Abstract
Most of the patient with visual impairment show category specific visual deficit such as letter (alexia), object (visual object agnosia), landmark (topographical agnosia), or faces (prosopagnosia). However, in rare cases, some patients show element specific visual impairment. In this session, I introduce such a patient. His main characteristic was visual impairment for two-dimensional object. The patient was a 62 year-old right handed man. Due to a progressive visual problem, he visited Showa University Hospital. The magnetic resonance imaging (MRI) showed a right dominant mild atrophy of the parieto-occipital lobe. In the neuropsychological examination, his feature was as follows. When the patient was asked to name the objects of photograph or line drawing, he could not identify them; however, he could identify the real object immediately after presentation. In order to define the effect of three-dimensional information, we examined the patient using two tasks: Binocular vs. Monocular (BM) task and Single Viewpoint (SV) task. In the BM task, the patient was asked to identify real objects using monocular or binocular vision. In the SV task, he was asked to name the real objects from single viewpoint using chin rest. As a result he showed no significant differences between monocular and binocular vision. On the other hand, his identification time was significantly delayed when he was asked to name the object from single view point rather than free view condition. Considering these results, we suspected that his disorder of recognition of two-dimensional object was due to disturbance of recognition from a single viewpoint. [J Physiol Sci. 2007;57 Suppl:S47]
