What is Neuroplasticity?
ability of neurons to change FUNCTION, CHEMICAL PROFILE, or STRUCTURE
3 mechanisms of neuroplasticity
Habituation
it is a decrease in response to repeated, benign stimulus
Effects are resolved or diminished after period when stimulus is not applied UNLESS prolonged repetition leading to more permanent structural changes
Techniques to increase habituation: tactile defensiveness, vestibular disorder
Experience-dependent plasticity
persistent, long lasting changes in strength of synaptic connections between neurons - involves memory & learning
(ie. learning to play an instrument)
Due to: synthesis of new proteins, growth of new synaptic connections, modification of existing connections
Mechanisms
Astrocytes & Experience-dependent plasticity
- what is their role
contribute by modulating NT release & receptor expression at post synaptic membrane
- absorb NT’s
Gliotransmitters are the modulators released by astrocytes
Memory classification
working memory - right @ that moment
STM
LTM: 2 types are neuroanatomically separate
Axonal Recovery in PNS
Distal segment undergoes Wallerian degeneration & cell body undergoes central chromatolysis
- glial cells clean up debris
Regeneration via sprouting:
1mm/day or 1in/month
Regeneration is increased by exercise!
Maladaptive changes w/ sprouting (2)
Sykinesis: co-contraction of muscles
Altered sensation: cross talk between pain & touch neurons
CNS Axonal Injury
Majority of damage occurs hours/days after initial injury due to cascade of events
Axonal regeneration does NOT occur due to:
Promising treatments for CNS axonal regrowth (2)
drugs that can block the development of Nogo
OR
stem cells that form new neurons and new connections
Synaptic changes following axonal injury in the CNS that aid in re-connecting(4)
Reorganization of Cerebral cortex
- genetic make-up impacts this why? 1 bad reason
cortical representation areas can be remapped by modifying sensory input, experience, learning & brain injury
Impact of genetic make-up:
Neurogenesis
neural stem cells are undifferentiated precursors to both glial cells and neurons
found in:
Factors that influence recovery of neuronal functioning (2)
Early rehab results in improved functional recovery & reduced comorbid effects of sedentary behavior
Is brain reorganization and plasticity still capable of happening in someone w/ a chronic stroke?
YES