Glossary

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

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. [13]
accommodation
A stage of child development in which children learn to react to novel entities by modifying their schemes of thought. Compare assimilation. [15]
acquired sociopathy
A personality change, often following focal damage to the frontal lobes, in which a person’s behavior becomes sociopathic. [13]
acquisition
In conditioning, the gradual learning of a conditioned response. Compare extinction. [8]
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]
actor-critic learning model
A framework for learning that posits two independent elements: a critic that learns rules mapping actions to rewards, and an actor that learns the optimal policy for selecting actions. [14]
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. [3]
adaptation
The process by which organisms come to achieve a better fit to their environment, typically through the process of natural selection. [15]
ADHD
See attention deficit hyperactivity disorder.
affective neuroscience
The study of the neurobiological basis of emotions. [10]
afferent neuron
An axon that conducts action potentials from the periphery to more central parts of the nervous system. Compare efferent neuron. [Appendix]
agonist
A neuropharmacological agent that mimics the action of a neurotransmitter. Compare antagonist. [2]
altruistic punishment
An action taken to harm another individual, at personal cost, in order to enforce a social norm (e.g., sacrificing one’s own money in order to punish someone who cheats in a game). [14]
ambiguity aversion
The tendency to prefer choice options whose outcome probabilities are known over options with unknown probabilities (i.e., that have ambiguity). [14]
amnesia
The pathological inability to remember or to establish memories. See also anterograde amnesia and retrograde amnesia. [8]
amygdala
A collection of nuclei in the temporal lobe that forms part of the limbic system; its major functions concern autonomic, emotional, and sexual behavior. [10, Appendix]
anchoring heuristic
A bias in decision making in which judgments are influenced by a number that serves as a reference point, or anchor, for further deliberations. [14]
anhedonia
Reduced experience of positive affect; often accompanies depression. [10]
anosognosia
Lack of awareness of one’s own disability. [5]
ANS
See approximate number system.
antagonist
A neuropharmacological agent that opposes or interferes with the action of a neurotransmitter. Compare agonist. [2]
anterior cingulate cortex
The portion of the midline frontal lobe comprising the anterior extent of the cingulate gyrus and adjacent cortex; its dorsal regions are associated with executive functions. [13]
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. [Appendix]
anterograde amnesia
The inability to lay down new memories. Compare retrograde amnesia. [8]
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. [3]
aphasia
A language deficit that arises from damage to one of the cortical language areas, typically in the left hemisphere. [12]
apparent motion
The sensation of motion elicited by presentation of a stimulus in two successive positions over a brief interval. [3]
approximate number system (ANS)
A neural circuit or set of circuits providing a non-symbolic, fuzzy sense of the quantity of objects or events perceived, shared by human adults, preverbal infants, and animals. [15]
aprosodia
The inability to inflect speech with the usual emotional color that the right hemisphere typically contributes to language. Characterized by a monotonic or “robotic” speech pattern. [12]
area 6
See supplementary motor cortex.
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. [6] 2. The degree of intensity of an emotion. [10]
assimilation
A stage of child development in which young children deal with novel entities by encompassing them in their preexisting thought schemes (e.g., assuming any woman who seems to be the child’s mother’s age is also a mother). Compare accommodation. [15]
association cortices
See cortical association areas.
associativity
In long-term potentiation, the enhancement of a weakly activated group of synapses when a nearby group is strongly activated. [8]
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. [6]
attention deficit hyperactivity disorder (ADHD)
A childhood disorder of unknown cause characterized by impulsiveness, short attention span, and continual activity. [13]
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 150 to 450 milliseconds of a successfully reported first target in the stream is decreased. [6]
attentional stream paradigm
A paradigm used in attention research in which two or more segregated series of stimuli are presented in parallel and subjects selectively attend to one of the series to perform a task. [6]
auditory brainstem response (ABR)
See brainstem evoked response.
auditory N1
The first major negative ERP wave elicited by an auditory stimulus, arising mainly from secondary auditory cortex and peaking at about 100 milliseconds after the stimulus; can be strongly modulated by auditory spatial attention. [6]
auditory scene
The overall perception of the auditory environment at any point in time. Analogous to the perception of a visual scene. [4]
australopithecines
Human-like primate species that lived in the Plio-Pleistocene era (5 to 1.5 million years ago) which were bipedal and dentally similar to humans, but had a brain size not much larger than modern apes. Which of these species gave eventual rise to humans remains a topic of debate amongst anthropologists. [15]
autism spectrum disorder
A childhood disorder of unknown cause, characterized by social disengagement that varies greatly in severity. [10]
autobiographical memory
Memory of one’s personal experience. [9]
autonomic ganglia
Collections of autonomic motor neurons outside the central nervous system that innervate visceral smooth muscles, cardiac muscle, and glands. [Appendix]
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). [Appendix]
awareness
A cognitive/perceptual state in which an individual both shows knowledge of an event or stimulus and can report the subjective experience of having that knowledge. Compare self-awareness. [7]
axon
The extension of a neuron that carries the action potential from the nerve cell body to a target. Compare dendrite. [Appendix]
axon hillock
The initial portion of an axon, closest to the cell body; the point where action potentials are typically initiated. [Appendix]

B

Baddeley model
A model, proposed by Alan Baddeley, positing that working memory consists of three memory buffers (the phonological loop, the visuospatial sketchpad, and the episodic buffer) that briefly maintain information, as well as a central executive that allocates attentional resources to the buffers. [13]
Balint’s syndrome
A neurological syndrome, caused by bilateral damage to the posterior parietal and lateral occipital cortex, that has three hallmark symptoms: (1) simultanagnosia, the inability to attend to and/or perceive more than one visual object at a time; (2) optic ataxia, the impaired ability to reach for or point to an object in space under visual guidance; and (3) oculomotor apraxia, difficulty voluntarily directing the eye gaze toward objects in the visual field with a saccade. Simultanagnosia is the sign most closely associated with the syndrome, and the one most studied from a cognitive neuroscience standpoint. [7]
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. [Appendix]
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. [5,13,Appendix]
basic emotion
An emotion that is innate, pan-cultural, evolutionarily old, shared with other species, and expressed by a particular physiological pattern and facial configuration. Compare complex emotion. [10]
basilar membrane
The membranous sheet in the cochlea of the inner ear that contains the receptor cells (hair cells) that initiate audition. [4]
behavioral economics
A new social science discipline that combines elements of traditional economics and psychology to explain real-world decisions, including observed biases in choice. [14]
behavioral LTP
A change in synaptic efficacy similar to long-term potentiation (LTP) that follows an actual learning experience. [8]
behaviorism
A perspective in cognitive psychology that holds that only directly observable behavior, and not internal mental states, can be studied scientifically. [1]
belt areas
See secondary auditory cortex.
BER
See brainstem evoked response.
biased competition
a theory of attention that proposes that stimulus inputs compete in a mutually inhibitory fashion for neural processing priority and that a key role of attention is to bias the processing towards those items that are attended. [6]
binding problem
The neural and cognitive processing problem by which the multiple features of an object (e.g., its color, shape, orientation) are integrated together to yield a single perceptual object. Tends to be called a “problem” because is it still mostly unclear how this is accomplished in the brain. [7]
binocular
Pertaining to both eyes. Compare monocular. [3]
binocular rivalry
The bi-stable visual experience that occurs when the right and left eyes are presented with incompatible or conflicting images and visual perception alternates between the two images every few seconds. [3,7]
blindsight
The ability of people who are blind, usually because of damage to portions of their visual cortex, to identify the properties of simple visual stimuli when forced to guess. [7]
blocked design
A task design used in PET studies and sometimes in fMRI studies where multiple trials of the same type are grouped together in blocks. The brain activity is then analyzed by comparing neural activity across the entire block against blocks containing another type of trials, or with a different cognitive condition. Compare event-related design. [2]
blood oxygenation level–dependent (BOLD) contrast
A measurement of brain activity using fMRI that is based on the local variations in deoxygenated hemoglobin that result from the changes in blood flow induced by neural activity. [2]
BOLD
See blood oxygenation level–dependent contrast.
bounded rationality
The idea that biological limitations on cognitive processing prevent people from making decisions or from reasoning in a fully rational manner. [14]
brain lesion
A localized region of brain damage. [Appendix]
brainstem
The portion of the brain that lies between the diencephalon and the spinal cord; comprises the midbrain, pons, and medulla. [Appendix]
brainstem evoked response (BER)
Also called auditory brainstem response (ABR). A series of small electrical brain waves that are elicited during the first 10 milliseconds after onset of a brief auditory stimulus and 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 pathways. [6]
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. [3]
Broca’s aphasia
Also called 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. [12]
Broca’s area
An area in the ventral posterior region of the left frontal lobe that helps mediate language expression; named after the nineteenth-century anatomist and neurologist Paul Broca. Compare Wernicke’s area. [12]

