Neuroscience Glossary

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Acetylcholine

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Neurotransmitter at motor neuron synapses in autonomic ganglia and a variety of central synapses; binds to two types of receptors: ligand gated ion channels (nicotinic receptors) and G-protein coupled receptors (muscarinic receptors)

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Achromatopsia, cerebral

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Loss of color vision as a result of damage to extrastriate visual cortex

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Action Potential

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The electrical signal conducted along acons or muscle fibers by which information is conveyed from one place to another in the nervous system

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Activation

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The time-dependent opening of ion channels in response to a stimulus, typically membrane depolarization.

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Adaptation

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The phenomenon of sensory receptor adjustment to different levels of stimulation; critical for allowing sensory systems to operate over a wide dynamic range.

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Adenylyl cyclase

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Membrane bound enzyme that can be activated by G-proteins to catalyze the synthesis of cyclic AMP from ATP

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Adrenal Medulla

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The central part of the adrenal gland that, under visceral motor stimulation, secretes epinephrine and norepinephrine into the bloodstream

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Adrenergic

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Refers to synaptic transmission mediated by the release of norepinephrine or epinephrine

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Adult

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The mature form of an animal, usually defined by the ability to reproduce

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Afferent

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An axon that conducts action potentials from the periphery toward the central nervous system.

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Agnosia

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The inability to name objects

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Alpha motor neurons

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Neurons in the ventral horn of the spinal cord that innervate skeletal muscle.

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Amacrine Cells

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Retinal neurons that mediate lateral interactions between bipolar cell terminals and the dendrites of ganglion cells.

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Amblyopia

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Diminished visual acuity as a result of the failure to establish appropriate visual cortical connections in early life.

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Amnesia

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The pathalogical inability to remember of establish memories; retrograde amnesia is the inability to recall existing memories, whereas anterograde amnesia is the inability to lay down new memories.

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Amphetamine

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A synthetically produced central nervous system stimulant with cocaine-like effects; drug abuse may lead to dependence

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Ampullae

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The juglike sweelings at the base of the semicircular canals that contain the hair cells and cupulae

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Amygdala

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A nuclear complex in the temporal lobe that forms part of the limbic system; its major functions concern autonomic, emotional and sexual behavior.

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Adrogen Insensitivity Syndrome

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A condition in which, due to a defect in the gene that codes for the androgen receptor, testosterone cannot act on its target tissues.

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Anencephaly

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A congenital defect of the neural tube closure, in which much of the brain fails to develop.

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Anosmia

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Lack of the sense of smell

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Anterior

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Toward the front; sometimes used as a synonym for rostral and sometimes used as a synonym for ventral

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Anterior Commissure

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A small midline fiber tract that lies at the anterior end of the corpus callosum; like the callosum it serves to connect the two hemispheres

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Anterior hypothalamus

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Region of the hypothalamus containing nuclei that mediate sexual behaviors; not to be confused with the region in rodent called the medial preoptic area, which lies anterior to hypothalamus and also contains nuclei that mediate sexual behavior (most notably the sexually dimorphic nucleus)

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Anterograde

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A movement of influence acting from the neuronal cell body toward the axonal target

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Anterolateral pathway/system

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Ascending sensory pathway in the spinal cord and brainstem that carries information about pain and temperature to the thalamus

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Antiserum

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Serum harvested from an animal immunized to an agent of interest

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Aphasia

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The inability to comprehend and/or produce language asa result of damage to the language areas of the cerebral cortex (or the white matter interconnections)

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Apoptosis

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Cell death resulting from a programmed pattern of gene expression; also known as programmed cell death

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Aprosodia

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The inability to infuse language with its normal emotional content

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Arachnoid mater

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One of the three coverings of the brain that make up the meninges; lies between the dura mater and the pia mater

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Association cortex

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Definied by the exclusion as those neocortical regions that are not involved in primary sensory or motor processing.

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Associativity

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In the hippocampus, the enhancement of a weakly activated group of synapses when a nearby group is strongly activated

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Astrocytes

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One of the three major classes of glial cells found in the central nervous system; important in regulating the ionic milieu of nerve cells and in some cases transmitter uptake.

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Astrotactin

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A cell surface molecule that causes neurons to adhere to redial glial fibers during neuronal migration

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Athetosis

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Slow writhing movements seen primarily in patients wtih disorders of the basal ganglia.

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ATPase pumps

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Membrane pumps that use the hydrolysis of ATP to translocate ions against their electrochemical gradients

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Atropy

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The physical wasting away of tissue, particularly muscle, in response to disuse.

