Glossary PDF

Glossary Courtesy of Dr. Sarah Moghadam, VA Palo Alto Health Care System, Palo Alto, CA and Dr. Ahmad Salehi, Dept....

Glossary Courtesy of Dr. Sarah Moghadam, VA Palo Alto Health Care System, Palo Alto, CA and Dr. Ahmad Salehi, Dept. of Psychiatry & Behavioral Sciences, Stanford Medical School activational effect!A temporary change in behavior resulting Numbers in brackets refer to the chapter(s) where the term from the administration of a hormone to an adult animal. is introduced. acupuncture The insertion of needles at designated points on 5-HT See serotonin. the skin in an attempt to alleviate pain or physiological malfunc- tion, or alter behavior. 5α-reductase!An enzyme that converts testosterone into dihydrotestosterone (DHT). acute flaccid myelitis!A sudden weakness or paralysis in limb(s) with decreased or absent reflexes. 17β-estradiol!Also called simply estradiol. The primary type of estrogen that is secreted by the ovary. adaptation!1. A trait that increases the probability that an individual will leave offspring in subsequent generations. α-fetoprotein!A protein found in the plasma of fetuses. In 2. The progressive loss of receptor sensitivity as stimulation is rodents, α-fetoprotein binds estrogens and prevents them from maintained. [6, 8, 10] entering the brain. Aδ fiber!A large, myelinated, and therefore fast- α-melanocyte-stimulating hormone (α-MSH)!A peptide that conducting axon, usually transmitting acute pain information. binds the melanocortin receptor. adenohypophysis See anterior pituitary. α-MSH See α-melanocyte-stimulating hormone. adenosine!An endogenous neuromodulator that generally re- α-synuclein!A protein implicated in Parkinson’s disease. duces neural activity. Caffeine interferes with adenosine binding. β-amyloid!A protein that accumulates in senile plaques in Al- [4, 14] zheimer’s disease. adequate stimulus!The type of stimulus for which a given sen- β-secretase!An enzyme that cleaves amyloid precursor sory organ is particularly adapted. protein, forming β-amyloid, which is suspected of causing Al- ADH See arginine vasopressin. zheimer’s disease. ADHD See attention deficit hyperactivity disorder. ∆9-tetrahydrocannabinol (THC)!The major active ingredient in cannabis thought to be responsible for adipose tissue!Tissue made up of fat cells. the “high” feeling. adrenal cortex!The outer rind of the adrenal gland, which se- cretes steroid hormones, including cortisol. [5, 15] A A1 See primary auditory cortex. adrenal gland!An endocrine gland atop the kidney. absence attack See simple partial seizure. adrenal medulla!The inner core of the adrenal gland, which secretes epinephrine and norepinephrine. [5, 15] absolute refractory phase!A brief period of complete insensitivity to stimuli. adrenal steroids!Also called adrenocorticoids. Steroid hormones secreted by the adrenal cortex, including glucocorti- accommodation!The process of focusing by the ciliary muscles coids such as cortisol and mineralocorticoids such as aldosterone. and the lens to form a sharp image on the retina. [5, 15] acetylcholine (ACh) A neurotransmitter produced and released adrenaline See epinephrine. by parasympathetic postganglionic neurons, by motor neurons, and by neurons throughout the brain. [2, 3, 4, 11] adrenocorticoids!Also called adrenal steroids. A class of steroid hormones that are secreted by the adrenal cortex. [5, 15] acetylcholinesterase (AChE)!An enzyme that inactivates the transmitter acetylcholine both at synaptic sites and adrenocorticotropic hormone (ACTH)!A tropic hormone elsewhere in the nervous system. secreted by the anterior pituitary gland that controls the produc- tion and release of hormones of the adrenal cortex. ACh See acetylcholine. adult neurogenesis!The birth of new neurons in the brain of an AChE See acetylcholinesterase. adult. acid See LSD. afferent!In reference to axons, carrying action potentials from a ACTH See adrenocorticotropic hormone. sensory organ to the central nervous system or from one region to actin!A protein that, along with myosin, mediates the contraction another region of interest. Compare efferent. of muscle fibers. affinity See binding affinity. action potential!The propagated electrical message of afterpotential!The positive or negative change in membrane a neuron that travels along the axon to the presynaptic axon potential that may follow an action potential. terminals. aggression!Behavior that is intended to cause pain or harm amplitude Magnitude or strength. In acoustics, the force sound (whether physical or emotional) to others, either individually or in exerts per unit area, usually measured as dynes per square groups. centimeter. agnosia!The inability to recognize objects, despite being able to ampulla!An enlarged region of each semicircular canal that con- describe them in terms of form and color. It may occur after local- tains the receptor cells (hair cells) of the vestibular system. ized brain damage. amusia!A disorder characterized by the inability to discern tunes agonist!A molecule, usually a drug, that binds a receptor mol- accurately. ecule and initiates a response like that of another substance, usu- amygdala!A group of nuclei in the medial anterior part of ally a neurotransmitter. [3, 4] the temporal lobe. [2, 15] agraphia!The inability to write. amyloid plaques See senile plaques. AIS See androgen insensitivity syndrome. amyloid precursor protein (APP)!A protein that, when alarm reaction!The initial response to stress. cleaved by several enzymes, produces β-amyloid. aldosterone!A mineralocorticoid hormone, secreted by the amyotrophic lateral sclerosis (ALS)!Also called Lou Gehrig’s adrenal cortex, that induces the kidneys to conserve sodium ions. disease. A disease in which motor neurons and their target muscles [5, 13] waste away. alexia!The inability to read. analgesia!Absence of or reduction in pain. allele One of two or more versions of a given gene or genetic lo- analgesic!Referring to painkilling properties. cus. Different alleles may differ in the functionality of the protein analogy!Similarity of function, although the structures of interest produced. [6, App] may look different. The human hand and an elephant’s trunk are allomone!A chemical signal that is released outside the body by analogous features. one species and affects the behavior of other species. anandamide!An endogenous substance that binds the cannabi- allopregnanolone!A naturally occurring steroid that modulates noid receptor molecule. GABA receptor activity in much the same way that benzodiaz- androgen insensitivity syndrome (AIS)!A syndrome caused epine anxiolytics do. by a mutation of the androgen receptor gene that renders tissues all-or-none property!The fact that the amplitude of the action insensitive to androgenic hormones like testosterone. Affected XY potential is independent of the magnitude of the stimulus. individuals are phenotypic females, but they have internal testes allostasis!The varying behavioral and physiological adjustments and regressed internal genital structures. that an individual makes in order to maintain optimal (rather androgens!A class of hormones that includes testosterone and than unchanging) functioning of a regulated system in the face of other male hormones. changing environmental stressors. androstenedione!The chief sex hormone secreted by the alpha motor neuron!A motor neuron that controls the main human adrenal cortex. contractile fibers (extrafusal fibers) of a muscle. angel dust See phencyclidine. alpha rhythm!A brain potential of 8–12 Hz that occurs during angiography!A brain-imaging technique in which a specialized relaxed wakefulness. X-ray image of the head is taken shortly after the cerebral blood ALS See amyotrophic lateral sclerosis. vessels have been filled with a radiopaque dye by means of altricial!Referring to animals that are born in a very immature a catheter. state and depend on maternal care, as human infants do. angiotensin II!A substance that is produced in the blood by the Alzheimer’s disease!A form of dementia that may appear in action of renin and that may play a role in the control of thirst. middle age but is more frequent among the elderly. angular gyrus!A brain region in which strokes can lead to word amacrine cells!Specialized retinal neurons that contact both the blindness. bipolar cells and the ganglion cells and are especially significant anion!A negatively charged ion, such as a protein or chloride ion. in inhibitory interactions within the retina. amblyopia Reduced visual acuity of one eye, that is not caused by annulospiral ending See primary sensory ending. optical or retinal impairments. [7, 10] anomia!The inability to name persons or objects. AMH See anti-müllerian hormone. anorexia nervosa!A syndrome in which individuals severely amine hormones!Also called monoamine hormones. A class of deprive themselves of food. hormones, each composed of a single amino acid that has been anorexigenic neurons!Neurons of the hypothalamic appetite modified into a related molecule, such as melatonin or epineph- system that inhibit feeding behavior. rine. anosmia!The inability to smell. amine neurotransmitter!A neurotransmitter based on modifi- cations of a single amino acid. anosognosia!Denial of illness. amino acid neurotransmitter!A neurotransmitter that is itself ANP See atrial natriuretic peptide. an amino acid. antagonist!1. A molecule, usually a drug, that interferes with or amnesia!Severe impairment of memory. prevents the action of a transmitter. 