; plays a role in declarative memory, emotion, and responses to olfactory stimuli. [1]
- parallel processing
- Also called parallel distributed processing. Simultaneous information processing by different components of a neural or artificial system. [2]
- paramedian pontine reticular formation (PPRF)
- A loose aggregation of neurons in the pons that organizes the activation of oculomotor neurons to produce coherent movements of both eyes. [8]
- paramedian section
- See sagittal section.
- parasympathetic division
- The component of the autonomic nervous system that mediates restorative metabolic functions. Compare sympathetic division. [1,8]
- parietal lobe
- The lobe of the brain that lies between the frontal lobe anteriorly and the occipital lobe posteriorly. [1]
- Parkinson’s disease
- A neurodegenerative process affecting the substantia nigra that results in a characteristic tremor at rest and a general paucity of movement. [9,23]
- pars compacta
- See substantia nigra pars compacta.
- pars reticulata
- See substantia nigra pars reticulata.
- parvocellular system
- The component of the primary visual processing pathway that is specialized in part for the detection of detail and color; so named because of the relatively small size of the neurons involved. Compare magnocellular system. [5]
- pathological dissociations
- Abnormal dissociational effects observed in patients with brain lesions or other perturbations of brain function. [15]
- patient H.M.
- A well-studied patient whose severe memory deficits (i.e., amnesia) following the removal of his temporal lobes highlighted the critical role of these regions for declarative memory. [13]
- payoff matrix
- In an interactive game, the set of rewards that can be obtained depending on the choices of the experimental subjects. [24]
- percept
- The subjective, conscious experience initiated by activation of the receptors of a sensory system. See also sensation. [4]
- perception
- The subjective awareness (taken to be conscious) of any aspect of the external or internal environment. [2,4]
- perceptual load
- The level of processing difficulty or complexity of a task being performed by an individual; usually measured by the time it takes for perceptual analyses of the stimuli. [10]
- perceptual priming
- A form of direct priming in which the test cue and the target are perceptually related. Compare conceptual priming. [2,15]
- perceptual skill learning
- Improvements in processing perceptual stimuli, whether familiar, transformed, or entirely novel. Compare cognitive skill learning. [15]
- performance
- Measurable indices of skill in performing a task. Compare competence.
- peripheral nervous system
- All the nerves and neurons that lie outside the brain and spinal cord. Compare central nervous system. [6]
- peristimulus histogram
- A graph that plots neuronal activity, typically firing rate or number of spikes, as a function of the time of stimulus presentation. [3]
- perseveration
- The repetition of a response despite changing stimuli or rules that make a different response more appropriate. [23]
- perspective
- The effects of representing three-dimensional objects and depth relationships on a two-dimensional surface. [5]
- perspective taking
- The ability to adopt the viewpoint of another individual. [19]
- PET
- See positron emission tomography.
- PFC
- See prefrontal cortex.
- phantom limb phenomenon
- The sensation that a limb or other missing part is present even though it is not (e.g., because of amputation). [7]
- pharmacological manipulation
- An experimental method in which drugs are used to examine the function of neurochemical systems and interactions in the brain. [3]
- phase
- Temporal characteristics of a repeating wave, especially important when two waves interact and either cancel or sum according to their relative phases. [3, 6]
- phenotype
- The visible (or otherwise discernible) characteristics of an animal that arise during development. Compare genotype.
- pheromone
- A chemical signal produced by an animal such as a rodent, typically from glands, that mediates aspects of social communication. [7]
- phoneme
- One of the set of basic perceptual units that distinguish one utterance from another in a given language. [20]
- phonetic
- Representing sounds with symbols. [20]
- phonological similarity effect
- The fact that working memory for letters is worse when the letters sound similar to each other than when they sound different. [16]
- photopic
- Pertaining to daylight levels of light, in which the predominant information is provided by cones. Compare scotopic. [4]
- photopic system
- The components of the visual system activated at relatively high light levels. Compare scotopic system. [4]
- photoreceptors
- Cells in the retina of the eye that are specialized to absorb photons, and thus to generate neural signals in response to light stimuli. See cones, rods. [4,5]
- phrenology
- Originating in the early nineteenth century, the attempt to create maps of brain function based on the pattern of bumps and valleys on the surface of the skull. [23]
- phylogeny
- The evolutionary history of a species or other taxonomic category. [26]
- pitch
- The perception of a periodic sound as being higher or lower on an ordinal scale; roughly, but only roughly, corresponds to sound frequency. [6]
- pituitary gland
- An endocrine structure comprising an anterior lobe made up of many different types of hormone-secreting cells, and a posterior lobe that secretes neuropeptides produced by neurons in the hypothalamus. [1]
- pixel
- Any one of the array of discrete elements that make up a two-dimensional digital image. [5]
- place cells
- Neurons found in the hippocampus that fire depending on the specific location of the animal. [14]
- place coding
- The idea that the meaning of a sensory stimulus derives from the locus that it activates on a sensory receptor sheet such as the retina or basilar membrane. [4]
- plasticity
- See neural plasticity.
- point of subjective equality
- In a bisection task, the stimulus value that subjects are equally likely to classify as an exemplar of either of the two anchor values. [22]
- polymodal
- Pertaining to more than one sensory modality.
- pons
- One of the three components of the brainstem, lying between the midbrain rostrally and the medulla caudally. [1]
- population vector
- A computational variable representing the weighted average response of a group or population of neurons. [8]
- positron emission tomography (PET)
- A method of noninvasive, hemodynamically based brain imaging that uses radioactively labeled molecules injected into the bloodstream that are taken up to a greater degree by active neurons. [3]
- postcentral gyrus
- The gyrus that lies just posterior to the central sulcus; contains the primary somatosensory cortex. [1]
- posterior
- In back of. [1]
- posterior parietal cortex
- The region of the parietal cortex surrounding the intraparietal sulcus. [23]
- postsynaptic
- Referring to the cell receiving the signal generated by the axon terminal of the presynaptic cell. Compare presynaptic. [1, Appendix]
- postsynaptic potential
- Abbreviated PSP. A synaptic potential originating in the postsynaptic cell. See also excitatory postsynaptic potential, inhibitory postsynaptic potential. [Appendix]
- power
- The rate of energy generation.
- PPRF
- See paramedian pontine reticular formation.
