19.8 NS: Central somatosensory pathways

Question 1

How is the dorsal column segregated? What originates here?

Answer 1

Topographically (lower down is closer to midline)

Afferents originate

Question 2

What nuclei are in the dorsal column nucleus? What do they do?

Answer 2

Gracile and cuneate nucleus. Recieve input from primary afferent

Question 3

What is the main tactile mechanoreceptive pathway? Where does it ducussate?

Answer 3

3 neuron sequence to reach somatosensory cortex

(medial leminiscus) decussates in the caudal medulla

Question 4

Where does information from face and body reach in the thalamus?

Answer 4

Face: medial
Body: lateral

Question 5

How is the primary somatosensory cortex (S1) organised?

Answer 5

Into 4 areas, somatotopically (e.g. digits are adjacent)

Question 6

What do areas 3b and 1 in S1 compare like?

Answer 6

They are mirrored

Question 7

What is interesting about organisation of a star-nosed mole’s brain?

Answer 7

Sense of environment comes from nose, most of somatosensory cortex is devoted to this organ

Question 8

What happens to cortical territory after amputation?

After repetitive behaviour task e.g. piano exercises?

Answer 8

It gets reassigned

Cortical representation expands through use

Question 9

What happens to mechanoreceptors after nerve regeneration?

Answer 9

Distribution of receptor types changes