Neural Plasticity Flashcards
What changes with learning?
- Movement
- Attention
- Error Detection and correction
- The nervous system
What is neural plasticity?
- Living nervous system
- Capacity of CNS to undergo changes in function and structure in response to use.
- Changes occur throughout the nervous system
- Occurs in motor learning and recovery of function
- May be favorable or unfavorable
Neural Plasticity: Basic Concept
Use -> Functional Change -> Structural Change
Types of Plasticity
Where do they occur?
- Habituation and Sensitization
- Occur in reflex pathways (non-declarative/implicit learning)
Habituation
- Decreased responsiveness as a result of repeated exposure
- Decrease in synaptic activity between sensory and motor neurons that can lead to long term reduction in number of synapses
EPSP = Excitatory Post Synpatic Potential
Sensitization
- Increased responsiveness as a result of exposure to a stimulus
- Increase in synaptic activity between sensory and motor neurons leads to long term increase in number of synapses
____ may dictate whether there is sensitization vs habituation
Perception of potential harm
Ex: Pain
Implicit Learning
- (Procedural and Associative)
- Learning to predict relationships and learning “automatic” sequences/patterns over time
- i.e. Trial and error (a.k.a. sensorimotor mapping over time)
- Involves Cerebellum and: premotor, sensorimotor, parietal cortices, BG
Non declarative
What are the short term plasticity changes?
Change in synpatic efficency
What are the long term plasticity changes?
- Formation of new synaptic connections
- Same idea as habituation/sensitization
What cells are important for long term plasticity changes? What is the functions of the cells function?
- Cerbellar climbing fibers
- Cerebellar purkinje cells
- Cerebellar mossy fibers
Ex: Motor Learning
Explicit Learning
- Requires awareness & attention, results in knowledge expressed consciously
- Involves the temporal lobe and:
- Sensory association cortex, hippocampus
- Long term potentiation (similar to sensitization)
Declarative
Role of cortical areas
- Cortex more involved early in learning
- For complex motor skills:
– Repetition improves synaptic efficiency between sensory and motor cortices
– With repetition, use sensorimotor cortex less and thalamocortical pathways more
Initial phases of learning activation and location
- Widely distributed activation
- Bilateral cortex, basal ganglia, cerebellum
Later phases of learning activation and location
- Less cortical activity & more subcortical
- Basal ganglia, cerebellum, thalamus
How is plasticity influenced by age?
learning requires more brain activity and more time/repetition
How is plasticity influenced by pathology
Require more brain activity for even simple tasks
____ of post concussion syndrom is correlated with in creased brain activity
Severity
What are the three types of nerve damage?
- Neuropraxia
- Axonotmesis
- Neurotmesis
Neuropraxia
Transient interrupted signal transmission
Axonotmesis
Axon damage only
Neurotmesis
Damage to axon and sheath = worst case scenario
How does degeneration/regeneration of a nerve work after injury?
- Anterograde degeneration: (occurs after neurotmesis) Distal to lesion axon degenerates to end
- Retrograde (proximal) degeneration: dying back toward cell body proximal of lesion
Degeneration/Regeneration after injury - Timeline
- Minutes after injury – swelling and myelin retraction from axon
- 2-3 days myelin begins to be digested
- By day 6 (maybe earlier), glial cells form a tube for possible regeneration
- Axonal sprouts may find adjacent tube and may regenerate
Regeneration of nerves occurs in the ____
PNS
CNS is mysterious and not understood.
What happens when there is an injury to the CNS?
- Can directly damage the neuron
- Neuronal function often indirectly affected by impaired:
– Cerebral blood flow
– CSF control
– Cerebral metabolism - These are usually transient and quickly reverse
Injury to the CNS - Transient Changes
- Loss of function in structurally intact brain area because of loss of input (diaschisis)
– Can be due to decrease in blood flow and metabolism - Cerebral edema commonly occurs after brain injury.
– May lead to compression of axons and blocking of conduction
Recovery of Function - What are the 4 Cellular Responses
- Altered synaptic efficency
- Recruitment/Unmasking silent synapses
- Neural Regeneration
- Collateral Sprouting
Recovery of Function - Altered Synaptic Efficency
Change in the balance between inhibition and facilitation at the synapse
Recovery of Function - Recruitment/Unmasking of synaptic synapses
Due to experience or lesion
Neural Regeneration
- Synaptogenesis (SLOW)
- The regeneration or formation of new synapses
- More sure of this in PNS than CNS currently
Collateral Sprouting
- Sprouting (SLOW)
- Neural growth and regeneration after injury.
- Collateral sprouting is the branching outgrowth of new axon terminals from uninjured axons.
Cortical Maps after CNS lesions
- Reorganization of affected hemisphere
– Primary motor cortex lesions = activation of PMA and SMA
– Adjacent cortex may take over as well - Uncrossed motor pathways may assist
- Cross modality-processing
– In absence of one sensory stimuli, we become responsive to others - Functional recovery is better when these changes are only temporary
A peripheral injury/pain leads to ____ of sensorimotor representations.
smudging
Cortical Changes after Amputation
- Intact muscles become more active with lower threshold and over wider area in cortex
- In humans, Stimulation of face and upper limb evoke phantom limb pain, suggests remapping of somatosensory system.
The amount of cortical shift varies with length of ____ pain
chronic low back
Role of Cerebellum - Recovery of Function
- Cerebellum is very important to motor recovery, basically the same role as in motor learning
- Individual constraints are altered, so…
- Recovery can be viewed as motor learning with a new set of individual abilities/constraints
Behavorial Substitution vs Compensation
- Substitution for long term
- Compensation for short term, then retrained back to normal function
Strategies to promote neuroplasticity
- Practice!
- Need a sensory rich environment
- Sensory stimulation helps with skill acquisition and increased task function (electrical stimulation)
____ is associated with cortical reorganization
Skill learning
- simple exercise and strength training is not enough (need sensory rich, task specific and lots of practice)
What are the 10 variables that affect plasticity?
- Use it or lose it
- Use it and improve it
- Specificity
- Repeition matters
- Intensity matters
- Time Matters
- Importance matters
- Age matters
- Transference (one trainined experience, enhances others)
- Interference
How can Cardiovascular exercise promote neuroplasticity?
- Moderate to Hig intensity releases BDNF
- Before or after practice
- Singe/Acute and Chronic Effects
Can genetic play a role in neuroplasticity?
Yes, but not much is known. May be positive or negative on plasticity.