2. A muscle that counteracts the effect of another muscle. [3, 4, 11] AMPA receptor!A glutamate receptor that also binds the glutamate agonist AMPA. anterior Also called rostral. In anatomy, toward the head end of an organism. Compare posterior. amphetamine!A molecule that resembles the structure of the catecholamine transmitters and enhances their activity. anterior cerebral arteries!Two large arteries, arising from the internal carotid arteries, that provide blood to the anterior poles amphetamine psychosis!A delusional and psychotic state, and medial surfaces of the cerebral hemispheres. closely resembling acute schizophrenia, that is brought on by repeated use of high doses of amphetamine. anterior pituitary!Also called adenohypophysis. The front divi- sion of the pituitary gland. It secretes tropic hormones. G–2!GLOSSARY anterograde amnesia!The inability to form new memories associative learning!A type of learning in which an associa- beginning with the onset of a disorder. tion is formed between two stimuli or between a stimulus and a anterograde degeneration!Also called Wallerian degeneration. response. It includes both classical and operant conditioning. The loss of the distal portion of an axon resulting from injury to astereognosis!The inability to recognize objects by touching and the axon. feeling them. anterolateral system!Also called spinothalamic system. A so- astrocyte!A star-shaped glial cell with numerous processes (ex- matosensory system that carries most of the pain and temperature tensions) that run in all directions. information from the body to the brain. ataxia!An impairment in the direction, extent, and rate of muscu- antibodies!Also called immunoglobulins. Large proteins that recog- lar movement. It is often caused by cerebellar pathology. nize and permanently bind to particular shapes, normally as part of atrial natriuretic peptide (ANP)!A hormone, secreted by the the immune system attack on foreign particles. [15, App] heart, that normally reduces blood pressure, inhibits drinking, and antidepressants!A class of drugs that relieve the symptoms promotes the excretion of water and salt at the kidneys. of depression. attention!Also called selective attention. A state or condition of antidiuretic hormone (ADH) See arginine vasopressin. selective awareness by which specific stimuli are selected for anti-müllerian hormone (AMH)!A protein hormone secreted enhanced processing. [8, 18] by the fetal testis that inhibits müllerian duct development. attention deficit hyperactivity disorder (ADHD)!A syn- antipsychotics!A class of drugs that alleviate symptoms of drome of distractibility, impulsiveness, and hyperactivity that, in schizophrenia, typically by blocking dopamine receptors. children, interferes with school performance. anxiety disorder!Any of a class of psychological disorders that attentional bottleneck!A filter that results from the limits include recurrent panic states and generalized anxiety disorder. intrinsic to our attentional processes, with the result that only the most important stimuli are selected for special processing. anxiolytics!A class of substances that are used to combat anxiety. attentional spotlight!The shifting of our limited selective at- Examples include alcohol, opiates, barbiturates, and tention around the environment to highlight stimuli for enhanced the benzodiazepines. [4, 16] processing. aphagia!Refusal to eat. aura!In epilepsy, the unusual sensations or premonition that may precede the beginning of a seizure. aphasia!An impairment in language understanding and/or production that is caused by brain injury. australopithecine!Referring to Australopithecus, a primate genus, known only from the fossil record and thought to be apical dendrite The type of dendrite that extends from an ancestor to humans. a pyramidal cell to the outermost surface of the cortex. autism spectrum disorder (ASD)!A range of conditions char- apolipoprotein E (ApoE)!A protein that may help break down acterized by social, communication, and behavioral challenges. amyloid. autocrine!Referring to a signal that is secreted by a cell into its apoptosis See cell death. environment and that feeds back to the same cell. APP See amyloid precursor protein. autoimmune disorder!A disorder caused when the immune appetitive behavior!The second stage of mating behavior. It system mistakenly attacks a person’s own body, thereby interfer- helps establish or maintain sexual interaction. ing with normal functioning. apraxia!An impairment in the ability to begin and execute skilled autonomic ganglia!Collections of nerve cell bodies, belonging voluntary movements, even though there is no muscle paralysis. to the autonomic division of the peripheral nervous system, that [11, 19] are found in various locations and innervate the major organs. aquaporins!Channels spanning the cell membrane that are spe- autonomic nervous system!The part of the peripheral nervous cialized for conducting water molecules into or out of the cell. system that supplies neural connections to glands and to smooth arachnoid!The thin covering (one of the three meninges) of muscles of internal organs. the brain that lies between the dura mater and pia mater. autoradiography!A histological technique that shows the distri- arborization!The elaborate branching of the dendrites of bution of radioactive chemicals in tissues. [2, 5] some neurons. autoreceptor!A receptor for a synaptic transmitter that is located arcuate fasciculus!A tract believed by some to connect Wer- in the presynaptic membrane, telling the axon terminal how much nicke’s area to Broca’s area. transmitter has been released. [3, 4] arcuate nucleus!An arc-shaped hypothalamic nucleus impli- AVP See arginine vasopressin. cated in appetite control. axo-axonic!Referring to a synapse in which a presynaptic axon area 17 See primary visual cortex. terminal synapses onto another axon’s terminal. arginine vasopressin (AVP)!Also called vasopressin or an- axo-dendritic!Referring to a synapse in which a presynaptic tidiuretic hormone (ADH). A peptide hormone from the posterior axon terminal synapses onto a dendrite of the postsynaptic neu- pituitary that promotes water conservation. ron, either via a dendritic spine or directly onto the dendrite itself. aromatase!An enzyme that converts some androgens into estro- gens. [5, 12] axon!A single extension from the nerve cell that carries action potentials from the cell body to other neurons. aromatization!The chemical reaction that converts testosterone to estradiol, and other androgens to other estrogens. axon collateral!A branch of an axon from a single neuron. aromatization hypothesis!The hypothesis that testicular an- axon hillock!A cone-shaped area from which the axon originates drogens enter the brain and are converted there into estrogens to out of the cell body. Functionally, it is the integration zone of the masculinize the developing nervous system in some rodents. neuron. [2, 3] ASD See autism spectrum disorder. axon terminal!Also called synaptic bouton. The end of an axon or axon collateral, which forms a synapse on a neuron or other target aspartate!An amino acid transmitter that is excitatory at many cell. synapses. G LOSSA RY ! G–3 axonal transport!The transportation of materials between the binding affinity!Also called simply affinity. The propensity of neuronal cell body and axon terminals. molecules of a drug (or other ligand) to bind to receptors. axo-somatic!Referring to a synapse in which a presynaptic axon binding problem!The question of how the brain understands terminal synapses onto the cell body (soma) of the postsynaptic which individual attributes blend together into a single object, neuron. when these different features are processed by different regions in the brain. B B cell See B lymphocyte. binge eating!The paroxysmal intake of large quantities of food, often of poor nutritional value and high in calories. B lymphocyte!Also called B cell. An immune system cell, formed in the bone marrow (hence the B), that mediates humoral im- binocular deprivation!Depriving both eyes of form vision, as by munity. sealing the eyelids. Bálint’s syndrome!Three co-occurring symptoms— bioavailable!Referring to a substance, usually a drug, that is simultagnosia, oculomotor apraxia, and optic ataxia—that may present in the body in a form that is able to interact with physi- occur after bilateral lesions of cortical attentional systems. ological mechanisms. ballistic movement!A rapid muscular movement that is biological psychology See behavioral neuroscience. generally preprogrammed. biotransformation!The process in which enzymes convert a bar detector See simple cortical cell. drug into a metabolite that is itself active, possibly in ways that are substantially different from the actions of the original