Neuro: Basal Ganglia

Question 1

The direct pathway of the basal ganglia leads to cortex ___________

Answer 1

excitation

Question 2

The GPi is (inhibited or activated) in the direct pathway

Answer 2

INHIBITED (allowing the thalamus to be disinhibited)

Question 3

What makes up the striatum?

Answer 3

• caudate
• nucleus accumbens
• putamen

Question 4

What makes up the lenticular nucleus?

Answer 4

putamen and the globus pallidus

Question 5

True or false: the basal ganglia has no major outputs to LMNs?

Answer 5

TRUE

it can only influence LMNs via the cerebral cortex

Question 6

Input to striatum from cortex is _____________ and glutamate is the NT

Answer 6

excitatory

Question 7

How does the basal ganglia mediate its output?

Answer 7

globus pallidus internal

substantia nigra reticulum

Question 8

True or False: BG output is inhibitory

Answer 8

TRUE (mediated via GABA)

Question 9

What is the main role of the BG?

Answer 9

to send the thalamus excitatory and inhibitory messages via the striatum

Question 10

What are 4 loops of the BG?

Answer 10

1) Motor (learned movements)
2) Cognitive (intention)
3) Limbic (emotion)
4) Oculomotor (fast eye movements)

Question 11

Walk thru the circuit of the direct pathway

Answer 11

SNc releases D1 –> excites the striatum which inhibits the GPi which can no longer inhibit the VA/VL of the thalamus so the Premotor cortex gets ACTIVATED

Question 12

In the indirect pathway, thalamic activity is ____________

Answer 12

decreased

Question 13

What is the circuit of the indirect pathway?

Answer 13

D2 inhibits striatum so inhibition of GPi is released allowing GPi to inhibit the thalamus

Question 14

Why is thalamic activity DECREASED in the indirect pathway?

Answer 14

because the striatum cannot inhibit GPi

Question 15

What is the purpose of the subthalamic nucleus?

Answer 15

part of the hyperdirect pathway

output is excitatory to GPi and SNr

inhibits unwanted movements

Question 16

The GPi receives ____________ input from the striatum and the GPe but ______________ input from the subthalamic nucleus

Answer 16

inhibitory (striatum and GPe)

excitatory (subthalamic nucleus)

Question 17

Hypokinesia is associated with _____________

Answer 17

Parkinsons

Question 18

Define bradykinetic syndrome

Answer 18

increased inhibitory output of GPm to VL thalamic motor nuclei

Question 19

What is a hyperkinetic syndrome?

Answer 19

decreased inhibitory output of GPm to VL thalamic motor nuclei –> enhanced motor stimulation

Question 20

Why can a lesion to the subthalamic nuclei cause hemiballismus?

Answer 20

because it lessens the stimulation of GPm (which inhibits the thalamus)

Question 21

Huntington’s Disease loses the __________ pathway

Answer 21

indirect (losing the inhibitory effect on the thalamus –> over excited)

Question 22

What are 3 etiologies of basal ganglia disorders?

Answer 22

1) infarct, hemorrhage, tumor in striatum or STN
2) Degenerative disorders (Parkinson’s, Huntington’s)
3) medication side effects

Question 23

Name 4 movement disorders that are unrelated to basal ganglia problems

Answer 23

1) essential tremor
2) myoclonus/asterixis
3) dystonia
4) tic