basal nuclei

Question 1

caudate nucleus

Answer 1

follows the lateral ventricle

head at anterior hor, body through the lateral ventricle and at latereal ventricle/inferior horn is the tail

the tip of caudate is the amygdala

Question 2

putamen

Answer 2

“husk”
laterally located

head of caudate is joined withthe putamen by the nucleus accumbens- contains striatum, recieves projections from the cerebral cortex, an input component to basal nucleus

Question 3

globus pallidus

Answer 3

has an external and internal segment, slightly pale

the putamen covers the globus pallidus

putamen+ globus pallidus= lenticular nuclei

internal segment- out put for basal nuclei

Question 4

subthalamic nucleus

Answer 4

in the diencephalon, located ventral to the thalamus, recieves input

Question 5

substantia nigra

Answer 5

in rostral midbrain
neurons in the compact- contain melanin, black
reticular- cells like internal segment of globus pallidus, out put

Question 6

blood supply

Answer 6

perforating vessels from circle of willis supply basal ganglia

striatum is supplied by the ACA and MCA via striate/lenticulostriate arteries

globus pallidus is supplied by the anterior choroidal artery

subthalamic nuceli and substantia nigra are supplied by the PCA and posterior communicating artery

Question 7

basal nuclei function

Answer 7

projections from the cortex provide input to the basal nuclei, basal nuclei project back to the cortex via the thalamus forming a loop

putamen, caudate, and stiratum receive input from the motor and somatosensory cortex, association cortex

motor= putamen, oculomotor= caudate, executive/association= caudate, emotion/motivation= ventral striatum

basal nuclei do not directly innervate motor neurons but indirectly influence it

Question 8

basal nuclei motor loop

Answer 8

inputs received by striatum/ caudate, putamen, and subthalamic nucleus

out puts from internal globus pallidus, and reticular substantia nigra

project to thalamic nuclei which project to the cortex

Question 9

direct pathway

Answer 9

cerebral cortex

Thalamus typically stimulates the cerebral cortex, the activity of the thalamus is kept in check by the internal segment of the globus pallidus and the substantia nigra reticular part

if you want to reach for something the cerebral cortex sends excitatory input to the striatum, input to the striatum also comes form substantia nigra compact part, input from substantia nigra compact part may be either excitatory or inhibitory depending on the receptor types on the striatum.

Striatum inhibits the GPi and SNr, the thalamus is no longer inhibited by the GPi and SNr and can cause movement

Question 10

indirect pathway

Answer 10

if you are reaching for something, it is necessary to move certain parts and not move certain parts of the body.

Striatum indirectly inhibits the GPi and SNr

some neurons from striatum inhibit the GPe (which normally inhibits the subthalamic nucleus, STN)

STN normally stimulates the GPi and SNr (which inhibit the thalamus from exciting the cortex)

Question 11

Neurotransmitters involved in basal nuclei

Answer 11

when a movement plan is formulated in the cortex, the cortex activates the direct pathway, which dis-inhibits the thalamus and allow for it to activate the cortex

dopamine from the SNc has different effects on the population of neurons in the striatum, dopamine stimulates direct pathway by activating D1 receptors

dopamine inhibits striatal neurons that have D2 receptors, inhibiting the indirect pathway (that inhibits movement) so it facilitates movement

bc dopamine activates the direct pathway and inhibits the indirect pathway, in both cases dopamine facilitates movement