The anatomy of object recognition—visual form agnosia caused by medial occipitotemporal stroke

HO Karnath, J Rüter, A Mandler… - Journal of …, 2009 - Soc Neuroscience
HO Karnath, J Rüter, A Mandler, M Himmelbach
Journal of Neuroscience, 2009Soc Neuroscience
The influential model on visual information processing by has suggested a dissociation
between action-and perception-related processing in a dorsal versus ventral stream
projection. It was inspired substantially by the observation of a double dissociation of
disturbed visual action versus perception in patients with optic ataxia on the one hand and
patients with visual form agnosia (VFA) on the other. Unfortunately, almost all cases with
VFA reported so far suffered from inhalational intoxication, the majority with carbon …
The influential model on visual information processing by has suggested a dissociation between action- and perception-related processing in a dorsal versus ventral stream projection. It was inspired substantially by the observation of a double dissociation of disturbed visual action versus perception in patients with optic ataxia on the one hand and patients with visual form agnosia (VFA) on the other. Unfortunately, almost all cases with VFA reported so far suffered from inhalational intoxication, the majority with carbon monoxide (CO). Since CO induces a diffuse and widespread pattern of neuronal and white matter damage throughout the whole brain, precise conclusions from these patients with VFA on the selective role of ventral stream structures for shape and orientation perception were difficult. Here, we report patient J.S., who demonstrated VFA after a well circumscribed brain lesion due to stroke etiology. Like the famous patient D.F. with VFA after CO intoxication studied by Milner, Goodale, and coworkers (, ; ; ; ,; ; ; ; ), J.S. showed an obvious dissociation between disturbed visual perception of shape and orientation information on the one side and preserved visuomotor abilities based on the same information on the other. In both hemispheres, damage primarily affected the fusiform and the lingual gyri as well as the adjacent posterior cingulate gyrus. We conclude that these medial structures of the ventral occipitotemporal cortex are integral for the normal flow of shape and of contour information into the ventral stream system allowing to recognize objects.
Soc Neuroscience