Chapter 1
17
dualism
The belief that the body is physical but the mind (or soul) is not.
monism
The belief that the world consists only of matter and energy and the mind is part of it.
blindsight
The ability of a person who cannot see objects in his or her blind field to accurately reach for them while remaining unconscious of perceiving them; caused by damage to the "mammalian" visual system of the brain.
corpus callosum
The largest commissure of the brain, interconnecting the areas of neocortex on each side of the brain.
split-brain operation
Brain surgery occasionally performed to treat a form of epilepsy; surgeon cuts the corpus callosum, which connects the two hemispheres of the brain.
cerebral hemispheres
The two symmetrical halves of the brain; constitute the major part of the brain.
generalization
Type of scientific explanation; a general conclusion based on many observations of similar phenomena.
reduction
Type of scientific explanation; a phenomenon is described in terms of the more elementary processes that underlie it.
reflex
An automatic, stereotyped movement produced as the direct result of a stimulus.
model
A mathematical or physical analogy for a physiological process; for example, computers have been used as models for various functions of the brain.
doctrine of specific nerve energies
Müller's conclusion that because all nerve fibers carry the same type of message, sensory information must be specified by the particular nerve fibers that are active.
experimental ablation
The research method in which the function of a part of the brain is inferred by observing the behaviors an animal can no longer perform after that part is damaged.
functionalism
The principle that the best way to understand a biological phenomenon (a behavior or a physiological structure) is to try to understand its useful functions for the organism.
natural selection
The process by which inherited traits that confer a selective advantage (increase an animal's likelihood to live and reproduce) become more prevalent in the population.
mutation
A change in the genetic information contained in the chromosomes of gametes, which can be passed on to an organism's offspring; provides genetic variability.
selective advantage
A characteristic of an organism that permits it to produce more than the average number of offspring of its species.
physiological psychologist
A scientist who studies the physiology of behavior, primarily by performing physiological and behavioral experiments with laboratory animals.
Chapter 2
101
sensory neuron
A neuron that detects changes in the external or internal environment and sends information about these changes to the central nervous system.
motor neuron
A neuron located within the central nervous system that controls the contraction of a muscle or the secretion of a gland.
interneuron
A neuron located entirely within the central nervous system.
central nervous system/CNS
The brain and spinal cord.
peripheral nervous system/PNS
That part of the nervous system outside the brain and spinal cord, including the nerves attached to the brain and spinal cord.
soma
The cell body of a neuron, which contains the nucleus.
dendrite
A branched, treelike structure attached to the soma of a neuron; receives information from the terminal buttons of other neurons.
synapse
A junction between the terminal button of an axon and the membrane of another neuron.
axon
The long, thin, cylindrical structure that conveys information from the soma of a neuron to its terminal buttons.
multipolar neuron
A neuron with one axon and many dendrites attached to its soma.
bipolar neuron
A neuron with one axon and one dendrite attached to its soma.
unipolar neuron
A neuron with one axon attached to its soma; the axon divides, with one branch receiving sensory information and the other sending the information into the central nervous system.
terminal button
The bud at the end of a branch of an axon; forms synapses with another neuron; sends information to that neuron.
transmitter substance/neurotransmitter
A chemical that is released by a terminal button; has an excitatory or inhibitory effect on another neuron.
membrane
A structure consisting principally of lipid molecules that defines the outer boundaries of a cell and also constitutes many of the cell organelles, such as the Golgi apparatus.
nucleus
A structure in the central region of a cell, enclosed by a membrane, containing the nucleolus and chromosomes.
nucleolus
An structure within the nucleus of a cell that produces the ribosomes.
ribosome
A cytoplasmic structure, made of protein, that serves as the site of production of proteins translated from mRNA.
chromosome
A strand of DNA, with associated proteins, found in the nucleus; carries genetic information.
deoxyribonucleic acid/DNA
A long, complex macromolecule consisting of two interconnected helical strands; along with associated proteins, strands of DNA constitute the chromosomes.
gene
The functional unit of the chromosome, which directs synthesis of one or more proteins.
messenger ribonucleic acid/mRNA
A macromolecule that delivers genetic information concerning the synthesis of a protein from a portion of a chromosome to a ribosome.
enzyme
A molecule that controls a chemical reaction, combining two substances or breaking a substance into two parts.
cytoplasm
The viscous, semiliquid substance contained in the interior of a cell.
mitochondria
An organelle responsible for extracting energy from nutrients.
adenosine triphosphate/ATP
A molecule of prime importance to cellular energy metabolism; its breakdown liberates energy.
endoplasmic reticulum
Parallel layers of membrane found within the cytoplasm of a cell. Rough endoplasmic reticulum contains ribosomes; smooth endoplasmic reticulum is the site of synthesis of lipids and provides channels for the segregation of molecules involved in various cellular processes.
Golgi apparatus
A complex of parallel membranes in the cytoplasm that wraps the products of a secretory cell.
exocytosis
The secretion of a substance by a cell through means of vesicles; the process by which neurotransmitters are secreted.
lysosome
An organelle surrounded by membrane; contains enzymes that break down waste products.
cytoskeleton
Formed of microtubules, neurofilaments, and microfilaments, linked to each other and forming a cohesive mass that gives a cell its shape.
microtubule
A long strand of bundles of protein filaments arranged around a hollow core; part of the cytoskeleton and involved in transporting substances from place to place within the cell.
neurofilament
One of the fibers of the cytoskeleton, made of long, continuous strands of protein similar to those found in hair.
microfilament
The thinnest of the fibers of the cytoskeleton; forms a meshwork just inside the membrane that holds membrane-bound proteins in place.
axoplasmic transport
An active process by which substances are propelled along microtubules that run the length of the axon.
anterograde
In a direction along an axon from the cell body toward the terminal buttons.
retrograde
In a direction along an axon from the terminal buttons toward the cell body.
glia
The supporting cells of the central nervous system.
astrocyte
A glial cell that provides support for neurons of the central nervous system, provides nutrients and other substances, and regulates the chemical composition of the extracellular fluid.
phagocytosis
The process by which cells engulf and digest other cells or debris caused by cellular degeneration.
oligodendrocyte
A type of glial cell in the central nervous system that forms myelin sheaths.
myelin sheath
A sheath that surrounds axons and insulates them, preventing messages from spreading between adjacent axons.
node of Ranvier
A naked portion of a myelinated axon, between adjacent oligodendroglia or Schwann cells.
microglia
The smallest of glial cells; act as phagocytes and protect the brain from invading microorganisms.
Schwann cell
A cell in the peripheral nervous system that is wrapped around a myelinated axon, providing one segment of its myelin sheath.
blood-brain barrier
A semipermeable barrier produced by the astrocytes and cells in the walls of the capillaries in the brain.
area postrema
A region of the medulla where the blood-brain barrier is weak; poisons can be detected there and can initiate vomiting.
electrode
A conductive medium that can be used to apply electrical stimulation or to record electrical potentials.
microelectrode
A very fine electrode, generally used to record activity of individual neurons.
membrane potential
The electrical charge across a cell membrane; the difference in electrical potential inside and outside the cell.
oscilloscope
A laboratory instrument capable of displaying a graph of voltage as a function of time on the face of a cathode ray tube.
resting potential
The membrane potential of a neuron when it is not being altered by excitatory or inhibitory postsynaptic potentials; approximately -70 mV in the giant squid axon.
depolarization
Reduction (toward zero) of the membrane potential of a cell from its normal resting potential.
hyperpolarization
An increase in the membrane potential of a cell, relative to the normal resting potential.
action potential
The brief electrical impulse that provides the basis for conduction of information along an axon.
threshold of excitation
The value of the membrane potential that must be reached in order to produce an action potential.
diffusion
Movement of molecules from regions of high concentration to regions of low concentration.
electrolyte
An aqueous solution of a material that ionizes-namely, a soluble acid, base, or salt.
cation
A positively charged particle.
anion
A negatively charged particle.
electrostatic pressure
The attractive force between atomic particles charged with opposite signs, or the repulsive force between atomic particles charged with the same sign.
intracellular fluid
The fluid contained within cells.
extracellular fluid
Body fluids located outside of cells.
sodium-potassium transporter
A protein found in the membrane of all cells that extrudes sodium ions from and transports potassium ions into the cell.
ion channel
A specialized protein molecule that permits specific ions to enter or leave cells.
voltage-dependent ion channel
An ion channel that opens or closes according to the value of the membrane potential.
all-or-none law
The principle that once an action potential is triggered in an axon, it is propagated, without decrement, to the end of the fiber.
rate law
The principle that variations in the intensity of a stimulus or other information being transmitted in an axon are represented by variations in the rate at which that axon fires.
cable properties
The passive conduction of electrical current, in a decremental fashion, down the length of an axon.
saltatory conduction
Conduction of action potentials by myelinated axons. The action potential "jumps" from one node of Ranvier to the next.
postsynaptic potential
Alterations in the membrane potential of a postsynaptic neuron, produced by liberation of transmitter substance at the synapse.
neuromodulator
A naturally secreted substance that acts like a neurotransmitter except that it is not restricted to the synaptic cleft but diffuses through the interstitial fluid.
endocrine gland
A gland that liberates its secretions into the extracellular fluid around capillaries and hence into the bloodstream.
target cell
The type of cell that is directly affected by a hormone or nerve fiber.
binding site
The location on a receptor protein to which a ligand binds.
ligand
A chemical that binds with the binding site of a receptor.
dendritic spine
A small bud on the surface of a dendrite, with which a terminal button from another neuron forms a synapse.
presynaptic membrane
The membrane of a terminal button that lies adjacent to the postsynaptic membrane.
postsynaptic membrane
The cell membrane opposite the terminal button in a synapse; the membrane of the cell that receives the message.
synaptic cleft
The space between the presynaptic membrane and the postsynaptic membrane.
synaptic vesicle
A small, hollow, beadlike structure found in terminal buttons; contains molecules of a neurotransmitter.
release zone
A region of the interior of the postsynaptic membrane of a synapse to which synaptic vesicles attach and release their neurotransmitter into the synaptic cleft.
cisterna
A part of the Golgi apparatus; through the process of pinocytosis, it receives portions of the presynaptic membrane and recycles them into synaptic vesicles.
pinocytosis
The pinching off of a bud of cell membrane, which travels to the interior of the cell.
postsynaptic receptor
A receptor molecule in the postsynaptic membrane of a synapse that contains a binding site for a neurotransmitter.
neurotransmitter-dependent ion channel
An ion channel that opens when a molecule of a neurotransmitter binds with a postsynaptic receptor.
ionotropic receptor
A receptor that contains a binding site for a neurotransmitter and an ion channel that opens when a molecule of the neurotransmitter attaches to the binding site.
metabotropic receptor
A receptor that contains a binding site for a neurotransmitter; activates an enzyme that begins a series of events that opens an ion channel elsewhere in the membrane of the cell when a molecule of the neurotransmitter attaches to the binding site.
G protein
A protein coupled to a metabotropic receptor; conveys messages to other molecules when a ligand binds with and activates the receptor.
second messenger
A chemical produced when a G protein activates an enzyme; carries a signal that results in the opening of the ion channel or causes other events to occur in the cell.
reuptake
The reentry of a transmitter substance just liberated by a terminal button back through its membrane, thus terminating the postsynaptic potential.
enzymatic deactivation
The destruction of a transmitter substance by an enzyme after its release-for example, the destruction of acetylcholine by acetylcholinesterase.
acetylcholine/ACh
A neurotransmitter found in the brain, spinal cord, and parts of the peripheral nervous system; responsible for muscular contraction.
acetylcholinesterase/AChE
The enzyme that destroys acetylcholine soon after it is liberated by the terminal buttons, thus terminating the postsynaptic potential.
neural integration
The process by which inhibitory and excitatory postsynaptic potentials summate and control the rate of firing of a neuron.
autoreceptor
A receptor molecule located on a neuron that responds to the neurotransmitter released by that neuron.
presynaptic inhibition
The action of a presynaptic terminal button in an axoaxonic synapse; reduces the amount of neurotransmitter released by the postsynaptic terminal button.
presynaptic facilitation
The action of a presynaptic terminal button in an axoaxonic synapse; increases the amount of neurotransmitter released by the postsynaptic terminal button.
gap junction
A special junction between cells that permits direct communication by means of electrical coupling.
peptide
A chain of amino acids joined together by peptide bonds.
steroid
A chemical of low molecular weight, derived from cholesterol. Steroid hormones affect their target cells by attaching to receptors found within the cell.
