Stroke outcome is highly variable. Experiments in this thesis test the hypothesis that experience prior to a stroke is an important variable in the manifestation of stroke. Optokinetic tracking was used to evaluate the effects of visual cortex stroke and MCA occlusion in rats. Normal laboratory rats showed a small, but significant decrease in tracking thresholds following visual cortex stroke. Animals with developmental visuomotor experience or reach training experience in adulthood, however, had tracking thresholds which were substantially increased, and the effects of visual cortex strokes were greater. MCA occlusions did not affect tracking behaviour. These data indicate that specific experiences engage neural plasticity that can alter brain function. These changes can, in turn, affect the behavioural manifestation of a stroke. Understanding the effect that environmental experience has on stroke outcome promises to enable better characterization of strokes, and set appropriate behavioural baselines for the measurement of recovery of function. / vi, 135 p. : ill. ; 29 cm

The influence of play behavior on the brain was investigated through plasticity and metaplasticity methodology. Regions in both cortical and sub-cortical areas were investigated. Animals in both studies either experienced play with juvenile partners or did not experience play by being paired with an adult. Play experience alone was shown to affect the plasticity in the prefrontal cortex, although it did not show structural changes to sub-cortical regions. If animals were given nicotine after play experiences, the affects of play in the prefrontal cortex were abolished. In addition, playful behaviors appear to prime some sub-cortical regions of the brain for expression of later plasticity. Thus, play appears to alter the structure of multiple brain areas, but do so in different ways. / ix, 67 leaves ; 29 cm