C

calcarine sulcus
The major sulcus on the medial aspect of the human occipital lobe; the primary visual cortex lies largely within this sulcus. [Appendix]
Cannon-Bard theory
Also called diencephalic theory. A theory of emotion, developed by Walter Cannon and Philip Bard in the 1920’s, emphasizing the role of the hypothalamus and related parallel processing routes for emotional expression and emotional experience. [10]
caudate
One of the three major nuclei that make up the basal ganglia in the cerebral hemispheres; 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. [Appendix]
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. [Appendix]
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. [Appendix]
central nervous system
The brain and spinal cord of vertebrates (by analogy, the central nerve cord and ganglia of invertebrates). Compare peripheral nervous system. [Appendix]
central sulcus
A major sulcus on the lateral aspect of the cerebral 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. [Appendix]
cerebellar cortex
The superficial gray matter of the cerebral hemispheres. [Appendix]
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. [5,Appendix]
cerebral achromatopsia
Loss of color vision as a result of damage to the visual cortex. [3]
cerebral aqueduct
The portion of the ventricular system that connects the third and fourth ventricles. [Appendix]
cerebral cortex
The superficial gray matter of the cerebellum. [1,Appendix]
cerebral hemispheres
Also called cerebrum. The two halves of the forebrain. [Appendix]
cerebral peduncles
The major fiber bundles that connect the brainstem to the cerebral hemispheres. [Appendix]
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. [Appendix]
chemical synapse
A synapse that uses a chemical transmitter agent; the most common type of synapse in the mammalian brain. [Appendix]
childhood amnesia
Also called pediatric amnesia. In adults, the inability to remember the early years of childhood. [8,15]
choreiform movement
Uncontrollable, dancelike (“choreiform”) writhing or twisting associated with damage to the basal ganglia, as occurs in disorders such as Huntington’s disease. [5]
choroid plexus
Specialized epithelium in the ventricular system that produces cerebrospinal fluid. [Appendix]
cingulate gyrus
The gyrus that surrounds the corpus callosum. [Appendix]
cingulate sulcus
A sulcus on the medial aspect of the cerebral hemispheres defined by the cingulate gyrus. [Appendix]
circle of Willis
A ring of arteries at the base of the midbrain; connects the posterior and anterior cerebral circulation. [Appendix]
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. [10]
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. Compare operant conditioning. [8]
coactivation
Two areas of the brain are said to be coactivated if they both show higher activity in a specific task. Statistically, coactivation is reflected by a positive correlation of activity between two areas. [2]
cochlea
The portion of the inner ear specialized for transducing sound energy into neural signals. [4]
cocktail party effect
An attentional phenomenon in which an individual can selectively focus attention on one particular speaker while tuning out other simultaneously occurring conversations. [6]
cognition
“Higher-order” mental processes. [1]
cognitive functions
The set of processes that allow humans and many other animals to perceive external stimuli, to extract key information and hold it in memory, and ultimately to generate thoughts and actions that help reach desired goals. [1]
cognitive map theory
A theory positing that the hippocampus mediates memory for spatial relations among objects in the environment. Compare episodic memory theory and relational memory theory. [9]
cognitive model
A explanatory framework that invokes unobserved internal states to predict how stimuli lead to actions. [1]
cognitive neuroscience
A scientific discipline that seeks to create models that explain the interrelations between brain function and cognitive functions. [1]
cognitive reappraisal
A form of emotion regulation in which individuals use cognitive resources to alter the meaning of a situation in order to reduce or change its emotional impact. [10]
cognitive science
A scientific discipline that seeks to understand and model the information processing associated with cognitive functions. [1]
coincidence detector
A neuron that detects simultaneous events, as in sound localization. [4]
color
The subjective sensations elicited in humans (and presumably many other animals) by different spectral distributions of light. [3]
color constancy
The similar color appearance of surfaces, despite different spectral returns from them; usually applied to the similar appearance of objects under different illuminants. Compare color contrast. [3]
color contrast
The different color appearance of surfaces despite similar spectral returns from them. Compare color constancy. [3]
color space
The depiction of human color experience in diagrammatic form by a space with three axes representing the perceptual attributes of hue, saturation, and color brightness. [3]
coma
A pathological state of profound and persistent unconsciousness. [7]
complementarity
The combination of data across multiple methods for measuring brain function, often to improve inferences about the nature of the generative neural processes. [1]
complex emotion
An emotion that is learned, socially and culturally shaped, evolutionarily new, and typically expressed by a combination of the response patterns that characterize basic emotions. Compare basic emotion. [10]
computerized tomography (CT)
An imaging method in which X-rays acquired at multiple angles are used to build a three-dimensional structural image of biological tissue. [2]
conceptual priming
A form of direct priming in which the test cue and the target are semantically related. Compare perceptual priming and semantic priming. [8]
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. [8]
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. [8]
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). Compare priming and skill learning. [8]
confabulation
In patients with memory disorders, the generation of false memories for complex autobiographical events. [9,13]
conjunction target
A target in a visual search task that is characterized by having a unique combination of two visual features. Because the time taken to find a conjunction target increases linearly with the number of distracters, its detection is thought to require serial focused attention to each item till the specified target is found. Compare pop-out stimulus. [7]
connectionist
Pertaining to the connectivity of neural networks whose connection weights vary according to experience. [12]
consciousness
An intriguing but puzzling concept that includes the ideas of wakefulness, awareness of the world, and awareness of the self as an actor in the world. [7]
consolidation
The strengthening of memory traces following encoding. [9]
consonant
Typically an unvoiced (atonal) element of speech that begins and/or ends syllables. [12]
context memory test
See source memory test. [9]
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. [10]
convergence
The combination of results across multiple experimental paradigms, often to support inferences about an unobservable internal state. [1]
corpus callosum
The large midline fiber bundle that connects the cortices of the two cerebral hemispheres. [Appendix]
correct rejection
In recognition memory test, correctly classifying an new item as “new.” Compare false alarm, hit, and miss. [9]
cortical association areas
Also called association cortices. The regions of cerebral neocortex that are not involved in primary sensory or motor processing. [3]
cortical columns
See cortical modules.
cortical magnification
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). [3]
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. [3]
cortisol
A steroid hormone released by the adrenal gland that is involved in the stress response. Called corticosterone in rodents. [10]
covert attention
The focusing of visual attention toward a location or item in the visual field without shifting the direction of gaze. Can apply to other sensory modalities or to attentional paradigms. Compare overt attention. [6]
CR
See conditioned response.
cranial nerve ganglia
The sensory or motor ganglia associated with the 12 cranial nerves. Compare dorsal root ganglia. [Appendix]
cranial nerves
Nerves projecting from the cranial motor nuclei to sense organs or muscles, mostly of the face, head, eyes, or neck. [Appendix]
CS
See conditioned stimulus.
CT
See computerized tomography.
cyclopean fusion
The normal sense, when looking at the world with both eyes, that we see it as if with a single eye. [3]

