The Japanese journal of neuropsychology

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ArticleTitle	Visual agnosia: a primer
Language	J
AuthorList	Katsuhiko Takeda
Affiliation	Department of Neurology, Mita hospital, University of International Health and Welfare
Publication	Japanese Journal of Neuropsychology: 24 (2), 117-126, 2008
Received
Accepted
Abstract	Visual agnosia is impairment in the ability to recognize objects in the absence of any sensory or intellectual impairment. At the simplest level agnosia has been described as either apperceptive or associative. However, more detailed investigation of agnosia indicates different types of deficits within each of these broad categories. In particular apperceptive agnosia is now considered to include a range of deficits. Integrative agnosia, due to poor perceptual integration of form information, was identified in a single case study reported by Riddoch and Humphreys. Another case DF had a profound visual form agnosia. The anoxic episode affected her vision for perception, but left her vision for action largely unscathed. Visual mental imagery refers to the recreation of a perceptual experience in the absence of visual input. While evidence indicates that visual perception and mental imagery share common underlying mechanisms there is evidence for a dissociation between the mental processes and perceptual processes. Several authors suggested that visual recognition impairments for living and non-living things might dissociate, and that our representations of different categories might be stored in anatomically distinct brain areas. The concept of category-specific agnosia, however, remains controversial.
Keywords	examinations of visual agnosia, classification of visual agnosia, integrative agnosia, perception and action dissociation, visual imagery