- pre-neural apparatus
- The components of a peripheral sensory system that amplify and filter stimuli before they reach the stage of neural transduction. [4]
- precentral gyrus
- The gyrus that lies just anterior to the central sulcus; contains the primary motor cortex. [1]
- prefrontal cortex
- Abbreviated PFC. Cortical regions in the frontal lobe that are anterior to the primary motor and premotor cortices; thought to be involved in planning complex cognitive behaviors and in the expression of personality and appropriate social behavior. [1]
- premotor cortex
- Part of the prefrontal cortex lying just anterior to the primary motor cortex; involved in planning movement. [8]
- premotor cortical areas
- Cortical areas, including the premotor cortex, supplementary motor cortex, and parts of the parietal cortex, that provide motor programming signals to the primary motor cortex. [8]
- premotor theory of attention
- A cognitive theory proposing that shifts of attention and preparation of goal-directed action are closely linked because they are controlled by shared sensorimotor mechanisms. [12]
- preoperational stage
- In Jean Piaget’s theory of cognitive development, the stage from ages 2 through 7 years in which children develop representational or symbolic abilities; follows the sensorimotor stage and precedes the concrete operations stage. [27]
- presynaptic
- Referring to the axonal ending that contacts (transmits a signal to) a target (postsynaptic) cell. [1, Appendix]
- primary auditory cortex (A1)
- The cortical target of the neurons in the medial geniculate nucleus; the terminus of the primary auditory pathway. [4,6]
- primary auditory pathway
- The pathway from the inner ear to the primary auditory cortex in the temporal lobe. [6]
- primary colors
- The four perceptual qualities or categories of human color vision (red, green, blue, and yellow) that are defined by a unique color sensation. [5]
- primary motor cortex
- A major source of descending projections to motor neurons in the spinal cord and cranial nerve nuclei; located in the precentral gyrus (Brodmann area 4) and essential for the voluntary control of movement. [8]
- primary motor neuron
- See lower motor neuron.
- primary reinforcer
- Also called unconditioned reinforcer. A stimulus whose rewarding properties come from its salutary effects on homeostatic processes; food, water, warmth, and sex are examples. Compare secondary reinforcer. [24]
- primary sensory cortex
- Any one of several cortical areas that directly receives the thalamic input for a particular sensory modality. [4]
- primary somatosensory cortex (S1)
- The cortex of the postcentral gyrus of the parietal lobe that receives mechanosensory input from the thalamus. Compare secondary somatosensory cortex. [4,7]
- primary visual cortex (V1)
- Also called Brodmann area 17 or striate cortex. The cortex in the calcarine fissure of the parietal lobe that receives visual input from the thalamus. [4]
- primary visual pathway
- The pathway from the retina via the lateral geniculate nucleus of the thalamus to the primary visual cortex; carries the information that allows conscious visual perception. [5]
- primate
- Any member of the order of mammals that includes lemurs, tarsiers, marmosets, monkeys, apes, and humans.
- priming
- Facilitated processing of a particular stimulus based on previous encounters with the same or a related stimulus. Compare skill learning. [2,13,15]
- principle of proper mass
- Principle stating that the mass of neural tissue controlling a particular function will be proportional and appropriate to the amount of information processing involved in performing the function in question. [26]
- prisoner’s dilemma
- An interactive game in which two players must decide whether to cooperate or to defect and take advantage of the other; the dilemma arises because its equilibrium solution—both players defecting—results in the worst overall outcome. [24]
- probabilistic classification learning
- An example of cognitive skill learning in which participants learn to classify stimuli on the basis of statistical information. [15]
- probability
- The likelihood of an event, usually expressed as a value from 0 (will never occur) to 1 (will always occur).
- probability distribution
- The probability of a variable having a particular value, expressed as a function of all the possible values of that variable.
- problem space
- The set of possible states of a problem; can be vast in complex games like chess. [25]
- procedural memory
- Unconscious memories such as motor skills and associations. [2]
- process-based model of prefrontal organization
- A model of prefrontal cortex organization proposing that ventrolateral regions are involved primarily in simple maintenance operations, whereas dorsolateral regions are involved in more complex processes involving monitoring and manipulating information within working memory. Compare content-based model of prefrontal organization. [16]
- processing
- All of the neural activity mediating a particular function.
- processing negativity
- A slow, long-lasting negative-wave activity that is elicited during auditory selective attention, the amplitude of which may reflect how much each stimulus matches an attentional “template.” [11]
- production aphasia
- See Broca’s aphasia.
- propranolol
- An antagonist of the β-adrenergic system. [18]
- proprioceptive system
- The mechanosensory subsystem that processes information arising from mechanical forces acting on muscles, tendons, and joints. [7]
- proprioceptors
- Sensory receptors (usually limited to mechanosensory receptors) that sense the internal forces acting on the body; muscle spindles and Golgi tendon organs are the preeminent examples. [7]
- prosodic
- Pertaining to the inflection in speech, often associated with emotion. [21]
- prosody
- The fluctuating pitch of speech. Gives emotional and other information to speech. [17]
- prosopagnosia
- The inability to recognize faces; usually associated with lesions of the right inferior temporal cortex. [19]
- prospect theory
- A quantitative decision-making model proposing that people make decisions in terms of the anticipated gains and losses from their current state, and that probabilities are subjective. Compare expected-utility theory. [24]
- proximal
- Closer to a point of reference In anatomy, often refers to a position close to the trunk of the body as opposed to at the extremities of the limbs. Compare distal.
- PSP
- See postsynaptic potential.
- psychoactive drug
- A chemical substance that acts primarily on the central nervous system, where it alters brain function, resulting in changes in perception, mood, consciousness, and/or behavior. [3]
- psychological refractory period
- The time interval proposed to reflect an attention-related processing bottleneck at the response selection stage, during which the selection of one response precludes the selection of another. [10]
- psychology
- The study of mental processes in humans and other animals.
- psychophysics
- The study of mental processes by quantitative methods, typically involving reports by human subjects of the percepts elicited by carefully measured stimuli.
- psychosomatic
- Pertaining to medical problems arising from the influence of the nervous system on bodily functions. This term is now out of fashion.
- pulvinar
- A nucleus of the thalamus that mediates interactions among several sensory association areas of the cortex. [1]
- punishment
- The delivery of an aversive stimulus. [24]
- pupillary light reflex
- The decrease in the diameter of the pupil that follows stimulation of the retina by light.
- putamen
- One of the three major nuclei that make up the basal ganglia. [1]
- pyriform cortex
- A component of the cerebral cortex in the temporal lobe pertinent to olfaction; so named because of its pearlike shape. [1,7]
R
- radial arm maze
- A device used to test spatial memory in animals.
- radial glial cells
- Glial cells that contact both the luminal and pial surfaces of the neural tube, providing a substrate for neuronal migration.
