Interhemispheric transfer of learning in brain-damaged patients

The purpose of the present study was to assess some of the mechanisms involved in the compensation of impaired cerebral functions in patients with unilateral brain lesions. Thirty patients with lesions of the left (dominant) hemisphere and 30 patients with lesions of the right (minor) hemispheres were studied. The subjects were blindfolded and submitted to some tests of manual performance, i.e. the relief maze test and identification of geometrical figures. The performances of each hand were determined, before and after ipsilateral and contra-lateral training. A post-training improvement index was also established. The hand related to the damaged hemisphere showed the worse performance. The post-training improvement was lower for the damaged hemisphere. The learning transfer test after contralateral training showed an improvement of the damaged hemisphere significantly greater than that of the healthy one. The authors conclude that in patients with unilateral brain lesions, the healthy hemisphere can compensate for some of the impaired higher cerebral functions by a transfer of information and learning to the damaged one.