substance. barbiturate!A powerful sedative anxiolytic derived from barbitu- ric acid, with dangerous addiction and overdose potential. bipolar cells!A class of interneurons of the retina that receive in- bariatric!Referring to treatment of obesity. formation from rods and cones and pass the information to retinal baroreceptor!A pressure receptor in the heart or a major artery ganglion cells. that detects a decrease in blood pressure. bipolar disorder!Formerly called manic-depressive illness. A basal dendrite One of several dendrites on a pyramidal cell that psychiatric disorder characterized by periods of depression that extend horizontally from the cell body. alternate with excessive, expansive moods. basal forebrain!A ventral region in the forebrain that has been bipolar neuron!A nerve cell that has a single dendrite at one end implicated in consciousness and sleep. and a single axon at the other end. basal ganglia!A group of forebrain nuclei, including caudate blind spot!The portion of the visual field from which light falls nucleus, globus pallidus, and putamen, found deep within the on the optic disc. Because there are no receptors in this region, cerebral hemispheres. [2, 11] light striking it cannot be seen. basal metabolism!The consumption of energy by the basic life- blood-brain barrier!The mechanisms that make the movement sustaining functions of the body. of substances from blood vessels into brain cells more difficult basilar artery!An artery, formed by the fusion of the vertebral than exchanges in other body organs, thus affording the brain arteries, that supplies blood to the brainstem and to the posterior greater protection from exposure to some substances found in the cerebral arteries. blood. [2, 4] basilar membrane!A membrane in the cochlea that contains the blotting Transferring DNA, RNA, or protein fragments to principal structures involved in auditory transduction. nitrocellulose following separation via gel electrophoresis. The blotted substance can then be labeled. [App] bass!An aspect of pitch corresponding to the subjective experi- ence of low-frequency sounds (especially musical sounds, such as border cell!A neuron that selectively fires when an animal bass guitar). arrives at the perimeter of a local spatial cognitive map. batrachotoxin!A toxin, secreted by poison arrow frogs, that bottom-up attention See reflexive attention. selectively interferes with Na+ channels. bottom-up process!A process in which lower-order mecha- Bcl-2!A family of proteins that regulate apoptosis. nisms, like sensory inputs, trigger additional processing by higher-order systems. There may be no conscious awareness until BDNF See brain-derived neurotrophic factor. late in the process. behavioral intervention!An approach to finding relations botulinum toxin!A toxin that cleaves SNAREs, disabling neu- between body variables and behavioral variables that involves in- rotransmitter release. tervening in the behavior of an organism and looking for resultant changes in body structure or function. bovine spongiform encephalopathy (BSE)!Also called mad cow disease. A disorder caused by improperly formed prion behavioral medicine See health psychology. proteins, leading to dementia and death. behavioral neuroscience!Also called biological psychology. The brain self-stimulation!The process in which animals will work study of the neural bases of behavior and mental processes. to provide electrical stimulation to particular brain sites, presum- Bell’s palsy!A disorder, usually caused by viral infection, in ably because the experience is very rewarding. which the facial nerve on one side stops conducting action poten- brain-derived neurotrophic factor (BDNF)!A protein, found tials, resulting in paralysis of one side of the face. in the brains of animals, that can keep some classes of neurons benzodiazepine agonists!A class of antianxiety drugs that alive. bind to sites on GABA A receptors. brainstem!The region of the brain that consists of the midbrain, benzodiazepines!A class of antianxiety drugs that bind with the pons, and the medulla. high affinity to receptor molecules in the central nervous system. Broca’s aphasia See nonfluent aphasia. One example is diazepam (Valium). Broca’s area!A region of the frontal lobe of the brain that is beta activity!EEG activity seen in wakefulness, comprising a mix involved in the production of speech. of many different high frequencies with low amplitude. BSE See bovine spongiform encephalopathy. binaural!Referring to two ears. G–4!G LOSSARY bulimia!Also called bulimia nervosa. A syndrome in which individ- cell differentiation!The developmental stage in which cells uals periodically gorge themselves, usually with “junk food,” and acquire distinctive characteristics, such as those of neurons, as the then either vomit or take laxatives to avoid weight gain. result of expressing particular genes. [7, App] bungarotoxin!A neurotoxin from the venom of the banded krait cell membrane!The lipid bilayer that ensheathes a cell. that selectively blocks acetylcholine receptors. cell migration!The movement of cells from site of origin to final C location. C fiber!A small, unmyelinated axon that conducts pain informa- cell nucleus!The spherical central structure of a cell that contains tion slowly and adapts slowly. the chromosomes. Ca 2+ See calcium ion. cell-autonomous Referring to cell processes that are directed by caffeine!A stimulant compound found in coffee, cacao, and other the cell itself rather than being under the influence of other cells. plants. cell-cell interactions!The general process during develop- CAH See congenital adrenal hyperplasia. ment in which one cell affects the differentiation of other, usually neighboring, cells. calcium ion (Ca 2+)!A calcium atom that carries a double positive charge because it has lost two electrons. central deafness!A hearing impairment that is related to lesions in auditory pathways or centers, including sites in the brainstem, CAM See cell adhesion molecule. thalamus, or cortex. cAMP See cyclic adenosine monophosphate. central nervous system (CNS)!The portion of the nervous cannabidiol (CBD)!An active ingredient in cannabis thought to system that includes the brain and the spinal cord. be responsible inducing a feeling of relaxation. central pattern generator!Neural circuitry that is responsible cannabinoid receptor!A category of cell membrane receptor for generating the rhythmic pattern of a behavior such as walking. proteins that selectively recognize and respond to cannabinoid transmitters and drugs. central sulcus!A fissure that divides the frontal lobe from the cannabis!Also called marijuana. Dried leaves and flowers of the parietal lobe. plant Cannabis sativa, typically smoked to obtain THC and CBD. cerebellum!A structure located at the back of the brain, dorsal to [4, 8] the pons, that is involved in the central regulation of movement. Cannon-Bard theory!The theory that our experience of emotion is independent of the simultaneous physiological changes that cerebral cortex!Also called simply cortex. The outer covering accompany it. of the cerebral hemispheres that consists largely of neuronal cell capsaicin!A compound synthesized by various plants to deter bodies and their branches. predators by mimicking the experience of burning. cerebral hemispheres!The right and left halves of the forebrain. carotid arteries!The major arteries that ascend the left and right sides of the neck to the brain, supplying blood to the anterior and cerebrocerebellum!The lateral portions of each cerebellar middle cerebral arteries. hemisphere. Cas9 CRISPR associated enzyme 9. A bacterial enzyme that cerebrospinal fluid (CSF)!The fluid that fills the cerebral induces a break in double-stranded DNA as part of the CRISPR ventricles. system. [App] cervical!Referring to the topmost eight segments of the spinal caspases!A family of proteins that regulate cell death (apoptosis). cord, in the neck region. cGMP See cyclic guanosine monophosphate. castration!Removal of the gonads, usually the testes. [5, 12] channelopathy!A genetic abnormality of ion channels, causing a CAT or CT See computerized axial tomography. variety of symptoms. cataplexy!Sudden loss of muscle tone, leading to collapse of the channelrhodopsin A protein that, in response to light of the body without loss of consciousness. proper wavelength, opens a channel to admit sodium ions, which catecholamine!A class of monoamines that serve as neurotrans- results in excitation of the neuron. mitters, including dopamine and norepinephrine. ChAT See choline acetyltransferase. cation!A positively charged ion, such as a potassium or sodium chemical transmitter See neurotransmitter. ion. chemically gated ion channel See ligand-gated ion channel. caudal See posterior. chemoaffinity hypothesis!The notion that each cell has caudate nucleus!One of the basal ganglia. It has a long exten- a chemical identity that directs it to synapse on the proper sion or tail. target cell during development. CBT See cognitive behavioral therapy. chemoattractants!Compounds that attract particular classes of CCK See cholecystokinin. axonal growth