- raphe nuclei
- Brainstem nuclei involved in the control of the sleep-waking cycle, among other functions. [28]
- rapid serial visual presentation (RSVP)
- A method of presenting stimuli in quick succession (about 5 to 15 per second) that is used in studies of visual processing and attention. [10]
- rate coding
- A computational principle in which information is encoded by the firing rate of neurons or other elements. [4]
- rationality
- Consistency in decision making that is based on a conscious evaluation of the circumstances. [24]
- reaction time
- The time it takes to initiate behavior in response to a stimulus.
- readiness potential
- An electrical potential recorded from the motor and premotor cortices with EEG electrodes that signals the intention to initiate a voluntary movement well in advance of the actual production of the movement. [9]
- real-world
- Pertaining to an external world that determines what we perceive, even though it is not directly knowable.
- recency effect
- The better immediate recall that is displayed for the last few items in a list compared to the items in the middle of the list. [13]
- receptive aphasia
- See Wernicke’s aphasia.
- receptive field
- The region of the receptor surface of a sensory neuron that, when stimulated, elicits a response in the neuron being examined. [4]
- receptive-field properties
- The defining characteristics of a neuron’s responses to stimuli within its receptive field. [4]
- receptor cells
- The cells in a sensory system that transduce environmental energy into neural signals (e.g., photoreceptors in the retina, hair cells in the inner ear). [4,6]
- receptor potential
- Also called generator potential. A membrane potential (hyperpolarizing or depolarizing) elicited by the interaction of energy with a sensory receptor cell. [1]
- receptor proteins
- The proteins in receptor cells that capture the energy in the process of sensory transduction (e.g., the opsins on photoreceptors). [7]
- reciprocal innervation
- A motor control process in which contraction of a particular muscle (e.g., the biceps) is coupled with simultaneous relaxation of its opposing muscle (e.g., the triceps). [8]
- recollection
- Remembering a past event, as well as specific associations and contextual details. Compare familiarity. [14]
- recursive processing
- Neural processing that enables reflection on other neural processes, arguably allowing humans or other animals to be aware of themselves and their mental content. [28]
- reentrant process
- Following a stimulus or event, a process in which neural activity is fed back to the same brain region activated earlier in the processing sequence. [11]
- reflectance
- The percentage of incident light reflected from a surface (often expressed as the reflectance efficiency function, in which the reflectance of a surface is measured at different wavelengths). [5]
- reflex
- A stereotyped response elicited by a defined stimulus. Usually taken to be restricted to “involuntary” actions (an assumption that is not necessarily appropriate).
- reflex arc
- The circuitry that connects a sensory input to a motor output. [1]
- reflexive attention
- See exogenous attention.
- refreshing
- Maintaining a piece of information active within working memory by briefly thinking about it. Compare rehearsal. [16]
- rehearsal
- Maintaining a piece of information active within working memory by thinking about it over and over. Compare refreshing. [2,16]
- relational memory theory
- The theory that the hippocampus is involved primarily in encoding and retrieving associations between items, including spatial associations but also other types of associations. [14]
- repetition enhancement
- The creation of new representations and the increase in activity that result from the repetition of stimuli during priming; associated with priming for novel stimuli. [15]
- repetition suppression
- A phenomenon observed in functional neuroimaging studies in which previously encountered stimuli evoke smaller hemodynamic responses than do novel stimuli. [15]
- representation
- 1. The way in which the brain encodes and processes symbolic information. Compare symbolic representation. [2] 2. The neural activity taken to underlie perception at the level of the association cortices.
- representativeness
- A heuristic for decision making and reasoning that evaluates the likelihood of an event according to how well it matches a particular category. [24]
- resolution
- The ability to distinguish two points in space. See also acuity. [5]
- resonance
- The tendency of any physical object to vibrate maximally at a certain frequency. [6,20]
- response conflict
- A state in which two or more possible responses are potentiated. [23]
- response phase
- The last of three phases of working memory, in which an action is executed on the basis of information that has been incorporated and maintained. Compare encoding phase and delay phase. [16]
- response selection
- A putative later stage of information processing in which an appropriate behavioral response to an event is selected. [10]
- reticular activating system
- A large region in the brainstem core whose many nuclei mediate overall arousal and level of awareness. [28]
- reticular formation
- A network of neurons and axons that occupies the core of the brainstem, giving it a reticulated appearance in myelin-stained material; major functions include control of respiration and heart rate, posture, and state of consciousness. [1,8]
- reticulospinal tract
- A pathway from the reticular formation in the brainstem to the spinal cord that plays an important role in anticipatory postural adjustments preceding voluntary movement. [8]
- retina
- The laminated neural component of the eye that contains the photoreceptors (rods and cones) and the initial processing circuitry for vision. [4,5]
- retinal disparity
- The geometric difference between the same points in the images projected on the two retinas, measured in degrees with respect to the fovea. [5]
- retinal ganglion cells
- The output neurons of the retina, whose axons form the optic nerve. [5]
- retinal image
- The image focused on the retina by the cornea and lens of the eye. [5]
- retrieval
- The recovery or accessing of stored memory traces. Compare encoding. [2,13]
- retrieval cue
- Any information that leads to the retrieval of memories, such as the hits provided by memory tests. [2,14]
- retrieval effort
- In functional neuroimaging studies, brain activity that is greater when recovery is low; possibly related to demanding search or monitoring processes. [14]
- retrieval mode
- See episodic retrieval mode.
- retrograde amnesia
- The inability to recall memories for events that happened before the lesion or brain disorder that caused the memory loss. Compare anterograde amnesia. [13]
- reward prediction error
- A quantity given by the difference between the reward that was expected and what actually occurs; the activity of some dopaminergic neurons seems to convey this quantity. [24]
- reward processing
- The cognitive processing that goes into determining goals and optimal outcomes and the behaviors most appropriate to achieving them, and evaluating the feedback when desired goals and outcomes have been achieved. [2,24]
- reward value
- The likelihood that a particular movement will yield a reward, multiplied by the amount of reward expected. [9]
- rhinencephalon
- Called visceral brain by James Papez. A historical term for the limbic system that emphasized its olfactory functions. [17]
- rhodopsin
- The photopigment found in vertebrate rods. Compare cone opsins. [5]
- right-frontal effect
- In ERP studies of recognition memory, the phenomenon whereby old items elicit greater positivity over right frontal regions 600 to 1200 milliseconds after the stimulus than do new items. Compare left-parietal effect. [14]
- right-hemisphere hypothesis
- A hypothesis that the right hemisphere is specialized for emotional functions. [17]
- risk
- Known probabilistic variation in the distribution of reward outcomes. [24]
- rods
- Photoreceptors that are specialized to operate at low light levels. Compare cones. [5]
- rostral
- Toward the nose, or anterior, when pertaining to the brain. Compare caudal. [1]
- RSVP
- See rapid serial visual presentation.
