8.9. The role of the cerebellum and basal ganglia in motor functions

Question 1

I. Basal ganglia
1. What are the main elements in Basal ganglia?

Answer 1

• Striatum (putamen + caudate nucleus)
• Pallidum (globus pallidus internus + externus)
• Subthalamic nuclei
• Substantia nigra
  => These components form a cortical-cortical loop, in that sense that input comes from the cortex and output is also sent to the cortex

Question 2

I. Basal ganglia
2A. What are the functions of basal ganglia?

Answer 2

• Acts as a motor cortex
• Muscle tone regulation (↓)
• Helps to generate movement patterns
• Allows us to learn different movements, like f.ex. play football or an instrument:

Question 3

I. Basal ganglia
2B. Describe the projection of basal ganglia

Answer 3

Projection of medial and lateral pathways:
- Medial PWs: provide background for body posture
- Lateral PWs: provide background for fine movements

Question 4

I. Basal ganglia
2C. How does basal ganglia allow us to learn movements?

Answer 4

Allows us to learn different movements, like f.ex. play football or an instrument:
- Learn movement patterns which are stored in striatum/cerebellum => the cortex will just give the signal to recall the already learned movement patterns
=> Learn movements until the action becomes automatic and unconscious

Question 5

II. Direct and indirect pathways
1. Basal ganglia have both Direct and indirect pathways
=> T/F?

Answer 5

TRUE!!!!!!

Question 6

II. Direct and indirect pathways
2. How does basal ganglia use the direct pathway?

Answer 6

• Using the direct pathway, we can recall/initiate something from the basal ganglia -> open the thalamocortical route
  => Either inhibit or activate (recall) something

Question 7

II. Direct and indirect pathways
3. How does basal ganglia use the indirect pathway?

Answer 7

• Using the indirect pathway, we can inhibit (close) the thalamocortical route

Question 8

II. Direct and indirect pathways
4. The basal ganglia need to be drive by … (which part?)

Answer 8

the substantia nigra

Question 9

II. Direct and indirect pathways
5. How is the basal ganglia driven by substantia nigra?

Answer 9

.

Question 10

II. Direct and indirect pathways
6. Make a schematic for direct and indirect pathways of basal ganglia

Answer 10

Question 11

III. Injury and pathology of basal ganglia
1. What is the most common injury of basal ganglia?

Answer 11

The basal ganglia needs a lot of blood, because they are constantly working and their metabolism is extremely high
=> therefore, the most common injury to the basal ganglia is hypoxia

Question 12

III. Injury and pathology of basal ganglia
2. How can pathologies of the basal ganglia characterized?

Answer 12

Pathologies of the basal ganglia can be characterized as hypokinetic or hyperkinetic
=> to describe the decreased or increased muscle tone and action associated with them.

Question 13

III. Injury and pathology of basal ganglia - Hypokinetic disease
3. Give an example of Hypokinetic disease

Answer 13

Parkinson’s disease

Question 14

III. Injury and pathology of basal ganglia - Hypokinetic disease
4. What are the features of Parkinson’s disease?

Answer 14

• Parkinson’s disease – substantia nigra is degenerated, increasing the inhibitory control of GPe.
• This disease also leads to decreased dopamine production
  => can be treated with L- DOPA (precursor to dopamine), which passes the BBB and can be metabolized into dopamine

Question 15

III. Injury and pathology of basal ganglia
5. Give an example of Hyperkinetic disease

Answer 15

Huntington’s disease: involuntary movements that cannot be modulated intentionally, problems with voluntary movement execution

Question 16

IV. Cerebellum
1. What are the features of cerebellum?

Answer 16

• Direct stimulation of the cerebellum does not evoke movements = silent region of the brain.
• The cerebellum has no direct influence on the spinal cord. It contains more neurons than the telencephalon

Question 17

IV. Cerebellum
2. What are the main functions of cerebellum?

Answer 17

• Regulate muscle tone
• Ensure postural background of fast movements
• Continuous control of small movements
• Regulates automatic movements (important in learning)

Question 18

IV. Cerebellum
3A. What are the functional divisions of cerebellum?

Answer 18

1. Vestibulocerebellum
2. Spinocerebellum
3. Cerebrocerebellum

Question 19

IV. Cerebellum - Functional divisions of cerebellum
3B. What are the features of vestibulocerebellum?

Answer 19

• Process input from vestibular system + relay nuclei of the eye
• Controls balance and certain eye movements
• Provides coordination of movements
• If impaired => nystagmus (impaired balance)

Question 20

IV. Cerebellum - Functional divisions of cerebellum
3C. What are the features of Spinocerebellum?

Answer 20

• Process inputs from the spinal cord
• Provides postural background of voluntary movements

Question 21

IV. Cerebellum - Functional divisions of cerebellum
3D. What are the features of Cerebrocerebellum?

Answer 21

• Process input from cortex (premotor + primary motor) + somatosensory cortex
• Important for (automatic) programmed movements -> skill movement
• If lost =>Dysmetry (cannot judge distance of objects)

Question 22

IV. Cerebellum - Neural connections in the cerebellum
4. What are the afferents and efferents of Neural connections in the cerebellum?

Answer 22

• Afferents = climbing fibers + mossy fibers
• Efferents = Purkinje cells
  => Ethanol can influence the cerebellar function (why we have altered movement when being drita full)

Question 23

IV. Cerebellum - Neural connections in the cerebellum
5. Make a schematic diagram of Neural connections in the cerebellum?

Answer 23