The research objectives are the further elucidation of the biologic events which occur in experimental cerebral ischemia with the final objective of devising modalities which will inhibit the progression of the ischemic process. To this end research emphasis will be placed on devising improved techniques to measure regional cerebral metabolism, to improve stoke models, to correlate physiologic, metabolic, and morphologic events in the same preparation, to investigate further the significance of the ischemia-induced changes in cerebral monoamine content, to compare the effects of partial ischemia and total ischemia on cerebral metabolism and recovery, to utilize short-lived isotopes in the study of regional brain oxygen and NH3 metabolism, and to study the effects of free radicals on the ischemic process.