Neuroscience Neuroplasticity in the PNS and CNS Donna Osterhout

Question 1

Effective repair of the nervous system (PNS only) requires:

Answer 1

1. Survival of nerve cell body
2. Clearance of the damaged distal axon
3. An environment that stimulates new axonal growth
4. Guidance cues for the axon to find its original cellular target

Question 2

What cells play a key role in promoting nerve regeneration after injury?

Answer 2

Schwann cells

Question 3

What is Wallerian degeneration?

Answer 3

Removal of distal axonal fragments and other damaged tissue after a PNS injury, Schwann cells can then align and guide the growing axon.

Question 4

T or F: Schwann cells can de-differentiate and proliferate to secrete ECM matrix molecules, neurotrophins and growth factors, which all stimulate axonal growth.

Answer 4

True

Question 5

Regenerating peripheral axons can reconnect with the target muscle because of the guidance cues provided by __1__ and the __2__ receptors that remain in the muscle.

Answer 5

1. bands of Bungner

2. acetylcholine

Question 6

What structures form the band of Bungner which guides regenerating axons?

Answer 6

ECM

Question 7

T or F: Reinnervation of muscles following peripheral motor nerve damage is precise.

Answer 7

True, because of ACh receptors

Question 8

What is the difference between oligodendrocytes and Schwann cells in terms of regenerative characteristics?

Answer 8

Oligodendrocytes do not unravel and break down like Schwann cells do, which is a key step for reinnervation.

Question 9

Does Wallerian degeneration occur in the CNS?

Answer 9

Yes. It starts at about the same time ost-injury, but the process is slower, and is mediated by different proteases. The axons will extend small processes in attempts to regenerate but it is unsuccessful. Myelin debris is inhibitory and blocks regeneration.

Question 10

What is a glial scar?

Answer 10

It is the body’s attempt at limiting CNS damage, however it forms a chemical and physical barrier to repair.

Question 11

What is CSPG?

Answer 11

Chondroitin sulfate proteoglycan, depositions of the glial scar

Question 12

Failure of CNS neurons to regenerate is due to (3 things):

Answer 12

1. CSPGs in the glial scar
2. Myelin debris that is not effectively cleared from the lesion site
3. The expression of molecules such as TNFs, FGFs, Lingo, Nogo and its receptors, interleukins, interferons in the area of the injury

Question 13

What cells produce the glial scar?

Answer 13

Astrocytes

Question 14

What are some research solutions to nerve injury?

Answer 14

1. Peripheral nerve graft
2. Chondroitinase ABC
3. Stem cells

Question 15

What is Chondroitinase ABC?

Answer 15

Enzyme that can remove sugar side chains from inhibitory proteogylcans that are expressed in the glial scar. Potential for creating a more permissive environment to regeneration.

Question 16

T or F: Physical therapy can stimulate the endogenous production of neurotrophins that promote repair.

Answer 16

True