S
- S1
- See primary somatosensory cortex.
- S2
- See secondary somatosensory cortex.
- saccades
- Ballistic eye movements that change the point of binocular visual fixation; normally occur at a rate of about three to four per second. [4,8]
- sagittal section
- Brain section taken in the plane that divides the two hemispheres; can be midsagittal section (at the midline), median section (near the midline), or paramedian section (at some distance from the midline). Compare coronal section, horizontal section, midsagittal section. [1]
- saliency maps
- A theoretical construct of visual attention in which the importance of different stimuli in the visual field is set by a combination of top-down processes based on behavioral goals and bottom-up processes resulting from how distinctive the different elements of a stimulus are compared to the background. [10]
- sampling
- The regular recording of the state of a system. [25]
- saturation
- The aspect of color sensation pertaining to the subjective sense of the perceptual distance of the color from neutrality (an unsaturated color is one that approaches a neutral gray). Compare brightness and hue. [5]
- scalar timing theory
- An information-processing model of interval timing comprising clock, memory, and decision stages. [22]
- scalar variability
- Variability (as measured by the standard deviation) that increases proportionally with the mean value. [22]
- schizophrenia
- A heterogeneous psychiatric condition characterized by disordered thought, withdrawal symptoms, and inaccurate beliefs about reality. [23]
- SCN
- See suprachiasmatic nucleus.
- scotoma
- A defect in the visual field resulting from injury or disease to a component of the primary visual pathway. [4,28]
- scotopic
- Pertaining to vision in dim light, where only the rods are operative. Compare photopic. [4]
- scotopic system
- The components of the visual system operating at relatively low levels of light. Compare photopic system. [4]
- SCR
- See skin conductance response.
- secondary auditory cortex (A2)
- Also called belt area. The cortical region surrounding the primary auditory cortex. [6]
- secondary reinforcer
- A stimulus that has no direct effects on homeostatic processes but is nevertheless rewarding; money is a paradigmatic example. Compare primary reinforcer. [24]
- secondary somatosensory cortex (S2)
- A higher-order somatosensory map in the parietal lobe adjacent to S1. Compare primary somatosensory cortex. [7]
- selection negativity
- A slow, later negative ERP wave elicited over visual sensory cortices that may reflect attention to a nonspatial visual feature. [11]
- selective attention
- The selective focusing of processing resources on a particular location or aspect of the external or internal environment. [10]
- self
- The subjective sense of existing as an individual. [19]
- self-awareness
- An awareness of oneself as a separate actor in the world. [28]
- semantic dementia
- A memory deficit that impairs semantic memory rather than episodic memory and is associated with left-lateralized atrophy of the anterior temporal cortex. [14]
- semantic memory
- A component of declarative memory that refers to general knowledge about the world, including knowledge of language, facts, and the properties of objects. Compare episodic memory. [2,13,14]
- semantic priming
- A form of indirect priming in which the prime and the target are semantically related. [15]
- semicircular canals
- The three elements of the vestibular component of the inner ear that provide a sense of acceleration and the position of the head in space. [7]
- sensation
- A confusing word that is often used to refer to the sense data that initiates sensory processing. In ordinary speech, however, it is used as a synonym for percept. [4]
- sensitive period
- See critical period.
- sensitivity
- The ability of a sensory system to respond to the energy in a stimulus. [6]
- sensitization
- The process by which a behavioral response to an otherwise benign stimulus increases in intensity, frequency, or duration when that stimulus is paired with an aversive stimulus. Compare habituation. [13]
- sensorimotor stage
- In Jean Piaget’s theory of cognitive development, the stage from birth to 2 years old that is dominated by reflex responses, with learning and intelligence guided and constrained largely by the infant’s sensory and motor abilities; precedes the preoperational stage. [27]
- sensory
- Pertaining to mechanisms or processes related to neural processing in sensory systems.
- sensory aphasia
- See Wernicke’s aphasia.
- sensory coding
- The manner in which information is generated in sensory systems. [4]
- sensory ganglia (sing. ganglion)
- Collections of neurons in the peripheral nervous system that comprise the cell bodies of afferent sensory neurons. [1]
- sensory memory
- Memory that receives information from sensory systems and holds a large amount of precategorical (i.e., not yet interpreted) information for a very brief interval, presumably in different stores for the different sensory modalities. [2]
- sensory neuron
- Any neuron involved in sensory processing. [1]
- sensory plasticity
- The ability of a sensory system to change as a result of experience or injury.[7]
- sensory stimulus
- Any pattern of energy impinging on a sensory receptor sheet such as the retina, skin, or basilar membrane. [4]
- sensory system
- All the components of the central and peripheral nervous system concerned with processing information arising from a particular stimulus category (e.g., light, sound stimuli). [1]
- sensory transduction
- The process by which energy in the environment is converted into electrical signals by sensory receptors. [4]
- sentence
- A sequence of words that expresses a complete and meaningful thought;. [20]
- septal forebrain nuclei
- See basal forebrain nuclei.
