|
Abstract:
|
Stroke is the leading cause of long -lasting disability in the United States and
disproportionately affects adults in later life . Age -related decreases in dexterity and
neural plasticity may contribute to the poorer prognosis of older stroke survivors , even
following rehabilitative physical therapy . The goal of these dissertation studies is to
determine how the cortical plasticity underlying motor skill learning , both before and after brain injury , changes in the aged brain .
The general hypothesis of these studies is that age -related changes in motor
performance and the limited ability to regain function following brain injury are
associated with dysfunctional plasticity of the forelimb representation in the motor
cortex . This hypothesis was tested in intact C57BL /6 mice by training them on a skilled
reaching task and deriving intracortical microstimulation evoked motor cortical
representations of the forelimb to determine training -induced changes in the function of
the motor cortex . After ischemic lesions , age -dependencies in the effects of rehabilitative training in skilled reaching on forelimb motor cortical representations were investigated .
Prior to injury , intact young and aged mice learned a skilled reaching task in similar time
frames and with similar success rates . Training -induced reorganization in the young mouse motor cortex occurred in the caudal forelimb area , which is homologous to the primary motor cortex of primates . However , the rostral forelimb area , a potential premotor cortex , was larger in aged mice compared to young mice . Following focal ischemic lesions of the forelimb area of the sensorimotor cortex , aged mice had larger lesions and were more impaired than young mice , but both groups regained reaching ability after 9 weeks of rehabilitative training . Post -operative training resulted in
plasticity of the rostral forelimb area in young mice , but we failed to see reorganization in the forelimb map of aged mice following rehabilitative training .
These dissertation studies suggest that more severe brain damage in response to
ischemia leads to poorer outcome in aged animals . Although the reorganization of motor cortex following initial skill learning and relearning following brain damage changes with age , the ability to learn motor tasks and improve function with rehabilitative training is maintained in healthy aging . |