Intro 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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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 epinephrine or norepinephrine.

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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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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 pathological inability to remember or 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 swellings at the base of the semicircular canals that contain the hair cells and cupulae.

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Ampullae

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The juglike swellings 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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Androgen 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 neural tube closure, in which much of the brain fails to develop.

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Anosmia

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Loss 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 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 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 or influence acting from the neuronal cell body toward the axonal target.

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Anterolateral pathway (anterolateral 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 as a result of damage to the language areas of the cerebral cortex (or their 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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Areflexia

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Loss of reflexes.

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Association cortex

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