Chapter 3
117
neuraxis
An imaginary line drawn through the center of the length of the central nervous system, from the bottom of the spinal cord to the front of the forebrain.
anterior
With respect to the central nervous system, located near or toward the head.
posterior
With respect to the central nervous system, located near or toward the tail.
rostral
"Toward the beak"; with respect to the central nervous system, in a direction along the neuraxis toward the front of the face.
caudal
"Toward the tail"; with respect to the central nervous system, in a direction along the neuraxis away from the front of the face.
dorsal
"Toward the back"; with respect to the central nervous system, in a direction perpendicular to the neuraxis toward the top of the head or the back.
ventral
"Toward the belly"; with respect to the central nervous system, in a direction perpendicular to the neuraxis toward the bottom of the skull or the front surface of the body.
lateral
Toward the side of the body, in a direction at right angles with the neuraxis and away from it.
medial
Toward the neuraxis, away from the side of the body.
ipsilateral
Located on the same side of the body.
contralateral
Located on the opposite side of the body.
cross section/frontal section
With respect to the central nervous system, a slice taken at right angles to the neuraxis.
horizontal section
A slice through the brain parallel to the ground.
sagittal section
A slice through the brain parallel to the neuraxis and perpendicular to the ground.
midsagittal plane
The plane through the neuraxis perpendicular to the ground; divides the brain into two symmetrical halves.
central nervous system
The brain and spinal cord.
peripheral nervous system
The nerves and ganglia located outside the central nervous system.
vertebral artery
An artery whose branches serve the posterior region of the brain.
internal carotid artery
An artery whose branches serve the rostral and lateral portions of the brain.
meninges
The three layers of tissue that encase the central nervous system: the dura mater, arachnoid membrane, and pia mater.
dura mater
The outermost of the meninges; tough, flexible, unstretchable.
arachnoid membrane
The middle layer of the meninges, between the outer dura mater and inner pia mater. The subarachnoid space beneath the arachnoid membrane is filled with cerebrospinal fluid, which cushions the brain.
pia mater
The layer of the meninges adjacent to the surface of the brain.
subarachnoid space
The fluid-filled space between the arachnoid membrane and the pia mater.
cerebrospinal fluid
A clear fluid, similar to blood plasma, that fills the ventricular system of the brain and the subarachnoid space surrounding the brain and spinal cord.
ventricle
One of the hollow spaces within the brain, filled with cerebrospinal fluid.
lateral ventricle
One of the two ventricles located in the center of the telencephalon.
third ventricle
The ventricle located in the center of the diencephalon.
cerebral aqueduct
A narrow tube interconnecting the third and fourth ventricles of the brain, located in the center of the mesencephalon.
fourth ventricle
The ventricle located between the cerebellum and the dorsal pons, in the center of the metencephalon.
choroid plexus
The highly vascular tissue that protrudes into the ventricles and produces cerebrospinal fluid.
arachnoid granulation
Small projections of the arachnoid membrane through the dura mater into the superior sagittal sinus; CSF flows through them to be reabsorbed into the blood supply.
superior sagittal sinus
A venous sinus located in the midline just dorsal to the brain, between the two cerebral hemispheres.
obstructive hydrocephalus
A condition in which all or some of the brain's ventricles are enlarged; caused by an obstruction that impedes the normal flow of CSF.
forebrain
The most rostral of the three major divisions of the brain; includes the telencephalon and diencephalon.
cerebral hemisphere
One of the two major portions of the forebrain, covered by the cerebral cortex.
subcortical region
The region located within the brain, beneath the cortical surface.
cerebral cortex
The outermost layer of gray matter of the cerebral hemispheres.
sulcus
A groove in the surface of the cerebral hemisphere, smaller than a fissure.
fissure
A major groove in the surface of the brain, larger than a sulcus.
gyrus
A convolution of the cortex of the cerebral hemispheres, separated by sulci or fissures.
primary visual cortex
The region of the cerebral cortex whose primary input is from the visual system.
calcarine fissure
A fissure located in the occipital lobe on the medial surface of the brain; contains most of the primary visual cortex.
primary auditory cortex
The region of the cerebral cortex whose primary input is from the auditory system.
lateral fissure
The fissure that separates the temporal lobe from the overlying frontal and parietal lobes.
primary somatosensory cortex
The region of the cerebral cortex whose primary input is from the somatosensory system.
central sulcus
The sulcus that separates the frontal lobe from the parietal lobe.
primary motor cortex
The region of the cerebral cortex that contains neurons that control movements of skeletal muscles.
frontal lobe
The anterior portion of the cerebral cortex, rostral to the parietal lobe and dorsal to the temporal lobe.
parietal lobe
The region of the cerebral cortex caudal to the frontal lobe and dorsal to the temporal lobe.
temporal lobe
The region of the cerebral cortex rostral to the occipital lobe and ventral to the parietal and frontal lobes.
occipital lobe
The region of the cerebral cortex caudal to the parietal and temporal lobes.
sensory association cortex
Those regions of the cerebral cortex that receive information from the regions of primary sensory cortex.
motor association cortex
The region of the frontal lobe rostral to the primary motor cortex.
prefrontal cortex
The region of the frontal lobe rostral to the motor association cortex.
corpus callosum
The largest commissure of the brain, interconnecting the areas of neocortex on each side of the brain.
neocortex
The phylogenetically newest cortex, including the primary sensory cortex, primary motor cortex, and association cortex.
limbic cortex
Phylogenetically old cortex, located at the edge ("limbus") of the cerebral hemispheres; part of the limbic system.
cingulate gyrus/cingulate cortex
A strip of limbic cortex lying along the lateral walls of the groove separating the cerebral hemispheres, just above the corpus callosum.
commissure
A fiber bundle that interconnects corresponding regions on each side of the brain.
limbic system
A group of brain regions including the anterior thalamic nuclei, amygdala, hippocampus, limbic cortex, and parts of the hypothalamus, as well as their interconnecting fiber bundles.
hippocampus/hippocampal formation
A forebrain structure of the temporal lobe, constituting an important part of the limbic system; includes the hippocampus proper (Ammon's horn), dentate gyrus, and subiculum.
amygdala
A structure in the interior of the rostral temporal lobe, containing a set of nuclei; part of the limbic system.
fornix
A fiber bundle that connects the hippocampus with other parts of the brain, including the mammillary bodies of the hypothalamus.
mammillary bodies/mammillary body
A protrusion of the bottom of the brain at the posterior end of the hypothalamus, containing some hypothalamic nuclei.
basal ganglia
A group of subcortical nuclei in the telencephalon, the caudate nucleus, the globus pallidus, and the putamen; important parts of the motor system.
diencephalon
A region of the forebrain surrounding the third ventricle; includes the thalamus and the hypothalamus.
thalamus
The largest portion of the diencephalon, located above the hypothalamus; contains nuclei that project information to specific regions of the cerebral cortex and receive information from it.
projection fiber
An efferent axon from a neuron in one region of the brain whose terminals form synapses with neurons in another region.
nucleus
An identifiable group of neural cell bodies in the central nervous system.
lateral geniculate nucleus
A group of cell bodies in the thalamus that receives fibers from the retina and projects fibers to the primary visual cortex.
medial geniculate nucleus
A group of cell bodies in the thalamus that receives fibers from the auditory system and projects fibers to the primary auditory cortex.
ventrolateral nucleus
A nucleus of the thalamus that receives inputs from the cerebellum and sends axons to the primary motor cortex.
hypothalamus
The group of nuclei of the diencephalon situated beneath the thalamus; involved in regulation of the autonomic nervous system, control of the anterior and posterior pituitary glands, and integration of species-typical behaviors.
optic chiasm
A cross-shaped connection between the optic nerves, located below the base of the brain, just anterior to the pituitary gland.
anterior pituitary gland
The anterior part of the pituitary gland; an endocrine gland whose secretions are controlled by the hypothalamic hormones.
neurosecretory cell
A neuron that secretes a hormone or hormonelike substance.
posterior pituitary gland
The posterior part of the pituitary gland; an endocrine gland that contains hormone-secreting terminal buttons of axons whose cell bodies lie within the hypothalamus.
midbrain/mesencephalon
The central of the the three major divisions of the brain, surrounds the cerebral aqueduct; includes the tectum and the tegmentum.
tectum
The dorsal part of the midbrain; includes the superior and inferior colliculi.
superior colliculi
Protrusions on top of the midbrain; part of the visual system.
inferior colliculi
Protrusions on top of the midbrain; part of the auditory system.
brain stem
The "stem" of the brain, from the medulla to the diencephalon, excluding the cerebellum.
tegmentum
The ventral part of the midbrain; includes the periaqueductal gray matter, reticular formation, red nucleus, and substantia nigra.
reticular formation
A large network of neural tissue located in the central region of the brain stem, from the medulla to the diencephalon.
periaqueductal gray matter
The region of the midbrain surrounding the cerebral aqueduct; contains neural circuits involved in species-typical behaviors.
red nucleus
A large nucleus of the midbrain that receives inputs from the cerebellum and motor cortex and sends axons to motor neurons in the spinal cord.
substantia nigra
A darkly stained region of the tegmentum that contains neurons that communicate with the caudate nucleus and putamen in the basal ganglia.
hindbrain
The most caudal of the three major divisions of the brain; includes the metencephalon and myelencephalon.
cerebellum
A major part of the brain located dorsal to the pons, containing the two cerebellar hemispheres, covered with the cerebellar cortex; an important component of the motor system.
cerebellar cortex
The cortex that covers the surface of the cerebellum
deep cerebellar nuclei
Nuclei located within the cerebellar hemispheres; receive projections from the cerebellar cortex and send projections out of the cerebellum to other parts of the brain.
cerebellar peduncle
One of three bundles of axons that attach each cerebellar hemisphere to the dorsal pons.
pons
The region of the metencephalon rostral to the medulla, caudal to the midbrain, and ventral to the cerebellum.
medulla/medulla oblongata
The most caudal portion of the brain; located in the myelencephalon, immediately rostral to the spinal cord.
spinal cord
The cord of nervous tissue that extends caudally from the medulla
spinal root
A bundle of axons surrounded by connective tissue that occurs in pairs, which fuse and form a spinal nerve.
cauda equina
A bundle of spinal roots located caudal to the end of the spinal cord.
caudal block
The anesthesia and paralysis of the lower part of the body produced by injection of a local anesthetic into the cerebrospinal fluid surrounding the cauda equina.
dorsal root
The spinal root that contains incoming (afferent) sensory fibers.
ventral root
The spinal root that contains outgoing (efferent) motor fibers.
spinal nerve
A peripheral nerve attached to the spinal cord.
afferent axon
An axon directed toward the central nervous system, conveying sensory information.
efferent axon
An axon directed away from the central nervous system, conveying motor commands.
dorsal root ganglion
A nodule on a dorsal root that contains cell bodies of afferent spinal nerve neurons.
cranial nerve
A peripheral nerve attached directly to the brain.
vagus nerve
The largest of the cranial nerves, conveying efferent fibers of the parasympathetic division of the autonomic nervous system to organs of the thoracic and abdominal cavities.
olfactory bulb
The protrusion at the end of the olfactory nerve; receives input from the olfactory receptors.
somatic nervous system
The part of the peripheral nervous system that controls the movement of skeletal muscles or transmits somatosensory information to the central nervous system.
autonomic nervous system/ANS
The portion of the peripheral nervous system that controls the body's vegetative function.
sympathetic division
The portion of the autonomic nervous system that controls functions that accompany arousal and expenditure of energy.
spinal sympathetic ganglia
Sympathetic ganglia either adjacent to the spinal cord in the sympathetic chain or located in the abdominal cavity.
sympathetic ganglion chain
One of a pair of groups of sympathetic ganglia that lie ventrolateral to the vertebral column.
preganglionic neuron
The efferent neuron of the autonomic nervous system whose cell body is located in a cranial nerve nucleus or in the intermediate horn of the spinal gray matter and whose terminal buttons synapse upon postganglionic neurons in the autonomic ganglia.
postganglionic neuron
A neurons of the autonomic nervous system that forms synapses directly with its target organ.
adrenal medulla
The inner portion of the adrenal gland, located atop the kidney, controlled by sympathetic nerve fibers; secretes epinephrine and norepinephrine.
parasympathetic division
The portion of the autonomic nervous system that controls functions that occur during a relaxed state.
