CH. 4. Plasticity after Brain Damage

Question 1

What are the two kinds of stroke, and what causes each kind?

Answer 1

The more common form, ischemia, is the result of an occlusion of an artery.

The other form, hemorrhage, is the result of a ruptured artery.

Question 2

Why is tPA not helpful in cases of hemorrhage

Answer 2

The drug tPA breaks up blood clots, and hemorrhage results from a ruptured blood vessel, not a blood cloth.

Question 3

After someone has had a stroke, would it be best (if possible) to direct stimulant drugs to the cells that were damaged or somewhere else?

Answer 3

It is best to direct a stimulant drug to the cells that had been receiving input from the damaged cells. Presumably, the loss of input has produced diaschisis.

Question 4

Is collateral sprouting a change in axons or dendritic receptors?

Answer 4

Axons

Question 5

Is denervation supersensitivity a change in axons or dendritic receptors?

Answer 5

Dendritic receptors

Question 6

What is responsible for the phantom limb experience?

Answer 6

Synapses that used to receive input from the now amputated part become vacant. Axons representing another part of the body take over those synapses. Now stimulation of this other part activates the synapses associ- ated with the amputated area, but that stimulation feels like the amputated area.

Question 7

A monkey that loses sensation from one arm stops using it, but a monkey that loses sensation from both arms does use them. Why?

Answer 7

A monkey that lost sensation in one arm is capable of moving it, but finds it easier to walk with the three intact limbs. When both arms lose their sensations, the monkey is forced to rely on them.