- septum pellucidum
- A sheet of tissue in the midline of the brain’s ventricular system (within the third ventricle). [1]
- sequential processing model
- A model in which a particular cognitive task is assumed to involve a series of sequential and independent processing stages. [2]
- sham rage
- An emotional reaction elicited in cats by electrical stimulation of the hypothalamus. [17]
- shared attention
- The allocation of processing resources toward an object or region of space cued by another individual. [19]
- sharpening model of repetition suppression
- A model positing that when a stimulus is repeated, neurons that carry critical information about the stimulus continue to fire vigorously, whereas neurons that are not essential for processing the stimulus respond less and less. Compare facilitation model of repetition suppression and fatigue model of repetition suppression. [15]
- short-term memory
- Memory that lasts seconds to minutes. Compare long-term memory. [2]
- sign language
- A means of communication by specific hand gestures. [21]
- signal detection theory
- A theoretical approach to extracting signal from noise using mathematical and statistical tools. [2]
- simulation
- The cognitive process involved in generating a potential future state, given knowledge of the current state of a system; critical for planning and reasoning. [23]
- simultanagnosia
- The inability to attend to, and/or perceive, more than one visual object at a time; a primary deficit seen in patients with Balint’s syndrome as a result of bilateral damage to lateral occipitoparietal cortex. [12]
- simultaneous contrast
- The ability of contextual information to alter the perception of a visual target, especially in regard to its luminance (i.e., lightness or brightness; simultaneous brightness contrast) or its color (simultaneous color contrast). [5]
- single-unit recording
- Also called simply unit recording. A method of studying the activity of single neurons using a microelectrode. [3,4]
- sinusoid
- The pattern defined by a sine (or cosine) function. [3,6]
- size constancy
- The sense that familiar objects maintain their size despite being seen at different distances from an observer. [5]
- size-distance relationship
- The diminished size of a retinal projection as a function of distance from the observer. [5]
- size principle
- The orderly recruitment of motor neurons by size to generate increasing amounts of muscle tension. [8]
- skeletal muscle
- Also called striated muscle. Muscle typically connected to bones of the skeleton that causes movement by applying force across joints. One notable exception is the extraocular muscles, which attach to the eyeball and move it within the eye socket. Compare smooth muscle. [8]
- skill learning
- Gradual improvement in the performance of a motor or cognitive task as a result of extensive experience and repeated practice. Compare priming. [13,15]
- skin conductance response (SCR)
- A stimulus-induced increase in the electrical conductance of the skin due to increased hydration. [17,18]
- Skinner box
- A device used in operant conditioning, in which animals such as pigeons or rats learn to press a lever to receive a food pellet. [15]
- smooth muscle
- Muscle within the internal viscera that is controlled by the autonomic nervous system. Compare skeletal muscle. [8]
- snake-in-the-grass effect
- The phenomenon in visual search behavior in which it is easier to identify an emotional target object dispersed among many neutral ones compared to a neutral object dispersed among many emotional ones. Compare face-in-a-crowd effect. [18]
- SNARC (spatial-numerical association of response codes)
- A behavioral effect whereby subjects are faster to make an oddity judgment when responding with the left hand compared to the right hand with small numerical values and conversely faster with the right hand with large numerical values. [22]
- SNc
- See substantia nigra pars compacta.
- SNr
- See substantia nigra pars reticulata.
- social cognition
- Information processing that contributes to behavior in interpersonal settings. [2]
- social referencing
- The use of emotions expressed by another individual to guide behavior. [19]
- software
- The programs that run computers. Compare hardware. [28]
- soma
- See cell body.
- somatic marker hypothesis
- 1. A theory, first advocated by Antonio Damasio and his colleagues, that motivated behavior is influenced by neural representations of body states (i.e., the “somatic markers”), whose reexperiencing can shape behavior positively or negatively. [18] 1. The hypothesis that evaluation of one’s own bodily states makes important contributions to decision making. [23]
- somatic motor system
- The components of the motor system that support skeletal movements mediated by the contraction of skeletal muscles. [1,8]
- somatosensory cortex
- That region of the mammalian neocortex that is concerned with processing sensory information from the body surface, subcutaneous tissues, muscles, and joints; in humans, located primarily in the posterior bank of the central sulcus and on the postcentral gyrus. [1,7]
- somatosensory system
- The parts of the nervous system that are involved in processing sensory information about the mechanical forces that act on both the body surface and on deeper structures, such as muscles and joints. [7]
- somatotopic map
- The corresponding anatomical arrangement of the sensory periphery and its central representation. [7]
- sound
- In common usage, both the physical characteristics of a sound stimulus and the perception that it generates. [6]
- sound spectrum
- The analysis of a sound stimulus showing the distribution of power as a function of frequency. [6]
- sound stimuli
- See sound. [6]
- sound wave
- The periodic compression and rarefaction of air molecules underlying a sound stimulus. [6]
- source-filter model
- A generally accepted model for the production of speech sound stimuli that entails the vocal-fold vibrations as a source and the rest of the vocal tract as a dynamic filter. [20]
- source memory test
- An explicit memory test that asks participants to remember not merely what events happened in the past but where, when, or how they happened. Compare item memory test. [2]
- spasticity
- A motor system disorder in which muscles are continuously contracted because of the loss of descending inhibitory inputs from upper motor neurons in the cortex and brainstem. [8]
- spatial-numerical association of response codes
- See SNARC.
- species
- A taxonomic category subordinate to genus; members of a species are defined by extensive similarities and the ability to interbreed.
- spectral differences
- Differences in the distribution of spectral power in a visual stimulus that give rise to perceptions of color. [4,5]
- spectrophotometer
- A device for measuring the spectral power distribution in light—that is, electromagnetic radiation with wavelengths between about 400 and 700 nanometers. [5]
- spectrum (pl. spectra)
- A plot of the amplitude of a stimulus such as light or sound as a function of frequency over a particular period of sampling time. [4,5,6]
- spinal column
- See vertebral column.
- spinal cord
- The portion of the central nervous system that extends from the lower end of the brainstem (the medulla) to the cauda equina. It sits within a protective tube, or column, created by the vertebrae of the spine. See vertebral column. [1,8]
- spinal motor neuron
- See lower motor neuron.
- spindle cells
- Unusual elongated bipolar neurons found in the anterior cingulate cortex and insula of humans and African apes, characterized by a single dendrite at one end and a single dendrite at the other. Because of their phylogenetic distribution and anatomical location, hypothesized to play an important role in higher cognitive function. Also called von Economo neurons, after the Romanian-Austrian neurologist Constantin von Economo. [26]
- spinocerebellum
- The region of the cerebellar cortex that receives input from the spinal cord. [9]
- spiral ganglion
- A ganglion associated with the auditory component of cranial nerve VIII. [6]
- split-brain patient
- An individual whose corpus callosum has been surgically interrupted as a treatment for epilepsy, functionally separating the left and right hemispheres. See also patient H.M. [13,21]
- stable order principle
- One of the five counting principles offered by psychologists Rochel Gelman and Charles Gallistel, stating that arbitrary symbols for number such as the count words one, two, and three must be used in the counting process. [22]
- standard consolidation theory
- A theory postulating that the hippocampus rapidly encodes an integrated representation of an event or concept, which is then slowly transferred to the cortex and eventually becomes independent of the hippocampus. [13]
- startle response
- A behavioral reaction to a sudden, intense auditory or visual stimulus that is mediated by a subcortical reflex circuit. [17]
- stereogram
- A pair of pictures of the same scene taken from slightly different angles that, when fused, create a sensation of stereoscopic depth. [5]
- stereopsis
- The special sensation of depth that results from fusion of the two eyes’ views of relatively nearby objects. [5]
- storage
- The retention of information over time. [2,13]
- strabismus
- Misalignment of the two eyes (often congenital); compromises normal binocular vision unless corrected at an early age. [27]
- stress
- An emotional reaction to a stimulus that causes intense physical or mental tension. [18]
- stress hormone
- See cortisol.
- stretch reflex
- Also called deep tendon reflex or myotatic reflex. A spinal reflex comprising the motor response to afferent sensory information arising from muscle spindles.[8]
- striate cortex
- See primary visual cortex.