Chapter 4
95
psychopharmacology
The study of the effects of drugs on the nervous system and on behavior.
drug effect
The changes a drug produces in an organism's physiological processes and behavior.
sites of action
The locations at which molecules of drugs interact with molecules located on or in cells of the body, thus affecting some biochemical processes of these cells.
pharmacokinetics
The process by which drugs are absorbed, distributed within the body, metabolized, and excreted.
intravenous injection/IV injection
Injection of a substance directly into a vein.
intraperitoneal injection/IP injection
Injection of a substance into the peritoneal cavity--the space that surrounds the stomach, intestines, liver, and other abdominal organs.
intramuscular injection/IM injection
Injection of a substance into a muscle.
subcutaneous injection/SC injection
Injection of a substance into the space beneath the skin.
oral administration
Administration of a substance into the mouth, so that it is swallowed.
sublingual administration
Administration of a substance by placing it beneath the tongue.
intrarectal administration
Administration of a substance into the rectum.
inhalation
Administration of a vaporous substance into the lungs.
topical administration
Administration of a substance directly onto the skin or mucous membrane.
intracerebral administration
Administration of a substance directly into the brain.
intracerebroventricular administration/ICV administration
Administration of a substance into one of the cerebral ventricles.
depot binding
Binding of a drug with various tissues of the body or with proteins in the blood.
albumin
A protein found in the blood; serves to transport free fatty acids and can bind with some lipid-soluble drugs.
dose-response curve
A graph of the magnitude of an effect of a drug as a function of the amount drug administered.
therapeutic index
The ratio between the dose that produces the desired effect in 50 percent of the animals and the dose that produces toxic effects in 50 percent of the animals.
affinity
The readiness with which two molecules join together.
tolerance
A decrease in the effectiveness of a drug that is administered repeatedly.
sensitization
An increase in the effectiveness of a drug that is administered repeatedly.
withdrawal symptom/withdrawal symptoms
The appearance of symptoms opposite to those produced by a drug when the drug is administered repeatedly and then suddenly no longer taken.
placebo
An inert substance given to an organism in lieu of a physiologically active drug; used experimentally to control for the effects of mere administration of a drug.
antagonist
A drug that opposes or inhibits the effects of a particular neurotransmitter on the postsynaptic cell.
agonist
A drug that facilitates the effects of a particular neurotransmitter on the postsynaptic cell.
direct agonist
A drug that binds with and activates a receptor.
receptor blocker
A drug that binds with a receptor but does not activate it ; prevents the natural ligand from binding with the receptor.
direct antagonist
A synonym for receptor blocker.
noncompetitive binding
Binding of a drug to a site on a receptor; does not interfere with the binding site for the principal ligand.
inverse agonist
A drug that attaches to a binding site on a receptor and interferes with the action of the receptor; does not interfere with the binding site for the principal ligand.
indirect agonist
A drug that attaches to a binding site on a receptor and facilitates the action of the receptor; does not interfere with the binding site for the principal ligand.
presynaptic heteroreceptor
A receptor located in the membrane of a terminal button that receives input from another terminal button by means of an axoaxonic synapse; binds with the neurotransmitter released by the presynaptic terminal button.
acetyl-CoA
A cofactor that supplies acetate for the synthesis of acetylcholine.
choline acetyltransferase/ChAT
The enzyme that transfers the acetate ion from acetyl coenzyme A to choline, producing the neurotransmitter acetylcholine.
botulinum toxin
An acetylcholine antagonist: prevents release by terminal buttons.
black widow spider venom
A poison produced by the black widow spider that triggers the release of acetylcholine.
neostigmine
A drug that inhibits the activity of acetylcholinesterase.
hemicholinium
A drug that inhibits the uptake of choline.
nicotinic receptor
An ionotropic acetylcholine receptor that is stimulated by nicotine and blocked by curare.
muscarinic receptor
A metabotropic acetylcholine receptor that is stimulated by muscarine and blocked by atropine.
atropine
A drug that blocks muscarinic acetylcholine receptors.
curare
A drug that blocks nicotinic acetylcholine receptors.
monoamine
A class of amines that includes indolamines such as serotonin and catecholamines such as dopamine norepinephrine, and epinephrine.
catecholamine/catecholamines
A class of amines that includes the neurotransmitters dopamine, norepinephrine, and epinephrine.
dopamine/DA
A neurotransmitter; one of the catecholamines.
L-DOPA
The levorotatory form of DOPA; the precursor of the catecholamines; often used to treat Parkinson's disease because of its effect as a dopamine agonist.
nigrostriatal system
A system of neurons originating in the substantia nigra and terminating in the neostriatum (caudate nucleus and putamen).
mesolimbic system
A system of dopaminergic neurons originating in the ventral tegmental area and terminating in the nucleus accumbens, amygdala, and hippocampus.
mesocortical system
A system of dopaminergic neurons originating in the ventral tegmental area and terminating in the prefrontal cortex.
Parkinson's disease
A neurological disease characterized by tremors, rigidity of the limbs, poor balance, and difficulty in initiating movements; caused by degeneration of the nigrostriatal system.
AMPT
A drug that blocks the activity of tyrosine hydroxylase and thus interferes with the synthesis of the catecholamines.
reserpine
A drug that interferes with the storage of monoamines in synaptic vesicles.
apomorphine
A drug that blocks dopamine autoreceptors at low doses; at higher doses blocks postsynaptic receptors as well.
methylphenidate/cocaine
A drug that inhibits the reuptake of dopamine.
monoamine oxidase/MAO
A class of enzymes that destroy the monoamines: dopamine, norepinephrine, and serotonin.
deprenyl
A drug that blocks the activity of MAO-B; acts as a dopamine agonist.
chlorpromazine
A drug that reduces the symptoms of schizophrenia by blocking dopamine D2 receptors.
clozapine
A drug that reduces the symptoms of schizophrenia, apparently by blocking dopamine D4 receptors.
norepinephrine/NE
One of the catecholamines; a neurotransmitter found in the brain and in the sympathetic division of the autonomic nervous system.
epinephrine
One of the catecholamines; a hormone secreted by the adrenal medulla; serves also as a neurotransmitter in the brain.
fusaric acid
A drug that inhibits the activity of the enzyme dopamine-beta-hydroxylase and thus blocks the production of norepinephrine.
moclobemide
A drug that blocks the activity of MAO-A; acts as a noradrenergic agonist.
locus coeruleus
A dark-colored group of noradrenergic cell bodies located in the pons near the rostral end of the floor of the fourth ventricle.
axonal varicosities
Enlarged regions along the length of an axon that contain synaptic vesicles and release a neurotransmitter or neuromodulator.
serotonin/5-HT
An indolamine transmitter substance; also called 5-hydroxytryptamine.
PCPA
A drug that inhibits the activity of tryptophan hydroxylase and thus interferes with the synthesis of 5-HT.
D system
A system of serotonergic neurons that originates in the dorsal raphe nucleus; its axonal fibers are thin, with spindle-shaped varicosities that do not appear to form synapses with other neurons.
M system
A system of serotonergic neurons that originates in the median raphe nucleus; its axonal fibers are thick and rounded and appear to form conventional synapses with other neurons.
fluoxetine
A drug that inhibits the reuptake of 5-HT.
fenfluramine
A drug that stimulates the release of 5-HT.
LSD
A drug that stimulates 5-HT2A receptors.
glutamate
An amino acid; the most important excitatory transmitter substance in the brain.
NMDA receptor
A specialized ionotropic glutamate receptor that controls a calcium channel that is normally blocked by Mg2+ ions; has several other binding sites.
AMPA receptor
An ionotropic glutamate receptor that controls a sodium channel; stimulated by AMPA and blocked by CNQX.
kainate receptor
An ionotropic glutamate receptor that controls a sodium channel; stimulated by kainic acid and blocked by CNQX.
metabotropic receptor
A metabotropic glutamate receptor.
PCP
Phencyclidine; a drug that binds with the PCP binding site of the NMDA receptor and serves as an inverse agonist.
GABA
An amino acid; the most important inhibitory transmitter substance in the brain.
allylglycine
A drug that inhibits the activity of GAD and thus blocks the synthesis of GABA.
muscimol
A direct agonist for the GABA binding site on the GABAA receptor.
bicuculline
A direct antagonist for the GABA binding site on the GABAA receptor.
benzodiazepine/benzodiazepines
A category of anxiolytic drugs; an indirect agonist for the GABAA receptor.
anxiolytic
An anxiety-reducing effect.
beta-CCM
A direct agonist for the benzodiazepine binding site of the GABAA receptor.
glycine
An amino acid; an important inhibitory transmitter substance in the lower brain stem and spinal cord.
strychnine
A direct agonist for the glycine receptor.
endogenous opioid/endogenous opioids
A class of peptides secreted by the brain that act as opiates.
enkephalin
One of the endogenous opioids.
naloxone
A drug that blocks opioid receptors.
anandamide
A lipid; the endogenous ligand for receptors that bind with THC, the active ingredient of marijuana.
adenosine
A nucleoside; a combination of ribose and adenine; serves as a neuromodulator in the brain.
caffeine
A drug that blocks adenosine receptors.
nitric oxide/NO
A gas produced by cells in the nervous system; used as a means of communication between cells.
nitric oxide synthase
The enzyme responsible for the production of nitric oxide.
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experimental ablation
The removal or destruction of a portion of the brain of a laboratory animal; presumably, the functions that can no longer be performed are the ones the region previously controlled.
lesion study
A synonym for experimental ablation.
excitotoxic lesion
A brain lesion produced by intracerebral injection of an excitatory amino acid, such as kainic acid.
6-hydroxydopamine/6-HD
A chemical that is selectively taken up by axons and terminal buttons of noradrenergic or dopaminergic neurons and acts as a poison, damaging or killing them.
sham lesion
A "placebo" procedure that duplicates all the steps of producing a brain lesion except for the one that actually causes the brain damage.
stereotaxic surgery
Brain surgery using a stereotaxic apparatus to position an electrode or cannula in a specified position of the brain.
bregma
The junction of the sagittal and coronal sutures of the skull; often used as a reference point for stereotaxic brain surgery.
stereotaxic atlas
A collection of drawings of sections of the brain of a particular animal with measurements that provide coordinates for stereotaxic surgery.
stereotaxic apparatus
A device that permits a surgeon to position an electrode or cannula into a specific part of the brain.
fixative
A chemical such as formalin; used to prepare and preserve body tissue.
formalin
The aqueous solution of formaldehyde gas; the most commonly used tissue fixative.
perfusion
The process by which an animal's blood is replaced by a fluid such as a saline solution or a fixative in preparing the brain for histological examination.
microtome
An instrument that produces very thin slices of body tissues.
scanning electron microscope
A microscope that provides three-dimensional information about the shape of the surface of a small object.
anterograde labeling method
A histological method that labels the axons and terminal buttons of neurons whose cell bodies are located in a particular region.
