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. / ix, 162 leaves : ill. ; 28 cm

The influence of experience during brain development was investigated on juvenile behavior, adult amphetamine sensitization, and neuronal structural plasticity in rats. Two experiential factors (i.e., tactile stimulation and stress) were studied either before or soon after birth. Early experience feminized social behavior in males; however, only stress enhanced anxiety-like behavior in males. Repeated amphetamine administration resulted in the development and persistence of behavioral sensitization. However, tactile stimulation attenuated the drug-induced behavioral sensitization whereas stress failed to influence the degree of sensitization. Neuroanatomical findings revealed that early experience altered the cortical and subcortical structures. Furthermore, drug exposure reorganized the brain structures involved in addiction but early experience prevented the drug-associated changes. Early adverse experience influences the subsequent exposure to a drug of abuse at anatomical level whereas a favorable experience has an effect both at behavioral and anatomical levels and thus may play a protective role against drug-induced sensitization and addiction. / xii, 263 leaves : ill. ; 29 cm