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Perception and Action > Week 11 Lecture 11 - Motor control part 2 > Flashcards

Week 11 Lecture 11 - Motor control part 2 Flashcards

1
Q

What are the connections in the Basal ganglia?

A

GPl = Lateral Globus Pallidus (external)
GPm = Medial Globus Pallidus (internal)
SNc = Substantia Nigra pars compacta
STN = Subthalamic nucleus

  • putamen
  • thalamus
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2
Q

What are the 2 pathways through the basal ganglia?

A
  • direct
  • indirect
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3
Q

What does the circuitry of the basal ganglia look like?

A

see summary sheet

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4
Q

Where does putamen recieve inputs from?

A

cortical areas (Striatum) –> excitatory

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5
Q

Where does GPm project back to?

A

cortex –> inhibitory

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6
Q

Is the direct pathway excitatory or inhibitory?

A

excitatory

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7
Q

What is the direct pathway?

A
  1. Excitatory signal from cortex
  2. Increased inhibitory signal from Putamen to GPm
  3. Reduced inhibitory signal from GPm to Thalmus
  4. Increased excitatory signal from thalamus to motor cortex
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8
Q

Is the indirect pathway inhibitory or excitatory?

A

inhibitory

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9
Q

What is the indirect pathway?

A
  1. Increased inhibitory signal from Putamen to GPl
  2. Reduced inhibitory signal from GPl to
    STN
  3. Increased excitatory input to GPm
  4. Increased inhibitory output to thalamus
  5. Reduced excitatory output to cortex
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10
Q

What does the direct pathway allow?

A

desired movements to occur

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11
Q

What does the indirect pathway prevent?

A

undesired movement occurring

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12
Q

What does Parkinson’s Disease look like in the basal ganglia?

A

Lack of dopamine has opposing effects on 2 pathways

Underactive direct pathway (increased GPm activity)

Overactive indirect pathway (increased GPm activity)

Both lead to increased inhibition of the thalamus and reduced excitation of the cortex

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13
Q

True or false?

Different BG loops project to different cortical areas

A

True
Cognitive as well as motor functions

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14
Q

What are treatments for Parkinson’s disease?

A

L-dopa
but drug induced dyskinesias

  • Newer dopaminergic drugs
  • Surgery – lesions and deep brain
    stimulation
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15
Q

What is deep brain stimulation as a treatment for Parkinson’s?

A

Battery-operated stimulator delivers electrical stimulation to targeted areas

Targets - thalamus, subthalamic nucleus, and globus pallidus

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16
Q

What does deep brain stimulation do the the pathways in the basal ganglia?

A

Reduces effect of indirect pathway:
* Reduced activity in the STN
* Reduced excitation of the GPm
* Reduced inhibition of the thalamus
* Greater excitation of the motor cortex

17
Q

What is Huntington’s disease?

A
  • inherited, autosomal dominant condition
  • Onset in 30’s or 40’s
  • Chorea – uncontrolled movements
  • Degeneration of putamen and caudate
  • Death from complications
  • No treatment at present
18
Q

How does HD affect the basal ganglia?

A

Underactivity of Indirect pathway
- Reduced inhibition of GPl
- Increased inhibition of STN
- Reduced activity of GPm
- Too much movement

19
Q

What cognitive impairments can occur with HD?

A

Can include difficulties with the following:
* Attention
* Executive function
* Speed of processing
* Prospective memory
* Emotion recognition

20
Q

What is Tourette’s syndrome?

A
  • Simple tics e.g. eye blinking, nose
    twitching
  • Complex tics e.g. scratching, gestures,
    utterances
  • May increase during times of stress
    and decrease when concentrating

> 1000 per 100,000 children (greater than
1 in 1000)
* Hereditary
* Links to obsessive-compulsive behaviours
* Developmental

21
Q

How does TS affect the basal ganglia?

A

Increased dopamine from substantia nigra
- Overactivity of the direct pathway –
leads to ‘disinhibition’ of an unwanted movement

22
Q

What is aberrant selection in TS?

A

‘Aberrant focus’ of activity in striatum leads to activity in the direct pathway

And disinhibition of undesired movement

May also explain obsessive compulsive behaviours

23
Q

How can TS sometimes be treated?

A

by blocking dopamine

24
Q

Give a summary of which BG pathways are affected in PD, HD and TS

A

see summary sheet

Perception and Action (10 decks)

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