Motor Control and Learning

Question 1

Akinesia

Answer 1

The inability to produce volitional movement

Question 1

Parkinson’s disease results from cell death in the region of the brain called the…these cells are a primary source of the neurotransmitter…

Answer 1

1. substantia nigra
2. dopamine

Question 2

… is administered as a synthetic cousin of dopamine that is highly effective in compensating for the loss of endogenous dopamine

Answer 2

L-dopa

Question 3

what are the two major subcortical structures of the motor system?

Answer 3

1. the cerebellum
2. Basal ganglia

Question 4

what is the lowest level of the hierarchy within the motor system? (anatomically)

Answer 4

the spinal cord
axons from the spinal cord provide the point of contact between the nervous system and muscles

Question 5

what is at the top of the motor hierarchy? (anatomically)

Answer 5

cortical regions that help translate abstract intentions and goals into movement patterns

Question 6

what is in between the spinal cord and the cortical regions? (4)

Answer 6

the primary motor cortex and brainstem structures, which with the assistance of the cerebellum and the basal ganglia, convert these patterns into commands to the muscles.

Question 7

what is an effector?

Answer 7

a part of the body that can move.

Question 8

What do Alpha motor neurons innervate?

(motor neurons are the final neural element of the motor system)

Answer 8

Innervate muscle fibers and produce contractions of the fibers

Question 9

Gamma motor neurons

Answer 9

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

Question 10

Where can you find motor neurons?

Answer 10

Originate in the spinal cord,
exit through the ventral root,
and terminate in the muscle fibers.

Question 11

An action potential in a motor neuron releases a neurotransmitter. What is the neurotransmitter for the alpha motor neuron?

Answer 11

Acetylcholine

Question 12

Alpha motor neurons receive peripheral input from…

Answer 12

Muscle spindles

Question 13

What is the stretch reflex?

Answer 13

When the stretch is unexpected, the alpha motor neurons are activated, causing the muscle to return to its original length

Question 14

What do reflexes allow? (2)

Answer 14

1. Reflexes allow postural stability to be maintained without any help from the cortex
2. Serve as protective functions (reflexes can contract a muscle to avoid a painful stimulus well before pain is consciously perceived)

Question 15

What are spinal interneurons innervated by?

Answer 15

Afferent sensory nerves from the skin, muscles, and joints, as well as upper motor neurons.

Question 16

Which part of the brain is essential for critical reflexes associated with breathing, eating, eye movements, and facial expressions.
They originate in the brain stem

Answer 16

The 12 cranial nerves

Question 17

What are the motor pathways referred to collectively as?

Answer 17

The extrapyramidal tracts,
the axons that travel directly from the cortex to the spinal segments.

Question 18

Where do extrapyramidal tracts receive input from?

Answer 18

Subcortical and cortical structures

Question 19

Extrapyramidal tracts are a primary source of…

Answer 19

Indirect control over the spinal activity modulating posture, muscle tone, and movement speed

Question 20

What is the difference between pyramidal and extrapyramidal tracts?

Answer 20

Pyramidal = tracts originate in the cortex and terminates in the spinal cord. Almost all fibers cross over to the contralateral side at the medullary pyramids.
Extrapyramidal = tracts orginate in various subcortical nuclei and terminate in both contralateral and ipsilateral regions of the spinal cord

Question 21

What does the basal ganglia include? (3)

Answer 21

1. The caudate nucleus
2. Putamen
3. Globus pallidus
   Three nuclei that surround the thalamus

Question 22

Functionally, what else is considered the basal ganglia?

Answer 22

The subthalamic nucleus AND the substantia nigra

Question 23

What is the cerebellum?

Answer 23

A massive, densely packed structure containing over 75% of all of the neurons in the human central nervous system

Question 24

Where do inputs to the cerebellum primarily project?

Answer 24

To the cerebellar cortex

Question 25

Where do the outputs of the deep cerebellar nuclei project to?

Answer 25

Project to the brainstem nuclei and cerebral cortex via the thalamus

Question 26

How is ataxia formed?

Answer 26

From damage to the cerebellum from stroke, tumor, or degenerative processes

Question 27

What happens to patients with ataxia?

Answer 27

They have difficulty maintaining balance and producing well-coordinated movements

Question 28

What is the input of the basal ganglia restricted to? And the output?

Answer 28

Mainly to the two nuclei forming the striatum. Output is almost exclusively by way of the internal segment of the globus pallidus and part of the substantia nigra.

Question 29

What are motor areas?

Answer 29

Cortical regions involved in voluntary motor functions, including the planning, control, and execution of movement.

Question 30

Which areas are included in motor areas?

Answer 30

The primary motor cortex, the premotor cortex, and the supplementary motor area

Question 31

Which brain parts are essential in producing movements?

Answer 31

The parietal and prefrontal cortex

Question 32

Which brain part is especially important for more complex, goal-oriented behaviors?

Answer 32

The prefrontal cortex

Question 33

What is the corticospinal tract? (CST)
What is it frequently referred to as?

Answer 33

Consists of axons that exit the cortex and project directly to the spinal cord.

Referred to as the pyramidal tract because the mass of axons resembles a pyramid as it passes through the medulla oblongata.

Question 34

About 80% of the CST axons cross (decussate) at the junction of the medulla and the spinal cord. What does this do?

Answer 34

It permits each cerebral hemispheres to control movements on the opposite side of the body.

Question 35

What is M1 and what is its other name?

Answer 35

The primary motor cortex, or Brodmann area 4

Question 36

Where is the primary motor cortex located?

Answer 36

In the most posterior portion of the frontal lobe, spanning the anterior wall of the central sulcus and extending onto the precentral gyrus

Question 37

What does M1 receive input from?

Answer 37

Almost all cortical areas implicated in motor control

Question 38

What is the output of M1?

Answer 38

Makes the largest contribution to the corticospinal tract (CST)

Question 39

What are the subdivisions of the M1?

Answer 39

The older rostral region
And
A more recently evolved caudal region

Question 40

Which subdivision of M1 is thought to be present in only humans and some of our primate cousins?

Answer 40

The caudal part (the evolved one)

Question 41

Which neurons support the dexterous control of our fingers and hands, including the ability to manipulate tools?

Answer 41

Corticomotoneurons or CM neurons

Question 42

What do corticomotoneurons/ CM neurons include?

Answer 42

Prominent projections to muscles of the upper limb

Question 43

If we cut out the …, direct cortical control of effectors that is essential for volitional movements will be lost.

Answer 43

The spinal interneurons

Question 44

Which non invasive method can be used toi map the brain’s somatotopy?

Answer 44

Transcranial magnetic stimulation (TMS)

Question 45

What do corticomotoneurons/ CM neurons specialize in?

Answer 45

Fine motor control

Question 46

Lesions of the primary motor cortex (M1) usually result in …

Answer 46

Hemiplegia, the loss of voluntary movements on the contralateral side of the body