[The significance of the study of aphasia, apraxia and agnosia at present time].

Neuropsychology initiated by the study of aphasia, apraxia and agnosia had been regarded as one division of psychiatry. This is one of the reasons why neuropsychology is minor territory in neurology. Some people say that neuropsychology seems difficult to understand, not scientific, not useful and is rather a man's taste than a medicine. I try to respond in this paper to these critics by way of analyzing our own cases while insisting on the today's importance of the study of aphasia, apraxia and agnosia. Our personal cases consist of the following three categories. 1) Primary progressive apraxia: proposal of the symptomatic concept suggested by the investigation of our own eight cases and those in the literature. 2) Musical alexia with agraphia in a trombone player: study of the cerebral localization in a person with special ability. 3) Disturbance of reaching proposal of intracerebral pathways in kinesthesia. Therefore it is highly possible that the significance of the study of aphasia, apraxia and agnosia should become enlarged now and after; and it seems urgent to answer its need that younger neurologists participate in this area.