Abstract:
Plasticity of residual cortical tissue has been identified as an important mediator of
functional post-stroke recovery. After neonatal stroke the thickness of residual tissue can
change, the tissue can move, and tissue can fill in the stroke core. Nevertheless, the
majority of preclinical stroke research utilizes adult rats. Thus, the purpose of the present
thesis was to systematically document such gross morphological changes in peri-infarct
tissue after stroke in the adult rat. Morphological changes were assessed in pial strip
devascularization, photothrombotic occlusion, and middle cerebral artery occlusion
models of stroke using histological and magnetic resonance imaging. Decreases in
cortical thickness, volume, and neural density were found to extend far beyond the stroke
infarct and included the sensorimotor regions of the intact hemisphere. Movement of
residual tissue towards the infarct was observed and confirmed using anatomical markers placed in intact cortical tissue at the time of stroke induction. I conclude that the
extensive time-dependent morphological changes that occur in residual cortical tissue
must be considered when evaluating plasticity-related cortical changes associated with
post-stroke recovery of function.