D

decision neuroscience
See neuroeconomics.
declarative memory
Also called explicit memory. Memory available to consciousness that can be expressed by language. Compare nondeclarative memory. [8]
default mode
Brain processes that occur in the absence of active executive control; a pattern of brain activation reflecting a set of cognitive processes that are typically more engaged during passive experience. [11]
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,” not engaged in any specific cognitive task, or directing attention inwardly. [7]
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. Compare trace conditioning. [8]
delay discounting
See temporal discounting.
delay line
The time delay generated by axons of different lengths; a mechanism important in coincidence detection. [4]
delay-period activity
In cognitive neuroscience studies of working memory, the observation of neural signals that persist while the research subject maintains information over time. [13]
dendrite
Also called dendritic branch or dendritic process. The extension of a neuron that receives synaptic input; usually branches near the cell body. Compare axon. [Appendix]
dendritic field potential
An electrical potential induced in the dendritic tree of a neuron by input from the axons of other neurons; this electrical activity can often also be detected at the scalp as an EEG or ERP response. Compare local field potential. [2]
dendritic spine
A small extension from the surface of a dendrite that receives synapses. [8]
depolarization
Changing the membrane potential of a neuron in the positive direction, which initiates an action potential if threshold is reached. Compare hyperpolarization. [Appendix]
depth
In vision the perception of distance from the observer. [3]
diaschisis
A disruption of the function of one brain area caused by focal damage to another, distant part of the brain. Often, the proper functioning of a brain area relies upon receiving input and stimulation from other, distant areas, so that if a distant area is damaged, the “down-stream” area can be affected as well. [2]
dichromat
A color-deficient human (and the majority of mammals) whose color vision depends on only two cone types. Compare trichromat. [3]
diencephalic theory
See Cannon-Bard theory.
diencephalon
The portion of the brain that lies just rostral to the brainstem; comprises the thalamus and hypothalamus. [Appendix]
diffusion decision model
See drift-diffusion model.
diffusion tensor imaging (DTI)
A method of MRI that can show the preferred directions of diffusion within tissue; useful for the imaging of fiber tracts of the brain. [2]
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. [8]
direct priming
Also called repetition priming. The facilitation of recall in which the prime and the target are identical or have the same name. Compare indirect priming. [8]
disinhibition syndrome
Also called frontal disinhibition syndrome. A collection of behavioral signs and symptoms, typically caused by damage to the ventral prefrontal cortex; mani-fested by a loss of control, inappropriate outbursts, and a lack of inhibition in social settings. Compare dysexecutive syndrome. [13]
dissociative identity disorder
A clinical condition characterized by at least two distinct and relatively enduring personalities that alternately control a person’s behavior. [11]
domain-specific theory
Theory which postulates that semantic memory is organized by semantic categories, such as living vs. nonliving things. Compare sensory/functional theory. [9]
dopamine
A catecholamine neurotransmitter involved in learning and reward evaluation, among other roles in the nervous system of humans and other animals. [14]
dopamine system
refers to the circuits in the brain that include neurons that release the neurotransmitter dopamine. The dopaminergic neurons, which are mostly located in the ventral tegmental area of the midbrain, the substantia nigra pars compacta, and the hypothalamus, have been particularly associated with reward. [2]
dorsal horn
The dorsal portion of the spinal cord gray matter, which contains neurons that process sensory information. Compare lateral horn and ventral horn. [Appendix]
dorsal root ganglia
The segmental sensory ganglia of the spinal cord that contain the first-order sensory neurons whose axons project centrally. Compare cranial nerve ganglia. [Appendix]
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. [3]
dorsolateral prefrontal cortex
A functional division of the prefrontal cortex roughly corresponding to the middle and superior frontal gyri, as located anterior to motor cortex and the frontal eye fields. Compare ventrolateral prefrontal cortex. [13]
dorsomedial prefrontal cortex
A functional division of the prefrontal cortex roughly corresponding to the medial surface dorsal to the corpus callosum. Compare ventromedial prefrontal cortex. [13]
double dissociation
A functional relationship in which one area of the brain is experimentally shown to be associated with a particular task or cognitive function and not with another task or function, whereas another area is shown to be involved in the second task or function but not the first. 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. [2]
drift-diffusion model
A mathematical description of decision-making behavior in terms of competing processes that drift in a random-walk fashion toward boundaries. Also called diffusion decision model. [14]
DTI
See diffusion tensor imaging.
dual-system model
A framework for decision making that posits the existence of two independent systems—typically, a fast emotional system and a slower cognitive system—whose interactions over time predict choices. [14]
dynamic causal modeling
A successor to structural equation modeling which tests directional models of functional connectivity against brain data to determine the relative likelihood of the activity in one area of the brain causing the activity in others. [2]
dysexecutive syndrome
Also called frontal dysexecutive 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. Compare disinhibition syndrome. [13]

E

eardrum
See tympanic membrane.
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. [6]
effector
A muscle or gland that provides the output of neural processing. [Appendix]
efferent neuron
An axon that conducts information away from the central nervous system. Compare afferent neuron. [Appendix]
electrophysiological recording
Any of various methods of recording electrical activity in the nervous system. [Appendix]
embodiment
A sense of physical location of the self within one’s own body. [11]
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. [10]
emotion regulation
The voluntary or involuntary deployment of resources to gain control over emotional responses. [10]
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. [10]
empathy
The ability to share the same feelings expressed by another individual. Compare sympathy. [11]
encoding
Also called learning. The incorporation of new information into a memory store, which requires the modification or creation of memory traces. Compare retrieval. [8]
endogenous attention
A form of attention in which processing resources are directed voluntarily to specific aspects of the environment; typically prompted by experimental instructions or, more normally, by an individual’s goals, expectations, and/or knowledge. Compare exogenous attention. [6]
endowment effect
A bias in decision making in which people will pay less to buy something than they would accept to sell the same thing, if they already possessed it. [14]
engram
Also called memory trace. The physical basis of a stored memory. [8]
enteric division
The division of the autonomic motor system that is specifically concerned with regulating the behavior of the gut. [Appendix]
epinephrine
A catecholaminergic neurotransmitter and hormone involved in many body functions, including the fight-or-flight response coordinated by the autonomic nervous system. [10]
episodic memory
Declarative memory that refers to memory for personally experienced past events. Compare semantic memory. [9]
episodic memory theory
A theory positing that the hippocampus is critical for episodic memory but not for semantic memory. Compare cognitive map theory and relational memory theory. [9]
ERN
See error-related negativity.
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. [11,13]
event-related design
A task design used in fMRI studies in which trials or events of different types may follow one another in randomized order and the neural responses from the different events can be extracted from the measured signals. Analogous to the extraction of event-related potentials (ERPs) from ongoing EEG and to the construction of peristimulus histograms from single-neuron recordings. Compare blocked design. [2]
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. [2]
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. [2]
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. [Appendix]
executive function
The cognitive functions that allow flexible and goal-directed control of thought and behavior. [13]
exogenous attention
Also called reflexive attention. A form of attention in which processing resources are directed to specific aspects of the environment in response to a sudden stimulus change, such as a loud noise or sudden movement, that attracts attention automatically. Compare endogenous attention. [6]
expected utility
The personal value (i.e., utility) placed on the potential outcome of a decision, as derived from the combination of the value and probability of its potential outcomes. Compare expected value. [14]
expected value
The average value in a particular currency (e.g., dollars) of the potential outcome of a decision as weighted by the relative probabilities of those outcomes. Compare expected utility. [14]
explicit memory
See declarative memory.
external ear
The cartilaginous elements of the visible ear (the pinna and concha). [4]
extinction
The gradual disappearance of a conditioned response that is no longer being rewarded. [8]
extracellular recording
Recording the electrical potentials in the extracellular space near active neurons. Compare intracellular recording. [2]
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. [3]
eyeblink conditioning
A paradigm in which a puff of air is repeatedly paired with a tone until the tone by itself elicits blinking. [8]

F

FA
See fractional anisotropy.
false alarm
In recognition memory test, incorrectly classifying a new item as “old.” Compare correct rejection, hit, and miss. [9]
familiarity
The feeling of having experienced an event at some point in the past, even though no specific associations or contextual detail come to mind. Compare recollection. [9]
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. [10]
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. [10]
feature integration theory
A model of attention 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. The model also proposes that attention is required to integrate the feature information from these separate maps into a perceptual whole. [7]
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. [6]
FFA
See fusiform face area.
fiber tract
Bundles of axons in the brain that carry neuronal signals between brain areas. [2]
fictive learning
The adjustment of rules for behavior based on reward outcomes that were observed, but not received directly. [14]
fissure
A deep cleft in the surface of the brain; can be either 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). [Appendix]
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. [10]
fMRI adaptation
One way of using repetition suppression within an fMRI paradigm that uses pairs of similar stimuli. If the second stimulus induces less activity than the first stimulus (or prime) in a particular brain area, then it can be inferred that the region in some way supports a process common to the two stimuli. [2]
fMRI
See functional magnetic resonance imaging.
folia (sing. folium)
The ridges and valleys that are apparent in the cerebellar cortex. [Appendix]
forebrain
The anterior portion of the brain that includes the cerebral hemispheres (the telencephalon and diencephalon). [Appendix]
form
The perception of object geometry or shape; one of the major visual perceptual qualities. [3]
formant
One of several frequencies that represent the natural resonances of different components of the vocal tract. [12]
fornix (pl. fornices)
An axon tract, best seen from the medial surface of the divided brain, that interconnects the hypothalamus and hippocampus. [Appendix]
fourth ventricle
The ventricular space that lies between the pons and the cerebellum. Compare third ventricle and lateral ventricles. [Appendix]
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. [3]
fractional anisotropy (FA)
The degree to which water diffuses in a preferred direction within tissue. Higher levels of fractional anisotropy are thought to reflect greater amounts of white-matter (i.e., fiber tract) integrity. [2]
framing effect
A mode of representing a decision-making scenario that changes the decisions people make, even though the basic structure of the problem is left unchanged. [14]
frequency band
A specific frequency range within a spectrum, usually referring to oscillatory electrical brain activity. [2]
frontal disinhibition syndrome
See disinhibition syndrome.
frontal dysexecutive syndrome
See dysexecutive syndrome.
frontal eye fields
A region of the prefrontal cortex in human and non-human primates, often associated with area 8a, that plays a key role in voluntary visual orienting movements. [5]
frontopolar cortex
The most anterior part of the prefrontal cortex. [13]
fugue state
Transient states of confusion in which self-relevant knowledge is temporarily unavailable to consciousness. [11]
functional connectivity
How the activity of one brain region varies with the activity in other brain regions. [2]
functional magnetic resonance imaging (fMRI)
A non-invasive method for imaging brain activity that uses imaging pulse sequences generated by a magnetic resonance scanner; the signal measured is caused by hemoglobin-based changes in blood oxygenation and blood flow that are induced by local neural activity. [2]
functional neural module
A specialized, encapsulated neural circuit that has evolved to process specific types of information relevant to solving the problems a particular species confronts in its natural environment. [15]
fundamental frequency
The first vibratory mode in the harmonic series evident in the sound spectra generated by a vibrating string or column of air. [4]
fusiform face area (FFA)
A region of the fusiform gyrus that shows enhanced responses to faces relative to other objects. [3,11]

