Key terms Exam 1

Question 1

declarative memory

Answer 1

Memories available to consciousness that can be expressed by language.

Question 2

long-term memory

Answer 2

Memories that last days, weeks, months, years, or a lifetime.

Question 3

nondeclarative memory

Answer 3

Unconscious memories such as motor skills and associations. Also called procedural memory.

Question 4

action potential

Answer 4

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

Question 5

afferent

Answer 5

A neuron or axon that conducts action potentials from the periphery toward the central nervous system.

Question 6

anterograde

Answer 6

Signals or impulses that travel “forward,” e.g., from the cell body to the axon terminal, from the presynaptic terminal to the postsynaptic cell, or from the CNS to the periphery.

Question 7

associational systems

Answer 7

Neural cell circuits that are not part of the relatively defined sensory (input) and motor (output) systems; they mediate the most complex and least well defined brain functions.

Question 8

astrocytes

Answer 8

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 reuptake.

Question 9

Axon

Answer 9

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

Question 10

axon hillock

Answer 10

Point at the cell body that is the site of an action potential’s initiation.

Question 11

central nervous system (CNS)

Answer 11

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

Question 12

chemical synapses

Answer 12

Synapses that transmit information via the secretion of chemical signals (neurotransmitters).

Question 13

cognitive neuroscience

Answer 13

The field of neuroscience devoted to studying and understanding cognitive functions.

Question 14

commissures

Answer 14

Axon tracts that cross the midline of the brain.

Question 15

computational mapping

Answer 15

Central process of assessing and integrating multiple stimulus attributes into an orderly representation that facilitates the extraction and processing of essential information (e.g., the number and configuration of odorant molecules in order to determine the source and nature of a smell).

Question 16

convergence

Answer 16

Innervation of a target cell by axons from more than one neuron. In vision refers specifically to the convergence of both rod and cone photoreceptor cells onto retinal ganglion cells.

Question 17

cortex

Answer 17

The superficial mantle of gray matter (a sheet-like array of nerve cells) covering the cerebral hemispheres and cerebellum, where most of the neurons in the brain are located.

Question 18

cranial nerve ganglia

Answer 18

The sensory ganglia associated with the cranial nerves; these correspond to the dorsal root ganglia of the segmental nerves of the spinal cord.

Question 19

dendrite

Answer 19

A neuronal process arising from the nerve cell body that receives synaptic input.

Question 20

divergence

Answer 20

The branching of a single axon to innervate multiple target cells.

Question 21

dorsal root ganglia (DRG)

Answer 21

The segmental sensory ganglia of the spinal cord; they contain the first-order neurons of the dorsal column/medial lemniscus and spinothalamic pathways.

Question 22

efferent

Answer 22

A neuron or axon that conducts information away from the central nervous system toward the periphery.

Question 23

efferent

Answer 23

A neuron or axon that conducts information away from the central nervous system toward the periphery.

Question 24

electrical synapses

Answer 24

Synapses that transmit information via the direct flow of electrical current at gap junctions.

Question 25

electrophysiological recording

Answer 25

Measure of the electrical activity across the membrane of a nerve cell by use of electrodes. Extracellular recording places the electrode outside but nearby the cell of interest; intracellular recording places the electrode is placed inside the cell of interest.

Question 26

enteric system

Answer 26

A subsystem of the visceral motor system, made up of small ganglia and individual neurons scattered throughout the wall of the gut; influences gastric motility and secretion.

Question 27

ganglion (ganglia)

Answer 27

Collection of hundreds to thousands of neurons found outside the brain and spinal cord along the course of peripheral nerves.

Question 28

gap junction

Answer 28

A specialized intercellular contact formed by channels that directly connect the cytoplasm of two cells.

Question 29

gene

Answer 29

Hereditary unit located on the chromosomes; genetic information is carried by linear sequences of nucleotides in DNA that code for corresponding sequences of amino acids.

Question 30

genomics

Answer 30

Scientific field focusing on the analysis of DNA sequences, including both protein-coding DNA (genes) and non-coding DNA.

