Neuroscience Week 3: Diencephalon

Question 1

Which of the following thalamic nuclei connects most notably with the visual system?

Answer 1

• The pulvinar (part of the extrageniculate visual pathway).
• Important for visual attention.

Question 2

Which of the following thalamic nuclei receives sensory afferents from the body?

Answer 2

Lateral Ventroposterior

• The ventroposterior nucleus further divides into medial and lateral nuclei, both of which receive sensory afferents (medial from the face, lateral from the body) and project them to the somatosensory cortex.
• Sensory information in the thalamus has a very specific somatosensory map in which the fist is adjacent to the mouth.
• Small ventroposterior strokes in the lateral portion of the ventroposteromedial nucleus and medial portion of the ventroposterolateral nucleus result in the characteristic cheiro-oral syndrome in which there is loss of sensation around the mouth and in the fist contralateral to the side of the thalamic infarct.
• The ventroposterior inferior nucleus is a less commonly discussed nucleus.

Question 3

Which of the following thalamic nuclei receives sensory afferents from the face?

Answer 3

Medial Ventroposterior

• The ventroposterior nucleus further divides into medial and lateral nuclei, both of which receive sensory afferents (medial from the face, lateral from the body) and project them to the somatosensory cortex.

Question 4

Which of the following is part of the auditory system?

Answer 4

Medial geniculate nucleus

• underneath the medial aspect of the pulvinar.
• Part of the auditory system; it receives afferents from the inferior colliculus, which it projects to the transverse temporal gyri (of Heschl).

Question 5

Which of the following is part of the visual system?

Answer 5

Lateral geniculate nucleus

• underneath the lateral aspect of the pulvinar.
• Involved in the visual system; it receives afferents from the optic tract, which it projects to the primary visual cortex.

Question 6

Which of the following modulates thalamic output?

Answer 6

Thalamic reticular nucleus

• Forms a shell around the rostral/ventral/lateral thalamus.
• Modulates thalamic output through its GABAergic neurons.
• The posterior limb of the internal capsulelies lateral to the reticular nucleus.
• The external medullary lamina is a white matter layer that surrounds the lateral aspect of the thalamus.

Question 7

Which of the following thalamic nuclei is involved in limbic-related processes?

Answer 7

The midline group nuclei

• Function in limbic-related processes and have important hippocampal connections.

Question 8

Which of the following helps form the ascending arousal system for wakefulness?

Answer 8

The intralaminar group

• Most notably helps form the ascending arousal system for wakefulness.