Basal Nuclei

Question 1

Striatum

Answer 1

functionally similar structures of the caudate and putamen

first stop for downward cortical projections in the basal ganglia stem

Question 2

Globus pallidus external

Answer 2

more lateral than GPi

part of the indirect loop
inhibits the subthalamic nuclei
inhibited by the striatum

Question 3

Globus pallidus internal

Answer 3

more medial than GPe

sends inhibitory fibers to the thalamus

-inhibited by striatum in the direct loop to dis-inhibit the thalamus

activated by the subthalamic nuclei in the indirect loop to inhibit the thalamus

functinally the same as SNr

Question 4

subthalamic nuclei

Answer 4

part of the indirect loop

activates the GPi to inhibit the thalamus

Question 5

D1 receptors

Answer 5

on the striatum in the direct loop cause depolarization of striatial cells–>more inhibition of GPi —>more disinhibition of thalamus—>more activation of cx

Question 6

D2 receptors

Answer 6

on the striatum in the indirect loop cause depolarization of striatal neurons which decreases their firing—> inc GPe activity—>more inhibition of STN—>less activation of GPi—>less inhibition of thalamus—>inc cx

Question 7

ACh on striatal cells

Answer 7

inhibits striatal cells of direct loop and activate striatal cells of indirect loop

net inhibition of thalamus and less cx activity

Question 8

lesions to the basal nuclei

Answer 8

DO NOT directly affect strength, coordination, or sensation

cause akinetic or hyperkinetic sx
voluntary systems affected
abnormalities of tone

Question 9

positive signs

Answer 9

involuntary movements
dyskinesia
tremor AT REST (that often goes away with movement)
Athetosis, chorea, ballism (violent flinging) (choreoathosis)

Question 10

Parkinson’s disease

Answer 10

degeneration of SNc
loss of DA neurons =more inhibition of thalamus by GPi

Hypokinesia and Bradykinesia (negative signs) =small shuffling steps, facial masking

tremor and rigidity, tremor at rest (pill rolling), loss of postural reflexes

Question 11

Huntington’s disease

Answer 11

Autosomal dominant disease that results in the degeneration of the striatum (caudate)

causes hyperkinesias(choreoathetosis), dementia, cognitive changes, psychoses

dec output from striatal neurons of indirect loop—>less inhibition of GPe—>more inhibition of STN—>less stimulation of GPi—>less inhibition of thalamus—>inc cx—>positive signs