Neuro: Basal Ganglia Flashcards Preview

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Flashcards in Neuro: Basal Ganglia Deck (23)
1

The direct pathway of the basal ganglia leads to cortex ___________

excitation

2

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

INHIBITED (allowing the thalamus to be disinhibited)

3

What makes up the striatum?

- caudate
- nucleus accumbens
- putamen

4

What makes up the lenticular nucleus?

putamen and the globus pallidus

5

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

TRUE

it can only influence LMNs via the cerebral cortex

6

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

excitatory

7

How does the basal ganglia mediate its output?

globus pallidus internal
substantia nigra reticulum

8

True or False: BG output is inhibitory

TRUE (mediated via GABA)

9

What is the main role of the BG?

to send the thalamus excitatory and inhibitory messages via the striatum

10

What are 4 loops of the BG?

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

11

Walk thru the circuit of the direct pathway

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

12

In the indirect pathway, thalamic activity is ____________

decreased

13

What is the circuit of the indirect pathway?

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

14

Why is thalamic activity DECREASED in the indirect pathway?

because the striatum cannot inhibit GPi

15

What is the purpose of the subthalamic nucleus?

part of the hyperdirect pathway

output is excitatory to GPi and SNr

inhibits unwanted movements

16

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

inhibitory (striatum and GPe)

excitatory (subthalamic nucleus)

17

Hypokinesia is associated with _____________

Parkinsons

18

Define bradykinetic syndrome

increased inhibitory output of GPm to VL thalamic motor nuclei

19

What is a hyperkinetic syndrome?

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

20

Why can a lesion to the subthalamic nuclei cause hemiballismus?

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

21

Huntington's Disease loses the __________ pathway

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

22

What are 3 etiologies of basal ganglia disorders?

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

23

Name 4 movement disorders that are unrelated to basal ganglia problems

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