cones. cell adhesion molecule (CAM)!A protein found on the chemorepellents!Compounds that repel particular classes of surface of a cell that guides cell migration and/or axonal axonal growth cones. pathfinding. chloride ion (Cl –)!A chlorine atom that carries a negative charge cell assembly!A large group of cells that tend to be active at the because it has gained one electron. same time because they have been activated simultaneously or in chlorpromazine!An antipsychotic drug, one of the class of phe- close succession in the past. nothiazines. cell body!Also called soma. The region of a neuron that is defined cholecystokinin (CCK)!A peptide hormone, released by the gut by the presence of the cell nucleus. after ingestion of food high in protein and/or fat, that also serves cell death!Also called apoptosis. The developmental process dur- as a signaling molecule in the brain. ing which “surplus” cells die. choline acetyltransferase (ChAT)!An enzyme involved in the synthesis of the neurotransmitter acetylcholine. G LOSSA RY ! G–5 cholinergic Referring to cells that use acetylcholine as their syn- coding!The rules by which action potentials in a sensory system aptic transmitter. [3, 4] reflect a physical stimulus. choroid plexus!A highly vascular portion of the lining of the codon A set of three nucleotides that uniquely encodes one par- ventricles that secretes cerebrospinal fluid. ticular amino acid. [App] chromosome!A complex of condensed strands of DNA and as- cognitive attribution theory!The theory that our emotional sociated protein molecules. It is found in the cell nucleus. [6, App] experience results from cognitive analysis of the context around chronic traumatic encephalopathy (CTE)!Also called us, such that physiological changes may accentuate emotions but dementia pugilistica or punch-drunk syndrome. The dementia that not specify which emotion we experience. develops in boxers or other athletes who are subjected to repeated cognitive behavioral therapy (CBT)!Psychotherapy aimed blows to the head. at correcting negative thinking and improving interpersonal ciliary muscle!One of the muscles that controls the shape of the relationships. lens inside the eye, focusing an image on the retina. cognitive map!A mental representation of a spatial relationship. cilium!A hairlike cellular extension. cingulate cortex!Also called cingulate gyrus. A region of medial cognitively impenetrable!Referring to data-processing opera- cerebral cortex that lies dorsal to the corpus callosum. tions of the central nervous system that are unconscious. cingulum See cingulate cortex. coincidence detector!A device that senses the co-occurrence of two events. circadian rhythm!A pattern of behavioral, biochemical, or physi- ological fluctuation that has a 24-hour period. coitus See copulation. circannual!Occurring on a roughly annual basis. co-localization!Also called co-release. In neurons, the appear- ance of more than one neurotransmitter in a given presynaptic circle of Willis!A vascular structure at the base of the brain that terminal. is formed by communicating arteries that interconnect the major cerebral arteries. communication!Information transfer between two individuals. circumvallate papillae!One of three types of small structures on the tongue that contain taste receptors, located in the back. comorbid!Referring to the tendency of certain diseases or disor- ders to occur together in individuals. circumventricular organ!An organ that lies in the wall of a cere- bral ventricle and monitors the composition of body fluids. competitive ligand!A substance that directly competes with the endogenous ligand for the same binding site on a receptor CJD See Creutzfeldt-Jakob disease. molecule. Cl – See chloride ion. complex cortical cell!A cell in the visual cortex that responds classical conditioning!Also called Pavlovian conditioning. best to a bar of a particular size and orientation anywhere within A type of associative learning in which an originally neutral a particular area of the visual field. (conditioned) stimulus acquires the power to elicit the response complex environment See enriched condition. normally elicited by another (unconditioned) stimulus after the two stimuli are paired. A response elicited by the unconditioned complex partial seizure!In epilepsy, a type of seizure that stimulus (US) is called an unconditioned response (UR); a response doesn’t involve the entire brain and therefore can cause a wide elicited by the conditioned stimulus (CS) alone is called a condi- variety of symptoms. tioned response (CR). computerized axial tomography (CAT or CT)!A noninva- claustrum!A thin sheet of neurons, situated within the white sive technique for examining brain structure in humans through matter lateral to the basal ganglia, that has been implicated in computer analysis of X-ray absorption at several positions around conscious awareness. the head. cloacal exstrophy!A rare medical condition in which XY indi- concentration gradient!Variation of the concentration of viduals are born completely lacking a penis. a substance within a region. clone To reproduce a gene so that it can be sequenced and/or concordant!Referring to any trait that is seen in both individuals manipulated. [App] of a pair of twins. closed-loop control mechanism!A control mechanism that concussion!Also called minor traumatic brain injury (mTBI). An provides a flow of information from whatever is being controlled injury resulting from a blow to the head and associated with to the device that controls it. temporary neurological symptoms such as memory loss or other cognitive impairments, pain, and visual disturbances. clozapine!A second-generation antipsychotic. conditional knockout!A gene that can be selectively deactivated CNS See central nervous system. in specific tissues and/or at a specific stage of development. cocaine!A drug of abuse, derived from the coca plant, that acts by conduction aphasia!An impairment in the repetition of words potentiating catecholamine stimulation. and sentences. coccygeal!Referring to the lowest spinal vertebra (which is also conduction deafness!A hearing impairment that is associated called the tailbone). with pathology of the external-ear or middle-ear cavities. cochlea!A snail-shaped structure in the inner ear that contains conduction velocity!The speed at which an action potential is the primary receptor cells for hearing. propagated along the length of an axon (or section of peripheral cochlear implant!An electromechanical device that detects nerve). sounds and selectively stimulates nerves in different regions of the conduction zone!The part of the neuron over which the nerve’s cochlea via surgically implanted electrodes. electrical signal may be actively propagated. It usually corre- cochlear nuclei!Brainstem nuclei that receive input from sponds to the cell’s axon. auditory hair cells and send output to the superior olivary cones!A class of photoreceptor cells in the retina that are respon- complex. sible for color vision. cocktail party effect!The selective enhancement of attention in confabulate!To fill in a gap in memory with a falsification. It order to filter out distracters, such as while listening to one person often occurs in Korsakoff’s syndrome. talking in the midst of a noisy party. G–6!GLOSSA RY congenital adrenal hyperplasia (CAH)!Any of several genetic cortex!Also called cerebral cortex or neocortex. The outer covering conditions that result in exposure of a fetus to excessive adrenal of the cerebral hemispheres that consists largely of nerve cell bod- androgens. ies and their branches. congenital hypothyroidism!Also called cretinism. Reduced cortical column!One of the vertical columns that constitute the stature and intellectual disability caused by thyroid deficiency basic organization of the neocortex. during early development. cortical deafness!A hearing impairment that is caused by a fault congenital insensitivity to pain!The condition of being born or defect in the cortex. without the ability to perceive pain. corticospinal system See pyramidal system. conjunction search!A search for an item that is based on two or cortisol!A glucocorticoid stress hormone of the adrenal cortex. [5, more features (e.g., size and color) that together distinguish the 15] target from distracters that may share some of the same attributes. cranial nerve!A nerve that is connected directly to the brain. connectionist model of aphasia!The theory proposing CREB!Cyclic AMP responsive element–binding protein, which that Wernicke’s area and Broca’s area, connected by the arcuate binds the promoter region of several genes involved in neural fasciculus, specialize in the receptive and expressive aspects of plasticity when activated by cAMP. language, respectively. Cre-recombinase!An enzyme normally made by bacteria that connexon!A protein assembly that provides an open ion chan- removes a segment of DNA flanked by two lox sites. [11, App] nel between two neurons, forming an electrical synapse between cretinism See congenital hypothyroidism. them. Creutzfeldt-Jakob disease (CJD)!A brain disorder in hu- consciously controlled attention See