Question 31

glial cells (glia)

Answer 31

The support cells associated with neurons (astrocytes, oligodendrocytes, and microglial cells in the central nervous system; Schwann cells in peripheral nerves; and satellite cells in ganglia).

Question 32

glial stem cells

Answer 32

Neural precursor cells in the adult brain that retain the capacity to proliferate and generate both additional precursor cells and differentiated glial cells (and, in some cases, differentiated neurons).

Question 33

gray matter

Answer 33

General term that describes regions of the central nervous system rich in neuronal cell bodies and neuropil; includes the cerebral and cerebellar cortices, the nuclei of the brain, and the central portion of the spinal cord.

Question 34

interneuron

Answer 34

Technically, a neuron in the pathway between primary sensory and primary effector neurons; more generally, a neuron whose relatively short axons branch locally to innervate other neurons. Also known as local circuit neuron.

Question 35

local circuit neuron

Answer 35

General term referring to a neuron whose activity mediates interactions between sensory systems and motor systems. Interneuron is often used as a synonym.

Question 36

microglial cells

Answer 36

One of the three major classes of glial cells found in the central nervous system; concerned primarily with repairing damage following neural injury.

Question 37

motor neuron

Answer 37

A broad term used to describe all the central and peripheral structures that support motor behavior.

Question 38

myelin

Answer 38

The multilaminated wrapping around many axons formed by oligodendrocytes or Schwann cells.

Question 39

myotatic reflex

Answer 39

A fundamental spinal reflex that is generated by the motor response to afferent sensory information arising from muscle spindles. The knee jerk reaction is a common example. Also called a "stretch" or "deep tendon" reflex.

Question 40

neurons

Answer 40

Cells specialized for the conduction and transmission of electrical signals in the nervous system. Also called nerve cells.

Question 41

neuropil

Answer 41

The dense tangle of axonal and dendritic branches, and the synapses between them, that lies between neuronal cell bodies in the gray matter of the brain and spinal cord.

Question 42

neurotransmitter

Answer 42

Substance released by synaptic terminals for the purpose of transmitting information from one cell (the presynaptic cell) to another (the postsynaptic cell).

Question 43

nucleus (pl. nuclei)

Answer 43

Collection of nerve cells in the brain that are anatomically discrete, and which typically serve a particular function.

Question 44

oligodendrocytes

Answer 44

One of the three major classes of glial cells found in the central nervous system; their major function is to lay down myelin.

Question 45

parasympathetic nervous system

Answer 45

A division of the visceral motor system in which the effectors are cholinergic ganglion cells located near target organs.

Question 46

peripheral nervous system (PNS)

Answer 46

All nerves and neurons that lie outside the brain and spinal cord.

Question 47

postsynaptic

Answer 47

Referring to the component of a synapse specialized for transmitter reception; downstream at a synapse.

Question 48

presynaptic

Answer 48

Referring to the component of a synapse specialized for transmitter release; upstream at a synapse.

Question 49

projection neuron

Answer 49

A neuron with long axons that project to distant targets.

Question 50

receptive field

Answer 50

The region of a receptive surface (e.g., the body surface, or a specialized structure such as the retina) within which a specific stimulus elicits the greatest action potential response from sensory cells.

Question 51

receptor potential

Answer 51

The membrane potential change elicited in receptor neurons during sensory transduction. Also called generator potential.

Question 52

retrograde

Answer 52

Signals or impulses that travel "backward," e.g., from the axon terminal toward the cell body, or from the postsynaptic cell to the presynaptic terminal, or from the periphery to the CNS.

Question 53

Schwann cells

Answer 53

Glial cells in the peripheral nervous system that lay down myelin (named after the nineteenth-century anatomist and physiologist Theodor Schwann).

Question 54

sensory system

Answer 54

Term sometimes used to describe all the components of the central and peripheral nervous system concerned with sensation.

Question 55

spinal cord

Answer 55

The portion of the central nervous system that extends from the lower end of the brainstem (the medulla) to the cauda equina.

