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neurology > Lecture 13 Motor Control 2 > Flashcards

Lecture 13 Motor Control 2 Flashcards

1
Q

What part of the brain decides the direction of a movement

A

Directional tuning in primary motor cortex (area 4)

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2
Q

What does a rapid change in body position initiate

A

Rapid compensatory feedback messages form brain stem vestibular nuclei to spinal cord motor neurons to correct postural instability

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3
Q

Before movements begin what does the brain stem reticular formation nuclei initiate

A

Feedforward anticipatory adjustments to stabilise posture

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4
Q

Damage to descending motor pathways causes spinal shock which is what

A

Initial hypotonia as spinal circuits are deprived of cortical input

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5
Q

Damage to descending motor pathways causes UMN syndrome which presents with what signs and symptoms

A

Tendon reflexes
Babinski sign
Spasticity
Loss of fine finger movements

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6
Q

Major subcortical input to area 6 comes from where

A

Ventral lateral nucleus (Vlo) in dorsal thalamus

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7
Q

Where does input to Vlo come from

A

Basal Ganglia

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8
Q

Basal ganglia are targets for what areas of the brain

A

Frontal, pre-frontal and parietal cortex

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9
Q

Describe the basal ganglia motor loop

A

From cortex through basal ganglia and thalamus back to SMA in cortex (area 6)

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10
Q

What are the major components of the basal ganglia

A

Corpus striatum: Caudate nucleus and Lentiform nucleus (putamen and Globus pallidium)

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11
Q

What is the fucntion of the corpus striatum

A

Input zones of the basal ganglia.

Receives inupts from all over cortex

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12
Q

Medium spiny neurones in putamen and caudate receive what type of cortical input

A

Excitatory cortical inputs on dendrites

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13
Q

What do the putamen and caudate integrate and how

A

Integrate massive somatosensory, premotor and motor cortical inputs due to their large dendritic tress

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14
Q

The putamen fire before what?

A

Limb/trunk movements

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15
Q

The caudate fires before what?

A

Eye movements

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16
Q

Cortex to putamen is what type of pathway

A

Excitatory

17
Q

Putamen to Globus Pallidum is what type of pathway

A

Inhibitory

18
Q

Globus pallidus to Vlo neurones is what type of pathway

A

Inhibitory

19
Q

Vlo back to SMA is what type of pathway

A

Excitatory

20
Q

What is the fucntional consequence of cortical activation of putamen

A

Excitatory

21
Q

Why does cortical activation of putamen boosts cortical exitation

A

Cortical activation excites putamen which inhibits GP which therefore releases Vlo from inhibition so activity of Vlo boosts SMA activity

22
Q

Describe the direct pathway of cortical input through the basal ganglia

A

Direct pathway acts as a positive feedback loop to the SMA cortex and enhances the initiation of movements by the SMA

23
Q

Describe the indirect pathway of cortical input through the basal ganglia

A

Antagonises the direct route

Striatum inhibits GPe, which when inhibits GPi and STN. Cortex excites STN, this excites GPi, which inhibits thalamus

24
Q

What is the purpose of the direct pathway of cortical input through the basal ganglia

A

Selects specific motor actions that are intended

25
Q

What is the purpose of the indirect pathway of cortical input through the basal ganglia

A

Suppresses competing/inappropriate actions

26
Q

Name 2 Basal Ganglia Disorders

A

Parkinson’s and Huntington’s Disease

27
Q

What are the features of Parkinson’s Disease

A 
Hypokinesia
Slowness
Difficulty to make voluntary movements
Rigidity
Tremors
28
Q

What causes Parkinson’s disease

A

Degeneration of neurones in substrantia nigra and their excitatory (dopaminergic) inputs to the striatum. The depletion of dopamine closes down activation of the focussed motor activities that funnel through the thalamus to the SMA

29
Q

What effect does dopamine have on cortical inputs

A

Can enhance cortical inputs through the direct pathway and suppress inputs through the direct pathway

30
Q

What are the features of Huntington’s disease

A 
Hyperkinesia
Dementia
Personality disorder 
Hereditary
Characteristic chorea- spontaneous, uncontrolled rapid flicks and major movements
31
Q

What causes Huntington’s Disease

A

Caused by profound loss of caudate, putamen and GP

Loss of inhibitory effects of the basal ganglia

32
Q

What is the function of the cerebellum

A

Instructs direction, timing and force

33
Q

What do lesions to the cerebellum produce

A

Uncoordinated inaccurate movements (ataxia)

Inability to touch nose with eyes shut

34
Q

What refines the motor loop for voluntary movement

A

Feedback loop through pons, cerebellum and thalamus back to cortex

neurology (44 decks)

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