PHA-L
Phaseolus vulgaris leukoagglutinin; a protein derived from lima beans used as an anterograde tracer; taken up by dendrites and cell bodies and carried to the ends of the axons.
immunocytochemical method
A histological method that uses radioactive antibodies or antibodies bound with a dye molecule to indicate the presence of particular proteins of peptides.
retrograde labeling method
A histological method that labels cell bodies that give rise to the terminal buttons that form synapses with cells in a particular region.
fluorogold
A dye that serves as a retrograde label; taken up by terminal buttons and carried back to the cell bodies.
computerized tomography/CT
The use of a device that employs a computer to analyze data obtained by a scanning beam of X rays to produce a two-dimensional picture of a "slice" through the body.
magnetic resonance imaging/MRI
An technique whereby the interior of the body can be accurately imaged; involves the interaction between radio waves and a strong magnetic field.
microelectrode
A very fine electrode, generally used to record activity of individual neurons.
single-unit recording
Recording of the electrical activity of a single neuron.
macroelectrode
An electrode used to record the electrical activity of large numbers of neurons in a particular region of the brain; much larger than a microelectrode.
electroencephalogram/EEG
An electrical brain potential recorded by placing electrodes on in the scalp.
2-deoxyglucose/2-DG
A sugar that enters cells along with glucose but is not metabolized.
autoradiography
A procedure that locates radioactive substances in a slice of tissue; the radiation exposes a photographic emulsion or a piece of film that covers the tissue.
Fos
A protein produced in the nucleus of a neuron in response to synaptic stimulation.
positron emission tomography/PET
The use of a device that reveals the localization of a radioactive tracer in a living brain.
functional MRI/fMRI
A modification of the MRI procedure that permits the measurement of regional metabolism in the brain.
microdialysis
A procedure for analyzing chemicals present in the interstitial fluid through a small piece of tubing made of a semipermeable membrane that is implanted in the brain.
multi-barreled micropipette
A group of micropipettes attached together, used to infuse several different substances by means of iontophoresis while recording from a single neuron.
microiontophoresis
A procedure that uses electricity to eject a chemical from a micropipette in order to determine the effects of the chemical on the electrical activity of a cell.
in situ hybridization
The production of DNA complementary to a particular messenger RNA in order to detect the presence of the RNA.
double labeling
Labeling neurons in a particular region by two different means; for example, by using an anterograde tracer and a label for a particular enzyme.
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sensory receptor
A specialized neuron that detects a particular category of physical events.
sensory transduction
The process by which sensory stimuli are transduced into slow, graded receptor potentials.
receptor potential
A slow, graded electrical potential produced by a receptor cell in response to a physical stimulus.
hue
One of the perceptual dimensions of color; the dominant wavelength.
brightness
One of the perceptual dimensions of color; intensity.
saturation
One of the perceptual dimensions of color; purity.
vergence movement
The cooperative movement of the eyes, which ensures that the image of an object falls on identical portions of both retinas.
saccadic movement
The rapid, jerky movement of the eyes used in scanning a visual scene.
pursuit movement
The movement that the eyes make to maintain an image on the fovea.
accommodation
Changes in the thickness of the lens of the eye, accomplished by the ciliary muscles, that focus images of near or distant objects on the retina.
retina
The neural tissue and photoreceptive cells located on the inner surface of the posterior portion of the eye.
rod
One of the receptor cells of the retina; sensitive to light of low intensity.
cone
One of the receptor cells of the retina; maximally sensitive to one of three different wavelengths of light and hence encodes color vision.
photoreceptor
One of the receptor cells of the retina; transduces photic energy into electrical potentials.
fovea
The region of the retina that mediates the most acute vision of birds and higher mammals. Color-sensitive cones constitute the only type of photoreceptor found in the fovea.
optic disk
The location of the exit point from the retina of the fibers of the ganglion cells that form the optic nerve; responsible for the blind spot.
bipolar cell
A bipolar neuron located in the middle layer of the retina, conveying information from the photoreceptors to the ganglion cells.
ganglion cell
A neuron located in the retina that receives visual information from bipolar cells; its axons give rise to the optic nerve.
horizontal cell
A neuron in the retina that interconnects adjacent photoreceptors and the outer processes of the bipolar cells.
amacrine cell
A neuron in the retina that interconnects adjacent ganglion cells and the inner processes of the bipolar cells.
lamella
A layer of membrane containing photopigments; found in rods and cones of the retina.
photopigment
A protein dye bonded to retinal, a substance derived from vitamin A; responsible for transduction of visual information.
opsin
A class of protein that, together with retinal, constitutes the photopigments.
retinal
A chemical synthesized from vitamin A; joins with an opsin to form a photopigment.
rhodopsin
A particular opsin found in rods.
transducin
A G protein that is activated when a photon strikes a photopigment; activates phosphodiesterase molecules, which destroy cyclic GMP and close cation channels in the photoreceptor.
dorsal lateral geniculate nucleus
A group of cell bodies within the lateral geniculate body of the thalamus; receives inputs from the retina and projects to the primary visual cortex.
magnocellular layer
One of the inner two layers of cells in the dorsal lateral geniculate nucleus; transmits information necessary for the perception of form, movement, depth, and small differences in brightness.
parvocellular layer
One of the four outer layers of cells in the dorsal lateral geniculate nucleus; transmits information necessary for perception of color and fine details.
calcarine fissure
A horizontal fissure on the inner surface of the posterior cerebral cortex; the location of the primary visual cortex.
striate cortex
The primary visual cortex.
optic chiasm
A cross-shaped connection between the optic nerves, located below the base of the brain, just anterior to the pituitary gland.
receptive field
That portion of the visual field in which the presentation of visual stimuli will produce an alteration in the firing rate of a particular neuron.
protanopia
An inherited form of defective color vision in which red and green hues are confused; "red" cones are filled with "green" cone opsin.
deuteranopia
An inherited form of defective color vision in which red and green hues are confused; "green" cones are filled with "red" cone opsin.
tritanopia
An inherited form of defective color vision in which hues with short wavelengths are confused; "blue" cones are either lacking or faulty.
negative afterimage
The image seen after a portion of the retina is exposed to an intense visual stimulus; consists of colors complementary to those of the physical stimulus.
complementary colors/complementary colours
Colors that make white or gray when mixed together.
simple cell
An orientation-sensitive neuron in the striate cortex whose receptive field is organized in an opponent fashion.
complex cell
A neuron in the visual cortex that responds to the presence of a line segment with a particular orientation located within its receptive field, especially when the line moves perpendicularly to its orientation.
sine-wave grating
A series of straight parallel bands varying continuously in brightness according to a sine-wave function, along a line perpendicular to their lengths.
spatial frequency
The relative width of the bands in a sine-wave grating, measured in cycles per degree of visual angle.
retinal disparity
The fact that points on objects located at different distances from the observer will fall on slightly different locations on the two retinas; provides the basis for stereopsis.
CO blob/cytochrome oxidase blob
The central region of a module of the primary visual cortex, revealed by a stain for cytochrome oxidase; contains wavelength-sensitive neurons; part of the parvocellular system.
ocular dominance
The extent to which a particular neuron receives more input from one eye than from the other.
blindsight
The ability of a person to reach for objects located in his or her "blind" field; occurs after damage restricted to the primary visual cortex.
extrastriate cortex
A region of visual association cortex; receives fibers from the striate cortex and from the superior colliculi and projects to the inferior temporal cortex.
color constancy/colour constancy
The relatively constant appearance of the colors of objects viewed under varying lighting conditions.
achromatopsia
Inability to discriminate among different hues; caused by damage to the visual association cortex.
inferior temporal cortex
In primates, the highest level of visual association cortex; located on the inferior portion of the temporal lobe.
visual agnosia
Deficits in visual perception in the absence of blindness; caused by brain damage.
apperceptive visual agnosia
Failure to perceive objects, even though visual acuity is relatively normal.
prosopagnosia
Failure to recognize particular people by the sight of their faces.
associative visual agnosia
Inability to identify objects that are perceived visually, even though the form of the perceived object can be drawn or matched with similar objects.
pulvinar
A large thalamic nucleus that projects to the visual association cortex and may play a role in compensating for eye and head movements.
Balint's syndrome
A syndrome caused by bilateral damage to the parieto-occipital region; includes optic ataxia, ocular apraxia, and simultanagnosia
optic ataxia
Difficulty in reaching for objects under visual guidance.
ocular apraxia
Difficulty in visual scanning.
simultanagnosia
Difficulty in perceiving more than one object at a time.
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pitch
A perceptual dimension of sound; corresponds to the fundamental frequency.
hertz/Hz
Cycles per second.
loudness
A perceptual dimension of sound; corresponds to intensity.
timbre
A perceptual dimension of sound; corresponds to complexity.
tympanic membrane
The eardrum.
ossicle
One of the three bones of the middle ear.
malleus
The "hammer"; the first of the three ossicles.
incus
The "anvil"; the second of the three ossicles.
stapes
The "stirrup" the last of the three ossicles.
cochlea
The snail-shaped structure of the inner ear that contains the auditory transducing mechanisms.
oval window
An opening in the bone surrounding the cochlea that reveals a membrane, against which the baseplate of the stapes presses, transmitting sound vibrations into the fluid within the cochlea.
organ of Corti
The sensory organ on the basilar membrane that contains the auditory hair cells.
hair cell
The receptive cell of the auditory apparatus.
Deiters's cell
A supporting cell found in the organ of Corti; sustains the auditory hair cells.
basilar membrane
A membrane in the cochlea of the inner ear; contains the organ of Corti.
tectorial membrane
A membrane located above the basilar membrane; serves as a shelf against which the cilia of the auditory hair cells move.
round window
An opening in the bone surrounding the cochlea of the inner ear that permits vibrations to be transmitted, via the oval window, into the fluid in the cochlea.
cilium
A hairlike appendage of a cell involved in movement or in transducing sensory information; found on the receptors in the auditory and vestibular system.
tip link
Elastic filaments that attach the tip of one cilium to the side of the adjacent cilium.
insertional plaque
The point of attachment of a tip link to a cilium.
cochlear nerve
The branch of the auditory nerve that transmits auditory information from the cochlea to the brain.
olivocochlear bundle
A bundle of efferent axons that travel from the olivary complex of the medulla to the auditory hair cells on the cochlea.
cochlear nucleus
One of a group of nuclei in the medulla that receive auditory information from the cochlea.
superior olivary complex
A group of nuclei in the medulla; involved with auditory functions, including localization of the source of sounds.
lateral lemniscus
A band of fibers running rostrally through the medulla and pons; carries fibers of the auditory system.
tonotopic representation
A topographically organized mapping of different frequencies of sound that are represented in a particular region of the brain.
place code
The system by which information about different frequencies is coded by different locations on the basilar membrane.
cochlear implant
An electronic device surgically implanted in the inner ear that can enable deaf people to hear.
rate code
The system by which information about different frequencies is coded by the rate of firing of neurons in the auditory system.
fundamental frequency
The lowest, and usually most intense, frequency of a complex sound; most often perceived as the sound's basic pitch.
overtone
The frequency of complex tones that occurs at multiples of the fundamental frequency.
phase difference
The difference in arrival times of sound waves at each of the eardrums.
vestibular sac
One of a set of two receptor organs in each inner ear that detect changes in the tilt of the head.
semicircular canal
One of the three ringlike structures of the vestibular apparatus that detect changes in head rotation.
utricle
One of the vestibular sacs.
saccule
One of the vestibular sacs.
ampulla
An enlargement in a semicircular canal; contains the cupula and the crista.
cupula
A gelatinous mass found in the ampulla of the semicircular canals; moves in response to the flow of the fluid in the canals.
vestibular ganglion
A nodule on the vestibular nerve that contains the cell bodies of the bipolar neurons that convey vestibular information to the brain.
cutaneous sense
One of the somatosenses; includes sensitivity to stimuli that involve the skin.
kinesthesia
Perception of the body's own movements.
organic sense
A sense modality that arises from receptors located within the inner organs of the body.
glabrous skin
Skin that does not contain hair; found on the palms and soles of the feet.
Ruffini corpuscle
A vibration-sensitive organ located in hairy skin.
