Neuroplasticity (Mixed)

Question 1

Describe what an injury to an axon in the PNS looks like physiologically

Answer 1

• cytoplasm leaks out
• segments retract from one another
• distal Wallerian degeneration
• glia clean up debris
• cell body undergoes central chromatolysis
• potential synapse degeneration and death

Question 2

Describe the ability of the CNS to recover

Answer 2

Doesn’t occur as well as in the PNS

Regeneration is limited by glial scars which release neurite outgrowth inhibitor (Nogo)

Question 3

Describe the post injury response in the CNS

Answer 3

The majority of the damage takes hours to days to evolve due to the cascade of cellular events which is why it can take time to see how a pt. will present

• white fiber tract damage leads to increased Ca influx
• leads to the disruption of axonal transport and results in build up
• leads to axonal swelling
• leads to axonal retraction ball
• leads to chromatolysis and Wallerian degeneration

Question 4

Term: degeneration of axon and myelin distally along with mm atrophy

Answer 4

Wallerian degeneration

Question 5

Describe regeneration of axons in the PNS

Answer 5

Regeneration occurs in the form of sprouting of damaged axons which is guided by nerve growth factor produced by Schwann cells and by Bands of Bungner

Recover is slow – 1 mm/day, but can be stimulated by exercise

Question 6

Term: cell body degenerative changes

Answer 6

Central chromatolysis

Question 7

Term: maladaptive rewiring; either alterned/crossed sensations or mm co-contraction

Answer 7

Synkinesis

Question 8

Term: Decrease in response to a repeated, benign stimulus due to a decrease in synaptic activity between sensory neurons and interneurons

Answer 8

Habituation

Question 9

Term: Involved with learning and memory

Answer 9

Exeperience-dependent plasticity

Question 10

3 Mechanisms of Neurplasticity

Answer 10

1. Habituation
2. Experience-dependent plasticity
3. Recovery following injury

Question 11

Describe the role of astrocytes in Experience-dependent plasticity

Answer 11

Astrocytes modulate NT release and receptor expression at the post-synaptic membrance via the release of gliotransmitters, they may also be responsible for new synapse formation

Question 12

Describe the mechanisms behind Experience-dependent plasticity

Answer 12

1. synthesis of new proteins
2. growth of new synaptic connections
3. modification of existing synapses

Question 13

Term: Persistent, long-lasting changes in the strength of synaptic connections between neurons and within neural networks

Answer 13

Exeperience-dependent plasticity

Question 14

Term: Allows other types of learning to occur by letting people pay attention to important stimulation but “tune out” stimulation that is less important

Answer 14

Habituation

Question 15

4 CNS synaptic changes following injury

Answer 15

1. Recovery of synpatic effectiveness
2. Denervation hypersensitivity (increase in receptors)
3. Synaptic hypereffectiveness (increase NT release)
4. Unmasking/disinhibition of silent synapses