Chapter 5 (The Sensorimotor System)

Question 1

receptor cell

Answer 1

A specialized cell that responds to a particular energy or substance and coverts this energy into a change in the electrical potential across its membrane.

Question 2

stimulus

Answer 2

A physical event that triggers a sensory response.

Question 3

labeled lines

Answer 3

The concept that each nerve input to the brain reports only a particular type of information.

Question 4

generator potential

Answer 4

A local change in the resting potential of a receptor cell that mediates between the impact of stimuli and the initiation of action potentials.

Question 5

sensory transduction

Answer 5

The process in which a receptor cell converts the energy in a stimulus into a change in the electrical potential across its membrane.

Question 6

Pacinian corpuscle (lamellated corpuscle)

Answer 6

A skin receptor cell type that detects vibration and pressure.

Question 7

threshold

Answer 7

The stimulus intensity that is just adequate to trigger and action potential at the axon hillock.

Question 8

Meissner’s corpuscle (tactile corpuscle)

Answer 8

A skin receptor cell type that detects light touch, responding especially to changes in stimuli.

Question 9

Merkel’s disc

Answer 9

A skin receptor cell type that detects light touch, responding especially to edges and isolated points on a surface.

Question 10

Ruffini corpuscle

Answer 10

A skin receptor cell type that detects stretching of skin.

Question 11

free nerve ending

Answer 11

An axon that terminates in the skin and has no specialized cell associated with it. Free nerve endings detect pain and/or changes in temperature.

Question 12

range franctionation

Answer 12

The means by which sensory systems cover a wide range of intensity values as each sensory receptor cell specializes in just one part of the overall range of intensities.

Question 13

somatosensory system

Answer 13

A set of specialized receptors and neural mechanisms responsible for body sensations such as touch and pain.

Question 14

receptive field

Answer 14

The stimulus region and features that affect the activity of a cell in a sensory system.

Question 15

adaptation

Answer 15

The progressive loss of receptor sensitivity as stimulation is maintained.

Question 16

phasic receptor

Answer 16

A receptor in which the frequency of action potentials drops rapidly as stimulation is maintained.

Question 17

tonic receptor

Answer 17

A receptor in which the frequency of action potentials declines slowly or not at all as stimulation is maintained.

Question 18

central modulation of sensory information

Answer 18

The process in which higher brain centers, such as the cortex and thalamus, suppress some sources of sensory information and amplify others.

Question 19

dorsal column system

Answer 19

A somatosensory system that delivers most touch stimuli via the dorsal columns of spinal white matter to the brain.

Question 20

dermatome

Answer 20

A strip of skin innervated by a particular spinal nerve.

Question 21

thalamus

Answer 21

The brain regions at the top of the brainstem that trade information with the cortex.

Question 22

primary sensory cortex

Answer 22

For a given sensory modality, the region of cortex that receives most of the information about that modality from the thalamus or, in the case of olfaction, directly from the secondary sensory neurons.

Question 23

nonprimary sensory cortex

Answer 23

Also called secondary sensory cortex. For a given sensory modality, the cortical regions receiving direct projections from primary sensory cortex for that modality.

Question 24

primary somatosensory cortex (S1)

Answer 24

The gyrus just posterior to the central sulcus where sensory receptors on the body surface are mapped. Primary cortex for receiving touch and pain information, in the parietal lobe.

Question 25

polymodal neuron

Answer 25

A neuron upon which information from different sensory systems converges.

Question 26

synesthesia

Answer 26

A condition in which stimuli in one modality evoke the involuntary experience of an additional sensation in another modality.

Question 27

pain

Answer 27

The discomfort normally associated with tissue damage.

Question 28

nociceptor

Answer 28

A receptor that respons to stimuli (e.g. pain or changes in temperature) that produce tissue damage or pose the threat of damage.

Question 29

transient receptor potential 2 (TRP2)

Answer 29

A receptor, found in some free nerve endings, that opens its channel in response to rising temperatures.

Question 30

A delta fiber

Answer 30

A moderately large, myelinated and therefore fast-conducting axon, usually transmitting pain information.

Question 31

C fiber

Answer 31

A small, unmyelinated axon that conducts pain information slowly and adapts slowly.

Question 32

anterolateral system (spinothalamic system)

Answer 32

A somatosensory system that carries most of the pain information from the body to the brain.

Question 33

substance P

Answer 33

A peptide transmitter that is involved in pain transmission.

Question 34

neuropathic pain

Answer 34

Pain that persists long after the injury that started it has healed. It is caused by damage to peripheral nerves and is often difficult to treat.

Question 35

cingulate cortex

Answer 35

Also called cingulum. A region of medial cerebral cortex that lies dorsal to the corpus callosum.

Question 36

analgesia

Answer 36

Absence of or reduction in pain.

Question 37

endorphin

Answer 37

One of the three kinds of endogenous opioids.

Question 38

transcutaneous electrical nerve stimulation (TENS)

Answer 38

The delivery of electrical pulses through electrodes attached to the skin, which excite nerves that supply the region to which pain is referred. TENS can relieve pain in some instances.

Question 39

naloxone

Answer 39

A potent antagonist of opiates that is often administered to people who have taken drug overdoses. It binds to receptors for endogenous opioids.

Question 40

placebo effect

Answer 40

Relief of a symptom, such as pain, that results following a treatment that is known to be ineffective or inert.

