Thalamus

Question 1

epithalamus

Answer 1

pineal and habenular nuclei

habenula- limbic relay nuclei w/ projections to brainstem. “negative reward”

pineal- under sympathetic control, releases melatonin, endocrine, circadian cycle

Question 2

stria medullaris thalami

Answer 2

input tract to habenula from thalamus

Question 3

which sensory pathways relay at thalamus

Answer 3

all except olfactory

allows for filtering of background sensory input

Question 4

internal medullary lamina

Answer 4

white matter tract running through thalamus that divides it into lateral and medial subnuclei

Question 5

where does thalamus project to?

Answer 5

all thalamic nuclei except reticular thalamic nucleus project to cortex

Question 6

do all thalamic inputs come from sensory tracts?

Answer 6

no. each subnucleus receives reciprocal connections from cortex

acts as a relay from cerebellar, basal ganglia, and limbic pathways

Question 7

what are the borders of the thalamus?

Answer 7

medially- third ventricle
laterally- internal capsule
caudally- midbrain reticular formation

Question 8

relay nuclei

Answer 8

receive input from sensory and motor systems and filter based off other modulatary inputs (cortex, brainstem). contain inhbitory activity critical to modulation

Question 9

association cortex

Answer 9

input from multiple cortex and output to association cortex (prefrontal and temporo-parietal association cortex)

Question 10

physiology of thalamic projection neurons

Answer 10

T-Ca channels modulate oscillatory mode- where thalami nuclei regularly fire 5x extremely quickly followed by a pause when the thalamus is inhibited

tonic mode- occurs when excitatory input, loss of regularity as it conveys information

Question 11

general rules of thalamus nuclei location

Answer 11

in the lateral group, the more anterior the nucleus, the more anterior the region to which it connects

anterior and medial groups are mostly limbic

damage to thalamus can depress activity of the cortex to which it connects- mimics symptoms of cortical damage

Question 12

lateral region of thalamus

Answer 12

ventral tier- relay nuclei

dorsal tier- association nuclei

metathalamus- medial and lateral geniculate- auditory and visual nuclei

Question 13

intralaminar nuclei

Answer 13

centromedian and parafascicular nuclei- found w/in internal medullary lamina

Question 14

which thalamic nucleus relay somatosensory sensations

Answer 14

ventral posterolateral (spinothalamic and medial lemniscal) and ventral posteromedial (trigemino-thalamic input)

Question 15

which thalamic nuclei relays to motor cortex

Answer 15

ventral lateral nucleus

input from cerebellar afferents and basal ganglia- projects to motor cortex

Question 16

which thalamic nuclei relays to premotor cortex

Answer 16

ventral anterior nucleus

input from cerebellum and primarily basal ganglia to premotor cortex

responsible for “ansillary” or postural movement. “patterned movement”

Question 17

which thalamic nuclei relays visual info

Answer 17

lateral geniculate

Question 18

which thalamic nuclei relays auditory info?

Answer 18

medial geniuculate

Question 19

pulvinar and lateral posterior nuclei

Answer 19

input from superior colliculus and association cortex

projects to secondary visual areas

function in attention and eye movement

Question 20

anterior nucleus and lateral dorsal

Answer 20

input from hippocampus and mammillary bodies

projects to posterior cingulate gyrus

functions unclear. seems to be involved in limbic

Question 21

lateral mediodorasal nucleus

Answer 21

input from superior colliculus, pifirorm cortex, and ventral pallidum

project to frontal eye fields and anterior cingulate

function in eye-head control/attention

Question 22

medial mediodorasal nucleus

Answer 22

input- solitary nucleus, substantia nigra, amygdala, ventral pallidum

project- insula, orbital, subcallosal

function in autonomic regulation and emotion. destruction damages memory

Question 23

reticular activating system

Answer 23

interlaminar nuclei send non specific projections to cortex. activated during switch from sleep to wake

Question 24

reticular thalamic nucleus

Answer 24

input from cortex

inhibts all thalamic nuclei

regulates thalamic excitability