Rinsho Shinkeigaku (Clinical Neurology)

Symposium 4

Neuropsychology of consciousness

Katsuhiko Takeda, M.D., Ph.D.1)

1)Department of Neurology, Mita Hospital, International University of Health and Welfare

The nature of the relation between neuropsychology and consciousness has become a major issue. DB had a left lower quadrant hemianopia. When questioned about his vision in the left lower field, DB reported that he saw nothing. When DB was asked to point to locations in the impaired field in which spots of light were turned on briefly, he was surprisingly accurate. Apparently, even though DB could not consciously perceive a light in his blind region, his brain knew where it had appeared. This phenomenon has become known as blindsight. DF suffered carbon monoxide poisoning. The result in DF was an extensive lesion of the lateral occipital region, including cortical tissue in the ventral visual pathway. The principal deficit that DF experienced was a severe inability to recognize objects, which is known as visual form agnosia. Despite her inability to identify objects or to estimate their size and orientation, DF still retained the capacity to appropriately shape her hand when reaching out to grasp something. The anoxic episode affected her vision for perception, but left her vision for action largely unscathed. These patients lack conscious awareness about some subset of information, even though he or she processes that information unconsciously.
Full Text of this Article in Japanese PDF (608K)

(CLINICA NEUROL, 53: 1240|1242, 2013)
key words: consciousness, awareness, blindsight, visual agnosia, vision and action

(Received: 1-Jun-13)