voluntary attention. mans, leading to dementia and death, that is caused by improperly consciousness!The state of awareness of one’s own existence folded prion proteins; the human equivalent of mad cow disease. and experience. [1, 18] conserved!In the context of evolution, referring to a trait that is crib death See sudden infant death syndrome. passed on from a common ancestor to two or more descendant CRISPR clustered regularly interspaced short palindromic repeats. species. A system of gene manipulation that evolved in single-celled organ- consolidation!A stage of memory formation in which informa- isms and is exploited by scientists for gene editing. [App] tion in short-term or intermediate-term memory is transferred to cross-tolerance!A condition in which the development of toler- long-term memory. ance for one drug causes an individual to develop tolerance for constraint-induced movement therapy (CIMT)!A therapy another drug. for recovery of limb movement after stroke or injury, in which crystallization The final stage of birdsong formation, in which the unaffected limb is constrained while the person is required to fully formed adult song is achieved. perform tasks with the affected contralateral limb. CSF See cerebrospinal fluid. contralateral!In anatomy, pertaining to a location on the oppo- CT or CAT See computerized axial tomography. site side of the body. Compare ipsilateral. CTE See chronic traumatic encephalopathy. convergence!The phenomenon of neural connections in which cue-induced drug use!An increased likelihood to use a drug many cells send signals to a single cell. (especially an addictive drug) because of the presence of environ- convergent evolution!The evolutionary process by which mental stimuli that were present during previous use of the same responses to similar ecological features bring about similarities drug. in behavior or structure among animals that are only distantly cupula!A small gelatinous structure, containing hair cells that related (i.e., that differ in genetic heritage). detect fluid movement within the semicircular canals of the ves- Coolidge effect!The propensity of an animal that has appeared tibular system. sexually satiated with a present partner to resume sexual activity curare!An alkaloid neurotoxin that causes paralysis by blocking when provided with a novel partner. acetylcholine receptors in muscle. cool-menthol receptor 1 (CMR1) See TRPM8. Cushing’s syndrome!A condition in which levels of adrenal copulation!Also called coitus. The sexual act. glucocorticoids are abnormally high. copulatory lock!Reproductive behavior in which the male’s pe- cyclic adenosine monophosphate (cyclic AMP, or nis swells after ejaculation so that the male and female are forced cAMP)!A second messenger activated in many target cells in to remain joined for 5–15 minutes. It occurs in dogs and some response to synaptic or hormonal stimulation. rodents, but not in humans. cyclic guanosine monophosphate (cyclic GMP, or co-release See co-localization. cGMP) A second messenger activated in some target cells in cornea!The transparent outer layer of the eye, whose curvature is response to synaptic or hormonal stimulation. fixed. It bends light rays and is primarily responsible for forming cytokines!Proteins that induce the proliferation of other cells, as the image on the retina. in the immune system. coronal plane Also called frontal plane or transverse plane. The cytoplasm See intracellular fluid. plane that divides the body or brain into front and back parts. Compare horizontal plane and sagittal plane. D corpora lutea!The structures formed from collapsed ovarian DA See dopamine. follicles subsequent to ovulation. The corpora lutea are a major dB See decibel. source of progesterone. DBS See deep brain stimulation. corpus callosum!The main band of axons that connects the two deafness!Hearing loss so profound that speech perception cerebral hemispheres. [2, 19] is lost. correlation!The covariation of two measures. death gene!A gene that is expressed only when a cell becomes committed to natural cell death (apoptosis). GLOSSA RY ! G–7 decibel (dB) A measure of sound intensity. dfMRI See dyadic functional MRI. declarative memory!A memory that can be stated or described. DHT See dihydrotestosterone. diabetes mellitus!Excessive glucose in the urine, caused by the decomposition of movement!Difficulty of movement in which failure of insulin to induce glucose absorption by the body. gestures are broken up into individual segments instead of being Diablo!A protein released by mitochondria, in response to high executed smoothly. It is a symptom of cerebellar lesions. calcium levels, that activates apoptosis. decorticate rage!Also called sham rage. Sudden intense rage diacylglycerol (DAG)!A common second-messenger compound characterized by actions (such as snarling and biting in dogs) that in postsynaptic cells. lack clear direction. dichotic presentation!The simultaneous delivery of different deep brain stimulation (DBS)!Mild electrical stimulation stimuli to the right and the left ears. [18, 19] through an electrode that is surgically implanted deep in the brain. [11, 16] diencephalon!The posterior part of the forebrain, including the thalamus and hypothalamus. deep dyslexia!Acquired dyslexia in which the person reads a word as another word that is semantically related. diffusion!The passive spread of molecules of one substance among molecules of another substance until a uniform concentra- default mode network!The regions of the brain that are active tion is achieved. [3, 13] when the brain is awake and at rest and attention is not being directed to external events. diffusion tensor imaging (DTI)!A modified form of MRI in which the diffusion of water in a confined space is exploited to degradation!The chemical breakdown of a neurotransmitter into produce images of axonal fiber tracts. [2, 9, 19] inactive metabolites. [3, 4] digestion!The process by which food is broken down to provide delayed non-matching-to-sample task!A test in which, on energy and nutrients. each trial, the participant must select the stimulus that was not seen previously. dihydrotestosterone (DHT)!The 5α-reduced metabolite of tes- tosterone; a potent androgen that is principally responsible for the delta wave!The slowest type of EEG wave, about 1 Hz, masculinization of the external genitalia in mammalian sexual characteristic of stage 3 sleep. differentiation. delusion!A false belief strongly held in spite of contrary evidence. dimer!A complex of two proteins that have bound together. directional selection!Selection that favors a shift in a character- dementia pugilistica See chronic traumatic encephalopathy. istic within a population. dementia!Drastic failure of cognitive ability, including memory discordant!Referring to any trait that is seen in only one indi- failure and loss of orientation. vidual of a pair of twins. dendrite!One of the extensions of the cell body through which dishabituation!The restoration of response amplitude following synaptic inputs are received. habituation. dendritic knob!A portion of an olfactory receptor cell present in disruptive selection!Selection that favors a divergence in the olfactory epithelium. a characteristic within a population. dendro-dendritic!Referring to a synapse in which a synaptic dissociative thinking!A condition, seen in schizophrenia, connection forms between the dendrites of two neurons. that is characterized by disturbances of thought and difficulty dentate gyrus!A strip of gray matter in the hippocampal forma- in relating events properly. tion. dissociative!A type of drug that produces a dreamlike state in deoxyribonucleic acid (DNA) A nucleic acid that is present which consciousness is partly separated from sensory inputs. in the chromosomes of cells and encodes hereditary information. distal!In anatomy, toward the periphery of an organism or the end [App] of a limb. Compare proximal. dependent variable!The factor that an experimenter measures diurnal!Active during the light periods of the daily cycle. to monitor a change in response to manipulation of an indepen- dent variable. divergence!The phenomenon of neural connections in which one cell sends signals to many other cells. depolarization!A reduction in membrane potential (the interior of the neuron becomes less negative). divided-attention task!A task in which the participant is asked to simultaneously focus attention on two or more stimuli. depressants!A class of drugs that act to reduce neural activity. dizygotic!Referring to twins derived from separate eggs ( fraternal twins). Such twins are no more closely related genetically than are depression!A psychiatric condition characterized by such symp- other full siblings. toms as an unhappy mood; loss of interests, energy, and appetite; and difficulty concentrating. DNA See deoxyribonucleic acid. dermatome!A patch of skin innervated by a particular spinal DNA sequencing The process by which the order of nucleotides nerve. in a gene, or amino acids in a protein, is determined. [App] dermis!The middle layer of skin, between the epidermis and dopamine (DA)!A monoamine transmitter found