23.2 Thalamus

Question 1

What is the primary function of the thalamus?

Answer 1

To relay motor and sensory signals to the cerebral cortex

Question 2

Where in the brain is the thalamus located?

Answer 2

At the core of the diencephalon, deep to the cerebral cortices

Question 3

Which three main parts is each half of the thalamus divided into?

Answer 3

Anterior, medial, lateral

Question 4

Which structure partitions the anterior, medial and lateral thalami?

Answer 4

Internal medullary lamina

Question 5

Which structure connects the left and right halves of the thalamus?

Answer 5

Interthalamic adhesion

Question 6

What is the afferent and efferent supply of the LGN (vision)?

Answer 6

Afferent - optic nerves
Efferent - V1

Question 7

What is the afferent and efferent supply of the MGN (auditory)?

Answer 7

Afferent: inferior colliculi
Efferent: A1

Question 8

What is the afferent and efferent supply of the pulvinar nuclei (visual attention)?

Answer 8

Afferent: superior colliculi
Efferent: V1, PPC (posterior parietal cortex), PFC (prefrontal cortex)

Question 9

What is the afferent and efferent supply of the ventral anterior (VA) nuclei?

Answer 9

Afferent: basal ganglia
Efferent: premotor cortex

Question 10

What is the afferent and efferent supply of the ventral lateral (VL) nuclei?

Answer 10

Afferent: basal ganglia AND cerebellum
Efferent: premotor cortex AND primary motor cortex

Question 11

What is the afferent and efferent supply of the VPL? (ventral posterior lateral)

Answer 11

Afferent: Dorsal column system AND anterolateral system
Efferent: S1

Question 12

What is the afferent and efferent supply of the VPM?

Answer 12

Afferent: trigeminal nerve (sensory), NTS (taste)
Efferent: S1

Question 13

What is the afferent and efferent supply of the anterior nuclei (limbic)

Answer 13

Afferent:
*Mammillary bodies
*subiculum (part of hippocampus)
Efferent:
*Cingulate gyrus

Question 14

What is the difference between primary (first order) thalamic nuclei and higher order thalamic nuclei?

Answer 14

Primary nuclei process info from peripheral sensory inputs
Higher order nuclei process info from the cortex (layer V)

Question 15

With what structure does the thalamus have reciprocal connections with?

Answer 15

Cortex. Thalamus sends afferent to cortex.

Question 16

How is the thalamus arranged?

Answer 16

topographically.

Question 17

How is the topographical organisation and reciprocal connections with cortex beneficial?

Answer 17

this provides an effective, gated switchboard system that allows certain information to be better condensed and pass through following parallel processing, decreasing the cortical processing power required and accelerating the interpretation of information at the same time as reducing the necessary cortical volume

Question 18

What is the function of the anterior nucleus?

Answer 18

Helps to control the generation of memories, and influences alertness

Question 19

What is the function of the ventral anterior nucleus?

Answer 19

Receives afferent inputs from the GPi/SNr of the basal ganglia system, providing the inhibitory signal that (at baseline) gates the release of movements from the premotor cortex to improve selection of appropriate, internally-generated movements

Question 20

What is the function of the ventral lateral nucleus?

Answer 20

coordination of movements

Question 21

What is the function of ventral posteromedial nucleus?

Answer 21

allowing the relay of tactile information to S1