thalamus (I)

Question 1

Thalamus

Answer 1

The gateway to the cerebral cortex, regulating information flow to the cortex.

Question 2

Thalamus organization

Answer 2

Organized as numerous discrete nuclei, which can be arranged into three functionally distinct groups:
1. Specific relay
2. Association
3. Intralaminar

Question 3

Which relay nuclei convey specific sensory modalities to the primary sensory cortex?

Answer 3

1. Ventral posterior lateral (VPL)
2. Ventral posterior medial (VPM)
3. Lateral geniculate nucleus (LGN)
4. Medial geniculate nucleus (MGN)

Question 4

Which relay nuclei connect the cerebellum and basal ganglia with the motor cortex?

Answer 4

1. Ventral anterior nuclei (VAN)
2. Ventral lateral nuclei (VLN)

Question 5

Complete the “Specific relay nuclei of the thalamus” table!

Answer 5

☆good luck bestie, slide 91☆

Question 6

Association nuclei

Answer 6

The association nuclei are interconnected with regions of association cortex.

→by far the biggest
→input comes directly from the cerebral cortex
(cerebral cortex → thalamus → cerebral cortex)
→project to regions of higher order
→allows different regions of the cortex to communicate indirectly

Question 7

Association nuclei of the thalamus

Answer 7

1. Medial Dorsal nucleus
   →connected to the prefrontal cortex, which is responsible for executive functions
2. Pulvinar
   →projects to parietal-temporal association cortex, which integrates sensory information and mediates language

Question 8

Complete the “Association nuclei of the thalamus” table!

Answer 8

☆good luck bestie (this one’s a bit better), slide 93☆

Question 9

Intralaminar nuclei

Answer 9

-project diffusely to many regions of the cortex as well as subcortical structures such as the basal ganglia
-may have a role in the ascending arousal system?
-exact function remains unknown

Question 10

Internal medullary lamina

Answer 10

Strip of white matter embedded with small clusters of neurons (intralaminar nuclei)

Question 11

Thalamic nuclei & reciprocal feedback

Answer 11

The thalamic nuclei receive reciprocal feedback from the cortical regions to which they project. The axons from the cortex to the thalamus vastly outnumber the projections from the thalamus to the cortex.

Question 12

Thalamic relay neuron modes

Answer 12

Thalamic neurons dynamically switch between two different firing modes:

1. Transmission mode
2. Bursting mode

Question 13

Transmission mode

Answer 13

-during wakefulness
-firing of single APs that faithfully relay sensory inputs
-mode it wants to be in when accurately relaying info up to the cerebral cortex

Question 14

Bursting mode

Answer 14

-during slow-wave sleep
-fire bursts of 3–8 APs, separated by quiet periods lasting 100s of milliseconds
-blocks flow of info (not relaying) since they’re locked in this bursting mode

Question 15

Bursting mode: AP pattern

Answer 15

1. Individual APs fired at a very high frequency
2. Slow hyperpolarization
3. Commencement of depolarization

Question 16

Can the bursting mode occur during wakefulness?

Answer 16

Yes!

It is just more regulated/balanced with transmission mode, probably regulating thalamic neurons better and in a more “thought out’/”intentional” manner

Question 17

T or F: Association nuclei also switch between two different modes.

Answer 17

True!

Question 18

How can you determine a thalamic neuron’s mode?

Answer 18

By measuring the resting membrane potential.

→ transmission mode: >-65 mV
→bursting mode: <-65 mV

Question 19

What would have if you apply NE to thalamic neurons?

Answer 19

It would put them in a transmission mode, since NE depolarizes the resting membrane potential of a neuron.

Question 20

Internal capsule (12)

Answer 20

Massive fiber tract through which information to and from the cerebral cortex travels.

→lies in the inferomedial portion of each cerebral hemisphere

alls axons coming out of the thalamus and going to the cerebral cortex MUST go through the internal capsule

Question 21

What happens if the internal capsule is damaged?

Answer 21

A stroke, for example, damaging the internal capsule would greatly hinder communication between different brain regions.