Pacinian corpuscle
A specialized, encapsulated somatosensory nerve ending that detects mechanical stimuli, especially vibrations.
Meissner's corpuscle
The touch-sensitive end organs located in the papillae, small elevations of the dermis that project up into the epidermis.
Merkel's disk
The touch-sensitive end organs found at the base of the epidermis, adjacent to sweat ducts.
prostaglandin
A member of a family of fatty acid derivatives that serve as hormones; first discovered in the prostate gland; involved in many physiological processes, including pain perception.
phantom limb
Sensations that appear to originate in a limb that has been amputated.
nucleus raphe magnus
A nucleus of the raphe that contains serotonin-secreting neurons that project to the dorsal gray matter of the spinal cord via the dorsolateral columns and is involved in analgesia produced by opiates.
gustducin
A G protein that plays a vital role in the transduction of sweetness and bitterness.
umami
The taste sensation produced by glutamate.
chorda tympani
A branch of the facial nerve that passes beneath the eardrum; conveys taste information from the anterior part of the tongue and controls the secretion of some salivary glands.
nucleus of the solitary tract/NST
A nucleus of the medulla that receives information from visceral organs and from the gustatory system.
olfactory epithelium
The epithelial tissue of the nasal sinus that covers the cribriform plate; contains the cilia of the olfactory receptors.
olfactory bulb
The protrusion at the end of the olfactory nerve; receives input from the olfactory receptors.
mitral cell
A neuron located in the olfactory bulb that receives information from olfactory receptors; axons of mitral cells bring information to the rest of the brain.
olfactory glomerulus
A bundle of dendrites of mitrial cells and the associated terminal buttons of the axons of olfactory receptors.
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skeletal muscle
One of the striated muscles attached to bones.
flexion
A movement of a limb that tends to bend its joints; opposite of extension.
extension
A movement of a limb that tends to straighten its joints; the opposite of flexion.
extrafusal muscle fiber
One of the muscle fibers that are responsible for the force exerted by contraction of a skeletal muscle.
alpha motor neuron
A neuron whose axon forms synapses with extrafusal muscle fibers of a skeletal muscle; activation contracts the muscle fibers.
intrafusal muscle fiber
A muscle fiber that functions as a stretch receptor, arranged parallel to the extrafusal muscle fibers, thus detecting changes in muscle length.
gamma motor neuron
A neuron whose axons form synapses with intrafusal muscle fibers.
motor unit
A motor neuron and its associated muscle fibers.
myofibril
An element of muscle fibers that consists of overlapping strands of actin and myosin; responsible for muscular contractions.
actin
One of the proteins (with myosin) that provide the physical basis for muscular contraction.
myosin
One of the proteins (with actin) that provide the physical basis for muscular contraction.
striated muscle
Skeletal muscle; muscle that contains striations.
neuromuscular junction
The synapse between the terminal buttons of an axon and a muscle fiber.
motor endplate
The postsynaptic membrane of a neuromuscular junction.
endplate potential
The postsynaptic potential that occurs in the motor endplate in response to release of acetylcholine by the terminal button.
Golgi tendon organ/GTO
The receptor organ at the junction of the tendon and muscle that is sensitive to stretch.
smooth muscle
Nonstriated muscle innervated by the autonomic nervous system, found in the walls of blood vessels, in the reproductive tracts, in sphincters, within the eye, in the digestive system, and around hair follicles.
cardiac muscle
The muscle responsible for the contraction of the heart.
monosynaptic stretch reflex
A reflex in which a muscle contracts in response to its being quickly stretched; involves a sensory neuron and a motor neuron, with one synapse between them.
decerebrate
Describes an animal whose brain stem has been transected.
decerebrate rigidity
Simultaneous contraction of agonistic and antagonistic muscles; caused by decerebration or damage to the reticular formation.
clasp-knife reflex
A reflex that occurs when force is applied to flex or extend the limb of an animal showing decerebrate rigidity; resistance is replaced by sudden relaxation.
agonist
A muscle whose contraction produces or facilitates a particular movement.
antagonist
A muscle whose contraction resists or reverses a particular movement.
somatotopic organization
A topographically organized mapping of parts of the body that are represented in a particular region of the brain.
supplementary motor area
A region of motor association cortex of the dorsal and dorsomedial frontal lobe, rostral to the primary motor cortex.
premotor cortex
A region of motor association cortex of the lateral frontal lobe, rostral to the primary motor cortex.
prefrontal cortex
The neocortex of the frontal lobes rostral to the supplementary motor area and premotor cortex.
lateral group
The corticospinal tract, the corticobulbar tract, and the rubrospinal tract.
ventromedial group
The vestibulospinal tract, the tectospinal tract, the reticulospinal tract, and the ventral corticospinal tract.
corticospinal tract
The system of axons that originates in the motor cortex and terminates in the ventral gray matter of the spinal cord.
pyramidal tract
An alternate term for the corticospinal tract.
lateral corticospinal tract
The system of axons that originates in the motor cortex and terminates in the contralateral ventral gray matter of the spinal cord; controls movements of the distal limbs.
ventral corticospinal tract
The system of axons that originates in the motor cortex and terminates in the ipsilateral ventral gray matter of the spinal cord; controls movements of the upper legs and trunk.
corticobulbar pathway
A bundle of axons from the motor cortex to the fifth, seventh, ninth, tenth, eleventh, and twelfth cranial nerves; controls movements of the face, neck, tongue, and parts of the extraocular eye muscles.
rubrospinal tract
The system of axons that travels from the red nucleus to the spinal cord; controls independent limb movements.
corticorubral tract
The system of axons that travels from the motor cortex to the red nucleus.
vestibulospinal tract
A bundle of axons that travels from the vestibular nuclei to the gray matter of the spinal cord; controls postural movements in response to information from the vestibular system.
tectospinal tract
A bundle of axons that travels from the tectum to the spinal cord; coordinates head and trunk movements with eye movements.
reticulospinal tract
A bundle of axons that travels from the reticular formation to the gray matter of the spinal cord; controls the muscles responsible for postural movements.
apraxia
Difficulty in carrying out purposeful movements, in the absence of paralysis or muscular weakness.
callosal apraxia
An apraxia of the left hand caused by damage to the anterior corpus callosum.
sympathetic apraxia
A movement disorder of the left hand caused by damage to the left frontal lobe; similar to callosal apraxia.
left parietal apraxia
An apraxia caused by damage to the left parietal lobe; characterized by difficulty in producing sequences of movements by verbal request or in imitation of movements made by someone else.
constructional apraxia
Difficulty in drawing pictures or diagrams or in making geometrical constructions of elements such as building blocks or sticks; caused by damage to the right parietal lobe.
caudate nucleus
A telencephalic nucleus; one of the input nuclei of basal ganglia along with the putamen; involved with control of voluntary movement.
putamen
A telencephalic nucleus; one of the input nuclei of the basal ganglia along with the caudate nucleus; involved with control of voluntary movement.
globus pallidus
A telencephalic nucleus; the primary output nucleus of the basal ganglia; involved with control of voluntary movement.
ventral anterior nucleus
One of the two thalamic nuclei that receive projections from the basal ganglia and send projections to the motor cortex.
ventrolateral nucleus
One of the two thalamic nuclei that receive projections from the basal ganglia and send projections to the motor cortex.
Huntington's chorea
An fatal inherited disorder that causes degeneration of the caudate nucleus and putamen; characterized by uncontrollable jerking movements, writhing movements, and dementia.
flocculonodular lobe
A region of the cerebellum; involved in control of postural reflexes.
vermis
The portion of the cerebellum located at the midline; receives somatosensory information and helps control the vestibulospinal and reticulospinal tracts through its connections with the fastigial nucleus.
fastigial nucleus
A deep cerebellar nucleus; involved in the control of movement by the reticulospinal and vestibulospinal tracts.
interposed nuclei
A set of deep cerebellar nuclei; involved in the control of the rubrospinal system.
pontine nucleus
A large nucleus in the pons that serves as an important source of input to the cerebellum.
dentate nucleus
A deep cerebellar nucleus; involved in the control of rapid, skilled movements by the corticospinal and rubrospinal systems.
mesencephalic locomotor region
A region of the reticular formation of the midbrain whose stimulation causes alternating movements of the limbs normally seen during locomotion.
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38
electromyogram/EMG
An electrical potential recorded from an electrode placed on or in a muscle.
electro-oculogram/EOG
An electrical potential from the eyes, recorded by means of electrodes placed on the skin around them; detects eye movements.
alpha activity
Smooth electrical activity of 8-12 Hz recorded from the brain; generally associated with a state of relaxation.
beta activity
Irregular electrical activity of 13-30 Hz recorded from the brain; generally associated with a state of arousal.
synchrony
High-voltage, low-frequency EEG activity, characteristic of slow-wave sleep or coma, during which neurons fire together in a regular fashion.
desynchrony
Irregular electrical activity recorded from the brain, generally associated with periods of arousal.
theta activity
EEG activity of 5-8 Hz that occurs intermittently during early stages of slow-wave sleep and REM sleep.
delta activity
Regular, synchronous electrical activity of approximately 1-4 Hz recorded from the brain; occurs during the deepest stages of slow-wave sleep.
REM sleep
A period of desynchronized EEG activity during sleep, at which time dreaming, rapid eye movements, and muscular paralysis occur; also called paradoxical sleep.
non-REM sleep
All stages of sleep except REM sleep.
slow-wave sleep
Non-REM sleep, characterized by synchronized EEG activity during its deeper stages.
basic rest-activity cycle/BRAC
A 90-min cycle (in humans) of waxing and waning alertness, controlled by a biological clock in the caudal brain stem; controls cycles of REM sleep and slow-wave sleep.
fatal familial insomnia
A fatal inherited disorder characterized by progressive insomnia.
rebound phenomenon
The increased frequency or intensity of a phenomenon after it has been temporarily suppressed; for example, the increase in REM sleep seen after a period of REM sleep deprivation.
locus coeruleus
A dark-colored group of noradrenergic cell bodies located in the pons near the rostral end of the floor of the fourth ventricle; involved in arousal and vigilance.
raphe nuclei
A group of nuclei located in the reticular formation of the medulla, pons, and midbrain, situated along the midline; contain serotonergic neurons.
basal forebrain region
The region at the base of the forebrain rostral to the hypothalamus; involved in thermoregulation and control of sleep.
POAH
The region of the preoptic area and the adjacent anterior hypothalamus, involved in thermoregulation and induction of slow-wave sleep.
PGO wave
Bursts of phasic electrical activity originating in the pons, followed by activity in the lateral geniculate nucleus and visual cortex; a characteristic of REM sleep.
peribrachial area
The region around the brachium conjunctivum, located in the dorsolateral pons; contains acetylcholinergic neurons involved in the initiation of REM sleep.
carbachol
A drug that stimulates acetylcholine receptors.
medial pontine reticular formation/MPRF
A region that contains neurons involved in the initiation of REM sleep; activated by acetylcholinergic neurons of the peribrachial area.
magnocellular nucleus
A nucleus in the medulla; involved in the atonia (muscular paralysis) that accompanies REM sleep.
drug dependency insomnia
An insomnia caused by the side effects of ever-increasing doses of sleeping medications.
sleep apnea
Cessation of breathing while sleeping.
narcolepsy
A sleep disorder characterized by periods of irresistible sleep, attacks of cataplexy, sleep paralysis, and hypnagogic hallucinations.
sleep attack
A symptom of narcolepsy; an irresistible urge to sleep during the day, after which the person awakes feeling refreshed.
cataplexy
A symptom of narcolepsy; complete paralysis that occurs during waking.
sleep paralysis
A symptom of narcolepsy; paralysis occurring just before a person falls asleep.
hypnagogic hallucination
A symptom of narcolepsy; vivid dreams that occur just before a person falls asleep; accompanied by sleep paralysis.