Question 41

acupuncture

Answer 41

The insertion of needles at designated points on the skin to alleviate pain or neurological inflammation.

Question 42

movement

Answer 42

A single relocation of a body part, usually resulting form a brief muscle contraction. (Less complex than an act.)

Question 43

reflex

Answer 43

A simple, highly stereotyped, and unlearned response to a particular stimulus (e.g., an eye blink in response to a puff of air).

Question 44

act

Answer 44

Complex behavior, as distinct from a simple movement.

Question 45

motor plan

Answer 45

Also called motor program. A plan for a series of muscular contractions, established in the nervous system prior to its execution.

Question 46

electromyography (EMG)

Answer 46

The electrical recording of muscle activity.

Question 47

closed-loop motor control

Answer 47

A control mechanism that provides a flow of information from whatever is being controlled to the device that controls it.

Question 48

open-loop motor control

Answer 48

A control mechanism in which feedback from the output of the system is not provided to the input control.

Question 49

ballistic

Answer 49

Referring to a rapid muscular movement that is generally fully preprogrammed and thus not susceptible to error correction during execution.

Question 50

antagonist

Answer 50

A muscle that counteracts the effect of another muscle.

Question 51

synergist

Answer 51

A muscle that acts together with another muscle.

Question 52

skeletal muscle

Answer 52

A muscle that is used for movement of the skeleton, typically under our conscious control.

Question 53

striate muscle

Answer 53

A type of muscle that has a striped appearance; it is generally under voluntary control.

Question 54

motoneuron

Answer 54

Also called motor neuron. A neuron that transmits neural messages to muscles (or glands).

Question 55

neuromuscular junction

Answer 55

The region where adjoining muscle fiber meet; the point where the nerve transmits its message to the muscle fiber.

Question 56

acetylcholine (ACh)

Answer 56

A neurotransmitter that is produced and released by parasympathetic postganglionic neurons, by motoneurons, and by neurons throughout the brain.

Question 57

final common pathway

Answer 57

The motoneurons of the spinal cord, so called because they receive and integrate all motor signals from the brain and then direct movement accordingly.

Question 58

proprioception

Answer 58

Body sense; information about the position and movement of the body that is sent to the brain.

Question 59

muscle spindle

Answer 59

A muscle receptor that lies parallel to ta muscle and sends impulses to the CNS when the muscle is stretched.

Question 60

intrafusal fiber

Answer 60

(within spindle) Any of the small muscle fibers that lie within each muscle spinal.

Question 61

Golgi tendon organ

Answer 61

Any of the receptor within tendons that send impulses to the CNS when a muscle contracts.

Question 62

stretch reflex

Answer 62

The contraction of a muscle in response to stretch of that muscle.

Question 63

pyramidal system or corticospinal system

Answer 63

The motor system that includes neurons within the cerebral cortex and their axons, which form the pyramidal tract.

Question 64

extrapyramidal system

Answer 64

A motor system that includes the basal ganglia and some closely related brainstem structures. Axons of this system pass into the spinal cord outside the pyramids of the medulla.

Question 65

primary motor cortex (M1)

Answer 65

The apparent executive region for the initiation of movement; primarily the precentral gyrus.

Question 66

precentral gyrus

Answer 66

The strip of frontal cortex, just in front of the central sulcus, that is crucial for motor control.

Question 67

nonprimary motor cortex

Answer 67

Frontal lobe regions adjacent to the primary motor cortex that contribute to motor control and modulate activity of the primary motor cortex.

Question 68

supplementary motor area (SMA)

Answer 68

A region of nonprimary motor cortex that receives input form the basal ganglia and modulates the activity of the primary motor cortex.

Question 69

premotor cortex

Answer 69

A region of nonprimary moto cortex just anterior to the primary motor cortex.

Question 70

plegia

Answer 70

Paralysis, the loss of the ability to move.

Question 71

paresis

Answer 71

Muscular weakness, often the result of damage to the motor cortex.

Question 72

apraxia

Answer 72

An impairment in the ability to carry out complex movements, even though there is no muscle paralysis.

Question 73

mirror neuron

Answer 73

A neuron that is active both when and individual makes a particular movement and when that individual sees another individual make the same movement.

Question 74

basal ganglia

Answer 74

A group of forebrain nuclei, including the caudate nucleus, globus pallidus, and putamen, found deep within the cerebral hemispheres.

Question 75

cerebellum

Answer 75

A structure located at the back of the brain, dorsal to the pons, that is involved in the central regulation of movement.

Question 76

ataxia

Answer 76

A loss of movement coordination, often caused by disease of the cerebellum.

Question 77

decomposition of movement

Answer 77

Difficulty of movement in which gestures are broken up into individual segments instead of being executed smoothly; it is a symptom of cerebellar lesions.

Question 78

Parkinson’s disease

Answer 78

A degenerative neurological disorder, characterized by tremors at rest, muscular rigidity, and reduction in voluntary movement, caused by a loss of dopaminergic neurons of the substantia nigra.

Question 79

substantia nigra

Answer 79

A brainstem structure in humans that innervates the basal ganglia and is named for its dark pigmentation.

Question 80

Huntington’s disease

Answer 80

A genetic disorder, with onset in middle age, in which the destruction of basal ganglia results in a syndrome of abrupt, involuntary writhing movements and changes in mental functioning.