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The Two Visual Systems Hypothesis: New Challenges and Insights from Visual form Agnosic Patient DF.
Robert L Whitwell1, A David Milner2, Melvyn A Goodale3
1Graduate Program in Neuroscience, The University of Western Ontario , London, ON , Canada ; Department of Psychology, The University of Western Ontario , London, ON , Canada ; Brain and Mind Institute, The University of Western Ontario , London, ON , Canada.
Frontiers in Neurology
|December 25, 2014
Summary
Patient DF
Area of Science:
- Neuroscience
- Cognitive Psychology
- Neurobiology
Background:
- Patient DF exhibits visual form agnosia after carbon monoxide poisoning.
- DF can still visually guide her grasping actions despite perceptual deficits.
- This dissociation supports the Two Visual Systems Hypothesis (TVSH).
Purpose of the Study:
- To review recent studies on Patient DF.
- To investigate the functional organization of the dorsal and ventral visual streams.
- To explore the impact of dorsal stream damage on visually guided grasping.
Main Methods:
- Review of recent studies focusing on Patient DF's visual perception and action.
- Analysis of neuroimaging and behavioral data related to DF's brain lesions and grasping abilities.
- Examination of DF's grip scaling and reliance on visual/haptic feedback.
Main Results:
- DF has confirmed dorsal and ventral brain damage, with increasing dorsal-stream lesions.
- Dorsal stream damage correlates with deficits in directing peripheral actions.
- DF shows a modest deficit in grip scaling but maintains a clear dissociation between perception and action.
Conclusions:
- DF's grasping ability relies on intact dorsal stream visuomotor networks.
- Visual feedforward processing in the dorsal stream supports visually guided grasping.
- Recent findings reinforce the TVSH model of visual processing for perception and action.
Keywords:
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