Lecture 5: CNS Plasticity After Injury

Question 1

How was the normal organization of somatosensory area 3b in owl monkeys revealed in detail using microelectrodes?

Answer 1

Microelectrodes implanted into several areas of the monkey’s brain recorded neuronal responses to peripheral stimulation. This allowed researchers to create a map of the body surface in the primary somatosensory cortex.

Question 2

Describe the orderly somatotopic representation in the brain?

Answer 2

There is orderly representation from lateral to medial of face, hand, arm, trunk, leg and foot. Digit 1 (thumb), is represented laterally and digit 5 is represented medially.

Question 3

Projections from which aspect of the hand dominate the hand representation area? How is dorsal hairy skin represented in the hand regions of cortex?

Answer 3

Most hand representation is from the glabrous surface of the hand. Dorsal hair skin is only represented in small islands.

Question 4

Explain why in practice, most plasticity studies have examined the cortex, rather than subcortical nuclei.

Answer 4

Brainstem and thalamus maps are 3 dimensional and deep in the brain, thus making them more difficult to map and access. Cortex maps are 2 dimensional and not as deep in the brain, making plasticity studies on the cortex easier.

Question 5

Describe changes in the somatosensory cortex after experimental section of median nerve

Question 6

Describe changes in the somatosensory cortex after experimental section of both median and ulnar nerve

Question 7

Describe changes in the somatosensory cortex after experimental section of radial nerve with median or ulnar nerve

Question 8

Describe changes in the somatosensory cortex after experimental section of a nerve but its allowed to regenerate

Question 9

Describe changes in the somatosensory cortex after experimental section of a nerve that is crushed and allowed to regenerate

Question 10

Describe changes in the somatosensory cortex after a flap of skin and its nerves are transferred from the digit to thumb

Question 11

Describe changes in the somatosensory cortex after amputation

Question 12

Describe changes in the somatosensory cortex after complete SCI

Question 13

Describe changes in the somatosensory cortex after incomplete SCI