Plasticity

neuroplasticity

the brains lifelong ability to change, adapt, and reorganize iteself by forming new neural connections and pathways in response to learning, experience, or injury

neural plasticity

neuroplasticity at a microlevel

behavioral plasticity

neuroplasticity at a macrolevel

recovery at a microlevel

restoration of the function within an area of the cortex that was initially lost after injury

recovery at macrolevel

capacity to perform a previously impaired tasks in the same manner as before the injury

compensation at microlevel

when a different neural tissue takes over function after injury loss

compensation at macrolevel

the use of a new strategy to perform the same tasks

1. reduction of edma

2. reperfusion

3. resolution of diaschisis

what are the 4 mechanisms of recovery?

reduction of edma

• swelling goes down and compression of brain tissue is reduced

• areas affected due to intracranial pressure begin to function normal again

reperfusion

• blood flow is restored to regions of hypoperfusion

• surrounding brain tissue becomes more functional due to refreshed blood in areas surrounding necrotic tissue

resolution of diaschisis

functions associated with brain structures remote from the area of damage that was initially impaired

1. neural degeneration

2. long term potential

3. unmasking of preexisting pathways 

4. cortical reorganization

what are 4 mechanisms of neuroplasticity

neuronal degeneration

components of injured neurons can be revived by dendric branching or collateral sprouting

dendric branching

increasing dendric connections and the number of synapses made per person

collateral sprouting

increase in axonal receptivity per neuron to other neurons through growth of new axonal branches

long term potential

persistent strength of synapses

the efficiency of transmission at the synaptic level is increased in surviving neurons

unmasking of pre-existing pathways

neural connections that were not activated before may be activated

cortical reorganization

brain behavior relationships are modified as areas of the brain tissue take over functions

acute phase

immediately following trauma, short period of shock during which many functions are affected

subacute phase

within a few hours- days there is a period of rapid recovery then steady improvement over several weeks

chronic phase

improvement gradually decreases as the months and years go by

reperfusion

happens within hours after stroke and means blood flow is restored to tissue

acute- physical repair of the penumbra area cells, scar tissue form, and the disturbed physiological functions improve

subacute-neural processing mechanisms reorganize impaired areas by taking advantage of intact brain regions spontaneously

chronic phase- new learning mechanisms govern the extent the person can be retained toperform a specific skill

what do the three phases of reperfusion look like?

recovery

imrpovement

physiological and structural

____ occurs after repair and resitution sturctural repair potential is reached

use strategies that bypass lesion site to further ____

Use of new strategies for ______ and ______ changes

• weak left hemisphere activation

  • global breakdown of the language network

what is the hemisphere role in the acute stage?

• bilateral cerebral activation but still stronger in the right

  • mild improvement in language function

what is the hemisphere role for the subacute stage?

• shift back to left hemisphere activation

• * normalization of activation pattern

what is the hemisphere role of the chronic stage?

eitiology of injury

lesion site and size

severity of cognitive impairments

aphasia types

age

education

handedness

physiological and emotional issues

time since stoke onset

what are examples of prognostic factors?