Action

Question 1

Substantia nigra

Answer 1

One of the nuclei that form the basal ganglia. Composed of two parts: the pars compacta (the primary source of dopamine) and the pars reticularis

Question 2

Effector

Answer 2

A part of the body that can move

Question 3

Alpha motor neurons

Answer 3

Innervate muscle fibers and produce contractions of the fibers

Question 4

Gamma motor neurons

Answer 4

Part of the proprioceptive system; important for sensing and regulating the length of muscle fibers

Question 5

Neurotransmitter for alpha motor neurons

Answer 5

Acetylcholine

Question 6

Muscle spindles

Answer 6

Sensory receptors in the muscles that provide information about how much the muscle is stretched

Question 7

Spinal interneurons

Answer 7

Neurons in the spinal cord that innervate motor neurons and are innervated by sensory nerves (from the skin, muscles, and joints) as well as descending motor fibers that originate in subcortical and motor cortical structures

Question 8

Extrapyramidal tracts

Answer 8

Motor pathways (including the vestibular nuclei, substantia nigra, and reticular formation nuclei) in the brain stem that send direct projections down the spinal cord

Question 9

Vestibulocerebellum

Answer 9

Region of the cerebellum that works with the brainstem vestibular nuclei to control balance and coordinate eye movements with body movements

Question 10

Spinocerebellum

Answer 10

Medial region of the cerebellum that receives sensory information from the visual and auditory systems as well as proprioceptive information from the spinocerebellar tract

Question 11

Neocerebellum

Answer 11

The lateral zones of the cerebellar hemispheres which are heavily innervated by descending fibers from regions in the parietal and frontal lobes

Question 12

Ataxia

Answer 12

Problems with sensory coordination of the distal limb movements; disrupts fine coordination

Question 13

Basal ganglia

Answer 13

Five nuclei: the caudate nucleus and putamen (together known as the striatum), the globus pallidus, the subthalamic nucleus, and the substantia nigra

Question 14

Basal ganglia nuclei that receive most of the input

Answer 14

The striatum (caudate and putamen)

Question 15

Basal ganglia nuclei involved in most output

Answer 15

Internal segment of the globus pallidus and part of the substantia nigra

Question 16

Corticospinal tract

Answer 16

Axons that exit the cortex and project directly to the spinal cord

Question 17

Hemiplegia

Answer 17

A result of lesions to the primary motor cortex–characterized by a loss of voluntary movements on the side of the body contralateral to the lesion

Question 18

Premotor cortex

Answer 18

Lateral aspect of Brodmann Area 6 (anterior to the primary motor cortex). Involved in external sensory-guided actions

Question 19

Supplementary motor cortex

Answer 19

Medial aspect of Brodmann Area 6 (anterior to the primary motor cortex). Involved in internally guided personal preferences and goals

Question 20

Apraxia

Answer 20

Condition that affects motor planning; associated with lesions to the secondary motor cortex. Apraxia patients have no motor or sensory impairment but can’t link simple motor gestures into meaningful actions.

Question 21

Ideomotor apraxia

Answer 21

Type of apraxia in which patients have a rough sense of the desired action but can’t execute it properly

Question 22

Ideational apraxia

Answer 22

Type of apraxia in which the patient’s knowledge about the intent of an action is disrupted. More often associated with parietal damage than with damage to secondary motor areas

Question 23

Central pattern generators

Answer 23

Neurons in the spinal cord that can produce an entire sequence of actions without any descending signals or external feedback signals

Question 24

Endpoint control

Answer 24

A hypothesis concerning how movements are planned in terms of the desired final location. Endpoint control models emphasize that the motor representation is based on the final position required of the limbs to achieve the movement goal

Question 25

Preferred direction

Answer 25

The tendency for a cell to exhibit greater activation during movements in a particular direction

Question 26

Population vector

Answer 26

Idea that each neuron can be considered to be contributing a “vote” to the overall activity level, and that the strength of the vote will correspond to how closely the movement matches the cell’s preferred direction. The activity of each neuron can be described as a vector, and the population vector is the sum of all the individual vectors

Question 27

Direct pathway in the basal ganglia

Answer 27

Involves fast, direct, inhibitory connections from the striatum to the internal segment of the globus pallidus and the pars reticularis of the substantia nigra.

Question 28

Indirect pathway in the basal ganglia

Answer 28

Takes a slower, roundabout route to the internal segment of the globus pallidus and the pars reticularis of the substantia nigra, first inhibiting the external segment of the globus pallidus, which then inhibits the subthalamic nucleus and internal segment of the globus pallidus.

Question 29

Dopamine pathway

Answer 29

The projection from the pars compacta of the substantia nigra to the striatum. The substantia nigra excites the direct pathway but inhibits the indirect pathway

Question 30

Hypokinesia

Answer 30

An absence or reduction in voluntary movement

Question 31

Bradykinesia

Answer 31

Slow movements (associated with Parkinson’s)

Question 32

Visuomotor adaptation

Answer 32

A form of sensorimotor adaptation in which the visual field is altered, resulting in a mismatch between proprioception and vision. With practice, the motor system adjusts to compensate for the mismatch

Question 33

M1 and the cerebellum in adapting to mismatch between the visual and proprioceptive systems

Answer 33

The cerebellum is essential for learning the new mapping, but M1 is important for consolidating new information

Question 34

Forward model

Answer 34

Refers to the idea that the brain generates predictions of expected events. In motor control, a forward model refers to the prediction of the expected sensory consequences of a movement

Question 35

Before their activation, neurons in the internal segment of the globus pallidus are

Answer 35

Pre-activated

Question 35

Before their activation, neurons in the internal segment of the globus pallidus are

Answer 35

Pre-activated

Question 36

Movements are triggered by

Answer 36

Inhibition of the internal segment of the globus pallidus by the striatum

Question 37

The striatum inhibits

Answer 37

… only the globus pallidus internal segment neurons controlling the selected movement in the striatum