Question 56

sympathetic nervous system

Answer 56

A division of the visceral motor system in vertebrates comprising, for the most part, adrenergic ganglion cells located relatively far from the related end organs.

Question 57

synaptic cleft

Answer 57

The space that separates pre- and postsynaptic neurons at chemical synapses.

Question 58

synaptic transmission

Answer 58

The chemical and electrical process by which the information encoded by action potentials is passed from a presynaptic (initiating) cell to a postsynaptic (target) cell.

Question 59

synaptic vesicles

Answer 59

Spherical, membrane-bound organelles in presynaptic terminals that store neurotransmitter molecules.

Question 60

visceral

Answer 60

Referring to the internal organs of the body cavity, particularly the gut.

Question 61

white matter

Answer 61

A general term that refers to large axon tracts in the brain and spinal cord; the phrase derives from the fact that axonal tracts have a whitish cast when viewed in the freshly cut material.

Question 62

action potential

Answer 62

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

Question 63

active transporters

Answer 63

Transmembrane proteins that actively move ions into or out of cells against their concentration gradients. Their source of energy may be ATP or the electrochemical gradients of various ions.

Question 64

depolarization

Answer 64

Displacement of a cell's membrane potential toward a less negative value.

Question 65

electrochemical equilibrium

Answer 65

The condition in which no net ionic flux occurs across a membrane because ion concentration gradients and opposing transmembrane potentials are in exact balance.

Question 66

equilibrium potential

Answer 66

The membrane potential at which a given ion is in electrochemical equilibrium.

Question 67

hyperpolarization

Answer 67

The displacement of a cell's membrane potential toward a more negative value.

Question 68

ion channels

Answer 68

Integral membrane proteins possessing pores that allow only certain ions to diffuse across cell membranes, thereby conferring selective ionic permeability.

Question 69

Nernst equation

Answer 69

A mathematical formula that predicts the electrical potential generated ionically across a membrane at electrochemical equilibrium.

Question 70

overshoot phase

Answer 70

The peak, positive-going phase of an action potential, caused by high membrane permeability to a cation such as Na+ or Ca2+.

Question 71

passive flow

Answer 71

The flow of electrical current across neuronal membranes that does not entail the action potential mechanism.

Question 72

receptor potential

Answer 72

The membrane potential change elicited in receptor neurons during sensory transduction. Also called generator potential.

Question 73

rising phase

Answer 73

The initial, depolarizing, phase of an action potential, caused by the regenerative, voltage-dependent influx of a cation such as Na+ or Ca2+.

Question 74

threshold potential

Answer 74

The level of membrane potential at which an action potential is generated.

Question 75

undershoot

Answer 75

The final, hyperpolarizing phase of an action potential, typically caused by the voltage-dependent efflux of a cation such as K+.

Question 76

conduction velocity

Answer 76

The speed at which an action potential is propagated along an axon.

Question 77

membrane conductance

Answer 77

The reciprocal of membrane resistance. Changes in membrane conductance result from, and are used to describe, the opening or closing of ion channels.

Question 78

membrane conductance

Answer 78

The reciprocal of membrane resistance. Changes in membrane conductance result from, and are used to describe, the opening or closing of ion channels.

Question 79

myelin

Answer 79

The multilaminated wrapping around many axons formed by oligodendrocytes or Schwann cells.

Question 80

myelination

Answer 80

Process by which glial cells (oligodendrocytes or Schwann cells) wrap around axons to form multiple layers of glial cell membrane, thus insulating the axonal membrane and increasing conduction velocity.

Question 81

nodes of Ranvier

Answer 81

Periodic gaps in the myelination of axons where action potentials are generated.

Question 82

refractory period

Answer 82

The brief period after the generation of an action potential during which a second action potential is difficult or impossible to elicit.

Question 83

saltatory conduction

Answer 83

Mechanism of action potential propagation in myelinated axons; so named because action potentials "jump" from one node of Ranvier to the next due to generation of action potentials only at these sites.