G

game theory
A subfield of behavioral economics that investigates how people make decisions in simple, well-controlled games. [14]
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. Compare nucleus. [Appendix]
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. [5]
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. [Appendix]
glomerulus (pl. glomeruli)
Any of the characteristic collections of neurons in the olfactory bulb that are formed by dendrites of mitral cells and terminals of olfactory receptor cells, as well as the axons and dendrites of local interneurons. [4]
grammar
The system of rules implicit in a language. [12]
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. [Appendix]
guided search
A cognitive model positing that there are two basic components that determine the allocation of attention during visual search : a component driven by stimulus (bottom-up) information and one driven by top-down influences based on high-level factors and behavioral goals. [7]
gustatory system
Also called taste system. The peripheral and central components of the nervous system dedicated to processing and perceiving taste stimuli. [4]
gyrus (pl. gyri)
Any of the ridges in the folded cerebral cortex. Compare sulcus. [Appendix]

H

habit
A well-established pattern of thought or behavior. [14]
habituation
The process by which a behavioral response to the same stimulus decreases in intensity, frequency, or duration when that stimulus is repeated over and over. Compare sensitization. [8]
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. [4]
harmonic series
The series of vibratory modes evident in the spectra produced by resonating objects. [4]
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.” [8]
hemiballismus
A neurological disorder resulting from unilateral damage to the basal ganglia; manifested by flinging movements of the limbs contralateral to the lesion. [5]
hemispatial neglect
A deficit in the ability to attend to the left side of space, and often to the left side of objects, typically caused by damage to the right parietal lobe. Occasionally damage to the left parietal lobe can cause corresponding deficits for attending to the right side of space, but much more rarely. [7]
heuristic
A rule or procedure derived from past experience that can be used to solve a problem (e.g., in decision making, perception, or some other aspect of cognition). [14]
hippocampus (pl. hippocampi)
A specialized cortical structure located in the medial portion of the temporal lobe; in humans, concerned with declarative memory, among many other functions. [10,Appendix]
hit
In recognition memory test, correctly classifying an old item as “old.” Compare correct rejection, false alarm, and miss. [9]
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 in this family). [15]
Homo
The genus of humans and their ancestors characterized by upright walking, a relatively large brain, certain advanced dental features, and toolmaking. [15]
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 negatively) to the dualist notion of a non-neurally based “self.” [2,4]
HPA axis
See hypothalamic-pituitary-adrenal axis.
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. [5]
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. [Appendix]
hyperscanning
An fMRI technique in which data are collected simultaneously across more than one MRI scanner, often while individuals are playing a multiplayer game. [14]
hypothalamic-pituitary-adrenal (HPA) axis
The primary information-processing pathway for stress responses; connects the hypothalamus, pituitary gland, and adrenal gland. [10]
hypothalamus
A collection of small but critical nuclei in the diencephalon that lies just inferior to the thalamus; governs reproductive, homeostatic, and circadian functions. [10,Appendix]

I

illumination
The light that falls on a scene or surface. [3]
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. [7]
imaging genomics
See neuroimaging genomics.
implicit memory
See nondeclarative memory.
indirect priming
The facilitation of recall by an item (the prime) that is not directly related to that item. For example, the word winter may indirectly prime both summer and snow. Compare direct priming. [8]
individual difference
Variation in a cognitive function or other trait across people, often as can be related to a particular biological predictor. [1,10]
inferior colliculi (sing. inferior colliculus)
Paired structures on the dorsal surface of the midbrain; concerned with auditory processing. Compare superior colliculi. [4,Appendix]
inhibition of return
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. [6]
inhibitory
Pertaining to a synaptic effect that makes the firing of the postsynaptic cell less likely. Compare excitatory. [Appendix]
instrumental learning
See operant conditioning.
insula
Literally “island” (in Latin). The portion of the cerebral cortex that is buried within the depths of the Sylvian fissure (lateral sulcus). [4,Appendix]
intention tremor
A tremor that occurs during performance of a voluntary motor act. Characteristic of cerebellar pathology. [5]
intentional stance
The assumption that others are agents motivated to behave in a way that is consistent with their current mental state. [11]
interaural intensity difference
The difference in the intensity of a sound stimulus at the two ears; contributes to sound localization. Compare interaural time difference. [4]
interaural time difference
The difference in the time of arrival of a sound stimulus at the two ears; contributes to sound localization. Compare interaural intensity difference. [4]
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. [Appendix]
interneuron
Also called local circuit neuron. Literally, a neuron in a circuit that lies between primary sensory and primary effector neurons; more generally, a neuron that branches locally to innervate other neurons. [Appendix]
interoception
The sense of the internal state of the organism. [11]
intracellular recording
Recording the potential between the inside and outside of a neuron with a microelectrode. Compare extracellular recording. [2]
inverse optics problem
The impossibility of knowing the world directly by means of light stimuli; arises because of the ambiguity of light patterns projected onto the retina. [3]
ion channel
A membrane protein that uses the passive energy of concentration gradients (created by ion pumps) to allow the passage of ions across the cell membrane. [Appendix]
ion pump
A membrane protein that uses metabolic energy to create ion concentration gradients across neuronal membranes. Compare ion channel. [Appendix]
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. [14]
ischemia
A paucity or complete lack of blood supply; a common cause of stroke. [Appendix]
item recognition test
Memory test that measure memory for the occurrence of items independently of their contexts. [9]

J

James-Lange theory
A theory, developed by William James and Carl Lange in the 1880’s, positing that emotions are determined by the pattern of feedback from the body periphery to the cerebral cortex. [10]
joint attention
The sharing of a common focus of attention across at least two individuals. [11]

K

Klüver-Bucy syndrome
A rare behavioral syndrome following damage to the anterior temporal lobe that includes a lack of appreciation for the motivational significance of objects in the environment, hyperorality, and altered sexual behavior; named after Heinrich Kluver and Paul Bucy. [10]

L

larynx
The portion of the upper respiratory tract that lies between the trachea and the pharynx. [12]
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. [6]
lateral fissure
Also called Sylvian fissure. The cleft on the lateral surface of the human brain that separates the temporal and frontal lobes. [Appendix]
lateral geniculate nucleus
The thalamic nucleus that relays information from the retina to the cerebral cortex. Compare medial geniculate nucleus. [3]
lateral horn
The lateral portion of the spinal cord gray matter, which mediates sympathetic motor responses. Compare dorsal horn and ventral horn. [Appendix]
lateral intraparietal area (LIP)
Also called area LIP. A part of the inferior parietal lobule that plays a key role in orienting attention and the eyes to a location in space. [14]
lateral prefrontal cortex
The portion of the frontal lobes that lies along the lateral surface of the cerebral cortex, usually restricted to regions anterior to motor cortex. [13]
lateral ventricles
The major ventricle in each of the two cerebral hemispheres. Compare third ventricle and fourth ventricle. [Appendix]
learning
1. See encoding. 2. The combined effect of all encoding, storage, and retrieval in gradually enhancing the performance of a particular task. [8]
left parietal effect
In ERP studies of recognition memory, the phenomenon, occurring at about 400 to 800 milliseconds after the stimulus, whereby old items elicit greater positivity over left parietal regions than do new items. Compare right frontal effect. [9]
levels of processing
Declarative memory encoding is usually better when information is processed at a semantic (deep) level rather than at a perceptual (shallow) level. [8]
LFP
See local field potential.
lightness
In vision, the apparent reflectance of a surface. Compare brightness. [3]
limbic system theory
The theory, developed by Paul MacLean in the 1940’s, positing that structures of the limbic forebrain constitute a system that generates emotions. [10]
LIP
See lateral intraparietal area.
lobes
The four major regions of the cerebral cortex: the frontal, parietal, occipital, and temporal lobes. [Appendix]
local circuit neuron
Also called interneuron. A neuron whose local connections contribute to processing circuitry. [5]
local field potential (LFP)
A dendritic field potential that is recorded intracranially close to the dendritic source (i.e., locally). [2]
localization of function
The idea that the brain may have distinct regions that support particular cognitive functions. [1]
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 attention. [7]
long-term depression (LTD)
A long-lasting diminishment of synaptic strength as a result of repetitive activity. Compare long-term potentiation. [8]
long-term potentiation (LTP)
A long-lasting enhancement of synaptic strength as a result of repetitive activity. Compare long-term depression. [8]
loudness
The sensory quality elicited by the intensity of sound stimuli. [4]
lower motor neuron
Also called primary motor neuron. A motor neuron that directly innervates muscle. Compare upper motor neuron. [5]
LTD
See long-term depression.
LTP
See long-term potentiation.
luminance
The physical measure of light intensity. [3]

