Neuroplasticity

Question 1

what are the different causes of an axonal injury in the PNS?

Answer 1

1. Stretch
2. Crush
3. Shear
4. Laceration

Question 2

what are the 2 ways axons in the PNS will regrow?

Answer 2

1. axonal sprouting
   
   1. collateral
   2. regenerative

Question 3

what are the steps in axonal regeneration following injury in the PNS?

Answer 3

1. injury to peripheral nerve
2. macrophages rapidly remove myelin debris
3. expression of growth-related factors
4. axon regrowth

Question 4

what are the causes of axonal injury in the CNS?

Answer 4

1. trauma
2. decreased blood flow (ischemia)
3. neurodegenerative disease

Question 5

T/F: CNS axons can regrow after injury

Answer 5

FALSE
typically cannot, instead the brain creates new pathways to compensate for axons lost

Question 6

what doesn’t the CNS regenerate axons?

Answer 6

1. CNS damage triggers necrosis and apoptotic cell death of severed axons
2. Clean up is slow
3. CNS environment is hostile to regenerative attempts
   
   1. astrocytes - glial scarring
   2. microglial activation

Question 7

what is glial scarring?

Answer 7

astrocytes enter injuried area and form a scar to block the apoptosis and further damage → problem with this is that it is a physical blockade/scar which blocs future attempts for regrowth of that axon

Question 8

what is the significance of microglial activation following CNS axonal damage?

Answer 8

microglial cells clear out debris from damage, but cannot differeniate between good and bad cells which ends up cleaning out more than they should

Question 9

T/F: there is a low level of glial cells that can proliferate throughout our lifetime

Answer 9

TRUE

Question 10

what are two areas in the brain that are an exception to the regeneration rule?

Answer 10

1. olfactory bulb
2. hippocampus

Question 11

define neuroplasticity

Answer 11

the ability of the nervous system to reorganize its structure, function and connections in response to injury or the environment, in support of learning, or in relation to therapy

Question 12

What are the neuroplasticity mechanisms based off of effect size?

Answer 12

1. chemical
   
   • short term memory
2. structural
   
   • strong sustained exposure to activities resulting in structural changes
3. functional
   
   • when sufficientyly stimulated, neurons can adopt new function and pass new info along (cortical remapping)

Question 13

what is synaptic pruning?

Answer 13

the ability to pick up on what is important and what is not important

prioritize the pathways that stay “open” and running

Question 14

what are the 2 neuroplasticity mechanisms, based off of how the brain responses to a stimulus?

Answer 14

1. Habituation
2. Learning and memory

Question 15

what is habituation?

Answer 15

a decrease in response to a repeated, benign stimulus

allows us to tune out non-important stimuli and focus on important stimuli

Question 16

what short term habituation

Answer 16

1. short term
   
   • stimulus given around 30 minutes → tends to be transient
   • presynaptic in nature → presynaptic neuron will dump less NT into the synaptic cleft which will blunt the reponse

Question 17

what is long-term habituation?

Answer 17

1. long term
   
   • over an hour
   • postsynaptic changes observed → changes in receptors and proteins being synthesized, tend to be more long lasting changes

Question 18

what are the different types of learning and memory development?

Answer 18

1. Experience-dependent plasticity
2. long-term potentiation and depression

Question 19

what is Long-term potentiation (LTP)?

Answer 19

process by which the synaptic connections between neurons become stronger by frequent activation

requires high intensity stimulation

Question 20

which does LTP require a high intensity stimulation?

Answer 20

1. it will alloow more glutamate to be dumped into synaptic cleft
2. more Na enters the cell
3. results in a larger depolarization event
4. this repels Mg out of the NMDA channel (electrostatic repulsion)
5. Ca can now move into the cell and act as a secondary messenger
6. this results in an increase in structural changes to the postsynaptic cell
   
   • increased in AMPA receptors (Na channel)
   • growth factors = creation of more synapses = cortical remapping

Question 21

what is long-term depression (LTD)?

Answer 21

conversino of active synapses into silent ones

“reset button”

low-intensity, prolonged stimulation required

Question 22

what are the 10 principles of Neuroplasticity?

Answer 22

1. Use it or Lose it
2. Use it and Improve it
3. Specificity matters
4. repetition matters
5. intensity matters
6. time matters
7. salience matters
8. age matters
9. transference or generalization
10. interference

Question 23

what is CINT?

Answer 23

constraint induced movement therapy → restraining the strong arm following a stroke for 23 out of 24 hours of the day, forces pt to use their paralytic arm