Lecture 10 - Neuroplasticity

Question 1

What are the Neuroplastic responses to NS damage?

Answer 1

Degeneration —> Regeneration –> Reorganization —> Recovery

Question 2

What is Neural Degeneration?

Answer 2

Deterioration and death of neurons

Question 3

What is Neural Degeneration common in?

Answer 3

• Neurodegenerative disease
• Normal Neurodevelopment

Question 4

What is the complex onset?

Answer 4

• Different in different types of neurons
• Different in different pathologies
• Modulated by nearby Glia Cells
• Modulated by activity of accepted neurons

Question 5

What are Axotomy models?

Answer 5

Cutting an axon

Question 6

What always happens in Axotomy models?

Answer 6

Anterograde degeneration the distal segment between the cut and synaptic terminal

Question 7

What do we often see in Axotomy models?

Answer 7

Retrograde degeneration of the proximal segment between the cut and cell body

Question 8

What do sometimes see in Axotomy models?

Answer 8

Transneuronal degeneration of neurons connected to the damaged neurons. Can be anterograde or retrograde (neurons that are synapse on the dead neuron may degenerate)

Question 9

What does anterograde mean?

Answer 9

Forward

Question 10

What does retrograde mean?

Answer 10

Backward

Question 11

What does trans mean?

Answer 11

Across/beyond

Question 12

What is Neural regeneration?

Answer 12

The regrowth of damaged neurons

Question 13

What is regeneration high in?

Answer 13

Invertebrates (frogs and geckos)

Question 14

What does regeneration not occur in?

Answer 14

Mammals in the CNS

Question 15

Where can regeneration be observed in mammals?

Answer 15

In the PNS but not common

Question 16

What influences regeneration?

Answer 16

Glia cells

Question 17

What do Schwann Cells do?

Answer 17

Promote regeneration

Question 18

How do Schwann Cells promote regeneration?

Answer 18

• Clean up cellular Debris of degeneration
• Release neurotrophic factors that stimulate growth
• CAMS that provide a pathway

Question 19

What do Oligodendrocytes?

Answer 19

Inhibit regeneration

Question 20

How do olioodendrocytes inhibit regeneration?

Answer 20

• Do not clean up debris
• Do not release neurotrophins and CAMs
• Release factors that inhibit regeneration

Question 21

What happens in the PNS, when you sever a Schwann cells sheaths ?

Answer 21

Often regenerate up incorrect sheaths and reach incorrect targets

Question 22

When is there no functional regeneration in Schwann cells?

Answer 22

When a nerve is damaged and the severed ends of the Schwann cells sheaths are widely separated

Question 23

What are the three patterns of Axonal Regeneration in the PNS?

Answer 23

1. Original Schwann cell myelin can remain intact (promote regeneration)
2. Severed ends separated by a few mm (may go to wrong target)
3. Severed ends are widely separated (no regeneration)

Question 24

What is collateral sprouting?

Answer 24

The neighbouring neuron of a dead neuron will spread a branch to create a connection with the post synaptic neuron

Question 25

What does experience drive?

Answer 25

Reorganization and organization

Question 26

What can induce reorganization?

Answer 26

Peripheral Damage

Cortical Damage

Question 27

In cats, what happened months after a retina lesion?

Answer 27

Cortical areas acquired new receptive fields from nearby portions of the retina (similar changes were observed within minutes)