Lecture 2- Neuroplasticity Flashcards
What can cause a PNS injury?
- stretch
- crush
- shear
- laceration
What is the first thing that happens when a neuron is injured?
Axon retracts away from its postsynaptic cell, while this is happening we also see Wallerian degeneration.
What is Wallerian degeneration?
When the myelin sheath gets peeled away and turns into debris.
What cells come in to clear debris from a neuronal injury?
- glial cells (astrocytes)
- macrophages
When the axon is ready to regrown we have ___________ cells come in and guide the axon to the appropriate target.
-Schwann cells
What are the 2 types of axonal sprouting (growth)?
- collateral
- regenerative
How are collateral and regenerative sprouting different?
- collateral- new branches formed from neighboring cells attach to the initial postsynaptic neuron
- regenerative- the damaged axon is the one that regrows and finds its original or a new target
In adults, our ability to regrow is _____, and can be ___________, but with time the PNS generally is able to figure out the appropriate pathways.
- slow
- inprecise
There is _mm of growth a day or _in a month.
- 1mm
- 1in
What can cause a CNS injury?
- trauma
- decreased blood flow (stroke)
- neurodegenerative disease (MS, Parkinson’s)
- The bad news is that our CNS axons typically _____ re-grow after injury.
- The good news is that our brain has an incredible capacity to create new ________ to compensate.
- do not
- pathways
CNS damage “triggers” _______ and _______ cell death of severed axons.
- necrosis
- apoptotic
What is necrosis?
cell death directly related to an injury
What is apoptosis?
Cluster of previous healthy tissue that is now dead, starts a cascading event where the neurons on the periphery die as well.
The clean up in the CNS is _____ because the lack of ____________ guidance and ___________ to clean.
- slow
- Schwann cells
- macrophages
In general, our CNS environment is _________ to regenerative attempts. Why?
- hostile
- astrocytes (glial cells) create glial scarring, microglial activation
What is glial scarring?
astrocytes go to area of injury and form a scar that blocks physical and chemical downstream effect of cell death.
What is the downside of glial scarring?
blocks any attempts of axons to regrow
What is the problem with microglial activation at the level of the CNS?
They do too much of a good thing, can’t distinguish between what is debris and supportive structures that came in to perform recovery.
What is neurogenesis?
process by which new neurons are formed in the brain
There is a low level of ______ (not neuronal) cells that can proliferate throughout our lifetime.
What are two examples of areas in our brain that have the ability to regenerate?
- glial
- olfactory bulb and hippocampus
If our CNS does not regenerate, why do people improve after neurological injuries?
neuroplasticity
What is neuroplasticity?
Our brain has the ability to change and adapt through our lifetime
-“The ability of the NS to respond to intrinsic stimuli by reorganizing its structure, function and connections… in response to the environment, in support of learning, in response to disease, or in relation to therapy”
Neuroplasticity is very _______ dependent
activity
What are the 3 main mechanisms of neuroplasticity?
- Chemical
- Structural
- Functional
To support learning chemically, what can our brains do?
The brain can increase activity occuring at synapse by increasing neurotransmitters, which can activate new postsynaptic receptors or modify the ones already there.
The chemical changes we see in neuroplasticity have __________ effects but they tend to be ________.
- immediate
- transient
We see more of a chemical response when talking about ____________.
short term memory
What are some structural changes that may occur when talking about neuroplasticity?
new dendritic growth
Structural changes take ____ time, but the effects are ______ lasting.
- more
- longer
We see more of a structural response when talking about ____________.
long term memory
To support learning functionally, what do our brains do?
- neurons can completely adopt new functions
- find a whole new route in the brain
Functional neuroplasticity is how we survive any ___________ injury.
neurological
Chemical, structural, and functional changes can occur in _________ of one another but more often occur _________.
- isolation
- together
What is synaptic pruning?
Eliminating fluff and remaps synapses in response to everything thats being experienced by the child
Cortical remapping occurs throughout our life, but is important after _______.
injury
The cortical remapping of the hand becomes ________ when blind due to having to read braille.
larger
Around 40-50% of people with amputations will experience __________ syndrome
phantom limb
_________ is the simplest form of neuroplasticity
habituation
What is habituation?
decrease in response to a repeated benign stimulus
Habituation can be either _____ or ____ term.
short or long
Habituation allows us to be successful in learning by letting us pay attention to whats important, while tuning out the __________ stuff.
non-essential, such as a fan going while studying
Short term habituation is any repeated stimulus that is applied for ___ minutes or less.
30min
The changes that we see in short term habituation tend to be _________ in nature.
presynaptic
With long term habituation, we will see changes at the ___________ sites.
postsynaptic
Our ability to learn and form memories is hinged on what concept?
Experience-Dependent Plasticity
In regards to Experience-Dependent Plasticity, our brain will attempt to _________ itself through the restructuring of its synapses to learn what was lost.
reorganize
What is Long-Term Potentiation?
process by which the synaptic connections between neurons become stronger by frequent activation
Long-term potentiation requires _____ intensity stimulation.
high
What is the most common excitatory neurotransmitter?
glutamate
What 2 receptors does glutamate bind with?
- AMPA
- NMDA
AMPA receptors are permeable to _________
sodium
NMDA receptors are also permeable to sodium, but also have a high permeability to ________.
calcium
NMDA receptors have a ________ blockade, what has to happen to get the molecule out of the way?
- magnesium
- receptor stays open for longer due to high stimulus, causing a larger depolarization and magnesium ion to be repelled away
What is the repulsion of the magnesium ion called?
Electrostatic Repulsion
Why are NMDA receptors known as coincidence receptors?
need both a pre and postsynaptic event to open the channel
The influx of calcium into the postsynaptic cell acts as a ________ messenger, activating secondary intracellular cascades to initiate for more long term effects
secondary
What are the 2 things calcium activates?
- increase in AMPA receptors to attach onto cellular wall to be available for later events, making the postsynaptic more sensitive and available to glutamate
- causes an increase in synthesis in proteins called growth factors, which are involved in creation of new synpases
What is Long-Term Depression?
- process in which synaptic connections become weaker
- before a synapse can create a new role due to injury, it has to “reset”
Long-term depresson is caused by ____ intensity prolonged stimulation.
low
Rehabilitation and Neuroplasticity
- Technology
- Pharmacology
- Physical Rehabilitation
- Cognitive Training
What are the 10 Principles of Neuroplasticity?
- ) USE IT OR LOSE IT
- ) USE IT AND IMPROVE IT
- ) SPECIFICITY MATTERS
- ) REPITITION MATTERS
- ) INTENSITY MATTERS
- ) TIME MATTERS (6 months post-injury)
- ) SALIENCE MATTERS (important to patient)
- ) AGE MATTERS
- ) TRANSFERENCE OR GENERALIZATION
- ) INTERFERENCE (don’t want to have to relearn)