M

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. [2]
magnetoencephalography (MEG)
A method of measuring at the scalp the electrical currents in the brain based on the detection of the magnetic fields produced by those currents. Like EEG, MEG activity is thought to reflect mainly the electrical currents produced in the dendritic trees of the large pyramidal cells in cortex. [2]
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. [3]
mammillary bodies
Small prominences on the ventral surface of the diencephalon; functionally, part of the caudal hypothalamus. [Appendix]
McGurk effect
The misperception of speech sounds due to conflicting visual stimuli. [12]
medial geniculate nucleus
The thalamic nucleus in the primary auditory pathway. Compare lateral geniculate nucleus. [4]
medulla
The most caudal of the three components of the brainstem, extending from the pons to the spinal cord. Compare midbrain and pons. [Appendix]
medullary pyramids
Longitudinal bulges on the ventral aspect of the medulla that signify the corticospinal tracts at this level of the nervous system. [5]
MEG
See magnetoencephalography.
memory
Processes by which information is encoded (learned), stored, and retrieved. [8]
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. [10]
memory search
A process during memory retrieval that explores possible locations of a target memory. [9]
memory trace
See engram.
mentalizing
Also called theory of mind. The ability to represent the internal mental states of other individuals. [11]
meta-analysis
The approach of combining results from multiple experiments, usually published studies that vary in their research methods, to improve the specificity and generalizability of the inferences that can be drawn. [1]
midbrain
The most rostral of the three components of the brainstem; identified by the superior and inferior colliculi on its dorsal surface, and the cerebral peduncles on its ventral aspect. Compare medulla and pons. [Appendix]
middle ear
The portion of the ear between the eardrum and the oval window; contains the three small bones that amplify sound stimuli mechanically. [4]
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. [1]
mirror drawing task
A sensorimotor skill learning task in which the subject is asked to trace the outline of a figure, such as a star, which can be only seen through its reflection on a mirror. Accuracy improves gradually with practice. [8]
mirror neuron
A neuron in the frontal or parietal cortex that shows similar electrophysiological responses to actions executed by oneself or to observation of the same actions being executed by another. [11]
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). [6]
miss
In recognition memory test, incorrectly classifying an old item as “new.” Compare correct rejection, false alarm, and hit. [9]
MMN
See mismatch negativity.
modality-specific attention
The focusing attention on the stimulus information specifically within one sensory modality. Compare supramodal attention. [6]
monitoring
The process that evaluates the appropriateness of a given behavior for the current context; examples include evaluating the accuracy of answers generated during a memory test or the adequacy of a response rule in an executive function paradigm. [9,13]
monocular
Pertaining to one eye. Compare binocular. [3]
mood regulation
The long-term balance between emotional and attentional processing. When these processes become skewed, mood disorders such as depression can occur. [10]
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 environ-ment. [15]
motion
The changing position of an object defined by speed and direction within a frame of reference. [3]
motion aftereffect
The persistence of perceived motion in the opposite direction when a motion stimulus has ceased. [3]
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. [3]
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. [Appendix]
motor neuron
A nerve cell that innervates skeletal or smooth muscle. [Appendix]
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. [5]
motor system
All the components of the central and peripheral nervous systems that support motor behavior. [Appendix]
MRI
See magnetic resonance imaging.
MST (middle superior temporal)
In primates, an extrastriate cortical region related to MT that is in part specialized for motion processing. [3]
MT (middle temporal)
In primates, an extrastriate cortical region related to MST that is in part specialized for motion processing. [3]
multiple-trace theory
A theory positing that episodic memories, consolidated or otherwise, always depend on the hippocampus. Compare standard consolidation theory. [9]
multisensory integration
The combining of sensory information from different sensory modalities, facilitating the linking of that information together into one perceptual object. [6]
multivoxel pattern analysis (MVPA)
A technique that analyzes patterns of activation across voxels in a particular brain region that consistently correspond to certain stimulus or event types, rather than the overall increase or decrease in activation of the entire region. [2]
MVPA
See multivoxel pattern analysis.
myelin
The membranous wrapping of axons by certain classes of glial cells that makes brain regions with axonal pathways look whitish. See white matter. [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. [15]

N

N2pc wave
A negative-polarity (“N” in N2pc) ERP component elicited by the detection of a pop-out stimulus target in a visual search array, thought to reflect either the shifting and focusing of attention to the location of the pop-out or the filtering of the nearby distracter items. It is elicited over posterior scalp sites (“p”), contralateral (“c”) to the side of the target, typically peaking at around 250 ms following the presentation of the stimulus array. [7]
Neanderthals
A subspecies of Homo sapiens that lived between 200,000 and 30,000 years ago in the Middle East and Europe. [15]
negative reinforcement
The withdrawal of a desirable stimulus. [14]
nerve cell
See neuron.
nervous system
The network of nerve cells throughout the body. [1]
neural circuit
A collection of interconnected neurons mediating a specific function. [Appendix]
neural correlate
A measure of brain function that covaries with the expression of a cognitive function. [1]
neural network
Typically refers to artificial network of interconnected nodes whose connections change in strength as a means of solving problems. Can also be used as a synonym for a neuronal circuit. [12]
neural precursor cell
Also called neural stem cells, these undifferentiated cells are defined by their capacity for self-renewal and ability to generate all the major cell types of the CNS including neurons, astrocytes, oligodendrocytes, and ependymal cells that line the ventricles of the brain. [15]
neural priming
See repetition suppression.
neuroeconomics
Also called decision neuroscience. 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. [14]
neuroglial cells
Also called neuroglia or glia. Any of several types of non-neural cells found in the peripheral and central nervous systems that carry out a variety of functions that do not directly entail signaling. [Appendix]
neuroimaging genomics
Also called imaging genomics. A method of relating differences in fMRI activity between people to specific genetic variations. This method can provide accounts of how genetics can influence brain structure and function, and thus in turn cognitive processes. [2]
neuromarketing
The use of measurements of physiology or brain function to shape the branding and advertising of consumer products. [14]
neuron
Also called nerve cell. A cell specialized for the conduction and transmission of electrical signals in the nervous system. [1,Appendix]
neurorealism
The tendency to consider a behavioral or mental phenomenon to be more real based on the presence of neuroscience data. [14]
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 cell that binds a neurotransmitter. [Appendix]
nociceptive system
See pain system.
nociceptor
A cell that responds specifically to potentially harmful stimuli. [4]
noise
A sound stimulus that is aperiodic. Compare tone. [4]
nondeclarative memory
Also called implicit memory. Memory expressed through performance; assumed to operate unconsciously. Compare declarative memory. [8]
noradrenaline
See norepinephrine.
norepinephrine
Also called noradrenaline. A catecholamin-ergic neurotransmitter and hormone released across synapses in postganglionic neurons of the sympathetic nervous system, in the adrenal medulla, and in some parts of the central nervous system. [10]
nucleus (pl. nuclei)
An anatomically discrete collection of neurons within the brain; typically serves a particular function. Compare ganglion. [Appendix]
nucleus accumbens
A subdivision of the ventral striatum that contains neurons sensitive to the neurotransmitter dopamine and contributes to learning and reward evaluation. [14]
nucleus of the lateral lemniscus
A brainstem nucleus in the primary auditory pathway. [4]
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. [4]