- striated muscle
- See skeletal muscle.
- striatum
- The input nuclei of the basal ganglia, consisting of the caudate and putamen. So called because of the striped appearance of these structures in brain sections. [1,9]
- stroke
- The clinical and neuropathological results of interruption of the blood supply to one or another region of the brain. [1]
- Stroop task
- A paradigm used to study the effects of stimulus conflict and attention, in which the experimenter presents a series of color words whose font color either matches or does not match the word meaning; subjects are faster to identify the font color when the word meaning is congruent, and slower when it is incongruent. [4,10,19,23]
- subcortical
- Pertaining to brain structures other than the cerebral cortex. [1]
- subitizing
- A cognitive operation distinct from counting that allows the fast and accurate perception of the numerosity of small sets of events or objects. [22]
- subliminal
- Pertaining to a stimulus that is below the threshold for detection.
- subsequent memory paradigm
- A method to determine the neural processes that predict whether an item will be remembered or forgotten on a subsequent memory test. [14]
- substantia nigra
- A nucleus at the base of the midbrain that receives input form a number of cortical and subcortical structures. The dopaminergic cells of the substantia nigra send their output to the caudate or putamen, and the GABA-ergic cells send their output to the thalamus. [1,24]
- substantia nigra pars compacta (SNc)
- A component of the midbrain substantia nigra nucleus that is important for dopamine production. [24]
- substantia nigra pars reticulata (SNr)
- A component of the midbrain substantia nigra nucleus that plays a key role in the suppression and initiation of saccadic eye movements. [9]
- sulcus
- Any of the valleys that arise from the enfolding of the cerebral hemisphere between the gyral ridges. See also fissure. Compare gyrus. [1]
- summation
- The additive effects of postsynaptic potentials (EPSPs and IPSPs) that are sequential in space and/or time. [Appendix]
- superior
- Above. [1]
- superior colliculi
- Paired structures that form part of the roof of the midbrain; important in orienting movements of the head and eyes. Compare inferior colliculi. [1,8]
- superior olivary complex
- A complex of brainstem nuclei in the primary auditory pathway. [6]
- supplementary motor cortex
- Also called supplementary motor area. A premotor area, lying anterior to the primary motor cortex on the medial surface of the cerebral hemisphere, that plays an important role in movement planning. [8,9]
- suprachiasmatic nucleus (SCN)
- A region of the brain, located in the hypothalamus, that is critical for regulating circadian rhythms. [22]
- supramodal attention
- The ability to focus attention on the stimulus information from multiple modalities at the same time. Compare intermodal attention. [11]
- syllable
- An elemental component of word. [20]
- syllogism
- A simple logical argument typically consisting of two premises and a conclusion. [25]
- Sylvian fissure
- See lateral fissure.
- symbolic representation
- A broad set of cognitive skills by which ideas are communicated using agreed-on stimuli (symbols) that stand for distinctive objects, conditions, or concepts. Compare representation (definition 1). [2]
- sympathetic division
- Part of the autonomic motor system that contributes to the mobilization of energy to prepare the body for action. Compare parasympathetic division. [1,8]
- sympathy
- Feelings of pity or concern for another individual’s plight. Compare empathy. [19]
- synapse
- A specialized point of contact between the axon of a neuron (the presynaptic cell) and a target (postsynaptic) cell. Information is transferred between the presynaptic and postsynaptic cells by the release and receipt of biochemical neurotransmitters. [1, Appendix]
- synaptic consolidation
- Consolidation involving changes in synapses that presumably allow the persistence of some forms of memory traces at the cellular level. Compare system consolidation. [13]
- synaptic potential
- A membrane potential generated by the action of a chemical transmitter agent. Synaptic potentials allow the transmission of information from one neuron to another. [1, Appendix]
- synaptic vesicles
- The organelles at synaptic endings that contain neurotransmitter agents. [1, Appendix]
- synaptogenesis
- The elaboration of synapses during neural development. [27]
- synesthesia
- A condition in which two sensory modalities interact abnormally such that, for example, numbers or musical notes elicit perceptions of color. [4]
- syntax
- The way in which words are combined to form sentences or phrases. [2,20]
- system consolidation
- Consolidation involving a reorganization of the brain regions that support the memory in question. In the case of declarative memory, refers to a decrease in the role of the hippocampus and an increase in the role of the cortex over time. Compare synaptic consolidation. [13]
- systematic process
- A process used for tasks or decisions that involves detailed, deliberate analyses of activated information during episodic memory retrieval. Compare heuristic process. [14]
T
- task switching
- The executive control process that is required when changing behavior rapidly and repeatedly between two different forms. [23]
- tastant
- An environmental molecule that, when bound to a receptor in the taste cells, elicits a taste percept. [7]
- taste
- The sensory modality comprising the perception of substances placed in the mouth. [7]
- taste buds
- Onion-shaped structures in the mouth and pharynx that contain taste cells. [7]
- taste cells
- The chemoreceptor cells in taste buds. [7]
- taste system
- See gustatory system.
- tectum
- Literally “roof” (Latin). The dorsal region of the brainstem. [1]
- tegmentum
- The central gray matter of the brainstem. [1]
- temperament
- A disposition to react to emotional situations either positively or negatively. Compare affect. [17]
- template matching
- The strategy that explains sensory perception through the recognition of patterns of sensory stimulation that correlate with stored information about objects and conditions experienced in the past. [2]
- temporal coding
- A computational principle in which information is encoded by the precise timing of neuronal activity. [4]
- temporal difference learning
- A form of learning that modulates behavior according to the difference between an obtained reward and an estimate, compiled over the recent past, of an expected reward. [24]
- temporal discounting
- The reduction in how strongly a person wants something over time. [24]
- temporal lobe
- The lobe of the brain that lies inferior to the lateral fissure. [1]
- temporoparietal junction
- A region of the neocortex that includes the posterior portion of the superior temporal gyrus and the angular gyrus of the parietal lobe. [19]
- thalamus
- A collection of nuclei that forms the major component of the diencephalon. Although its functions are many, a primary role of the thalamus is to relay sensory information from the periphery to the cerebral cortex. [1]
- theory of mind
- Also called mentalizing. The ability to represent the internal mental states of other individuals. [2,19]
- threshold
- 1. The lowest energy level of a stimulus that causes a perceptual response. [4] 2. The level of membrane potential at which an action potential is generated. [Appendix]
- timbre
- The quality of sound by which stimuli that elicit the same pitch and loudness are distinguished; often taken to arise from the distribution of power in the waveform, as opposed to its periodicity. [6]
- TMS
- See transcranial magnetic stimulation.
