3.18.14 34 Motor Systems III (Basal Ganglia)

Question 1

What is the striatum?

Answer 1

Caudate nucleus and Putamen

-functionally similar, attached by striate fibers and by nucleus accumbens

Question 2

What are the four inputs to the striatum?

Answer 2

Cortex (Glutamate)
Substantia nigra (Dopamine) (R)
Central Medial nucleus of the Thalamus (R)
Raphe Nuclei (Serotonin)

Question 3

What are the three outputs of the striatum?

Answer 3

External Globus Pallidus
Internal Globus Pallidus
Substantia Nigra (R)

Question 4

Where does the External GP project?

Answer 4

Subthalamic nucleus

Question 5

Where does the Internal GP project?

Answer 5

Subthalamic nucleus (R)
Thalamus (VA/VL)
Tegmentum

Question 6

To what five structures does the substantia nigra project?

Answer 6

Subthalamic nucleus (R)
Striatum (R)
Spinal cord
Thalamus (VA/VL)
Tegmentum

Question 7

What projects to the subthalamic nucleus?

Answer 7

External GP
Internal GP (R)
Substantia nigra (R)

Question 8

To what two structures does the subthalamic nucleus project?

Answer 8

Internal GP (R)
Substantia Nigra (R)

Question 9

What projects to the VA/VL?

Answer 9

Internal GP
Substantia Nigra
Cerebellum

Question 10

To what structure does the VA/VL project?

Answer 10

Cortex (R)

Question 11

To what structures does the CM project?

Answer 11

Cortex (R)

Striatum

Question 12

Describe the direct pathway

Answer 12

1. Cortex excites…
2. Striatum which inhibits…
3. Internal GP and Substantia Nigra, which normally inhibit…
4. Thalamus which excites…
5. Supplementary motor area

Question 13

Describe the indirect pathway

Answer 13

1. Cortex excites…
2. Striatum which inhibits…
3. External GP, which normally inhibits…
4. Subthalamic nucleus which excites…
5. Internal GP and Substantia Nigra which inhibit…
6. Thalamus which normally excites
7. Supplementary motor area

Question 14

What is “uninhibited” in the direct pathway, leading to movement?

Answer 14

Thalamus; the striatum turns off iGP and SN to release the thalamus

Question 15

What is “uninhibited” in the indirect pathway, leading to inhibition of movement?

Answer 15

Subthalamic nucleus; the striatum turns of eGP to release subthalamic nucleus, allowing excitation of iGP and SN to inhibit the thalamus

Question 16

What structure is affected by Parkinson’s disease? How does this affect movement?

Answer 16

Substantia Nigra

SN usually dampens and regulates the thalamus; without, involuntary movements and lack of control occur

Question 17

What structure is affected by hemiballismus? How does this affect movement?

Answer 17

Subthalamic nucleus

ST usually activates iGP/SN to inhibit the thalamus; without, involuntary movements and lack of control occur

Question 18

What structure is affected by Huntington’s disease?

Answer 18

Striatum (Caudate and Putamen)

Question 19

Describe athetosis

Answer 19

Slow, writhing movements

Question 20

Describe chorea

Answer 20

Sudden, brisk, graceful movements