[Efficacy and limitation of cognitive rehabilitation].

The "higher brain dysfunction" illustrates various cognitive and behavioral consequences resulted from organic brain damage. Individually-tailored cognitive rehabilitation aims to directly and explicitly ameliorate disability of people with higher brain dysfunction. In this symposium, the efficacy and limitation of cognitive rehabilitation was discussed with particular interest in the two cognitive domains, i.e., language and memory. In the realm of aphasia rehabilitation, two mechanisms have been postulated for language restitution following aphasia: 1) partial recovery of left-hemisphere language-related areas, and 2) activation of their homologous counterparts in the right hemisphere. Although the both hemispheres may eventually contribute for functional reorganization of the language network, recent functional imaging studies of aphasic patients have demonstrated that the residual left hemisphere is primarily important for aphasia recovery. A recently presented hypothesis was described in which suppressing the right hemisphere may lead to better aphasia recovery. It is now widely accepted in the field of memory rehabilitation for individuals with amnesia/dementia that the theoretical framework of "errorless learning" is a guiding principle. Error elimination during learning is essential for favorable outcome of memory training. We should be aware of functional organization of the brain which underlies the efficacy of cognitive rehabilitation.