Motor Control and Diseases 2

Question 1

Describe in general terms the roles played by the basal ganglia and cerebellum in motor control and learning

Answer 1

Basal ganglia and cerebellum influence movement indirectly by regulating the function of upper motor neurons

The basal ganglia includes the caudate, putamen, and globus pallidus, these are regulated by the substantia nigra

Cerebellum involved in perfecting motor actions

Question 2

State the symptoms of Parkinson’s disease (PD)

Answer 2

PD is due to degeneration of the substantia nigra, leads to hypokinesis

Hypokinesia - insufficiency of movement

Bradykinesia - slow movements

Akinesia - no movements

Rigidity - from increased muscle tone

Resting tremor

Impaired balance

Shuffling gait

Non-motor disorders (e.g. mood disorders)

Question 3

Understand that these arise from the loss of dopaminergic cells in the substantia nigra which results in the loss of dopamine.

Answer 3

PD caused by the death of dopaminergic neurons in the substantia nigra region of the brain

80% of the brain’s dopamine found in the SN

Degeneration of these neurons marked by the presence of Lewy bodies - intracellular protein aggregates

Question 4

Recall the symptoms of Huntington’s Disease (HD) and how these relate to the differences in the mechanisms underlying HD and PD

Answer 4

HD is due to degeneration of the striatum, leads to hyperkinesis then akinesis

Symptoms -
-Early - hyperkinesia or dyskinesia (involuntary jerking/twitching)
-Late - akinesia, dystonia, dementia, psychosis

Basal ganglia in huntingtons
-Early on - degeneration in the striatum reduces the indirect path inputs to the `GPe
-This increases the inhibition of the GPi, resulting in the VLo disinhibiting and there is inappropriate initiation of movement
-Later - the striatal direct path and GPe neurons also degenerate, releasing the GPi to over-inhibit the VLo

Question 5

Know that both PD and HD can be inherited and that knowledge of the genes involved is enhancing our understanding of the diseases and informing new treatments

Answer 5

Both PD and HD have an inherited, genetic element

Mutations in multiple genes predispose you to getting PD

Only mutations in HTT cause HD, if you have the mutation you are certain to get the disease

PD genes encode proteins involved either in protein degradation pathways or in mitochondrial function

The function of HTT protein is unclear, may be involved in intracellular transport