in the mid- the hypodermis. brain—especially the substantia nigra—and basal forebrain. desynchronized EEG!Also called beta activity. A pattern of EEG dopamine hypothesis!The hypothesis that schizophrenia activity comprising a mix of many different high frequencies with results from either excessive levels of synaptic dopamine or exces- low amplitude. sive postsynaptic sensitivity to dopamine. dexamethasone suppression test!A test of pituitary-adrenal dorsal column nuclei!Collection of neurons in the medulla that function in which the participant is given dexamethasone, a syn- receive somatosensory information via the dorsal columns of the thetic glucocorticoid hormone, which should cause a decline in the spinal cord. These neurons send their axons across the midline production of adrenal corticosteroids. and to the thalamus. G–8!G LOSSARY dorsal column system!A somatosensory system that delivers ectoderm!The outer cellular layer of the developing embryo, giv- most touch stimuli via the dorsal columns of spinal white matter ing rise to the skin and the nervous system. to the brain. ectopia!Something out of place—for example, clusters of neurons dorsal!In anatomy, toward the back of the body or the top of the seen in unusual positions in the cortex of someone who has dys- brain. Compare ventral. lexia. dorsal root!The branch of a spinal nerve, entering the dorsal ectopic transmission!Cell-cell communication based on release horn of the spinal cord, that carries sensory information from the of neurotransmitter in regions outside traditional synapses. peripheral nervous system to the spinal cord. ectotherm!An animal whose body temperature is regulated by, dose-response curve (DRC)!A formal plot of a drug’s effects and whose heat comes mainly from, the environment. Examples (on the y-axis) versus the dose given (on the x-axis). include snakes and bees. Down syndrome A syndrome caused by inheriting an extra copy edema!The swelling of tissue, such as in the brain, in response to of chromosome 21, usually accompanied by intellectual disability. injury. edge detector See simple cortical cell. down-regulation!A compensatory reduction in receptor avail- EEG See electroencephalogram and electroencephalography. ability at the synapses of a neuron. [3, 4] efferent!In reference to axons, carrying information from the DRC See dose-response curve. central nervous system to the periphery. Compare afferent. DREADDs (designer receptors exclusively activated by efficacy!Also called intrinsic activity. The extent to which a drug designer drugs)!Artificially modified ACh receptors that activates a response when it binds to a receptor. respond solely to matching exogenous ligands. ejaculation!The forceful expulsion of semen from the penis. DTI See diffusion tensor imaging. electrical synapse!Also called gap junction. The region between DTI tractography!Also called fiber tracking. Visualization of the neurons where the membranes are so close that changes in poten- orientation and terminations of white matter tracts in the tial can flow from one to the other without being translated into a living brain via diffusion tensor imaging. chemical message. dual dependence!Dependence for emergent drug effects that electroconvulsive therapy (ECT)!A last-resort treatment occur only when two drugs are taken simultaneously. for intractable depression, in which a strong electrical current is dualism!Within the concept of separation of soul and body, the passed through the brain, causing a seizure. notion promoted by René Descartes that the mind is subject only electroencephalogram (EEG)!A recording of gross electrical to spiritual interactions while the body is subject only to material activity of the brain recorded from electrodes placed on the scalp. interactions. duplex theory!A theory that we localize sound by combining electroencephalography (EEG)!The recording and study of information about intensity differences and latency differences gross electrical activity of the brain recorded from large electrodes between the two ears. placed on the scalp. dura mater!The outermost of the three meninges that surround electromyography (EMG)!The electrical recording of muscle the brain and spinal cord. activity. [11, 14] dyadic functional MRI (dfMRI)!A form of fMRI in which the electro-oculography (EOG)!The electrical recording of eye brains of two socially-interacting people are scanned simultane- movements. ously in a single scanner. electrostatic pressure!The propensity of charged molecules or dynorphins!One of three kinds of endogenous opioids, substanc- ions to move toward areas with the opposite charge. es that reduce pain perception. [4, 8] embryo!The earliest stage in a developing animal. dyskinesia!Difficulty or distortion in voluntary movement. embryonic stem cell!A cell, derived from an embryo, that has dyslexia!A reading disorder attributed to brain impairment. Ac- the capacity to form any type of tissue. quired dyslexia occurs as a result of injury or disease. Developmental dyslexia is associated with brain abnormalities present from birth. EMG See electromyography. emotion!A subjective mental state that is usually accompanied dysphoria!Unpleasant feelings; the opposite of euphoria. by distinctive behaviors, feelings, and involuntary physiological changes. dystrophin!A protein that is needed for normal muscle function. emotional dyscontrol syndrome A condition consisting of temporal lobe disorders that may underlie some forms of human E violence. ear canal!A tube leading from the pinna to the middle ear. encephalization factor!A measure of brain size relative to body eardrum See tympanic membrane. size. early-selection model!A model of attention in which the at- encoding!A stage of memory formation in which the information tentional bottleneck filters out stimuli before even preliminary entering sensory channels is passed into short-term memory. perceptual analysis has occurred. endocannabinoid!An endogenous ligand of cannabinoid recep- easy problem of consciousness!The problem of how to read tors, thus an analog of cannabis that is produced by the brain. [4, current conscious experiences directly from people’s brains as 13] they’re happening. endocast!A cast of the cranial cavity of a skull, especially useful EC See enriched condition. for studying fossils of extinct species. ecological niche!The unique assortment of environmental op- endocrine!Referring to glands that release chemicals to the inte- portunities and challenges to which each organism is adapted. [6, rior of the body. These glands secrete the principal hormones. 14] endocrine gland!A gland that secretes hormones into the blood- Ecstasy See MDMA. stream to act on distant targets. G LOSSA RY ! G–9 endogenous ligand!Any substance that is produced within the ERP See event-related potential. body and selectively binds to the type of receptor that is under estradiol See 17β-estradiol. study. estrogens!A class of steroid hormones produced by female go- endogenous opioids!A family of peptide transmitters that bind nads. to opioid receptors and act like opiates. They have been called the body’s own narcotics. The three kinds are enkephalins, endor- estrus!The period during which female animals are sexually phins, and dynorphins. [4, 8] receptive. endogenous!Produced inside the body. eukaryote Any organism whose cells have the genetic material contained within a nuclear envelope. [App] endogenously controlled attention See voluntary attention. event-related potential (ERP)!Also called evoked potential. endophenotype!Behavioral or physical characteristics accompa- Averaged EEG recordings measuring brain responses to repeated nying susceptibility to a particular disorder, which may be used to presentations of a stimulus. [3, 18] identify those at risk. evoked potential See event-related potential. endorphins!One of three kinds of endogenous opioids, substanc- es that reduce pain perception. [4, 8] evolution!In biology, the processes by which successive genera- tions of individuals change over very long periods of time. endotherm!An animal whose body temperature is regulated chiefly by internal metabolic processes. Examples include evolution by natural selection!The Darwinian theory that mammals and birds. evolution proceeds by differential success in reproduction. engram!The physical basis of a memory in the brain. It is some- evolutionary psychology!A research field that asks how evo- times referred to as a memory trace on the assumption that it lutionary selection pressures have shaped the behavior of humans involves changes in a neural circuit rather than a single neuron. and other animals. [6, 15] enkephalins!One of three kinds of endogenous opioids, sub- excitatory postsynaptic potential (EPSP)!A depolarizing stances that reduce pain perception. [4, 8] potential in the postsynaptic neuron that is caused by excitatory connections. EPSPs increase the probability that the postsynaptic enriched condition (EC)!Also called complex environment. neuron will fire an action potential. A condition in which laboratory rodents are group-housed with a wide variety of stimulus objects. excitotoxicity!The property