REM without atonia
A neurological disorder in which the person does not become paralyzed during REM sleep and thus acts out dreams.
circadian rhythm
A daily rhythmical change in behavior or physiological process.
zeitgeber
A stimulus (usually the light of dawn) that resets the biological clock responsible for circadian rhythms.
suprachiasmatic nucleus/SCN
A nucleus situated atop the optic chiasm. It contains a biological clock responsible for organizing many of the body's circadian rhythms.
intergeniculate leaflet/IGL
A part of the lateral geniculate nucleus that receives information from the retina and projects to the SCN.
neuropeptide Y
A peptide released by the terminals of the neurons that project from the IGL to the SCN.
pineal gland
A gland attached to the dorsal tectum; produces melatonin and plays a role in circadian and seasonal rhythms.
melatonin
A hormone secreted during the night by the pineal body; plays a role in circadian and seasonal rhythms.
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sexually dimorphic behavior
A behavior that has different forms or that occurs with different probabilities or under different circumstances in males and females.
gamete
A mature reproductive cell; a sperm or ovum.
sex chromosome
The X and Y chromosomes, which determine an organism's gender. Normally, XX individuals are female, and XY individuals are male.
gonad
An ovary or testis.
organizational effect
The effect of a hormone on tissue differentiation and development.
activational effect
The effect of a hormone that occurs in the fully developed organism; may depend on the organism's prior exposure to the organizational effects of hormones.
Müllerian system/Mullerian system
The embryonic precursors of the female internal sex organs.
Wolffian system
The embryonic precursors of the male internal sex organs.
anti-Müllerian hormone/anti-Mullerian hormone
A peptide secreted by the fetal testes that inhibits the development of the Müllerian system, which would otherwise become the female internal sex organs.
defeminizing effect
An effect of a hormone present early in development that reduces or prevents the later development of anatomical or behavioral characteristics typical of females.
androgen
A male sex steroid hormone. Testosterone is the principal mammalian androgen.
masculinizing effect
An effect of a hormone present early in development that promotes the later development of anatomical or behavioral characteristics typical of males.
testosterone
The principal androgen found in males.
dihydrotestosterone
An androgen, produced from testosterone through the action of the enzyme 5à reductase.
androgen insensitivity syndrome
A condition caused by a congenital lack of functioning androgen receptors; in a person with XY sex chromosomes, causes the development of a female with testes but no internal sex organs.
persistent Müllerian duct syndrome/persistent Mullerian duct syndrome
A condition caused by a congenital lack of functioning anti-Müllerian hormone receptors; in a male, causes development of both male and female internal sex organs.
Turner's syndrome
The presence of only one sex chromosome (an X chromosome); characterized by lack of ovaries but otherwise normal female sex organs and genitalia.
gonadotropin releasing hormone
A hypothalamic hormone that stimulates the anterior pituitary gland to secrete gonadotropic hormone.
gonadotropic hormone
A hormone of the anterior pituitary gland that has a stimulating effect on cells of the gonads.
follicle-stimulating hormone/FSH
The hormone of the anterior pituitary gland that causes development of an ovarian follicle and the maturation of its oocyte into an ovum.
luteinizing hormone/LH
A hormone of the anterior pituitary gland that causes ovulation and development of the ovarian follicle into a corpus luteum.
estradiol
The principal estrogen of many mammals, including humans.
estrogen
A class of sex hormones that cause maturation of the female genitalia, growth of breast tissue, and development of other physical features characteristic of females.
menstrual cycle
The female reproductive cycle of most primates, including humans; characterized by growth of the lining of the uterus, ovulation, development of a corpus luteum, and (if pregnancy does not occur), menstruation.
estrous cycle
The female reproductive cycle of mammals other than primates.
ovarian follicle
A cluster of epithelial cells surrounding an oocyte, which develops into an ovum.
corpus luteum
A cluster of cells that develops from the ovarian follicle after ovulation; secretes estradiol and progesterone.
progesterone
A steroid hormone produced by the ovary that maintains the endometrial lining of the uterus during the later part of the menstrual cycle and during pregnancy; along with estradiol, it promotes receptivity in female mammals with estrous cycles.
refractory period
A period of time after a particular action (for example, an ejaculation by a male) during which that action cannot occur again.
Coolidge effect
The restorative effect of introducing a new female sex partner to a male that has apparently become "exhausted" by sexual activity.
aromatization
A chemical reaction catalyzed by an aromatase; the process by which testosterone is transformed into estradiol.
oxytocin
A hormone secreted by the posterior pituitary gland; causes contraction of the smooth muscle of the milk ducts, the uterus, and the male ejaculatory system; also serves as a neurotransmitter in the brain.
prolactin
A hormone of the anterior pituitary gland, necessary for production of milk; has an inhibitory effect on male sexual behavior.
lordosis
A spinal sexual reflex seen in many four-legged female mammals; arching of the back in response to approach of a male or to touching the flanks, which elevates the hindquarters.
pheromone
A chemical released by one animal that affects the behavior or physiology of another animal; usually smelled or tasted.
Lee-Boot effect
The increased incidence of false pregnancies seen in female animals that are housed together; caused by a pheromone in the animals' urine; first observed in mice.
Whitten effect
The synchronization of the menstrual or estrous cycles of a group of females, which occurs only in the presence of a pheromone in a male's urine.
Vandenbergh effect
The earlier onset of puberty seen in female animals that are housed with males; caused by a pheromone in the male's urine; first observed in mice.
Bruce effect
Termination of pregnancy caused by the odor of a pheromone in the urine of a male other than the one that impregnated the female; first identified in mice.
vomeronasal organ
A sensory organ that detects the presence of certain chemicals, especially when a liquid is actively sniffed; mediates the effects of some pheromones.
accessory olfactory bulb
A neural structure located in the main olfactory bulb that receives information from the vomeronasal organ.
medial nucleus of the amygdala
A nucleus that receives olfactory information from the olfactory bulb and accessory olfactory bulb; involved in the effects of odors and pheromones on reproductive behavior.
congenital adrenal hyperplasia/CAH
A condition characterized by hypersecretion of androgens by the adrenal cortex; in females, causes masculinization of the external genitalia.
spinal nucleus of the bulbocavernosus/SNB
A nucleus located in the lower spinal cord; in some species of rodents, present only in males.
medial preoptic area/MPA
An area of cell bodies just rostral to the hypothalamus; plays an essential role in male sexual behavior.
sexually dimorphic nucleus
A nucleus in the preoptic area that is much larger in males than in females; first observed in rats; plays a role in male sexual behavior.
vasopressin
A hormone secreted by the posterior pituitary gland that controls the secretion of urine by the kidneys; also serves as a neurotransmitter in the brain.
ventromedial nucleus of the hypothalamus/VMH
A large nucleus of the hypothalamus located near the walls of the third ventricle; plays an essential role in female sexual behavior.
periaqueductal gray matter/PAG
The region of the midbrain that surrounds the cerebral aqueduct; plays an essential role in various species-typical behaviors, including female sexual behavior.
parturition
The act of giving birth.
stria terminalis
A long fiber bundle that connects portions of the amygdala with the hypothalamus.
ventral tegmental area
A nucleus in the ventral midbrain; plays an essential role in maternal behavior.
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medial nucleus
A group of subnuclei of the amygdala that receives sensory input, including information about the presence of odors and pheromones, and relays it to the medial basal forebrain and hypothalamus.
central nucleus
The region of the amygdala that receives information from the basolateral division and sends projections to a wide variety of regions in the brain; involved in emotional responses.
basal nucleus
A group of subnuclei of the amygdala that receives sensory input from the lateral and basolateral nuclei and relays information to other amygdaloid nuclei and to the periaqueductal gray matter.
conditioned emotional response
A classically conditioned response that occurs when a neutral stimulus is followed by an aversive stimulus; usually includes autonomic, behavioral, and endocrine components such as changes in heart rate, freezing, and secretion of stress-related hormones.
coping response
A response through which an organism can avoid, escape from, or minimize an aversive stimulus; reduces the stressful effects of an aversive stimulus.
orbitofrontal cortex
The region of the prefrontal cortex at the base of the anterior frontal lobes.
akinetic mutism
A motor disorder characterized by a relative lack of movement and lack of speech; caused by damage to the cingulate gyrus.
display rule
A culturally determined rule that modifies the expression of emotion in a particular situation.
volitional facial paresis
Difficulty in moving the facial muscles voluntarily; caused by damage to the face region of the primary motor cortex or its subcortical connections.
emotional facial paresis
Lack of movement of facial muscles in response to emotions in people who have no difficulty moving these muscles voluntarily; caused by damage to the insular prefrontal cortex, subcortical white matter of the frontal lobe, or parts of the thalamus..
Wada test
A test often performed before brain surgery; verifies the functions of one hemisphere by testing patients while the other hemisphere is anesthetized.
James-Lange theory
A theory of emotion that suggests that behaviors and physiological responses are directly elicited by situations, and that feelings of emotions are produced by feedback from these behaviors and responses.
defensive behavior
A species-typical behavior by which an animal defends itself against the threat of another animal.
threat behavior
A stereotypical species-typical behavior that warns another animal that it may be attacked if it does not flee or show a submissive behavior.
submissive behavior
A stereotyped behavior shown by an animal in response to threat behavior by another animal; serves to prevent an attack.
predation
Attack of one animal directed at an individual of another species, on which the attacking animal normally preys.
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homeostasis
The process by which the body's substances and characteristics (such as temperature and glucose level) are maintained at their optimal level.
ingestive behavior
Eating or drinking.
system variable
A variable that is controlled by a regulatory mechanism; for example, temperature in a heating system.
set point
The optimal value of the system variable in a regulatory mechanism.
detector
In a regulatory process, a mechanism that signals when the system variable deviates from its set point.
correctional mechanism
In a regulatory process, the mechanism that is capable of changing the value of the system variable.
negative feedback
A process whereby the effect produced by an action serves to diminish or terminate that action; a characteristic of regulatory systems.
satiety mechanism
A brain mechanism that causes cessation of hunger or thirst, produced by adequate and available supplies of nutrients or water.
intracellular fluid
The fluid contained within cells.
extracellular fluid
All body fluids outside cells: interstitial fluid, blood plasma, and cerebrospinal fluid.
intravascular fluid
The fluid found within the blood vessels.
interstitial fluid
The fluid that bathes the cells, filling the space between the cells of the body (the "interstices").
isotonic
Equal in osmotic pressure to the contents of a cell. A cell placed in an isotonic solution neither gains nor loses water.
hypertonic
The characteristic of a solution that contains enough solute that it will draw water out of a cell placed in it, through the process of osmosis.
hypotonic
The characteristic of a solution that contains so little solute that a cell placed in it will absorb water, through the process of osmosis.
hypovolemia
Reduction in the volume of the intravascular fluid.
nephron
A functional unit of the kidney; extracts fluid from the blood and carries the fluid, through collecting ducts, to the ureter.
ureter
One of two tubes that carries urine from the kidneys to the bladder.
aldosterone
A hormone of the adrenal cortex that causes the retention of sodium by the kidneys.
vasopressin
A hormone secreted by the posterior pituitary gland that causes the kidneys to excrete a more concentrated urine, thus retaining water in the body.
supraoptic nucleus
A hypothalamic nucleus that contains cell bodies of neurons that produce antidiuretic hormone and transport it through their axons to the posterior pituitary gland.
paraventricular nucleus
A hypothalamic nucleus that contains cell bodies of neurons that produce antidiuretic hormone and oxytocin and transport them through their axons to the posterior pituitary gland.
diabetes insipidus
The loss of excessive amounts of water through the kidneys; caused by lack of secretion of vasopressin.
osmometric thirst
Thirst produced by an increase in the osmotic pressure of the interstitial fluid relative to the intracellular fluid, thus producing cellular dehydration.
osmoreceptor
A neuron that detects changes in the solute concentration of the interstitial fluid that surrounds it.