O

occlusion
The blocked view of distant objects by nearer objects. [3]
odor
The perception elicited by a soluble chemical that interacts with olfactory receptors. [4]
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. [4,Appendix]
olfactory epithelium
Pseudostratified epithelium that contains olfactory receptor cells, supporting cells, and mucus-secreting glands in the nasal cavity. [4]
olfactory nerve
The first cranial nerve; runs from the olfactory mucosa to the olfactory bulb. [Appendix]
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. [4]
olfactory tract
The projection from the olfactory bulbs to higher olfactory centers. [4,Appendix]
oligodendrocyte
Glial cells with sheetlike processes that form the myelin sheath that insulates nerve axons. [15]
operant conditioning
Also called instrumental learning. The altered probability of a behavioral response engendered by associating responses with rewards (or punishments). Compare classical conditioning. [8]
optic ataxia
A neurological condition associated with damage to the dorsal parietal cortex and characterized by deficits in visually guided reaching. [5]
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. [Appendix]
optogenetics
A method in which genes that code for light-sensitive ion channels or light-sensitive ion transporters are introduced into neurons. Once these genes are expressed, and the channels or transporters are integrated into the cell membrane, the neuron’s activity may be controlled by stimulation with light. [2]
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 decision making. [13]
organelle
A subcellular component visible in a light or electron microscope (e.g., nucleus, ribosome, endoplasmic reticulum). [Appendix]
oval window
The site where the middle-ear bones transfer vibrational energy to the cochlea. [4]
overt attention
The focusing of attention (typically visual) by voluntarily shifting gaze. Compare covert attention. [6]

P

P20–50 attention effect
An enhanced positive-polarity ERP wave elicited by an attended auditory stimulus, occurring between 20 and 50 milliseconds after stimulus onset; this effect provided particularly strong support for early-selection models of attention. [6]
P3
See P300.
P300
Also called P3. A large positive ERP wave elicited by stimuli that are surprising, are of an infrequent event type, or are task-relevant targets, usually when occurring within a stream of other sensory events; typically peaks between 300 and 500 milliseconds after the stimulus. [6,13]
pain
The highly unpleasant percepts generated by stimuli that are potentially damaging. [4]
pain system
A system for warning an animal about potentially harmful stimuli. While largely responsive to mechanical stimuli, it is also closely related to responses to temperature and noxious chemicals. [4]
parahippocampal gyrus
A cortical gyrus in the medial temporal lobe adjacent to the hippocampus; plays a role in declarative memory, emotion, and responses to olfactory stimuli. [Appendix]
parasympathetic division
Sometimes referred to as the “rest and digest” system. The component of the autonomic motor system that mediates restorative metabolic functions. Compare sympathetic division. [Appendix]
parieto-occipital sulcus
Sulcus between the occipital and parietal lobes of the cerebral hemispheres. [Appendix]
Parkinson’s disease
A neurodegenerative process affecting the substantia nigra that results in a characteristic tremor at rest and a general paucity of movement. [5]
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. [3]
pediatric amnesia
See childhood amnesia.
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. [6]
perceptual priming
A form of direct priming in which the test cue and the target are perceptually related. Compare conceptual priming. [8]
peripheral nervous system
All the nerves and neurons that lie outside the brain and spinal cord. Compare central nervous system. [Appendix]
peristimulus time histogram (PSTH)
A graph that plots neuronal activity, typically firing rate or number of spikes, as a function of the time of stimulus presentation. [2]
perseveration
The repetition of a response despite changing stimuli or rules that make a different response more appropriate. [13]
persistent vegetative state
A state that results from profound damage to the brain, perhaps by injury or disease, that is characterized by a lack of awareness. A patient with persistant vegetative state typically can still react to stimuli and exhibit degrees of wakefulness and quiescence. [7]
perspective taking
The ability to adopt the viewpoint of another individual. [11]
PET
See positron emission tomography.
PFC
See prefrontal cortex.
pheromone
A chemical signal produced by an animal such as a rodent, typically from glands, that mediates aspects of social communication. [4]
phone
One of about 200 different sound stimuli the human vocal apparatus can produce. A subset of these is used in any given spoken language (approximately 40 in English). [12]
phoneme
The basic perceptual unit that distinguishes one utterance from another in a given language. [12]
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. [1,13]
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. [Appendix]
pons
One of the three components of the brainstem, lying between the midbrain rostrally and the medulla caudally. [Appendix]
pop-out stimulus
An item in a visual scene or visual array that differs from all of the other items in the scene (distracters) in one featural dimension (such as color, orientation, texture, shape, size). Because the time taken to find a pop-out stimulus is mostly independent of the number of distracter items, its detection is thought to be accomplished by the processing of all the items across the visual field in parallel. Compare conjunction target. [7]
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. [2]
postcentral gyrus
The gyrus that lies just posterior to the central sulcus; contains the primary somatosensory cortex. Compare precentral gyrus. [Appendix]
posterior parietal cortex
The region of the parietal cortex surrounding the intraparietal sulcus. [13]
posttraumatic stress disorder (PTSD)
A clinical condition that emerges following the experience of one or more traumatic, stressful events. Symptoms include heightened arousal, emotional numbness, avoidance of event reminders, and persistent reexperiencing of the traumatic event(s). [10]
power motivation
An enduring preference for having impact on other people or the world at large. [11]
PPI
See psychophysiological interaction analysis.
precentral gyrus
The gyrus that lies just anterior to the central sulcus; contains the primary motor cortex. Compare postcentral gyrus. [Appendix]
prefrontal cortex (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. [13]
premotor cortex
Part of the prefrontal cortex lying just anterior to the primary motor cortex; involved in planning move-ment. [5]
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. [5]
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 sensory-motor mechanisms. [7]
primary auditory cortex (A1)
The cortical target of the neurons in the medial geniculate nucleus; the terminus of the primary auditory pathway. Compare secondary auditory cortex. [4]
primary auditory pathway
The pathway from the inner ear to the primary auditory cortex in the temporal lobe. [4]
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 (area 4) and essential for the voluntary control of movement. Compare premotor cortical areas. [5]
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. [14]
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]
primary visual cortex
Also called striate cortex or V1. The cortex in the calcarine fissure of the parietal lobe that receives visual input from the thalamus. Compare extrastriate visual cortical areas. [3]
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. [3]
priming
Facilitated processing of a particular stimulus based on previous encounters with the same or a related stimulus. Compare conditioning and skill learning. [8]
probability weighting
A core assumption of prospect theory, such that the subjective probability of an outcome can differ systematically from the objective probability. [14]
processing negativity
A slow, long-lasting negative-polarity ERP wave that is elicited during auditory selective attention, the amplitude of which reflects how well each stimulus matches an attentional “template.” Compare selection negativity. [6]
production aphasia
See Broca’s aphasia.
propranolol
An antagonist of the beta-adrenergic system. [10]
prosodic
Pertaining to the inflection in speech, often associated with emotion. [12]
prosody
The fluctuating pitch of speech; gives emotional and other information to speech. [10]
prosopagnosia
The inability to recognize faces; usually associated with lesions of the right inferior temporal cortex. [3]
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. [14]
PSTH
See peristimulus time histogram.
psychological construct
A theoretical concept, often generated by converging results across experiments, that cannot be directly observed but serves to explain and unify a body of research. [1]
psychophysiological interaction (PPI) analysis
An fMRI analysis technique that uses the time courses of activity in different brain areas to analyze how interactions between them differ as a function of the cognitive task being performed. For example, it analyzes whether the correlation in activity between two areas, rather than activity itself, differs in one task versus another. [2]
PTSD
See posttraumatic stress disorder.
pulvinar
A nucleus of the thalamus that mediates interactions among several sensory association areas of the cortex. [Appendix]
punishment
The delivery of an aversive stimulus. [14]
putamen
One of the three major nuclei that make up the basal ganglia. [Appendix]
pyriform cortex
A component of the cerebral cortex in the temporal lobe pertinent to olfaction; so named because of its pearlike shape. [4,Appendix]