by which neurons die when over- stimulated, as with large amounts of glutamate. enteric nervous system!An extensive mesh-like system of neurons that governs the functioning of the gut. executive function!A neural and cognitive system that helps develop plans of action and organizes the activities of other high- enterotype!Each individual’s personal composition of gut micro- level processing systems. biota. exocrine gland!A gland whose secretions exit the body via ducts. entrainment!The process of synchronizing a biological rhythm to an environmental stimulus. exocytosis!In neurons, the process by which a synaptic vesicle fuses with the presynaptic terminal membrane to release neu- enzyme A complicated protein whose action increases the prob- rotransmitter into the synaptic cleft. ability of a specific chemical reaction. [App] exogenous!Arising from outside the body. EOG See electro-oculography. exogenous ligand!Any substance that originates outside the ependymal layer See ventricular zone. body and selectively binds to the type of receptor that is under epidemiology!The scientific study of patterns of disease study. in a population. exogenously controlled attention See reflexive attention. epidermis!The outermost layer of skin, over the dermis. expression The process by which a cell makes an mRNA tran- epigenetic regulation!Process affecting the expression of a script of a particular gene. [App] particular gene or genes without affecting the sequence of nucleo- external ear!The part of the ear that we readily see (the pinna) tides making up the gene itself. and the canal that leads to the eardrum. epigenetic transmission!The passage of epigenetic modifica- external fertilization!The process by which eggs are fertilized tions of a gene from one generation to another. outside of the female’s body, as in many fishes and amphibians. epigenetics!The study of factors that affect gene expression extinction!Short for extinction of simultaneous double stimulation. without making any changes in the nucleotide sequence of the In the context of neurology, an inability to recognize the double genes themselves. nature of stimuli presented simultaneously to both sides of the epilepsy!A brain disorder marked by major sudden changes in body. People experiencing extinction report the stimulus from the electrophysiological state of the brain that are referred to as only one side. seizures. extracellular compartment!The fluid space of the body that epinephrine Also called adrenaline. A compound that acts both exists outside the cells. as a hormone (secreted by the adrenal medulla under the control extracellular fluid!The fluid in the spaces between cells (inter- of the sympathetic nervous system, which prepares the body for stitial fluid) and in the vascular system. action) and as a synaptic transmitter. [5, 15] extrafusal fiber!One of the ordinary muscle fibers that lie episodic memory!Memory of a particular incident or a particu- outside the spindles and provide most of the force for muscle lar time and place. contraction. EPSP See excitatory postsynaptic potential. extraocular muscle!One of the muscles attached to the eyeball equilibrium!In a neuron, the state in which the number of ions that controls its position and movements. crossing a membrane in one direction is matched by the number extrapyramidal system!A motor system that includes the basal crossing in the opposite direction. ganglia and some closely related brainstem structures. equilibrium potential!The voltage across a permeable mem- extrastriate cortex!Visual cortex outside of the primary visual brane that exactly counteracts the movement of ions from the (striate) cortex. side with a high concentration to the side with a low concentra- tion. G–10!GLOSSARY F fornix!A fiber tract that extends from the hippocampus to the FA See fractional anisotropy. mammillary body. face blindness See prosopagnosia. Fourier analysis!The mathematical decomposition of a com- plex pattern into a sum of sine waves of various frequencies and facial feedback hypothesis The hypothesis that our emotional amplitudes. experience is affected by the sensory feedback we receive during particular facial expressions, such as smiling. fourth ventricle!The passageway within the pons that receives cerebrospinal fluid from the third ventricle and releases it to sur- facial nerve!Cranial nerve VII, which receives information from round the brain and spinal cord. the face and controls the superficial muscles there. fovea!The central portion of the retina, packed with the most FAS See fetal alcohol syndrome. photoreceptors and therefore the center of our gaze. fast-twitch muscle fiber!A type of striated muscle that con- fractional anisotropy (FA)!The tendency of water to diffuse tracts rapidly but fatigues readily. more readily along the long axis of an enclosed space, such as an fatal familial insomnia!An inherited disorder in which humans axon. FA is the basis of diffusion tensor imaging. sleep normally at the beginning of their life but stop sleeping in fragile X syndrome!A condition that is a frequent cause of midlife and die 7–24 months later. inherited intellectual disability and is produced by a fragile site fear conditioning!A type of classical conditioning where a pre- on the X chromosome that seems prone to breaking because the viously neutral stimulus is repeatedly paired with shock or some DNA there is unstable. other unpleasant experience, causing the individual to act fearful free nerve ending!An axon that terminates in the skin without in response to the stimulus. [15, 16] any specialized cell associated with it and that detects pain and/or feature integration theory!The idea that conjunction searches changes in temperature. involve multiple cognitive feature maps—overlapping representa- free-running!Referring to a rhythm of behavior shown by an ani- tions of the search array based on individual stimulus attributes. mal deprived of external cues about time of day. frequency!The number of cycles per second in a sound wave; feature search!A search for an item in which the target pops out measured in hertz (Hz). right away because it possesses a unique attribute. frontal eye field (FEF)!An area in the frontal lobe of the brain fecal transplantation!A medical procedure in which gut containing neurons important for establishing gaze in accordance microbiota, via fecal matter, are transferred from a donor to with cognitive goals (top-down processes) rather than with any a host. characteristics of stimuli (bottom-up processes). FEF See frontal eye field. frontal lobe!The most anterior portion of the cerebral cortex. fetal alcohol syndrome (FAS)!A disorder, including intel- frontal plane See coronal plane. lectual disability and characteristic facial anomalies, that affects children exposed to too much alcohol (through maternal inges- FSH See follicle-stimulating hormone. tion) during fetal development. [4, 7] functional MRI (fMRI)!Magnetic resonance imaging that detects fetus!A developing individual after the embryo stage. changes in blood flow and therefore identifies regions of the brain that are particularly active during a given task. fiber tracking See DTI tractography. functional tolerance!Decreased responding to a drug after filopodia!Very fine, tubular outgrowths from the growth cone of repeated exposures, generally as a consequence of up- or down- an axon or dendrite. regulation of receptors. final common pathway!The information-processing pathway fundamental!The predominant frequency of an auditory tone or consisting of all the motor neurons in the body. Motor neurons are a visual scene. known by this collective term because they receive and integrate all motor signals from the brain and then direct movement ac- fungiform papillae!One of three types of small structures on cordingly. the tongue that contain taste receptors, located in the front of the tongue. first-generation antipsychotics!A major class of antischizo- phrenic drugs that share an antagonist activity at dopamine D2 fusiform gyrus!A region on the inferior surface of the cortex, at receptors. [4, 16] the junction of temporal and occipital lobes, that has been associ- ated with recognition of faces. flaccid paralysis!A loss of all movement and reflexes below the level of transection of the spinal cord. G flavor!The sense of taste combined with the sense of smell. G protein-coupled receptors (GPCRs)!A large family of cell-membrane-spanning receptors that, when activated extracel- flower spray ending See secondary sensory ending. lularly, use G proteins on their intracellular surface to affect the fluent aphasia!Also called Wernicke’s aphasia. A language im- receiving cell. [4, 5] pairment characterized by fluent, meaningless speech and little G proteins!A class of proteins that are next to the intracellular language comprehension. It is related to damage in Wernicke’s portion of a receptor and that are activated when the receptor area. binds an appropriate ligand on the extracellular surface. fMRI See functional MRI. GABA See gamma-aminobutyric acid. foliate papillae!One of three types of small structures on the gamete!A sex cell (sperm