OVLT/organum vasculosum of the lamina terminalis
A circumventricular organ located anterior to the anteroventral portion of the third ventricle; served by fenestrated capillaries and thus lacks a blood-brain barrier.
volumetric thirst
Thirst produced by hypovolemia.
colloid
A soluble, gluelike substance made of large molecules that cannot penetrate cell membranes.
salt appetite
A craving for sodium chloride.
renin
A hormone secreted by the kidneys that causes the conversion of angiotensinogen in the blood into angiotensin.
angiotensinogen
A protein in the blood that can be converted by renin to angiotensin.
angiotensin
A peptide hormone that constricts blood vessels, causes the secretion of aldosterone, and produces thirst and a salt appetite.
saralasin
A drug that blocks angiotensin receptors.
losartan
A drug that blocks angiotensin receptors.
nucleus of the solitary tract
A nucleus of the medulla that receives information from visceral organs and from the gustatory system.
subfornical organ/SFO
A small organ located in the confluence of the lateral ventricles, attached to the underside of the fornix; contains neurons that detect the presence of angiotensin in the blood and excite neural circuits that initiate drinking.
median preoptic nucleus
A small nucleus situated around the decussation of the anterior commissure; plays a role in thirst stimulated by angiotensin.
zona incerta
An oblong extension of the midbrain reticular formation, extending from the midbrain to the medial diencephalon.
furosemide
A diuretic; a drug that increases the production of urine.
esophageal fistula
A diversion of the esophagus so that when an animal eats or drink, the substance does not reach the stomach.
pylorus
The ring of smooth muscle at the junction of the stomach and duodenum that controls the release of the stomach contents.
duodenum
The portion of the small intestine immediately adjacent to the stomach.
hepatic portal vein
The vein that receives blood from the digestive system and passes it to the liver.
atrial natriuretic peptide
A peptide secreted by the atria of the heart when blood volume is higher than normal; increases water and sodium excretion, inhibits renin, vasopressin, and aldosterone secretion, and inhibits sodium appetite.
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glycogen
A polysaccharide often referred to as animal starch; stored in liver and muscle; constitutes the short-term store of nutrients.
insulin
A pancreatic hormone that facilitates entry of glucose and amino acids into the cell, conversion of glucose into glycogen, and transport of fats into adipose tissue.
glucagon
A pancreatic hormone that promotes the conversion of liver glycogen into glucose.
triglyceride
The form of fat storage in adipose cells; consists of a molecule of glycerol joined with three fatty acids.
glycerol
A substance (also called glycerine) derived from the breakdown of triglycerides, along with fatty acids; can be converted by the liver into glucose.
fatty acid
A substance derived from the breakdown of triglycerides, along with glycerol; can be metabolized by most cells of the body except for the brain.
fasting phase
The phase of metabolism during which nutrients are not available from the digestive system; glucose, amino acids, and fatty acids are derived from glycogen, protein, and adipose tissue during this phase.
absorptive phase
The phase of metabolism during which nutrients are absorbed from the digestive system; glucose and amino acids constitute the principal source of energy for cells during this phase, and excess nutrients are stored in adipose tissue in the form of triglycerides.
sensory-specific satiety
Satiety for a specific food that has been ingested recently in the absence of general satiety for all foods.
conditioned flavor aversion
The avoidance of a relatively unfamiliar flavor that previously caused (or was followed by) illness.
glucoprivation
A dramatic fall in the level of glucose available to cells; can be caused by a fall in the blood level of glucose or by drugs that inhibit glucose metabolism.
lipoprivation
A dramatic fall in the level of fatty acids available to cells; usually caused by drugs that inhibit fatty-acid metabolism.
methyl palmoxirate/MP
A drug that inhibits fatty-acid metabolism and produces lipoprivic hunger.
mercaptoacetate/MA
A drug that inhibits fatty-acid metabolism and produces lipoprivic hunger.
capsaicin
An ingredient in hot peppers that can destroy small, unmyelinated sensory axons that innervate the internal organs.
2,5-AM
A drug that inhibits carbohydrate metabolism in the liver by making phosphate unavailable, thus blocking the production of ATP.
L-ethionine
A drug that inhibits carbohydrate metabolism in the liver by making adenosine unavailable, thus blocking the production of ATP.
sham feeding
Feeding behavior of an animal with an open gastric or esophageal fistula that prevents food from remaining in the stomach.
cholecystokinin/CCK
A hormone secreted by the duodenum that regulates gastric motility and causes the gallbladder (cholecyst) to contract; appears to provide a satiety signal transmitted to the brain through the vagus nerve.
ob mouse
A strain of mice whose obesity and low metabolic rate is caused by a mutation that prevents the production of leptin.
leptin
A hormone secreted by adipose tissue; decreased food intake and increased metabolic rate, primarily by inhibiting NPY-secreting neurons in the arcuate nucleus.
lateral parabrachial nucleus
A nucleus in the pons that receives gustatory information and information from the liver and digestive system and relays it to the forebrain.
neuropeptide Y/NPY
A peptide neurotransmitter whose release stimulates feeding, insulin and glucocorticoid secretion, decreased breakdown of triglycerides, and a decrease in body temperature.
arcuate nucleus
A nucleus in the base of the hypothalamus that controls secretions of the anterior pituitary gland; contains NPY-secreting neurons involved in feeding and control of metabolism.
galanin
A peptide neurotransmitter whose release stimulates ingestion of fats.
fenfluramine/FEN
A drug that causes the release of serotonin and inhibits eating.
agouti mouse
A strain of mice whose yellow fur and obesity are caused by a mutation that causes the production of a peptide that blocks MC4 receptors in the brain.
melanocortin-4 receptor/MC4-R
A receptor normally stimulated by the hormone melanocortin; responsible for the production of melanin; also plays a role in control of appetite.
anorexia nervosa
A disorder that most frequently afflicts young women; exaggerated concern with overweight that leads to excessive dieting and often compulsive exercising; can lead to starvation.
bulimia nervosa
Bouts of excessive hunger and eating, often followed by forced vomiting or purging with laxatives; sometimes seen in people with anorexia nervosa.
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perceptual learning
Learning to recognize a particular stimulus.
stimulus-response learning
Learning to automatically make a particular response in the presence of a particular stimulus; includes classical and instrumental conditioning.
classical conditioning
When a neutral stimulus is followed several times by an unconditional stimulus that produces a defensive or appetitive response (the unconditional response), the first stimulus (now called a conditional stimulus) itself evokes the response (now called a conditional response).
Hebb rule
The hypothesis proposed by Donald Hebb that the cellular basis of learning involves strengthening of a synapse that is repeatedly active when the postsynaptic neuron fires.
instrumental conditioning
A learning procedure whereby the effects of a particular behavior in a particular situation increase (reinforce) or decrease (punish) the probability of the behavior; also called operant conditioning.
reinforcing stimulus
An appetitive stimulus that follows a particular behavior and thus makes the behavior become more frequent.
punishing stimulus
An aversive stimulus that follows a particular behavior and thus makes the behavior become less frequent.
motor learning
Learning to make a new response.
long-term potentiation
A long-term increase in the excitability of a neuron to a particular synaptic input caused by repeated high-frequency activity of that input.
hippocampal formation
A forebrain structure of the temporal lobe, constituting an important part of the limbic system; includes the hippocampus proper (Ammon's horn), dentate gyrus, and subiculum.
entorhinal cortex
A region of the limbic cortex that provides the major source of input to the hippocampal formation.
granule cell
A small, granular cell; those found in the dentate gyrus send axons to field CA3 of the hippocampus.
dentate gyrus
Part of the hippocampal formation; receives inputs from the entorhinal cortex and projects to field CA3 of the hippocampus.
field CA3
Part of the hippocampus; receives inputs from the dentate gyrus and projects to field CA1.
pyramidal cell
A category of large neurons with a pyramid shape; found in the cerebral cortex and Ammon's horn of the hippocampal formation.
field CA1
Part of the hippocampus; receives inputs from field CA3 and projects out of the hippocampal formation via the subiculum.
population EPSP
An evoked potential that represents the EPSPs of a population of neurons.
associative long-term potentiation
A long-term potentiation in which concurrent stimulation of weak and strong synapses to a given neuron strengthens the weak ones.
NMDA receptor
A specialized ionotropic glutamate receptor that controls a calcium channel that is normally blocked by Mg2+ ions; involved in long-term potentiation.
AP5
2-amino-5-phosphonopentanoate; a drug that blocks NMDA receptors.
AMPA receptor
An ionotropic glutamate receptor that controls a sodium channel; when open, produces EPSPs.
dendritic spike
An action potential that occurs in the dendrite of some types of pyramidal cells.
protein kinase
An enzyme that attaches a phosphate (PO4) to a protein and thereby causes it to change its shape.
CaM-KII
Type II calcium-calmodulin kinase, an enzyme that must be activated by calcium; may play a role in the establishment of long-term potentiation.
tyrosine kinase
A type of protein kinase that may play a role in the establishment of long-term potentiation.
nitric oxide synthase
An enzyme responsible for the production of nitric oxide.
long-term depression
A long-term decrease in the excitability of a neuron to a particular synaptic input caused by stimulation of the terminal button while the postsynaptic membrane is hyperpolarized or only slightly depolarized.
short-term memory
Memory for a stimulus that has just been perceived.
delayed matching-to-sample task
A task that requires the subject to indicate which of several stimuli has just been perceived.
transcranial magnetic stimulation
Stimulation of the cortex by the magnetic field produced by alternating current passing through a coil placed against the skull; disrupts normal activity of the affected brain region.
nucleus basalis
A nucleus of the basal forebrain that contains most of the acetylcholine-secreting neurons that send axons to the neocortex; degenerates in patients with Alzheimer's disease.
MGm
The medial division of the medial geniculate nucleus; transmits auditory and somatosensory information to the lateral nucleus of the amygdala.
extinction
With respect to classical conditioning, the reduction or elimination of a conditional response by repeatedly presenting the conditional stimulus without the unconditional stimulus.
self-stimulation
Making a response that causes the electrical stimulation of a particular region of the brain through an implanted electrode.
medial forebrain bundle/MFB
A fiber bundle that runs in a rostral-caudal direction through the basal forebrain and lateral hypothalamus; electrical stimulation of these axons is reinforcing.
mesolimbic system
A system of dopaminergic neurons whose cell bodies are located in the ventral tegmental area and whose terminal buttons are located in the nucleus accumbens, amygdala, lateral septum, hippocampus, and bed nucleus of the stria terminalis.
nucleus accumbens
A nucleus of the basal forebrain near the septum; receives dopamine-secreting terminal buttons from neurons of the ventral tegmental area and is thought to be involved in reinforcement and attention.
mesocortical system
A system of dopaminergic neurons whose cell bodies are located in the ventral tegmental area and whose terminal buttons are located in the cerebral cortex and hippocampus.
conditioned reinforcer
A previously neutral stimulus that has been paired with an appetitive stimulus, which then itself becomes capable, of reinforcing a response.
conditioned punisher
A previously neutral stimulus that has been followed by an aversive stimulus, which then itself becomes capable of punishing a response.
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anterograde amnesia
Amnesia for events that occur after some disturbance to the brain, such as head injury or certain degenerative brain diseases.
retrograde amnesia
Amnesia for events that preceded some disturbance to the brain, such as a head injury or electroconvulsive shock.