R

raphe nuclei
Brainstem nuclei involved in the control of the sleep-wake cycle, among other functions related to arousal. [7]
rational choice model
A framework for explaining choice behavior that assumes that decision makers are consistent in their preferences and procedures for generating choices. [14]
rationality
Consistency in decision making that is based on a conscious evaluation of the circumstances. [14]
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 actual production of the movement. [5]
recall test
Memory test that requires generating the target information. [9]
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. [3]
receptor potential
A membrane potential change that arises at a sensory receptor in the periphery due to a stimulus from the environment. [Appendix]
recollection
Remembering a past event, as well as specific associations and contextual details. Compare familiarity. [9]
recovery
During memory retrieval, the process of accessing stored memory traces. [9]
recurrent
See reentrant.
reentrant
Also called recurrent. Following a stimulus or event, describing a process in which neural activity is fed back to the same brain region, typically a sensory area, that was activated earlier in the processing sequence. [7]
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. [6]
reference dependence
A core assumption of prospect theory, such that outcomes are evaluated in terms of their relative change (positive or negative) from the current state. [14]
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). [3]
reflexive attention
See exogenous attention.
relational memory theory
A theory positing that the hippocampus is involved primarily in encoding and retrieving associations between items, including spatial associations but also other types of associations. Compare cognitive map theory and episodic memory theory. [9]
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. Compare repetition suppression. [8]
repetition priming
See direct priming.
repetition suppression
Also called neural priming. A phenomenon observed in functional neuroimaging studies in which previously encountered stimuli evoke smaller hemodynamic responses than do novel stimuli. Compare repetition enhancement. [2,8]
repetitive TMS (rTMS)
A method in which the brain is stimulated with a repeated sequence of magnetic field pulses, ranging from less than 1 per second up to 30 Hz or more. [2]
resonance
The tendency of any physical object to vibrate maximally at a certain frequency. [4]
resting-state connectivity
The patterns of functional connectivity of the brain while a person is awake but not engaged in any specific task or activity. [2]
reticular activating system
A region in the brainstem containing a set of subregions (brainstem “nuclei”) that mediate overall arousal and level of awareness. [7]
retinal disparity
The geometrical difference between the same points in the images projected on the two retinas, measured in degrees with respect to the fovea. [3]
retrieval
The recovery or accessing of stored memory traces. Compare encoding. [8]
retrieval cue
Any information that leads to the retrieval of memories, such as the hits provided by memory tests. [9]
retrieval mode
The mental state of episodic retrieval (the retrieval of episodic memories), which is assumed to be qualitatively different from the mental states of other cognitive abilities. [9]
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. [8]
reversal learning
The capacities for recognizing that the rules mapping environmental events to behavior have changed and for adjusting behavior accordingly. [13]
reward prediction error (RPE)
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. [14]
reward value
The likelihood that a particular movement will yield a reward, multiplied by the amount of reward expected. [5]
right frontal effect
In ERP studies of recognition memory, the phenomenon, occurring at 600 to 1200 milliseconds after the stimulus, whereby old items elicit greater positivity over right frontal regions than do new items. Compare left parietal effect. [9]
right-hemisphere hypothesis
A hypothesis positing that the right hemisphere is specialized for emotional functions. Compare valence hypothesis. [10]
risk aversion
The tendency to prefer lower-risk options when making decisions, even in some situations when those options have reduced expected value. [14]
RPE
See reward prediction error.
rTMS
See repetitive TMS.

S

S1
See primary somatosensory cortex.
S2
See secondary somatosensory cortex.
saccade
A ballistic eye movement that changes the point of binocular visual fixation; normally occur at a rate of about three to four per second. [3,5]
saliency map
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. [7]
satisficing
An approach to decision making in which a decision maker does not seek the best possible option, but instead chooses the first option that meets some threshold for acceptability. [14]
savant syndrome
A rare clinical condition characterized by extraordinary talent in a particular ability, such as art or math, often in the face of general physical or mental disability. [10]
schizophrenia
A heterogeneous psychiatric condition characterized by disordered thought, withdrawal symptoms, and inaccurate beliefs about reality. [13]
SCR
See skin conductance response.
secondary auditory cortex (A2)
Also called belt areas. The cortical region surrounding the primary auditory cortex. Compare primary auditory cortex. [4]
secondary reinforcer
A stimulus that has no direct effects on homeostatic processes but is nevertheless rewarding; money is a paradigmatic example. Compare primary reinforcer. [14]
secondary somatosensory cortex (S2)
A higher-order somatosensory map in the parietal lobe adjacent to S1. Compare primary somatosensory cortex. [4]
selection negativity
A slow, sustained, negative-polarity ERP wave, typically starting about 150 milliseconds after an attended visual stimulus, resulting from attention to a nonspatial visual feature of the stimulus. Compare processing negativity. [6]
self
The subjective sense of existing as an individual. [11]
self-awareness
An awareness of oneself as a separate actor in the world. Compare awareness. [7]
self-reflexive thought
The ability to consider one’s own being as an object of thought. [11]
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. [9]
semantic memory
Declarative memory that refers to general knowledge about the world, including knowledge of language, facts, and the properties of objects. Compare episodic memory. [9]
semantic priming
A form of indirect priming in which the prime and the target are semantically related. Compare conceptual priming. [8]
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. [8]
sensory 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. [3]
sensory aphasia
See Wernicke’s aphasia.
sensory/functional theory
Theory which postulates that semantic memory is organized by sensory and functional properties of real objects. Compare domain-specific theory. [9]
sensory ganglia
Collections of neurons in the peripheral nervous system that comprise the cell bodies of afferent sensory neurons. [Appendix]
sensory neuron
A nerve cell that is involved in sensory processing. [Appendix]
sensory system
All the components of the central and peripheral nervous systems concerned with processing information arising from a particular stimulus category (e.g., light, sound stimuli). [Appendix]
septal forebrain nuclei
See basal forebrain nuclei.
sham rage
An emotional reaction elicited in cats by electrical stimulation of the hypothalamus, characterized by hissing, growling, and attack behaviors directed randomly toward innocuous targets. [10]
sharpening theory
Priming theory which proposes that when a stimulus is repeated neurons that are not essential fire less, leading to a more efficient “sharpened” representation and a reduction in neural activity. [8]
simultaneous lightness/brightness 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). [3]
single-unit recording
A method of studying the activity of single neurons using a microelectrode. [3]
situation selection
A form of emotion regulation in which individuals select situations that minimize the likelihood of experiencing negative emotions. [10]
skill learning
Gradual improvement in the performance of a motor or cognitive task as a result of extensive experience and repeated practice. Compare conditioning and priming. [8]
skin conductance response (SCR)
A stimulus-induced increase in the electrical conductance of the skin due to increased hydration. [10]
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. [8]
SMA
See supplementary motor area.
SME
See subsequent memory effect.
SNr
See substantia nigra pars reticulata.
social neuroscience
The study of the neural basis of interpersonal and intergroup processes. [10]
social referencing
The use of emotions expressed by another individual to guide one’s own behavior. [11]
soma
See cell body.
somatic marker hypothesis
A theory, first advocated by Antonio Damasio and his colleagues, that motivated behavior is influenced by neural representations of body states (the “somatic markers”), whose reexperiencing can shape behavior positively or negatively; the hypothesis that evaluation of one’s own body states makes important contributions to decision making. [13]
somatic motor system
The components of the motor system that support skeletal movements mediated by the contraction of skeletal muscles. [Appendix]
somatic sensory cortex
Also called somatosensory cortex. Region of the parietal lobe that receives information about touch, pressure and vibration at the body surface. [Appendix]
somatotopic
refers to a representation of the body mapped on to the cortex of the brain in a topgraphically preserved way, meaning that adjacent locations on the surface of the body have adjacent representations in the cortex, even if perhaps stretched or distorted. The primary motor cortex and the somatosensory area of the brain are two somatotopically organized areas. [2]
somatotopic map
The corresponding anatomical arrangement of the sensory periphery and its central representation. [4]
sound spectrum
The analysis of a sound stimulus showing the distribution of power as a function of frequency. [4]
sound wave
The periodic compression and rarefaction of air molecules underlying a sound stimulus. [4]
source memory test
Also called context memory test. An explicit test of memory that asks participants to remember not merely what events happened in the past but where, when, or how they happened. [9]
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. [12]
specificity
In long-term potentiation, only the synapses activated during stimulation show enhancement; other synapses, even on the same neuron, are not affected. [8]
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. [Appendix]
spinal reflex arc
Circuit that includes the afferent to efferent components of a response at the level of the spinal cord. [Appendix]
split-brain patient
An individual whose corpus callosum has been surgically interrupted as a treatment for epilepsy, functionally separating the left and right hemispheres. [12]
spreading activation
Hypothetical mechanism whereby the activation of a node in the semantic network spreads to associated nodes. [8]
standard consolidation theory
A theory positing 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. Compare multiple-trace theory. [9]
startle response
A behavioral reaction to a sudden, intense auditory or visual stimulus that is mediated by a subcortical reflex circuit. [10]
stereopsis
The special sensation of depth that results from fusion of the two eyes’ views of relatively nearby objects. [3]
storage
The retention of information over time. [8]
stress hormone
Any of several hormones, including cortisol, epinephrine, and norepinephrine, that are secreted by the adrenal gland when stimulated by its sympathetic innervation. [10]
striate cortex
See primary visual cortex.
striatum
The input nuclei of the basal ganglia, consisting of the caudate and the putamen. So called because of the striped appearance of these structures in brain sections. [5,Appendix]
stroke
The clinical and neuropathological result of interruption of the blood supply to one or another region of the brain. [Appendix]
structural equation modeling
A mathematical method of analyzing fMRI data by which two or more models of functional connectivity may be tested against brain data. The method aims at determining the relative likelihood of one model over another given the observed data. [2]
subcortical
Pertaining to brain structures other than the cerebral cortex. [Appendix]
subsequent memory effect (SME)
In functional neuroimaging studies, greater study-phase activity for items that are remembered rather than forgotten in a later memory test. [9]
substantia nigra
A nucleus at the base of the midbrain that receives input from a number of cortical and subcortical structures. The dopaminergic cells of the substantia nigra send their output to the caudate or putamen. [Appendix]
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. [5]
sulcus (pl. sulci)
Any of the valleys that arise from the folding of the cerebral hemisphere between gyri. See also fissure. [Appendix]
superior colliculi (sing. superior colliculus)
Paired structures that form part of the roof of the midbrain; important in orienting movements of the head and eyes. Compare inferior colliculi. [5,Appendix]
superior olivary complex
A complex of brainstem nuclei in the primary auditory pathway. [4]
supplementary motor area (SMA)
See supplementary motor cortex.
supplementary motor cortex
Also called supplementary motor area or area 6. 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. [5]
supramodal attention
The focusing of attention on stimulus information across multiple modalities at the same time. Compare modality-specific attention. [6,7]
Sylvian fissure
See lateral fissure.
sympathetic division
Sometimes referred to as the “fight or flight” system. The component of the autonomic motor system that contributes to the mobilization of energy to prepare the body for action. Compare parasympathetic division. [Appendix]
sympathy
Having feelings of pity or concern for another individual’s plight without experiencing the same feelings expressed by that individual. Compare empathy. [11]
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 cleft
The small space between a presynaptic and postsynaptic element across which neurotransmitters must diffuse when released. [Appendix]
synaptic consolidation
Memory consolidation involving changes in synapses that presumably allow the persistence of some forms of memory traces at the cellular level. Compare system consolidation. [9]
synaptic potential
A membrane potential change (or a conductance change) generated by the action of a chemical transmitter agent. Synaptic potentials allow the transmission of information from one neuron to another. Compare receptor potential. [Appendix]
synaptic vesicle
The organelle at a synaptic ending that contains neurotransmitter agents. [Appendix]
synaptogenesis
The elaboration of synapses during neural development. [15]
syntax
The way in which words are combined to form sentences or phrases. [12]
system consolidation
Memory 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. [9]

