Plasticity & recovery Flashcards
Plasticity
Brain’s capacity for continuously changing its structure, & ultimately its function, throughout a lifetime
Metaplasticity
Idea that many factors that result in changes in the brain interact with one another to produce different kinds of changes under different combinations of factors
Recovery for what cognitive function is most extensive?
Language functions
3 possible outcomes of behavioral fx following brain injury
Compensation, diaschisis, recovery assoc. w/ neuro changes
3 neurological implications of brain damage
Cell death
Survival with reduced total input
Reinnervation (whole or in part)
Spontaneous recovery is due to
Resolution & absorption from hematomas, decrease in swelling, return of electrolyte & neurochemical balance
What area of the CNS is most likely to be plastic?
Cortex
Significant recovery in behavior is associated with
Growth in the dendritic trees & thus number of connections
Synapse supersensitivity
Compensates for loss of presynaptic elements; remaining dendrites become hypersensitive to incoming stimuli
Sprouting
Remaining nerve fibers develop branches that occupy sites left empty by damaged neurons, thus reinnervating unoccupied areas
Denervation supersensitivity
In areas of damage, postsynaptic processes may become supersensitive to NT substance leaking from pre-lesion neurons thus allowing activation of post-lesion pathways & restitution of normal functioning
Substitution
Existing intact brain structures assume functions previously held by lesioned areas
More complete & rapid recovery from aphasia is seen in closed head injuries or stroke?
Closed head injuries
Neural competition hypothesis
Following cerebral insult in early stages of development, there occurs a relocation of fx, resulting in a decrease in synaptic sites available for mediating behaviors; leads to “crowding” phenomenon; in longer term, there remain fewer synaptic sites available to be taken up by new, emerging skills, leading to cumulative deficits & increased problems w/ development progressions
Effects of early brain injury on development
Development may lag with later emergence of skills than peers; impairments may emerge as the impact of poor skill acquisition results in increasing discrepancies with peers; info processing & exec fx may fail to mature
How does the severity of the lesion impact plasticity in children?
Small lesions & very large unilateral lesions may cause interhemispheric reorganization; moderate or bilateral focal lesions fail to cause interhemispheric reorganization; in diffuse injuries, there is a dose-response relationship between severity & outcome
How does gender impact plasticity following childhood injury?
Possibly more diffuse organization of function & in females & earlier LH maturation, so there is evidence of greater likelihood of transfer of fx to the less specific RH
Vulnerability more common in males, greater for RH
How does psychosocial context impact plasticity in childhood injury?
Plasticity is associated with high SES, access to rehab, early intervention
Effects of hemidecortication on language function
After the complete removal of LH most people are capable of some language & do not experience the dense global aphasia seen in pts with large LH strokes
How may the phenomenon of diaschisis help to account for functional recovery after a focal brain injury?
As the functional continuity between various areas of the brain is disrupted following a lesion, & as this disruption extends beyond the direct effect of the lesion, resolution of these disruptions may help account for recovery of fx
Why might symptoms of early brain injury return with aging?
As pts age, the mechanisms that promoted recovery earlier in life may be called on to compensate for neuronal deterioration