Korsakoff's syndrome
Permanent anterograde amnesia caused by brain damage resulting from chronic alcoholism or malnutrition.
confabulation
The reporting of memories of events that did not take place without the intention to deceive; seen in people with Korsakoff's syndrome.
short-term memory
Immediate memory for events, which may or may not be consolidated into long-term memory.
long-term memory
Relatively stable memory of events that occurred in the more distant past, as opposed to short-term memory.
consolidation
The process by which short-term memories are converted into long-term memories.
priming
A phenomenon in which exposure to a particular stimulus automatically facilitates perception of that stimulus or related stimuli.
declarative memory
Memory that can be verbally expressed, such as memory for events in a person's past.
nondeclarative memory
Memory whose formation does not depend on the hippocampal formation; a collective term for perceptual, stimulus-response, and motor memory.
perirhinal cortex
A region of limbic cortex adjacent to the hippocampal formation that, along with the parahippocampal cortex, relays information between the entorhinal cortex and other regions of the brain.
parahippocampal cortex
A region of limbic cortex adjacent to the hippocampal formation that, along with the perirhinal cortex, relays information between the entorhinal cortex and other regions of the brain.
working memory
Memory of what has just been perceived and what is currently being thought about; consists of new information and related information that has recently been retrieved from long-term memory.
reference memory
A form of long-term memory of stable conditions and contingencies in the environment; includes perceptual memory and stimulus-response memory.
place cells
A neuron of the hippocampus that becomes active when the animal is in a particular location in the environment.
theta rhythm
EEG activity of 5-8 Hz; an important indication of the physiological state of the hippocampus.
ventral angular bundle
The bundle of axons that conveys information from the hippocampal formation to the basolateral amygdala.
recurrent collateral
A branch of an axon leaving a particular region of the brain that turns back and forms synapses with neurons near the one that gives rise to it.
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cerebrovascular accident
A "stroke"; brain damage caused by occlusion or rupture of a blood vessel in the brain.
aphasia
Difficulty in producing or comprehending speech not produced by deafness or a simple motor deficit; caused by brain damage.
Broca's aphasia
A form of aphasia characterized by agrammatism, anomia, and extreme difficulty in speech articulation.
function word
A preposition, article, or other word that conveys little of the meaning of a sentence but is important in specifying its grammatical structure.
content word
A noun, verb, adjective, or adverb that conveys meaning.
Broca's area
A region of frontal cortex, located just rostral to the base of the left primary motor cortex, that is necessary for normal speech production.
agrammatism
One of the usual symptoms of Broca's aphasia; a difficulty in comprehending or properly employing grammatical devices, such as verb endings and word order.
anomia
Difficulty in finding (remembering) the appropriate word to describe an object, action, or attribute; one of the symptoms of aphasia.
apraxia of speech
Impairment in the ability to program movements of the tongue, lips, and throat required to produce the proper sequence of speech sounds.
Wernicke's area
A region of auditory association cortex on the left temporal lobe of humans, which is important in the comprehension of words and the production of meaningful speech.
Wernicke's aphasia
A form of aphasia characterized by poor speech comprehension and fluent but meaningless speech.
pure word deafness
The ability to hear, to speak, and (usually) to read and write without being able to comprehend the meaning of speech; caused by damage to Wernicke's area or disruption of auditory input to this region.
transcortical sensory aphasia
A speech disorder in which a person has difficulty comprehending speech and producing meaningful spontaneous speech but can repeat speech; caused by damage to the region of the brain posterior to Wernicke's area.
autotopagnosia
Inability to name body parts or to identify body parts that another person names.
arcuate fasciculus
A bundle of axons that connects Wernicke's area with Broca's area; damage causes conduction aphasia.
conduction aphasia
An aphasia characterized by inability to repeat words that are heard but normal speech and the ability to comprehend the speech of others.
circumlocution
A strategy by which people with anomia find alternative ways to say something when they are unable to think of the most appropriate word.
prosody
The use of changes in intonation and emphasis to convey meaning in speech besides that specified by the particular words; an important means of communication of emotion.
pure alexia
Loss of the ability to read without loss of the ability to write; produced by brain damage.
whole-word reading
Reading by recognizing a word as a whole; "sight reading."
phonetic reading
Reading by decoding the phonetic significance of letter strings; "sound reading."
surface dyslexia
A reading disorder in which a person can read words phonetically but has difficulty reading irregularly spelled words by the whole-word method.
phonological dyslexia
A reading disorder in which a person can read familiar words but has difficulty reading unfamiliar words or pronounceable nonwords.
word-form dyslexia
A disorder in which a person can read a word only after spelling out the individual letters.
spelling dyslexia
An alternative name for word-form dyslexia.
direct dyslexia
A language disorder caused by brain damage in which the person can read words aloud without understanding them.
phonological dysgraphia
A writing disorder in which the person cannot sound out words and write them phonetically.
orthographic dysgraphia
A writing disorder in which the person can spell regularly spelled words but not irregularly spelled ones.
developmental dyslexia
A reading difficulty in a person of normal intelligence and perceptual ability; of genetic origin or caused by prenatal or perinatal factors.
planum temporale
A region of the superior temporal lobe; normally larger in the left hemisphere.
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schizophrenia
A serious mental disorder characterized by disordered thoughts, delusions, hallucinations, and often bizarre behaviors.
positive symptom
A symptom of schizophrenia evident by its presence: delusions, hallucinations, or thought disorders.
thought disorder
Disorganized, irrational thinking.
delusion
A belief that is clearly in contradiction to reality.
hallucination
Perception of a nonexistent object or event.
negative symptom
A symptom of schizophrenia characterized by the absence of behaviors that are normally present: social withdrawal, lack of affect, and reduced motivation.
chlorpromazine
A dopamine receptor blocker; a most commonly prescribed antischizophrenic drug.
clozapine
An "atypical" antipsychotic drug; blocks D4 receptors in the nucleus accumbens.
tardive dyskinesia
A movement disorder that can after prolonged treatment with antipsychotic medication, characterized by involuntary movements of the face and neck.
supersensitivity
The increased sensitivity of neurotransmitter receptors; caused by damage to the afferent axons or long-term blockage of neurotransmitter release.
epidemiology
The study of the distribution and causes of diseases in populations.
seasonality effect
The increased incidence of schizophrenia in people born during late winter and early spring.
latitude effect
The increased incidence of schizophrenia in people born far from the equator.
major affective disorder
A serious mood disorder; includes unipolar depression and bipolar disorder.
bipolar disorder
A serious mood disorder characterized by cyclical periods of mania and depression.
unipolar depression
A serious mood disorder that consists of unremitting depression or periods of depression that do not alternate with periods of mania.
tricyclic antidepressant
A class of drugs used to treat depression; inhibits the reuptake of norepinephrine and serotonin; named for the molecular structure.
specific serotonin reuptake inhibitor/SSRI
A drug that inhibits the reuptake of serotonin without affecting the reuptake of other neurotransmitters.
electroconvulsive therapy/ECT
A brief electrical shock, applied to the head, that results in an electrical seizure; used therapeutically to alleviate severe depression.
lithium
An element; lithium carbonate is used to treat bipolar disorder.
phosphoinositide system
A biochemical pathway responsible for the production of several second messengers.
carbamazepine
A drug (trade name: Tegretol) used to treat seizures originating from a focus, generally in the medial temporal lobe.
monoamine hypothesis
A hypothesis that states that depression is caused by a low level of activity of one or more monoaminergic synapses.
5-HIAA
A breakdown product of the neurotransmitter serotonin (5-HT).
tryptophan depletion procedure
A procedure involving a low tryptophan diet and a tryptophan-free amino acid "cocktail" that lowers brain tryptophan and consequently decreases the synthesis of 5-HT.
subsensitivity
Decreased sensitivity of neurotransmitter receptors; a compensatory response to their prolonged stimulation.
seasonal affective disorder
A mood disorder characterized by depression, lethargy, sleep disturbances, and craving for carbohydrates during the winter season when days are short.
summer depression
A mood disorder characterized by depression, sleep disturbances, and loss of appetite.
phototherapy
Treatment of seasonal affective disorder by daily exposure to bright light.
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anxiety disorder
A psychological disorder characterized by tension, overactivity of the autonomic nervous system, expectation of an impending disaster, and continuous vigilance for danger.
panic disorder
A disorder characterized by episodic periods of symptoms such as shortness of breath, irregularities in heartbeat, and other autonomic symptoms, accompanied by intense fear.
anticipatory anxiety
A fear of having a panic attack; may lead to the development of agoraphobia.
agoraphobia
A fear of being away from home or other protected places.
obsessive-compulsive disorder
A mental disorder characterized by obsessions and compulsions.
obsession
An unwanted thought or idea with which a person is preoccupied.
compulsion
The feeling that one is obliged to perform a behavior, even if one prefers not to do so.
Tourette's syndrome
A neurological disorder characterized by tics and involuntary vocalizations and sometimes by compulsive uttering of obscenities and repetition of the utterances of others.
Sydenham's chorea
An autoimmune disease that attacks parts of the brain including the basal ganglia and produces involuntary movements and often the symptoms of obsessive-compulsive disorder.
autistic disorder
A chronic disorder whose symptoms include failure to develop normal social relations with other people, impaired development of communicative ability, lack of imaginative ability, and repetitive, stereotyped movements.
phenylketonuria
A hereditary disorder caused by the absence of an enzyme that converts the amino acid phenylalanine to tyrosine; causes brain damage unless a special diet is implemented soon after birth.
fragile X syndrome
A genetic disorder caused by a faulty gene on the X chromosome; the leading genetic cause of mental retardation.
stress
A general, imprecise term that can refer either to a stress response or to a stressor (stressful situation).
stressor
A stimulus (or situation) that produces a stress response.
stress response
A physiological reaction caused by the perception of aversive or threatening situations.
fight-or-flight response
A species-typical response preparatory to fighting or fleeing; thought to be responsible for some of the deleterious effects of stressful situations on health.
glucocorticoid
One of a group of hormones of the adrenal cortex that are important in protein and carbohydrate metabolism, secreted especially in times of stress.
corticotropin-releasing factor/CRF
A hypothalamic hormone that stimulates the anterior pituitary gland to secrete ACTH (adrenocorticotrophic hormone).
adrenocorticotropic hormone/ACTH
A hormone released by the anterior pituitary gland in response to CRF; stimulates the adrenal cortex to produce glucocorticoids.
posttraumatic stress disorder
A psychological disorder caused by exposure to a situation of extreme danger and stress; symptoms include recurrent dreams or recollections; can interfere with social activities and a feeling of hopelessness.
psychoneuroimmunology
The branch of neuroscience involved with interactions between environmental stimuli, the nervous system, and the immune system.
natural killer cell
A white blood cell that destroys cells infected by viruses.
antigen
A protein present on a microorganism that permits the immune system to recognize it as an invader.
antibody
A protein produced by a cell of the immune system that recognizes antigens present on invading microorganisms.
B-lymphocyte
A white blood cell that originates in the bone marrow; part of the immune system.
immunoglobulin
An antibody released by B-lymphocytes that bind with antigens and help destroy invading microorganisms.
T-lymphocyte
A white blood cell that originates in the thymus gland; part of the immune system.
cytokine
A category of chemicals released by certain white blood cells when they detect the presence of an invading microorganism ; causes other white blood cells to proliferate and mount an attack against the invader.
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tolerance
The fact that increasingly large doses of drugs must be taken to achieve a particular effect; caused by compensatory mechanisms that oppose the effect of the drug.
withdrawal symptoms
The appearance of symptoms opposite to those produced by a drug when the drug is suddenly no longer taken; caused by the presence of compensatory mechanisms.
substance dependence
A maladaptive pattern of substance abuse that includes taking increasing doses of the drug or other signs of addiction.
substance abuse
A maladaptive pattern of substance use short of addiction that interferes with a person's health or social situation.
negative reinforcement
The removal or reduction of an aversive stimulus that is contingent on a particular response, with an attendant increase in the frequency of that response.
dynorphin
An endogenous opioid; the natural ligand for kappa opiate receptors.
conditioned place preference
The learned preference for a location in which an organism encountered a reinforcing stimulus, such as food or a reinforcing drug.
naloxone
A drug that blocks mu opiate receptors; antagonizes the reinforcing and sedative effects of opiates.
pimozide
A drug that blocks dopamine receptors.
antagonist-precipitated withdrawal
Sudden withdrawal from long-term administration of a drug caused by cessation of the drug and administration of an antagonistic drug.
CREB
Cyclic AMP-responsive element-binding protein; a nuclear protein to which cyclic AMP can bind and affect the activity of a gene or set of genes.
drug discrimination procedure
An experimental procedure in which an animal shows, through instrumental conditioning, whether the perceived effects of two drugs are similar.