Basal Ganglia

Question 1

Function of basal ganglia

Answer 1

INHIBIT involuntary movements at rest (ex. tremors)

FACILITATE voluntary movements (initiate, continue, and complete an action)

Question 2

Nuclei that make up basal ganglia (5)

Answer 2

Caudate nucleus (floor lateral ventricles; tail of caudate nucleus ends up in temporal horn of lateral ventricle)
Lentiform nucleus – putamen and globus pallidus
Subthalamic nucleus
Substantia nigra

Question 3

What is the corpus striatum made up of?

Answer 3

Caudate nucleus and putamen of lentiform nuclei

Question 4

Major input of striatum

Answer 4

Corticostriate fibers – from cortex
Nigrostriate fibers – from substantia nigra [feedback loop]
Thalamostriate fibers – from thalamus

Question 5

Major output of striatum

Answer 5

Striatonigral fibers – to the substantia nigra [feedback loop]
Striatopallidal fibers – to the globus pallidus

Question 6

Major input of pallidum

Answer 6

Striatopallidal fibers – from the striatum

Subthalamic fasciculus – from the subthalamic nucleus

Question 7

Major output of pallidum

Answer 7

Pallidothalamic fibers (composed of lenticular fascicularis and ansa lenticularis) – to the thalamus
Pallidosubthalamic fibers – to the subthalamus

Question 8

The mantra of the basal ganglia path

Answer 8

Cortex –> striatum –> pallidum –> thalamus

Question 9

Basic pathway of motor loop

Answer 9

Closed – supplementary motor cortex (area 6) –> caudate nucleus and putamen –> pallidum and substantia nigra –> VL nucleus of the thalamus –> supplementary motor cortex

Open – somatosensory cortex (areas 3, 1, 2), primary motor cortex (area 4) and premotor cortex (area 6) –> caudate nucleus and putamen

Question 10

Basic pathway of association loop

Answer 10

Closed – prefrontal cortex (areas 9, 10) –> caudate nucleus –> pallidum and substantia nigra –> VA and DM nuclei of thalamus –> prefrontal cortex

Open – premotor cortex (area6) and posterior parietal cortex (area 7) –> caudate nucleus

Question 11

Basic pathway of oculomotor loop

Answer 11

Closed – frontal eye field (area 8) –> caudate nucleus –> pallidum and substantia nigra –> VA and DM nuclei of thalamus –> frontal eye field

Open – prefrontal cortex (areas 9, 10) and posterior parietal cortex (area 7) –> caudate nucleus

Question 12

Basic pathway of limbic loop

Answer 12

Closed – anterior cingulate gyrus (area 24) and orbitofrontal cortex (areas 10, 11) –> ventral striatum and caudate nucleus –> ventral pallidum and substantia nigra –> VA and DM nuclei of the thalamus –> anterior cingulate gyrus and orbitofrontal cortex

Open – temporal lobe, hippocampus, amygdala, and entorhinal area (area 24) –> ventral striatum and caudate nucleus

Question 13

Dyskinesia

Answer 13

Unintentional, purposeless, disorderly movements; can be hyper- or hypo-kinetic, and these occur at rest

Question 14

Athetosis

Answer 14

Display of slow, vermicular, involuntary movements; usually affects hands and feet; caused by degeneration of the lateral pallidum, which allows the VL nucleus of the thalamus to spontaneously fire to the motor cortex

Question 15

Hemiballismus

Answer 15

Involuntary, ballistic movements on one side of the body, affecting proximal muscles of the limbs; results from a cerebrovascular lesion of the ganglial branch of the posterior cerebral artery, which involves the contralateral subthalamic nucleus

Question 16

Bradykinesia

Answer 16

Reduced motion caused by increased inhibition from the basal ganglia

Question 17

Chorea

Answer 17

Random, jerky movements

Question 18

2 signs present for Tourette’s

Answer 18

Motor and vocal tics (vocal are unique)

Question 19

Striatum: input or output gate?

Answer 19

Input

Question 20

Pallidum: input or output gate?

Answer 20

Output

Question 21

Thalamus is (excitatory/inhibitory) to (what)?

Answer 21

Excitatory to the cortex

Question 22

Pallidum is (excitatory/inhibitory) to (what)?

Answer 22

Inhibitory to the thalamus

Question 23

What is important to note about lesions in the basal ganglia?

Answer 23

NO PARALYSIS can occur