Environmental influence on recovery after brain lesions--experimental and clinical data.

One aim of rehabilitation after brain lesions should be to optimise the function of the remaining intact brain. Experimental studies on focal cerebral infarcts in the rat have demonstrated that postischemic environmental enrichment significantly improves functional outcome, increases dendrite branching and number of dendritic spines in the contralateral cortex, influences expression of many genes and modifies lesion-induced stem cell differentiation in the hippocampus. Furthermore, environmental factors can interact with specific interventions such as necrotic grafting and drug treatment, which underlines the importance of general stimulation and activation in rehabilitation after brain damage. Animal laboratories often provide an environment with little stimulation. This should be taken into account when evaluating the clinical relevance of animal studies on long-term functional outcome after brain lesions.