Basal Ganglia and Cerebellum I

Question 1

What is the sensory feedback learning loop?

Answer 1

Sensory perception –> Neuronal circuit–> Controller –>/–| Motor output then back to Sensory perception

Question 2

What are the 4 nuclei of the Basal ganglia and what are they connected to?

Answer 2

1. Striatum (caudate and putamen)
2. Globus pallidus
3. Substantia nigra
4. Subthalamic nucleus
   Connected to the cortex, thalamus and brainstem

Question 3

What is the Basal ganglia involved in?

Answer 3

Voluntary movement and inhibiting inappropriate involuntary movements. Its connections with the frontal cortex shows its involved in memory, cognition and emotion

Question 4

What are the components and neurons of the basal ganglia microcircuit?

(basically components and what neurons they all use)

Answer 4

SNr: dopaminergic neurons
Striatum: Medium spiny neurons/ GABAergic
Globus pallidus: GABA
Cortex/ glutamate: cortical pyramidal neurons
STN: glutamate

Question 5

What do the cortical striatal loops have a role in?

Answer 5

Executive function and motivation

Question 6

What are the main characteristics of Parkinson’s disease?

Answer 6

Idiopathic
Loss of cells in SNr
Reduction in dopamine
Tremor at rest and shuffling gait

Question 7

What can you see in a coronal section of a brain with Parkinson’s disease?

Answer 7

Substantia nigra is very diminished. By time patients show motor symptoms there is a loss of 60% of dopaminergic neurons

Question 8

Why is dopamine important?

Answer 8

It inhibits the the inhibitory pathway and promotes the direct one, therefore allowing for fluid movement. No dopamine causes ‘start’ and ‘stop’ movements which is the tremor you can see in Parkinson’s disease

Question 9

What are Lewy bodies in Parkinson’s diseased brain?

Answer 9

Fibrillar aggregates

Question 10

How does the drug Levodopa work in Parkinson’s disease?

Answer 10

Ingest in tablet or liquid form - becomes converted into dopamine.

However there will be death of cells in the brain even if you give them more dopamine and eventually there won’t be enough cells to take it in.

But it has to be taken combined with other medication

Question 11

What does long term use of Levodopa result in?

Answer 11

Dyskinesia’s (over stimulation). Less effective as more cells are lost.

Question 12

What are the ‘on’ and ‘off’ effects of Levodopa?

Answer 12

Person randomly switches from being able to move and being immobile

Question 13

What is deep brain stimulation?

Answer 13

Used in Parkinson’s disease. Surgically implant a pulse generator in subthalamic nucleus. Works well in patients who haven’t lost too many cells