Session 6 - Lecture 1: Motor Disorders

Question 1

Name the structures that form the basal ganglia.

Answer 1

Caudate nucleus, globus pallidus, putamen (receives dopamine from the substantia nigra), subthalamic nucleus and amygdaloid complex.

Question 2

What two structures form part of the lentiform nucleus?

Answer 2

Putamen and globus pallidus.

Question 3

Which structure of the basal ganglia consist of three main parts, name them?

Answer 3

Caudate nucleus, head, body and tail.

Question 4

Describe the direct pathway of the basal ganglia circuit.

Answer 4

Substantia nigra pars compacta –> putamen via D1R –> GABA –> inhibits globus pallidus and substantia nigra pars reticulata –> reduces inhibition of thalamus and CST –> increased movement via motor cortex and CST.
Motor cortex also increases activity of sub thalamic nucleus which increases the activity of the substantia nigra.

Question 5

Describe the indirect pathway of the basal ganglia circuit.

Answer 5

Substantia nigra inhibits putamen via D2R –> inhibition of globus pallidus –> inhibition of subthalamic nucleus –> reduced activity of globus pallidus and substantia nigra –> increased movements.

Question 6

Describe and explain in terms of the basal ganglia pathway, the symptoms of Parkinson’s disease.

Answer 6

Tremor, rigidity, bradykinesia (slow movements), psychiatric features (dementia, depression), mask like facies, micrographic and hypophonia (soft speech). Substantia nigra pars compacta affected so there is a reduction in the direct pathway activity, this leads to decreased movements.

Question 7

Describe and explain in terms of the basal ganglia pathway, the symptoms of Huntington’s disease.

Answer 7

Choreiform movements (repetitive, rapid, jerky and involuntary), dystonia (repetitive muscle contractions/abnormal fixed posture), incoordination and psychiatric features. There are reduced GABA effects on the globus pallidus –> reduced activity of the ‘brakes’ –> increased movements.

Question 8

Describe and explain in terms of the basal ganglia pathway, the symptoms of hemiballismus.

Answer 8

Explosive movements of the limbs due to damage of the subthalamic nucleus, reduces the activity of the ‘brakes’ and therefore increases movements.

Question 9

Describe the presentation of a cerebellar lesion.

Answer 9

Ipsilateral, dysdiadochokinesia, ataxia, nystagmus, intention tremor, slurred speech and hypotonia.

Question 10

In terms of movement, which areas of the cerebellum are important for limb and trunk movement.

Answer 10

The hemispheres deal with limb movement and the vermis deals with trunk movement.

Question 11

What role does the cerebellum play in terms of movement?

Answer 11

Controls the sequence in which movements need to occur in.