Motor Control II - Role of the Cerebellum and Basal Ganglia Flashcards

1
Q

What is the role of the cerebellum?

A
  • closely involved with brainstem mechanisms
  • control of muscle tone
  • sensorimotor coordination
  • motor learning
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the role of the basal ganglia?

A
  • integrated of sensory and motor information

cortex –> basal ganglia –> cortex loop (via thalamus)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Neither the cerebellum nor basal ganglia project……

A

beyond the brain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What 2 motor disorders are associated with the basal ganglia?

A

Parkinson’s Disease

Huntington’s Disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the 3 anatomical and functional components of the cerebellum? In what regions of the cerebellum are they found?

A
  1. spino-cerebellum (medial region of cerebellum)
  2. vestibulo-cerebellum (caudal region of cerebellum)
  3. cerebro(ponto)-cerebellum (lateral hemispheres)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Describe the connections and functions of the spino-cerebellum

A
  • sensory input from the spinal cord
  • output to the reticular formation and red nucleus
  • then to motor cortex
  • then output to spinal cord
  • control of axial musculature and posture
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the result of damage to the spino-cerebellum?

A
  • hypotonia
  • ataxia (unsteady, staggering gait)
  • dysmetria (inaccurate termination of movement and ‘intention tremor’
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Describe the connections and functions of the vestibulo-cerebellum

A
  • input from and output to vestibular nucleus

- contro over posture/balance, also eye movement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the result of damage to the vestibulo-cerebellum?

A

slow saccades = fast tracking ocular movement impaired
nystagmus = due to failed vestibulo-oculomotor integration
ataxia = unsteady, staggering gait

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe the connections and functions of the cerebro(ponto)-cerebellum

A
  • an intracerebral motor loop
  • cortex–>pons–>cerebellum –> dentate nucleus –> ventrolateral thalamus –> cortex
  • instructs M1 regarding movement direction, timing and force
  • compares intended movements with actual movements and sends compensatory instructions to M1
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the result of damage to the cerebro(ponto)-cerebellum?

A
  • incoordination/ataxia
  • dysmetria - intention tremor - inaccruate termination of movement
  • asynergy - uncoordiatned agonist and antagonist muscles
  • dysarthria - inarticulate speech - poor oesophageal muscular control
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

List the components of the circuitry of the cerebellar cortex

A
parallel fibres
purkinje cell
granule cell layer
white matter 
(mossy fibres, climbing fibres)
---> deep cerebellar nuclei
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the inputs into the circuitry of the cerebellar cortex?

A
  1. climbing fibres input from inferior olive - excitatory and act on Purkinje cells
  2. mossy fibres from brainstem nuclei - indirectly excite Purkinje cells via parallel fibres of Granule cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the outputs of the cerebellar cortex circuitry?

A

only purkinje cells - project to deep cerebellar nuclei

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What do deep cerebellar nuclei do?

A
  • compare input from mossy and climbing afferent input
    from mossy and climbing afferent input
    before = via collaterals form axons to purkinje cells
    after = cerebellar processing via inhibitory purkinje cell output
    –> error signal
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the mechanism behind motor memory?

A
  • granule cell parallel fibre - purkinke cell synapses
  • shows use dependent plasticity
  • thought to be involved in motor learning
17
Q

What are the 4 functions of the cerebellum?

A

1, regulates posture indirectly by adjusting output of major descending motor pathways

  1. acts as a comparator identifying and correcting discrepancies between intended movement actual movement
  2. acts as a timer, sequencing motor activation resulting in smooth performance
  3. role in motor memory and in instigating learned motor sequences when appropriate
18
Q

What are the basal ganglia?

Which nuclei are included?

A
  • a group of associated subcortical nuclei
    Striatum = putamen, caudate nucleus, nucleus acucmbens
    Globus Pallidus
    Substantia Nigra
    Subthalamic Nuclei
19
Q

Draw the basic basal ganglia circuit

Colour code

A

see lecture

20
Q

Describe the direct and indirect pathways

A

draw diagram and explain inhibition/disinhibition
DIRECT = acts to facilitate movement
INDIRECT = acts to inhibit movement

21
Q

What is the neurotransmitter for the:

  • excitatory pathways
  • inhibitory pathways
  • modulatory pathways
A
  • excitatory pathways = GLUTAMATE
  • inhibitory pathways = GABA
  • modulatory pathways = DOPAMINE
22
Q

What is the effect of dopamine on the

  • direct pathway
  • indirect pathway
A

DIRECT
- dopamine acts on excitatory D1 receptors to further reduce BG output and facilitate movement
INDIRECT
- dopamine acts on inhibitory D2 receptors, reduces Stn activity and BG output and also facilitates movement

23
Q

What leads to motor dysfunction?

A
  • imbalance between the direct and indirect pathways
24
Q

Give examples of hypo and hyperkinetic disorders

A
Hypokinetic 
- Parkinson's
Hyperkinetic 
- Huntington's
- Hemiballism
- Tardive Dyskinesia
25
What affect does Parkinson's have on the basal gala pathway?
- dopamine loss in nigro-striatal pathway - excessive inhibition of thalami-cortical pathway - driven by increases in activity in the sub thalamic nucleus
26
What affect does Huntington's have on the basal ganglia pathway?
- loss on striatal output neurones in indirect pathway - suppression of STN - predominance of direct pathway - decrease BG output - overactive thalamocortical pathway - involuntary movement
27
What are the symptoms of the Parkinson's disease
rigidity bradykinesia tremor
28
What are the symptoms of Huntingtons disease?
excessive choreiform movements | - uncontrollable, relatively rapid motor patterns distrust normal motor activity
29
What is the cause of hemiballism?
- damage to subthalamic nucleus (usually by unilateral intracerebral thrombosis
30
What is the effect of hemiballism?
violent flailing movements of limbs contralateral to damaged side
31
What is the cause of tardive dyskinesia?
- increased dopamine receptor sensitivity, due to long-term exposure to antipsychotic dopamine receptor antagonist drugs
32
What is the effect of tardive dyskinesia?
- uncontrolled movement, especially of facial and trunk muscles