chapter 9: motor system

Question 1

Describe role of motor cortex, basal ganglia, cerebellum, and spinal cord in general motor system functioning.

Answer 1

cortex plans and initiates, basal ganglia and cerebellum coordinate movement, spinal cord conducts information to muscles.

Question 2

In initiating movement, which areas of the cortex perform which functions.

Answer 2

Parietal cortex (Broadmann Areas 5 and 7) send goals, prefrontal cortex (BA 9-11, 45-47) plans, premotor cortex (BA 6) sequences, motor cortex (BA 4) executes actions.

Question 3

What is the anatomical name/location of the primary motor cortex?

Answer 3

The precentral gyrus.

Question 4

Both the motor and somatosensory homunculi represent the body (right-side up/upside down).

Answer 4

Upside down; feet in central fissure, head near inferior lateral surface.

Question 5

What are ethological behaviours?

Answer 5

Behaviours an animal might use in everyday activities.

E.g. defensive posture, reaching movements, climbing and leaping postures

Question 6

What dimensions are included in ethological movements?

Answer 6

Part of body to be moved, destination to which it is directed, function of movement.

Question 7

Ethological movements can be elicited from __________ cortex stimulation (visual-__________-motor connections).

Answer 7

parietal

movements evoked form parietal lobe map in manner similar to those caused by frontal.

Question 8

__________ connections integrate sensory and somatosensory information to evoke ethological movements via __________ cortex stimulation.

Answer 8

visual-parietal-motor, parietal

Question 9

What is the movement lexicon?

Answer 9

The set of movement patterns used to build behaviours.

Question 10

Describe compensation/compensatory behaviour (in the context of the motor system).

Answer 10

Compensation: modifications/replacements from existing lexicon to replace impaired movements.

Question 11

How do stroke studied indicate redundancy in the cortex?

Answer 11

Studies indicate that movement is encoded in multiple places in the cortex.

Question 12

Damage to primary motor cortex impairs __________ movements, while damage to the premotor cortex impairs __________ movements.

Answer 12

individual, complex

Question 13

Which cortical areas coordinate/blend more basic (pre-learned) movements, such as walking or climbing movements?

Answer 13

The motor planning areas.

Question 14

What did corticomotor-neuron activity studies (monkey wrist study) indicate about motor cortex planning and execution?

Answer 14

• Motor cortex involved in planning movement
• Activity increased during movement and increased with recruitment
• Neurons encode direction (direction-dependent firing)
• Movement encoded by population of neurons

Question 15

What are mirroring movements?

Answer 15

Movements learned and modified based on interaction with others.

Question 16

Where are mirror neurons found? When are they active?

Answer 16

Ventral premotor area; active both when performing movement and observing others do it.

Question 17

Which areas of the brain are involved in subcortical motor control?

Answer 17

Basal ganglia, cerebellum, brainstem.

Question 18

Which parts of the basal ganglia are involved in motor control?

Answer 18

Caudate, putamen, globus pallidus.

Question 19

Damage to which parts of the basal ganglia results in hyperkinetic movement disorders?

Answer 19

Caudate, putamen.

Question 20

Which movement disorders display hyperkinetic symptoms?

Answer 20

Huntington’s disease, Tourette’s syndrome.

Question 21

What are dyskinesias?

Answer 21

A type of hyperkinetic symptom: unwanted writhing and twitching movements

Question 22

Which movement disorder displays hypokinetic symptoms?

Answer 22

Parkinson’s disease.

Question 23

What causes hypokinetic movement disorders?

Answer 23

Loss of dopamine input from the substantia nigra.

Question 24

Movement disorders indicate that the role of the basal ganglia is to __________ __________.

Answer 24

modulate movements

Question 25

Output from the interior portion of the globus pallidus (GPi) projects to which areas involving movement?

Answer 25

The thalamus and motor cortex.

Question 26

If predominant input to GPi is inhibitory, thalamus (is/is not) inhibited and movement (does/does not) occur. This is the (direct/indirect) pathway.

Answer 26

thalamus is not inhibited, movement does occur, direct pathway.

Question 27

if predominant input to GPi is excitatory, thalamus (is/is not) inhibited and movement (does/does not) occur. This is the (direct/indirect) pathway.

Answer 27

thalamus is inhibited, movement does not occur, indirect pathway.

Question 28

Decreasing activity of the interior portion of globus pallidus (increases/decreases) symptoms of Parkinson’s.

Answer 28

decreases

Question 29

What aspects of motor control is each area of the cerebellum involved in? (flocculus, midline, lateral areas)

Answer 29

Flocculus: balance; receives input from vestibular system
Midline: controls midline of body
Lateral areas: movement of limbs and hands

Question 30

How does damage to the cerebellum affect timing of movements?

Answer 30

Affects ability to move in regular rhythm, accurately perceive time, monitor movement accuracy.

Question 31

How is the cerebellum involved in motor feedback?

Answer 31

Cortex sends copy of motor command to cerebellum, sensory and visual input also sent, cerebellum compares intention with results and generates required correction.

Question 32

What kind of movement pathways originate in the brainstem (as opposed to the motor cortex)?

Answer 32

Coarse movements of the entire body, such as walking/running behaviours.

Question 33

What movements are controlled by the corticobulbar tracts?

Answer 33

Facial movements.

Question 34

What movements are controlled by the corticospinal tracts?

Answer 34

Movements of the limbs, digits, body.

Question 35

Which layer of the neocortex do the corticobulbar and corticospinal tracts originate in?

Answer 35

Layer V.

Question 36

Approximately __% of descending motor pathways decussate on ventral surface of brainstem (pyramids).

Answer 36

95

Question 37

(Lateral/Anterior) corticospinal tract decussates and contralaterally influences movements of limbs and digits.

Answer 37

Lateral

Question 38

(Lateral/Anterior) corticospinal tract does not decussate and ipsilaterally influences movements of the trunk.

Answer 38

Anterior

Question 39

Lateral, intermediate, and medial spinal motor neurons control which body areas respectively?

Answer 39

Lateral: fingers and hand
Intermediate: limbs
Medial: trunk

Question 40

__________ binding to receptors at neuromuscular junction causes muscle contraction.

Answer 40

Acetylcholine