Motor control 2

Question 1

How is I that each neuron has a preferred direction but the overall movement can be different?

Answer 1

The overall movement vector is encoded by the integrated activity of all the neurons

Question 2

What is the function of feedback messages?

Answer 2

compensatory messages to correct postural instability after there is a change in body position

Question 3

Where are the feedback messages travelling from and to?

Answer 3

brainstem vestibular nuclei –> spinal cord motor neurons

Question 4

Function of feed forward anticipatory adjustments

Answer 4

before movements begin initiations are made to stabilise posture as you know you are going to have a need to stabilise posture

Question 5

What area is responsible for feedforward adjustments?

Answer 5

brainstem reticular formation nuclei controlled by the cortex

Question 6

Where is the ventral lateral nucleus found?

Answer 6

dorsal thalamus

Question 7

What does the ventro lateral nucleus arise from?

Answer 7

basal ganglion

Question 8

What cortical area does the Vlo give large subcortical input to?

Answer 8

6

Question 9

Corpus striatum - 2 principle nuclei

Answer 9

caudate nucleus and putamen

Question 10

Where do the 2 principle input nuclei receive input from?

Answer 10

all over the cortex

Question 11

Where do the inhibitory putamen project to?

Answer 11

globus pallidus and substantia nigra

Question 12

List pathway of basal ganglia motor loop and say if each step is excitatory or inhibitory

Answer 12

cortex -> putamen (E)
putamen -> globus pallidus (I)
globus pallidus -> Vlo (I)
vLo -> SMA (E)

Question 13

Function of direct pathway

Answer 13

selects specific motor actions

Question 14

Indirect pathway function

Answer 14

suppresses competing/inappropriate action

Question 15

Indirect pathway explanation

Answer 15

striatum inhibits Gpe
inhibits Gpi + STN
cortex stimulates STN, excites Gip and inhibits thalamus

Question 16

Hypokinesia and Parkinsons

Answer 16

slowness, difficult to make voluntary movements, tremor of hands and jaw, rigidity

Question 17

Cause of Parkinsons

Answer 17

degeneration of neurons in substantia nigra and their dopaminergic/excitatory inputs to striatum

Question 18

What can dopamine do to cortical inputs?

Answer 18

enhance them through direct pathway and suppress inputs through indirect pathway

Question 19

Depletion of dopamine causes what?

Answer 19

closes down activation of focussed motor activities that funnel through thalamus to SMA

Question 20

Huntington’s disease

Answer 20

hypokinesia, personality disorders and dementia

hereditary, rare and progressive

Question 21

Characteristic chorea of huntington’s

Answer 21

spontaneous, uncontrolled, rapid flicks and major movements with no purpose

Question 22

Huntington’s disease cause

Answer 22

Major loss of caudate, putamen and globus pallidus

loss of ongoing inhibitory effects of basal ganglia

Question 23

Lesions of cerebellum

Answer 23

in co-ordinated inaccurate movements

Question 24

How would you test ataxia clinically?

Answer 24

unable to touch nose with eyes closed

Question 25

Components of cortico-ponto-cerebellar projection

Answer 25

layer 5, areas 4+6, somatosensory cortex

Question 26

How does the cerebellum communicate back to cortex?

Answer 26

via ventrolateral thalamus

Question 27

Cerebellum main function

Answer 27

instruct direction, timing and force

Question 28

What loop refines the basal ganglia motor loop?

Answer 28

cortico-ponto medullary projection