or ovum) that contains only unpaired tongue that contain taste receptors, located along the sides of the chromosomes and therefore has only half the usual number of tongue. chromosomes in other cells. follicles!Ovarian structures containing immature ova. gamma efferent See gamma motor neuron. follicle-stimulating hormone (FSH)!A gonadotropin, named gamma motor neuron!Also called gamma efferent. A motor for its actions on ovarian follicles. neuron that innervates the contractile tissue (the intrafusal fiber) forebrain!Also called prosencephalon. The anterior division of the in a muscle spindle. brain, containing the cerebral hemispheres, the thalamus, and the gamma-aminobutyric acid (GABA)!A widely distributed hypothalamus. [2, 7] inhibitory amino acid transmitter. G LOSSA RY ! G–11 ganglion cells!A class of cells in the retina whose axons form the glutamatergic!Referring to cells that use glutamate as their optic nerve. synaptic transmitter. gap junction See electrical synapse. glycine!An amino acid transmitter, often inhibitory. gas neurotransmitter!A soluble gas, such as nitric oxide or car- glycogen!A complex carbohydrate derived from glucose. bon monoxide, that is produced and released by a neuron to alter glycogenesis!The physiological process by which glycogen is the functioning of another neuron. produced. gel electrophoresis A method of separating molecules of dif- glycogenolysis!The conversion of glycogen back into glucose, fering size or electrical charge by forcing them to flow through a triggered when blood concentrations of glucose drop too low. gel. [App] glymphatic system!A lymphatic system in the brain that par- gender!The behaviors and attitudes that a given culture considers ticipates in removal of wastes and the movement of nutrients and to be masculine or feminine, or an alternative. signaling compounds. gene!A length of DNA that encodes the information for con- GnIH See gonadotropin-inhibiting hormone. structing a particular protein. [6, App] GnRH See gonadotropin-releasing hormone. gene amplification See polymerase chain reaction. goiter!A swelling of the thyroid gland resulting from iodine gene expression!The process by which a cell transcribes a par- deficiency. ticular gene and makes the protein it encodes. Goldman equation!An equation predicting the potential differ- general anesthetic!A drug that renders an individual uncon- ence across a membrane based on the concentrations of multiple scious. ions on opposite sides of the membrane, as well as its relative generator potential See receptor potential. permeability to each ion. genetic polymorphisms!The phenomenon in which there exist Golgi stain!A cell stain that fills a small proportion of neurons multiple (sometimes many) different alleles at an individual locus with a dense dark product. within a gene. Golgi tendon organ!One of the receptors located in tendons genetics!The study of inheritance, including the genes encoded that send action potentials to the central nervous system reporting in DNA. muscle tension. genome Also called genotype. All the genetic information that gonadotropin!Any anterior pituitary hormone that selectively one specific individual has inherited. [7, App] stimulates the gonads to produce steroids and gametes. genotype!Also called genome. All the genetic information gonadotropin-inhibiting hormone (GnIH)!A hypothalamic that one specific individual has inherited. peptide hormone that reduces gonadotropin secretion from the genus!A group of species that resemble each other because of pituitary. shared inheritance. gonadotropin-releasing hormone (GnRH)!A hypothalamic GH See growth hormone. hormone that controls the release of luteinizing hormone and follicle-stimulating hormone from the pituitary. ghrelin!A peptide gut hormone believed to act on the hypothala- mus to increase hunger. gonads!The sexual glands (ovaries in females, testes in males), which produce gametes for reproduction. glial cells!Also called glia or neuroglia. Nonneuronal brain cells that provide structural, nutritional, and other types of support to grammar!All of the rules for usage of a particular language. the brain. grand mal seizure See tonic-clonic seizure. global aphasia!The total loss of ability to understand language granule cell!A type of small nerve cell. or to speak, read, or write. gray matter!Areas of the brain that are dominated by cell bodies globus pallidus!One of the basal ganglia. and are devoid of myelin. glomerulus!A complex arbor of dendrites from a group of olfac- grid cell!A neuron that selectively fires when an animal crosses tory cells. the intersection points of an abstract grid map of the local envi- GLP-1!A peptide gut hormone believed to act on the hypothala- ronment. mus and brainstem to suppress appetite. gRNA See guide RNA. glucagon!A hormone, released by pancreatic alpha cells, that gross neuroanatomy!Anatomical features of the nervous sys- increases blood glucose. tem that are apparent to the naked eye. glucocorticoids!A class of steroid hormones, released by the growth cone!The growing tip of an axon or a dendrite. adrenal cortex, that affect carbohydrate metabolism and inflam- growth hormone (GH)!Also called somatotropin or somatotropic mation. hormone. A tropic hormone, secreted by the anterior pituitary, that glucodetector!A cell that detects and informs the nervous sys- influences the growth of cells and tissues. tem about levels of circulating glucose. guevedoces!Literally, “eggs at 12” (in Spanish). A nickname for gluconeogenesis!The metabolism of body fats and proteins to individuals who are raised as girls but at puberty change appear- create glucose. ance and begin behaving as boys do. glucose!A sugar molecule used by the body and brain for energy. guide RNA (gRNA) A strand of RNA designed to hybridize with a targeted nucleotide sequence in DNA in order to guide the glucose transporter A molecule that conducts glucose mol- Cas9 enzyme to break the DNA at that site. [App] ecules through the external membrane of a cell for use inside. gustatory system!The taste system. glutamate!An amino acid transmitter, the most common excit- gut microbiota!The microorganisms that normally inhabit the atory transmitter. [4, 8] digestive tract. glutamate hypothesis!The hypothesis that schizophrenia may gyrus!A ridged or raised portion of a convoluted brain surface. be caused, in part, by understimulation of glutamate receptors. G–12!GLOSSARY H huntingtin!A protein produced by a gene called HTT that may habituation!A form of nonassociative learning in which an or- contain too many trinucleotide repeats. When it does, the protein ganism becomes less responsive following repeated presentations causes Huntington’s disease in a carrier. of a stimulus. Huntington’s disease!A progressive genetic disorder character- hair cell!A cochlear auditory receptor cell. ized by abrupt, involuntary movements and profound changes in mental functioning. hallucinogens!A class of drugs that alter sensory perception and produce peculiar experiences. hybridization The process by which a string of nucleotides be- comes linked to a complementary series of nucleotides. [App] halorhodopsin!An ion channel protein that, when stimulated by light, hyperpolarizes neurons. hydrocephalus!A ballooning of the ventricles, at the expense of the surrounding brain, which may occur when the circulation of hard problem of consciousness!The problem of how to read cerebrospinal fluid is blocked. people’s subjective experience of consciousness and determine the qualia that accompany perception. hyperphagia!Excessive eating. harmonics!Multiples of a particular frequency called the funda- hyperpolarization!An increase in membrane potential (the inte- mental. rior of the neuron becomes even more negative). health psychology!Also called behavioral medicine. A field that hypertonic!Referring to a solution with a higher concentration studies psychological influences on health-related processes, such of salt than that found in interstitial fluid and blood plasma (more as why people become ill or how they remain healthy. than about 0.9% salt). hearing loss!Decreased sensitivity to sound, in varying hypocretins!Also called orexins. Neuropeptides produced in the degrees. hypothalamus that are involved in switching between sleep states, in narcolepsy, and in the control of appetite. Hebbian synapse!A synapse that is strengthened when it successfully drives the postsynaptic cell. [7, 17] hypodermis!Also called subcutaneous tissue. The innermost layer of skin, under the dermis. hemiparesis!Weakness of one side of the body. hypofrontality hypothesis!The hypothesis that schizophrenia hemiplegia!Partial paralysis involving one side of the body. may result from underactivation of the frontal lobes. hemispatial neglect!A syndrome in which the person fails to hypophyseal portal system!Also called pituitary portal system. pay any attention to objects presented to one side of the body and A system of capillaries spanning between the neurosecretory cells may even deny connection with that side. of the hypothalamus and the secretory tissue of hermaphrodite!An individual possessing the reproductive