FUNCTIONAL RECOVERY AFTER BRAIN INFARCTION - PLASTICITY AND NEURAL TRANSPLANTATION

In the past, little attention has been given to the role of brain plas ticity for the long term functional outcome in experimental stroke alt hough there is substantial evidence for plasticity in other experiment al models of neurological disorders. Under clinical conditions, functi onal improvement occurs in most stroke survivors during the initial mo nths after the ischemic incidence. Recent PET studies in stroke patien ts, investigated two months or later after stroke, indicate a consider able potential for functional plasticity in the adult human cerebral c ortex. Research aimed at the identification of the mechanisms underlyi ng functional recovery should be given high priority, particularly wit h regard to environmental factors and pharmacological interventions. P ilot experiments of environmental enrichment significantly improved th e functional outcome of laboratory animals after brain infarction. Fet al neocortical tissue grafted into the infarcted area in adult rats re ceived afferent fibres from the intact brain and responded to contrala teral sensory stimulation with increased metabolic activity, indicatin g functional integration between neocortical grafts and host afferent systems. However, reciprocal connections from the graft to the host ti ssue were rare, and it remains to be shown whether grafting will be ab le to restore the complex cortical organization of the infarcted tissu e.