- tonal
- Pertaining to a sound stimulus that, by virtue of its periodic repetition, produces the perception of a tone. [20]
- tone
- The sound heard in response to a particular frequency of vibration or combination of vibrations. [6]
- tonic
- Pertaining to sustained activity in response to an ongoing stimulus. Compare phasic.
- tonotopic organization
- The central arrangement of tone analysis in the auditory system that roughly corresponds to the peripheral responsiveness of the basilar membrane. [6]
- top-down processing
- The idea that cognitive influences arising from higher-order cortical regions influence lower-order cortical or subcortical processing. Compare bottom-up processing.
- topographic representation
- A mapping that reflects the organization of the sensory periphery. [4]
- trace conditioning
- A form of classical conditioning in which there is a brief time interval between the end of the conditioned stimulus and the start of the unconditioned stimulus. [15]
- tract
- A major white matter (axonal) pathway in the brain. [1]
- transcranial magnetic stimulation (TMS)
- A method in which a rapidly changing, strong magnetic field is generated next to the skull, thereby delivering transient electrical stimulation to the underlying cortex; the electrical stimulation typically disrupts the local cortical activity, thereby facilitating inferences concerning the cognitive function(s) in which that brain area is involved. [3]
- transduction
- The cellular and molecular process by which energy is converted into neural signals.
- transfer-appropriate processing
- The hypothesis that memory performance depends on a match between the conditions surrounding the encoding and retrieval of a stimulus. [2]
- trial
- A single occurrence of an event in an experiment. [3]
- trichromat
- A person or other animal whose color vision depends on three retinal cone types that absorb long, medium, and short wavelengths of light, respectively. Compare dichromat and monochromat. [5]
- trigeminal chemosensory system
- The chemosensory system that responds to irritating chemicals that enter the nose or mouth. [7]
- triune brain
- The theory that the brain evolved in three stages, from reptiles (subcortical) to older mammals (three-layered cortex) to newer mammals (six-layered cortex). [17]
- trophic
- Pertaining to the ability of one tissue or cell to support the growth and/or function of another.
- tropic
- Pertaining to the influence of one tissue or cell on the direction of movement (or outgrowth) of another.
- truncal ataxia
- A neurological disorder characterized by poorly coordinated locomotion and associated with damage to the medial portions of the cerebellum. [9]
- trust game
- Also called investment game. An experimental paradigm in behavioral economics in which one player (an investor) offers money to another (a trustee), in hopes of reciprocation. [24]
- tuning curve
- The function obtained when a neuron’s receptive field is tested with stimuli at different orientations; the peak of the tuning curve defines the maximum sensitivity of the neuron in question. [3,4]
- Turing test
- A hypothetical test in which, through detailed interrogation, subjects judge whether they interacting with a human or a computer. [28]
- tympanic membrane
- The eardrum. [6]
U
- ultimatum game
- An experimental paradigm in behavioral economics in which one player proposes a fixed transaction, which the other player may either accept or reject; if the transaction is rejected, then neither player receives anything. [24]
- uncertainty
- The psychological state of having limited information when making a decision. [24]
- unconditioned reinforcer
- See primary reinforcer.
- unconditioned response (UR)
- In classical conditioning, the innate reflex that is naturally triggered by a particular stimulus. Compare conditioned response. [15]
- unconditioned stimulus (US)
- In classical conditioning, the stimulus that naturally triggers the innate reflex. Compare conditioned stimulus. [15]
- unit recording
- See single-unit recording.
- universal grammar
- The hypothesis that all human languages share fundamental rules. [2,20]
- upper motor neuron
- A neuron that gives rise to a descending projection that controls the activity of lower motor neurons in the brainstem and spinal cord. [8]
- upper motor neuron syndrome
- A clinical condition characterized by signs and symptoms that result from damage to descending motor systems, including paralysis, spasticity, and a positive Babinski sign. Compare lower motor neuron syndrome. [8]
- UR
- See unconditioned response.
- US
- See unconditioned stimulus.
- utility
- The personal worth associated with a good; may deviate from the stated value of that good depending on an individual’s preferences, biases, or current state. [24]
- utilization behavior
- A cognitive dysfunction, typically associated with frontal lobe damage, in which an individual reflexively uses objects presented to them (e.g., spontaneously pounding a hammer).
V
- V1
- See primary visual cortex.
- V2
- See secondary visual cortex.
- V4
- An area of extrastriate visual cortex that is probably important in color vision, although it processes other information as well. [4,5]
- V5
- See MT+.
- valence
- The degree of pleasantness or unpleasantness of a stimulus. [2,17]
- valence hypothesis
- A hypothesis about the hemispheric organization of emotions in the cerebral cortex postulating that positive emotions are preferentially processed in the left hemisphere and negative emotions are preferentially processed in the right hemisphere. [17]
- validly cued
- Pertaining to an attentional cuing paradigm in which the target following a cue occurs in the location indicated by the cue. Compare invalidly cued. [10]
- variable
- A measurement that can, in principle, assume any value within an appropriate range.
- vector model
- A way to graphically represent the relationships among emotions by ordering them along two orthogonal axes of positive and negative valence. Compare circumplex model. [17]
- ventral
- For the long body axis, stipulates the direction toward the belly (as in ventral horn). When speaking of the brain, pertains to the bottom (e.g, a view of the brain from the bottom looking up). Compare dorsal. [1]
- ventral horn
- Also called anterior horn. The ventral portion of the spinal cord gray matter, which contains the primary motor neurons. Compare dorsal horn and lateral horn. [1,8]
- ventral posterior nuclear complex (VPN)
- A group of thalamic nuclei that receives the somatosensory projections from the dorsal column nuclei and the trigeminal nuclear complex. [7]
- ventral roots
- See ventral spinal roots.
- ventral spinal roots
- The collection of nerve fibers containing motor axons that exit ventrally from the spinal cord and contribute the motor component of each segmental spinal nerve. Compare dorsal spinal roots. [1,8]
- ventral stream
- The stream of visual information directed from the primary visual cortex toward the temporal lobe that is especially pertinent to object recognition. Compare dorsal stream. [4]
- ventral tegmental area (VTA)
- A part of the midbrain that contains many dopaminergic neurons and that is important for reward and learning. [1,24]
- ventricles
- The spaces in the vertebrate brain that represent the lumen of the embryonic neural tube. [1]
- ventricular system
- The system of fluid spaces in the brain that contain cerebrospinal fluid arising from the central space in the embryonic brain rudiment. [1]
- ventromedial prefrontal cortex
- The ventral portion of the prefrontal cortex surrounding the hemispheric midline; plays a key role in the control of emotions and social behavior. [23]
- vermis
- Medial portion of the cerebrocerebellum that plays a key role in the unconscious correction of movement errors based on inputs from muscle proprioceptors and vestibular inputs. [9]
- vertebral column
- Also called the spinal column. The skeletal structure that encloses the spinal cord. It is divided into five regions: cervical (neck; 8 vertebrae), thoracic (chest; 12 vertebrae), lumbar (abdominal region; 5 vertebrae), sacrum (pelvis; 5 vertebrae), and coccyx (the tailbone). [1]
- vertebrate
- An animal with a vertebral column, or “backbone” (technically, a member of the subphylum Vertebrata).
