Basal ganglia

Question 1

Striatum

Answer 1

Afferent:
Corticostriate fibers from 4 lobes
Thalamostriate fibers from intralaminar nuclei
Nigrostriate fibers from substansia nigra

Efferent:
Striopallidal fibers to globus pallidus
Strionigral fibers to substansia nigra

Question 2

Globus pallidus

Answer 2

Afferent:
Striopallidal fibers

Efferent:
Pallidothalamic fibers to thalamus VA,VL
Lenticular fasciculus to subthalamus

together with substansia nigra have high rate of spontaneous firing and inhibit the flow of information from thalamus to cortex

Question 3

Basal ganglia

Answer 3

grey masses in cerebral hemispheres
*lentiform nucleus- globus pallidus and putamen
*caudate nucleus
*claustrum
Corpus striatum= caudate nucleus + putamen

Question 4

Anterior limb of internal capsule

Answer 4

1. Thalamo-cortical: pain and limbic
2. Fronto-pontine: Arnold path
3. Cortico-fugal: extrapyramidal

Question 5

Genu of internal capsule

Answer 5

Corticobulbar path

Question 6

Posterior limb of internal capsule

Answer 6

1. corticospinal- pyramidal
2. Somatosensory - thalamo-cortical
3. Turk path

Question 7

Caudate nucleus

Answer 7

dorsal striatum
association area of striatum
head: input from prefrontal cortex
few neurons participates in motor function
participates in cognitive functions

Question 8

Putamen

Answer 8

dorsal striatum
sensorimotor part of striatum
fibers from motor and somatosensory cortex
participates in motor function of basal ganglia

Question 9

Nucleus accumbens

Answer 9

ventral striatum
region in basal forebrain
afferent: prefrontal association cortices, basolateral amygdala, hippocampus
efferent: basal ganglia, globus pallidus, substansia nigra, formatio reticularis

Question 10

Function of basal ganglia

Answer 10

• modulate and regulate specific cortical functions
• information is processed and relayed back to cortex via specific thalamic nuclei
• motor activity: from cortical areas, both during preparation and planning and during actual execution

Question 11

Direct loop between basal ganglia and cortex

Answer 11

Corticostriate fibers activate striatal GABA-ergic inhibitory neurons - inhibits GABAergic inhibitory neurons in globus pallidus and substansia nigra(disinhibition) - thalamocortical glutaminerg fibers activate cortical areas

Question 12

Indirect loop between basal ganglia and cortex

Answer 12

Corticostriate fibers activate striatal GABAergic inhibitory neurons - inhibit GABAergic inhibitory neurons in globus pallidus (ex.) (disinhibition) - glutaminergic subthalamic nucleus activated - activates inhibitory neurons in globus pallidus (int.) and substansia nigra - Gabaergic inhibitory neurons inhibit dorsal thalamic neurons

Question 13

Nigrostriatal system

Answer 13

to striatum
from substansia nigra and centromedian and parafascicular nuclei of dorsal thalamus

excite GABAergic striatal neurons of direct loop