Thalamus

Question 1

What is the functionnal difference between the dorsal and the ventral thalamus ?

Answer 1

The dorsal thalamus project to the cortex, the ventral thalamus does not.

Question 2

Which distinction can we do within the dorsal thalamus ?

Answer 2

First order nuclei and the Superior order nuclei

Question 3

Describe the First order nuclei

Answer 3

First order nuclei : Inputs from “primary” subcortical regions by type II (driver) afferents, Modulated by type I (modulator) cortical afferents and Project to the cerebral cortex (primary areas)

Question 4

Describe the Superior order nuclei

Answer 4

Superior order nuclei : Cortical inputs from type II (driver) afferents, Modulated by type I (modulator) cortical afferents and project to other cortical areas (and sometimes sub cortical).

Question 5

Describe type I and type II connections of the dorsal thalamus.

Answer 5

Type I : thin, diffuse axons, covered with small
terminals “modulator”
Type II: Thick branched axons, ending with
bouquets of large terminals “drivers”

Question 6

What does the ventroposterior complex refers to ?

Answer 6

Ventroposterio lateral Nu,

Ventroposterior medial Nu,

Question 7

Describe the Ventroposterio lateral Nu (localisation, aff, eff)

Answer 7

somatosensory relay of the body - pronounced somatotopy - projection to area 1, 2, 3 of the primary somatosensory cortex (upper part)
Input somatosensory pathways (driver)

Question 8

Describe the Ventroposterior medial Nu

Answer 8

somatosensory relay of the head - pronounced somatotopy - projection to area 1, 2, 3 of the primary somatosensory cortex (bottom part).
Input somatosensory pathways (driver)

Question 9

From where come the inputs arriving at the VPL ?

Answer 9

Main systems :
Spinal cord (spino thal tract)
Cuneate and gracile Ni (medial lemniscus)

Integration centers Brainstem ?
Locus coerulus (NA)
Dorsal raphe (5-HT)
Laterodorsal tegmental Nu (ACh)

Question 10

From where come from the inputs arriving at the VPM ?

Answer 10

Main systems: Principal and spinal trigeminal Ni

Integration centers Brainstem : 
Locus coerulus (NA)
Dorsal raphe (5-HT)
Laterodorsal tegmental Nu (ACh)

Question 11

Describe the posterior nucleus ? (Po)

Answer 11

Somatosensory associative
Input somatosensory pathways (diffuse)
Input cortex S1, S2, motor (driver)
Projections cortex S1, S2, motor, insular
\+ striatum, Amg
Sensori-motor interface?

main systems input : spino-thalamic tract, cuneate and gracile (medial lemniscus) and principal and spinal trigeminal Ni/

Question 12

Where is located the Lateral geniculate body ?

Answer 12

On the ventro-caudal part of the thalamus.

Question 13

What are the subdivision of the Lateral Geniculate body ?

Answer 13

The ventral part and the dorsal part.

Question 14

What is the role of the dorsal part of the lateral geniculate body ? What are its input ? its output ?

Answer 14

It is a relay for vision with a pronounced visuotopy
Input retina (driver)
Projection primary visual cortex (area 17

Question 15

What is the role of the ventral part of the lateral geniculate body ?

Answer 15

part of ventral thalamus =>No cortical projection
reciprocal connections with visual centers
intra-thalamic projection, hypothal, brainstem..

Question 16

Describe the role of Pulvinar + Lateral posterior N

Answer 16

Associative Nu for vision
few sub-cortical inputs
Major input: cortical (driver)
\+ superior colliculus (driver?)
Projection : Polymodal posterior association
cortex
polymodal.
role in visual attention?