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Attention

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The selection of a particular sensory stimulus or mental process for further analysis

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Auditory meatus

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Opening of the external ear canal

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Auditory space map

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Topographic representation of sound source location, as occurs in the inferior colliculus

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Autonomic nervous system

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The components of the nervous system (peripheral and central) concerned with the regulation of smooth muscle, cardiac muscle, and glands

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Axon

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The neuronal process that carries the action potential from the nerve cell body to a target

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Axoplasmic transport

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The process by which materials are carried from nerve cell bodies to their terminals (anterograde transport) or from nerve cell terminals to te neuronal cell body (retrograde transport)

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Baroreceptors

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Sensory receptors in the visceral motor system that respond to changes in blood pressure

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Basal ganglia

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A group of nuclei lying deep in the subcortical white matter of the frontal lobes that organize motor behavior. The caudate and putamen and the globus pallidus are the major components of the basal ganglia; the subthalamic nucleus and substantia nigra are often included

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Basal lamina

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aka basement membrane. A thing layer of extracellular matrix material (primarily collagen, laminin, and fibronectin) that surrounds muscle cells and Schwann cells. Also underlies all epithelial sheets

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Basilar membrane

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The membrane that forms the floor of the cochlear ducts, on which the cochlear hair cells are located

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Basket cells

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Inhibitory interneurons in the cerebellar cortex whose cell bodies are located within the Purkinje cell layer and whose axons make basketlike terminal arors around Purkinje cell bodies

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Biogenic amines

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The bioactive amine neurotransmitters; includes the catecholamines (epinephrine, norepinephrin, dopamine), serotonin, and histamine.

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Bipolar cells

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Retinal neurons that provide a direct link between photoreceptor terminals and ganglion cell dendrites.

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Blastomere

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A cell produced when the egg undergoes cleavage

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Blastula

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An early embryo during the stage whent he cells are typically arranged to form a hollow sphere

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Blind spot

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The region of visual space that falls on the optic disk; due to the lack of photorecceptors in the opotic disk, objects that lie completely witin the blind spot are not perceived.

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Blood-brain barrier

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A diffusion barrier between the brain vasculature and the substance of the brain formed by tight junctions between capillary endothelial cells.

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Bouton

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A swelling specialied for the release of neurotransmitter that occurs along or at the end of an axon

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Bradykinesia

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Pathologically slow movement

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Brain-derived Neurotrophic Factor

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One member of a family of neurotrophic factors, the best-known constituent of which is nerve growth factor

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Brainstem

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The portion of the brain that lies between the diencephalon and the spinal cord; comprises the midbrain, pons and medulla

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Broca's aphasia

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Difficulty producing speech as a result of damage to Broca's area in the left frontal lobe

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Broca's Area

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An area in the left frontal lobe specialized for the production of language

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CA1

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A region of the hippocampus that shows a robust form of long term potentiation

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CA3

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A region of the hippocampuse containing the neurons that form the Scaffer collaterals

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Cadherins

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A family of calicum-dependent ccell adhesion molecules found on the surfaces of growth cones and the cells over which they grow

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Calcarine sulcus

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The major sulcus on the medial aspect of the occipital lobe; the primary visual cortex lies largely within this sulcus

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cAMP response element binding protein (CREB)

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A protein activated by cyclic AMP that binds to specific regions of DNA, thereby increasing the transcriptioon rates of nearby genes

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cAMP response elements (CRE's)

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Specific DNA sequences that bind transcription factors activated by cAMP

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Carotid bodies

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Specialized tissue masses found at the bifucation of the carotid arteries in humans and other mammals that respond to chemical composition of the blood (primarily the partial pressure of oygen and carbon dioxide)`

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Catecholamines

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A term referring to molecules containing a catechol ring and an amino group; examples are the neurotransmitters epinephrine, norepinephrine, and dopamine

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Cauda equina

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The collection of segmental ventral and dorsal roots that extend from the caudal end of the spinal cord to their exit from the spinal cord

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Caudal

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posterior or tailward

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Caudate Nucleus

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One of the three major commponents of the basal ganglia (the other two are the globus pallidus and putamen)

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Cell adhesion molecules

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A family of molecules on cell surfaces tat cause them to stick to one another (ex: fibronectin and laminin)

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Central nervous system

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The brain and spinal cord of vertebrates (by analogy the central nerve cord and ganglia of invertebrates)

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Cenral pattern generator

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Oscillatory spinal cord or brain stem circuits responsible for prorammed rhythmic movements such as locomotion

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Cerebellar ataxia

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A pathological inability to make coordinated movements associated with lesions to the cerebellum.

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Cerebellar Cortex

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The superficial gray matter of the cerebellum.

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Cerebellum

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Prominent hindbrain structure concerned with motor coordination, posture, and balance. Composed of a three-layered cortex and deep nuclei; attached to the brain stem by cerebellar peduncles.

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Cerebral Aquaduct

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The portion of the ventricular system that connects the third and fourth ventricles.