Chapter 8 Sensorimotor

Question 1

Sensory feedback

Answer 1

Sensor signals that are produced by a response and are often used to guide the continuation of the response.

Question 2

Posterior parietal association cortex

Answer 2

An area of association cortex that receives input from the visual, auditory, and somatosensory systems and is involved in the perception of spatial location and guidance of voluntary behavior.

Question 3

Frontal eye field

Answer 3

A small area of prefrontal cortex that controls eye movements.

Question 4

Apraxia

Answer 4

A disorder in which patients have great difficulty performing movements when asked to do so out of context but can readily perform them spontaneously in natural situations.

Question 5

Contralateral neglect

Answer 5

A disturbance of the patient’s ability to respond to visual, auditory, and somatosensory stimuli on the side of the body opposite to a site of brain damage, usually the left side of the body following damage to the right parietal lobe.

Question 6

Dorsolateral prefrontal association cortex

Answer 6

The area of the prefrontal association cortex that plays a role in the evaluation of external stimuli and the initiation of complex voluntary motor responses.

Question 7

Secondary motor cortex

Answer 7

Areas of the cerebral cortex that receive much of their input from association cortex and send much of their output to primary motor cortex.

Question 8

Supplementary motor area

Answer 8

The area of secondary motor cortex that is within and adjacent to the longitudinal fissure.

Question 9

Premotor cortex

Answer 9

The area of secondary motor cortex that lies between the supplementary motor area and the lateral fissure.

Question 10

Cingulate motor areas

Answer 10

Two small areas of secondary motor cortex located in the cingulate gurus of each hemisphere.

Question 11

Mirror neurons

Answer 11

Neurons that fire both when a person makes a particular movement and when he person observes somebody else making the same movement.

Question 12

Primary motor cortex

Answer 12

The cortex of the precentral gyrus, which is the major point of departure for motor signals descending from the cerebral cortex into lower levels of the sensorimotor system.

Question 13

Somatotopic

Answer 13

Organized, like the primary somatosensory cortex, according to a map of the surface of the body.

Question 14

Motor homunculus

Answer 14

The somatotopic map of the human primary motor cortex. (Homunculus means “little man.”)

Question 15

Stereognosis

Answer 15

The process of identifying objects by touch.

Question 16

Astereognosia

Answer 16

An inability to recognize objects by touch that is not attributable to a simple sensory deficit or to general intellectual impairment.

Question 17

Dorsolateral corticorubrospinal tract

Answer 17

The descending motor tract that synapses in the red nucleus of the midbrain, decussates, and descends in the dorsolateral spinal white matter.

Question 18

Betz cells

Answer 18

Large pyramidal neurons of the primary motor cortex that synapse directly on motor neurons in the lower regions of the spinal cord.

Question 19

Posterior parietal association cortex involved in

Answer 19

Plays a role in integrating information about original positions of the parts of the body that are to be moved, positions of any external objects with which the body will interact, in directing behavior by providing spatial information, and in directing attention.

Question 20

Dorsolateral corticospinal tract

Answer 20

The motor tract that leaves the primary motor cortex, descends to the medullary pyramids, decussates, and then descends in the contralateral dorsolateral spinal white matter.

Question 21

Ventromedial corticospinal tract

Answer 21

The direct ventromedial motor pathway, which descends ipsilaterally from the primary motor cortex directly into the ventromedial areas of the spinal white matter.

Question 22

Ventromedial cortico-brainstem-spinal tract

Answer 22

The indirect ventromedial motor pathway, which descends bilaterally from the primary motor cortex to several interconnected brain stem motor structures and then descends in the ventromedial portions of the spinal cord.

Question 23

Tectum

Answer 23

The “roof,” or dorsal surface, of the Mesencephalon; it includes the superior and inferior colliculi.

Question 24

Vestibular nucleus

Answer 24

The brain stem nucleus that receives information about balance from receptors in the semicircular canals.

Question 25

Reticular formation

Answer 25

A complex network of nuclei in the core of the brain stem that contains, among other things, motor programs that regulate complex species-common movements such as walking and swimming.

Question 26

Motor units

Answer 26

A single motor neuron and all of the skeletal muscle fibers that are innervated by it.

Question 27

Motor end-plate

Answer 27

The receptive area on a muscle fiber at a neuromuscular junction.

Question 28

Motor pool

Answer 28

All of the motor neurons that innervate the fibers of a given muscle.

Question 29

Flexors

Answer 29

Muscles that act to bend or flex a joint.

Question 30

Extensors

Answer 30

Muscles that act to straighten or extend a joint.

Question 31

Synergistic muscles

Answer 31

Pairs of muscles whose contraction produces a movement in the same direction.

Question 32

Antagonistic muscles

Answer 32

Pairs of muscles that act in opposition.

Question 33

Isometric contraction

Answer 33

Contraction of a muscle that increases the force of its pull but does not shorten the muscle.

Question 34

Dynamic contraction

Answer 34

Contraction of a muscle that causes the muscle to shorten.

Question 35

Golgi tendon organs

Answer 35

Receptors that are embedded in tendons and are sensitive to the amount of tension in the skeletal muscles to which their tendons are attached.

Question 36

Muscle spindles

Answer 36

Receptors that are embedded in skeletal muscle tissue and are sensitive to changes in muscle length.

Question 37

Intrafusal muscle

Answer 37

A threadlike muscle that adjusts the tension on a muscle spindle.

Question 38

Intrafusal motor neuron

Answer 38

A motor neuron that innervated an interfusal muscle.

Question 39

Skeletal muscle (extrafusal muscle)

Answer 39

Striated muscle that is attached to the skeleton and is usually under voluntary control.

Question 40

Patellar tendon reflex

Answer 40

The stretch reflex that is elicited when the patellar tendon is struck.

Question 41

Stretch reflex

Answer 41

A reflexive counteracting reaction to an unanticipated external stretching force on a muscle.

Question 42

Spindle afferent neurons

Answer 42

Neurons that carry signals from muscle spindles into the spinal cord via the dorsal root.

Question 43

Withdrawal reflex

Answer 43

The reflexive withdrawal of a limb when it comes in contact with a painful stimulus.

Question 44

Reciprocal innervation

Answer 44

The principal of spinal cord circuitry that causes a muscle to automatically relax when a muscle that is antagonistic to it contracts.

Question 45

Cocontraction

Answer 45

The simultaneous contraction of antagonistic muscles.

Question 46

Recurrent collateral inhibition

Answer 46

The inhibition of a neuron that is produced by its own activity via a collateral branch of its axon and an inhibitory interneuron.

Question 47

Central sensorimotor programs

Answer 47

Patterns of activity that are programmed into the sensorimotor system.

Question 48

Motor equivalence

Answer 48

The ability of the sensorimotor system to carry out the same basic movements in different ways that involve different muscles.

Question 49

Response-chunking hypothesis

Answer 49

The idea that practice combines the central sensorimotor programs that control individual responses into programs that control sequences of responses (chunks of behavior).