1
Q

Why is movement difficult to replicate electronically?

A

β†’ The brain predicts movement

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2
Q

What are the basal ganglia?

A

β†’ A group of nuclei inside the brain

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3
Q

What kind of a disease is Parkinsons?

A

β†’ basal ganglia degenerative disease

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4
Q

What do the basal ganglia act as?

A

β†’ Relay stations

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5
Q

What are the 3 different circuits in the brain?

A

β†’ Motor
β†’ Associative
β†’ Limbic

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6
Q

How are the basal ganglia segregated?

A

β†’ Anatomically

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7
Q

What is the main output of the basal ganglia?

A

β†’ inhibitory

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8
Q

What are the 2 basal ganglia pathways?

A

β†’ One decreases output activity (increases movement)

β†’ One increases output activity (decreases movement)

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9
Q

What sends inputs to the basal ganglia?

A

β†’ The striatum

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10
Q

What is the indirect stop pathway?

A

β†’ Activates the inhibitory nucleus and makes movement less likely to happen

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11
Q

What is the direct go pathway?

A

β†’ Inhibits the inhibitory pathway

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12
Q

Where is dopamine produced?

A

β†’ In the substantia nigra

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13
Q

What is the Alexander and Delong model?

A

β†’ Changes in firing rate (of the output nuclei) determine the degree of thalamic inhibition and the amount of movement possible

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14
Q

What is bradykinesia?

A

β†’ A lack of movement

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15
Q

What happens in Parkinsons?

A

β†’ Substantia nigra degenerates
β†’ Not enough dopamine
β†’ Inhibitory output of the basal ganglia turns up
β†’ Inhibits the thalamus and inhibits the motor cortex
β†’ rate of firing of the output nucleus goes up

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16
Q

What is hemiballismus and what is it caused by?

A

β†’ A flinging movement of one side of the body

β†’ caused by a subthalamic nucleus stroke

17
Q

What role does the subthalamic nucleus have?

A

β†’ it is a key node in the stop pathway

18
Q

What happens if the subthalamic nucleus is removed?

A

β†’ excessive inhibition of the stop pathway or an inhibitory output nucleus
β†’ the Gpi/SNr is not stopping the thalamus
β†’ excessive movement

19
Q

What is a clinical issue with the Alexander and Delong model?

A

β†’ lesioning the thalamus does not cause prominent akinesia

β†’ lesioning the GPi does not cause dyskinesia

20
Q

What is the beta frequency?

A

β†’ 20-30 Hz

21
Q

What is the firing like in people with motor disorders?

A

β†’ the neurons have a bursty pattern

β†’ the rate of firing is not abnormal but the pattern of firing is

22
Q

in a normal situation what do brain electrodes pick up and what happens in Parkinsons?

A

β†’ lots of different frequencies firing

β†’ Everything becomes synchronised

23
Q

When does dopamine release occur?

A

β†’ At the beginning of movement

24
Q

People with Parkinsons still produce dopamine, why is this not enough for movement to occur?

A

β†’ There is a baseline level of dopamine release
β†’ additional dopamine release happens at the beginning of movement
β†’ people with Parkinsons have low baseline dopamine
β†’ When a stimulus occurs the additional dopamine released it not enough to pass the threshold for movement.

25
Q

How do you define moving?

A

β†’ Change from one stable sensory state to another stable sensory state

26
Q

What are the 3 things required for changing sensory states?

A

β†’ Turning down current sensory state
β†’ Accurate prediction of the new sensory state
β†’ Stabilising the new sensory state

27
Q

What is involved in stabilising sensory states?

A

β†’ Beta power

28
Q

What is beta power like when sitting still and why?

A

β†’ It is high

β†’ stops you having other unneeded movements such as jumping

29
Q

If you want to move what happens to beta power?

A

β†’ It is turned down which allows you to change state

30
Q

What allows prediction of movement in the brain?

A

β†’ The brain builds internal models of the world

31
Q

What is the forward model?

A

β†’ Brain sends a copy of the movement to the cerebellum to check if the movement is correct

32
Q

What does the forward model do?

A

β†’ Comparing what happened with what was expected to happen

33
Q

What happens when there is damage to the cerebellum?

A

β†’ movement becomes steady and uncoordinated because the comparison can’t happen
β†’ the brain is unprepared for obstacles

34
Q

What is abnormal in Parkinsons?

A

β†’ initiation
β†’ Scaling
β†’ and persistence of movement