T

taste
The sensory modality comprising the perception of substances placed in the mouth. [4]
taste bud
An onion-shaped structure in the mouth or pharynx that contains taste cells. [4]
taste system
See gustatory system.
tegmentum
The central gray matter of the brainstem. [Appendix]
temperament
A disposition to react to emotional situations either positively or negatively. [10]
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. [14]
temporal discounting
Also called delay discounting. The reduction in the desirability of an outcome based on the delay in time until it will be delivered. [14]
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. [11]
thalamus
A collection of nuclei that forms the major component of the diencephalon. Has many functions; a primary role is to relay sensory information from the periphery to the cerebral cortex. [4,10,Appendix]
theory of mind
See mentalizing.
third ventricle
Compare fourth ventricle and lateral ventricles. The midline component of the ventricular system at the level of the diencephalon. [Appendix]
threshold potential
The membrane potential at which a nerve cell fires an action potential. [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. [4]
TMS
See transcranial magnetic stimulation.
tonal
Pertaining to a sound stimulus that, by virtue of its periodic repetition, produces the perception of a tone. [12]
tone
The sound heard in response to a particular frequency of vibration or combination of vibrations that are strongly periodic. Compare noise. [4]
tonotopic organization
The central arrangement of tone analysis in the auditory system that roughly corresponds to the peripheral responsiveness of the basilar membrane. [4]
topographical mapping
The specification of spatial relationships in the retina and in other stations of the primary visual pathway. [3]
topography
In vision, the study of spatial relationships at different levels of the primary visual pathway. [3]
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. Compare delay conditioning. [8]
tract
A major white matter (axonal) pathway in the brain. [Appendix]
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 enabling inferences concerning the cognitive function(s) in which that brain area is involved. [2]
transfer-appropriate processing
The hypothesis that memory performance depends on a match between the conditions surrounding the encoding and retrieval of a stimulus. [9]
transmittance
The percentage of light energy that reaches a detector when passed through a filter. [3]
trial
A single occurrence of an experimental event in a study. [2]
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. [3]
trigeminal chemosensory system
The chemosensory system that responds to irritating chemicals that enter the nose or mouth. [4]
tuning curve
The function obtained when a neuron’s receptive field is tested with stimuli at different orientations; its peak defines the maximum sensitivity of the neuron in question. [2,3]
tympanic membrane
The eardrum. [4]

U

unconditioned reinforcer
See primary reinforcer. [14]
unconditioned response (UR)
In classical conditioning, the innate reflex that is naturally triggered by a particular stimulus. Compare conditioned response. [8]
unconditioned stimulus (US)
In classical conditioning, the stimulus that naturally triggers the innate reflex. Compare conditioned stimulus. [8]
uncus
Part of the cerebral cortex near the hippocampus and associated with hippocampal function. [Appendix]
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. [5]
UR
See unconditioned response.
Urbach-Wiethe syndrome
A rare, congenital dermatological disease that occasionally produces calcifications in temporal lobe structures. [10]
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. [14]

V

V1
See primary visual cortex.
V4
An area of extrastriate visual cortex that is probably important in color vision, although it processes other information as well. [3]
valence
The degree of pleasantness of a stimulus. [10]
valence hypothesis
A hypothesis postulating that positive emotions are preferentially processed in the left hemisphere and negative emotions are preferentially processed in the right hemisphere. Compare right-hemisphere hypothesis. [10]
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. [10]
ventral horn
The ventral portion of the spinal cord gray matter, which contains the primary motor neurons. Compare dorsal horn and lateral horn. [Appendix]
ventral posterior nuclear complex
A group of thalamic nuclei that receives the somatosensory projections from the dorsal column nuclei and the trigeminal nuclear complex. [4]
ventral stream
A partially segregated visual processing pathway passing from the primary visual cortex toward the temporal lobe that is especially pertinent to object recognition. Compare dorsal stream. [3]
ventral striatum
The portion of the ventral caudate and putamen that encompasses the nucleus accumbens. [14]
ventral tegmental area (VTA)
A part of the midbrain that contains many dopaminergic neurons and is important for reward and learning. [14,Appendix]
ventrolateral prefrontal cortex
A functional division of the prefrontal cortex roughly corresponding to the inferior frontal gyrus and surrounding sulci, as located anterior to motor cortex. Compare dorsolateral prefrontal cortex. [13]
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. Compare dorsomedial prefrontal cortex. [13]
vertical integration model
A model of emotion that integrates cortical, subcortical, and visceral processes. [10]
visceral motor system
See autonomic motor system.
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. [6,7]
visual spatial attention
Attention directed to a location in visual space. [6]
voiced
Pertaining to a speech sound stimulus characterized by laryngeal harmonics—typically a vowel sound. [12]
volatility
The degree to which the rules governing environmental events (e.g., the delivery of rewards) are changing or stable over time. [13]
vowel
Typically a voiced (tonal) element of speech that forms the nucleus of syllables. [12]
VTA
See ventral tegmental area.

W

wakefulness
The state in which one is not asleep. [7]
Weber-Fechner law
The principle that the just-noticeable difference in a stimulus increment is a constant fraction (the Weber fraction) of the stimulus; named after two Germans: physiologist-anatomist Ernst Weber, and physicist-philosopher Gustav Fechner. [15]
Wernicke’s aphasia
Also called 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. [12]
Wernicke’s area
An area of cortex in the superior and posterior region of the left temporal lobe that helps mediate language comprehension; named after the nineteenth-century neurologist and psychiatrist Carl Wernicke. Compare Broca’s area. [12]
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. [Appendix]
Wisconsin Card Sorting Test
A cognitive test that involves classifying a set of cards, each showing one or more images of a simple shape, into categories based on rules that periodically change throughout the session. [13]
working memory
Memory held briefly in the mind that enables completion of a particular task (e.g., efficiently searching a room for a lost object). [8,13]
Go