- vestibular nuclei
- Brainstem nuclei that process information about the position of the head and about body acceleration. [7]
- vestibular system
- The sensory system dedicated to generating information about the position of the head in space and the acceleration of the body. [7,8]
- vestibulo-ocular reflex (VOR)
- An involuntary movement of the eyes in response to displacement of the head; allows retinal images to remain stable while the head is moved. [9]
- vestibulocerebellum
- The part of the cerebellar cortex that receives direct input from the vestibular nuclei or vestibular nerve. [9]
- vestibulospinal pathways
- Medial and lateral projections from the vestibular nuclei in the brainstem to the spinal cord that play a key role in postural and locomotor control. [8]
- visceral nervous system
- See autonomic nervous system.
- vision
- The process by which the visual system (eye and brain) uses information conveyed by light to generate appropriate percepts and visually guided responses. [4,5]
- visual acuity
- See acuity.
- visual association cortices
- The neocortex in occipital lobe, and in the adjacent regions of the parietal and temporal lobes, devoted to higher-order visual processing. [5]
- visual cliff paradigm
- An experimental paradigm that is used to study depth perception in infants. [27]
- visual field
- The area of visual space normally seen by one or both eyes (referred to, respectively, as the monocular and binocular fields). [5]
- visual habituation paradigm
- A paradigm used to test infant perception and cognition. Infants are habituated to a single stimulus or multiple exemplars from a category; they are then shown new exemplars of the familiar category or a novel category and longer looking at the exemplars from the novel category is taken as evidence that the infant can discriminate the two categories. [27]
- visual N1
- Also called N100 wave. The first major negative ERP wave elicited by a visual stimulus, peaking at about 180 milliseconds after a stimulus over the parietal-occipital scalp; thought to derive from visual cortical regions in parietal and occipital cortex. Compare visual P1. [11]
- visual P1
- Also called P100 wave. The first major positive ERP wave elicited by a visual stimulus, peaking at about 100 milliseconds after a stimulus over the occipital scalp contralateral to the side of the visual stimulus; thought to derive mainly from the low-level extrastriate visual areas V2, V3, and V4, it is the earliest-latency ERP component affected by attention. Compare visual N1. [11]
- visual perception
- The manifestation in consciousness of the empirical significance of visual stimuli (and not, therefore, a necessary accompaniment of visually guided behavior, which often occurs without any particular awareness of what is being seen). [5]
- visual percepts
- Mental constructs that represent the empirical significance of light stimuli. [5]
- visual pigment
- Also called opsins. A pigment—in humans, rhodopsin or one of the three cone opsins—that absorbs light and initiates the process of vision. [4,5]
- visual processing
- Transformations carried out by the visual system on information in the retinal stimulus. [4,5]
- visual qualities
- The descriptors of visual percepts (e.g., brightness, color, depth, form, and motion). [5]
- visual search
- The searching in a visual scene with multiple stimulus items for a particular type of item possessing one or more specific feature attributes. [10]
- visual spatial attention
- Attention directed to a location in visual space. The observer’s actions undertaken to deal with the object or objects in the scene giving rise to the visual stimuli. [10]
- vocal cords
- Also called vocal folds. The bands or folds in the larynx that oscillate as air passes through the glottis, thus producing a vibration that is subsequently shaped by the rest of the vocal tract. [20]
- vocal folds
- See vocal cords.
- vocal tract
- The vocal pathway that shapes speech sounds; comprises the larynx, pharynx, and buccal cavity. [20]
- vocalization
- Any sound produced by the vocal tract, which may or may not qualify as speech. [20]
- voiced
- Pertaining to a speech sound stimulus characterized by laryngeal harmonics; typically a vowel sound. [20]
- von Economo neurons
- See spindle cells.
- VOR
- See vestibulo-ocular reflex.
- voxel
- An imaging volume unit; its exact size parameters vary with the technology used. (In fMRI, a voxel often represents a volume of about 27 mm3.) [3]
- VPN
- See ventral posterior nuclear complex.
- VTA
- See ventral tegmental area.
W
- wakefulness
- The state in which one is not asleep. [28]
- wavelength
- The interval between two wave crests or troughs in any periodic function; for light, the standard measure of the energy of different photons. [4,5,6]
- Weber’s law
- The principle that the just noticeable difference in a stimulus increment is a constant fraction (the Weber fraction) of the stimulus; named after the nineteenth-century German physiologist and anatomist Ernst Weber. [22]
- Wernicke’s aphasia
- Also called comprehension aphasia, receptive aphasia, or sensory aphasia. A language deficit arising from damage to Wernicke’s area in the posterior temporal lobe and characterized by an inability to link objects or ideas and the words that signify them and to subjectively comprehend this relationship. Compare Broca’s aphasia. [21]
- Wernicke’s area
- A region of cortex in the superior and posterior region of the left temporal lobe that helps mediate language comprehension; named after the nineteenth-century neurologist Carl Wernicke. Compare Broca’s area. [6,21]
- white light
- Broadband light that is perceived as lacking color (i.e., as neutral). [5]
- white matter
- The large axon tracts in the brain and spinal cord; these tracts have a whitish cast when viewed in freshly cut material. Compare gray matter. [1,27]
- Williams’ syndrome
- A rare genetic disorder that is characterized by distinctive facial features and a cheerful personality. [27]
- Wisconsin Card Sorting Test
- A cognitive test that involves classifying a set of cards, each showing one or more simple shapes, into categories based on rules that periodically change throughout the session. [23]
- word
- A speech sound or combination of sounds that communicates a meaning; an elemental component of a sentence. [20]
- word length effect
- The fact that people can hold more words in working memory when the words are short than when they are long. [16]
- working memory
- Memory held briefly in the mind that enables a particular task to be accomplished (e.g., efficiently searching a room for a lost object). [13]
- working memory load
- Also called simply memory load. The number of items being held in working memory. [16]
- working memory maintenance
- Retaining information in an active state for a relatively brief time, in order to achieve specific goals. This central function of working memory corresponds to the traditional concept of short-term memory. [16]
