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Patient DF's visual brain in action: Visual feedforward control in visual form agnosia
Robert L Whitwell1, A David Milner2, Cristiana Cavina-Pratesi2
1The Brain and Mind Institute, The University of Western Ontario, London, Ontario N6A 5B7, Canada; The Graduate Program in Neuroscience, The University of Western Ontario, London, Ontario N6A 5B7, Canada.
Vision Research
|September 10, 2014
Summary
Patient DF, with visual form agnosia, cannot perceive object width but can still scale her grip to grasp them. Experiments confirm this spared grasping relies on visual feedforward processing, not online feedback.
Area of Science:
- Neuroscience
- Cognitive Psychology
- Visual Perception
Background:
- Patient DF has visual form agnosia due to ventral stream damage, impairing object width perception.
- Despite perceptual deficits, DF demonstrates intact grip scaling for object manipulation.
Purpose of the Study:
- To investigate the reliance of DF's grip scaling on visual and haptic feedback.
- To determine if spared grasping in DF is mediated by dorsal stream visual feedforward processing.
Main Methods:
- Assessed DF's grip scaling with vision suppressed during grasping.
- Tested the impact of haptic feedback on perceptual estimates and grip scaling.
- Examined grip scaling with congruent and incongruent visual-haptic feedback.
Main Results:
- DF's grip scaling remained accurate without vision and dissociated from impaired perception.
- Haptic feedback did not improve DF's perceptual estimates.
- DF's grip scaling adapted to visual targets even with incongruent haptic feedback.
Conclusions:
- DF's preserved ability to scale grasps is independent of online visual or haptic feedback.
- Results support the hypothesis that spared grasping in DF relies on dorsal stream visual feedforward processing.
Keywords:
GraspingHaptic feedbackPatient DFTwo visual systems hypothesisVisual feedbackVisual form agnosiaMore Related Videos
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