CLINICAL AND POSITRON EMISSION TOMOGRAPHY STUDIES OF VISUAL APPERCEPTIVE AGNOSIA

Assessments of higher visual functioning and regional cerebral blood n ow (rCBF) using positron emission tomography were obtained in three vi sual apperceptive agnosics. Their clinical impairment included difficu lty appreciating the perceptual features of line drawings, letters, an d other visual material, despite relatively intact elementary visual f unctioning and access to visual information in semantic memory. rCBF w as significantly reduced in temporooccipital cortices. Our findings su ggest that apperceptive agnosia is associated with massive ventral vis ual system dysfunction that interferes with visual perceptual processi ng needed for object recognition.