Chapter 10 Neuroplasticity

Question 1

What is a common way to study neural degeneration?

Answer 1

cut the axons of neurons (axotomy) and observe the effects

Question 2

What two types of degeneration occur?

Answer 2

1. Anterograde degeneration

2. Retrograde Degeneration

Question 3

What is Anterograde Degeneration?

Answer 3

degeneration of the distal segment (between cut portion and the terminals)
-occurs quickly over a few hours

Question 4

What is Retrograde Degeneration?

What does a change in cell body size indicate?

Answer 4

Degeneration of the segment between the cut portion and the cell body

• occurs slowly over few days
• decrease in cell body size suggests cell will die
• increase in cell body size suggests cell will attempt to replace the cut segment.

Question 5

What is Transneuronal degeneration?

Answer 5

is the death of neurons resulting from the disruption of input from or output to other nearby neurons
-damage spread between neurons within a network

Question 6

How does Anterograde degeneration spread?

Answer 6

from damaged neuron to the neuron it synapses with

Question 7

How does Retrograde Degeneration spread?

Answer 7

Spreads from damaged neuron to the neuron that synapses on it

Question 8

Is Regeneration possible in the CNS and PNS of adult mammals?

Answer 8

Virtually nonexistent in CNS

Unlikely (but possible) in PNS

Question 9

What are three concepts associated with Neural Regeneration in the PNS

Answer 9

1. PNS neurons can regenerate starting 2-3 days after injury
2. Recovery depends on the nature of the injury
3. Schwann cells clear debris and promote regeneration

Question 10

Why is neural regeneration impossible in CNS?

Answer 10

Oligodendroglia (which myelinate CNS neurons) do not clear debris or guide and stimulate regeneration

• actively block regeneration
• cause chronic blockage for struggling axons

Question 11

What is Collateral Sprouting?

Answer 11

axon branches sprout from nodes of ranvier to connect to adjacent neurons

Question 12

What are 3 studies of Neural Regeneration?

Answer 12

1. Kaas and colleagues - made small lesions in one retina and removed other retina
2. Pons and Colleagues - mapped S1 in monkeys whose contralateral arm sensory neuron had been cut
3. Sanes, Suner and Donogue: Transected motor neurons of rat whiskers

Question 13

What did Kaas and colleagues find following the lesion of one retina and removal of the other?

Answer 13

Regions of visual cortex that originally responded to the lesioned part of the retina now responded to adjacent portions of the retina

Question 14

What did Pons and Colleagues find when they mapped S1 in monkeys whose contralateral arm sensory neurons had been cut?

Answer 14

Found that the cortical face representation had expanded into the former hand region
-phantom limb pain

Question 15

What did Sanes, Suner and Donoghue find after they transected motor neurons that controlled the muscles of rat whiskers?

Answer 15

The area of the motor cortex had had controlled whisker movement now activated other muscles of the face

Question 16

What two mechanisms might explain the reorganization of neural circuits?

Answer 16

1. strengthening of existing connections through the release from inhibition
2. Establishment of new connections via collateral sprouting

Question 17

What are three treatments for Brain Damage?

Answer 17

1. Reducing brain damage by blocking neurodegeneration
2. Promoting regeneration
3. Neuro-transplantation

Question 18

What are three chemicals that can block or limit neurodegeneration?

Answer 18

1. Apoptosis inhibitor Protein
2. Nerve Growth Factor
3. Estrogens

Question 19

How did Cheng et al promote regeneration?

Answer 19

Transplanted sections of myelinated peripheral nerves into spinal cord

Question 20

What is an example of neuro-transplantation?

Answer 20

Fetal tissue transplants used to treat parkinson’s diesease