Lecture 4: Thalamus and Internal Capsule

Question 1

What is the role of the thalamus

Answer 1

• Receives inputs from spinal cord, brainstem, cerebellum, basal ganglia, hippocampal complex + and sends them via internal capsule to relevant part of cortex.
• Prioritises inputs–Modules the level of input they have to the cortex
• Integrates complementary and competing signals
• Bulk of thalamus for integrating info from association cortices.

Question 2

What is the input and output of the anterior nuclear group and its purpose

Answer 2

Input: Limbic system
Output: Pre frontal cortex
Integration between primal and rational thinking, as well as memory and emotional processing. The fibres going to and from the frontal cortex are going through here.

Question 3

What is the input and output of the Medial nuclear group and Lateral Nuclear group (including Pulvinar) and its purpose

Answer 3

Input: Frontal and Parietal association cortex,
Output: Widespread to other areas needed to understand language
Integration of inputs from the frontal and parietal cortex - eg. language + emotion/mood.

Question 4

What is the input and output of the Intralaminar nuclear group and its purpose

Answer 4

Part of reticular formation circuitry involved in consciousness, sleep behaviours and regulation of sensitivity of gravity opposing muscles.

Question 5

What are the 2 groups of the Metathalamus and what are their inputs and outputs/ purpose

Answer 5

Medial Geniculate body: input from cochlear, output to 1’ auditory cortex

Lateral Geniculate body: input from eyes, output to 1’ Visual cortex

Question 6

What are the input and outputs of the 3 parts of the Ventral nuclear group

Answer 6

Ventro Anterior and Ventro Lateral
input from GPI, substantia nigra, Cerebellum. Output to Premotor cortex.

Ventro Posterior has input from Cranial and Spinal nerves –Trigeminothalamic medial lemniscus (discriminative sensation) and Spinothalamic tracts (pain, temp, light touch).
Output is to 1’ Somatosensory cortex

Question 7

Where is the homuncular representation in ventral nuclear group. Where is the motor info going vs sensory info

Answer 7

There is a homuncular representation of the body with head in medial part, legs in lateral part of VP

Motor information is being carried by the va-vl, sensory by the vpl-vpm (dorsal part)

Question 8

Describe the arrangement of fibres in the internal capsule going to and from thalamus

Answer 8

There is a homuncular representation of input and output fibres with the face at the genu (crook of the internal capsule) and legs in Posterior limb of Internal Capsule

More medial = Input fibres (sensory fibres, basal ganglia, spinal cord going toward cortex)

More Lateral= Output fibres (upper motor neuron already had thalamic output going to s.c)

Anterior limb of internal capsule has Limbic input and frontal output information which will end up into the frontal region.