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Grasping the past. delay can improve visuomotor performance.
A D Milner1, H C Dijkerman, L Pisella
1Espace et Action, INSERM Unité 534, 16 avenue Lépine, 69676 Bron, France. a.d.milner@durham.ac.uk
Current Biology : CB
|December 1, 2001
Summary
Optic ataxia, caused by posterior parietal cortex damage, impairs visually guided grasping. However, patients can improve grip scaling with practice, suggesting off-line visuomotor networks independent of the PPC.
Area of Science:
- Neuroscience
- Cognitive Psychology
- Visuomotor Control
Background:
- Optic ataxia results from posterior parietal cortex (PPC) damage, affecting visually guided prehension.
- This condition disrupts hand transport and in-flight finger adjustments for object properties.
Purpose of the Study:
- To investigate the role of the PPC in real-time grasping versus memory-guided actions.
- To explore the potential for alternative visuomotor networks in patients with optic ataxia.
Main Methods:
- Case study of a patient (I.G.) with optic ataxia.
- Assessed grip scaling during direct reaching and pantomimed grasping.
- Utilized practice and catch trials with object substitution to test memory-guided calibration.
Main Results:
- Patient I.G. showed impaired grip scaling in direct grasping but intact scaling during pantomimed grasps.
- Following practice, I.G. improved real grasping calibration.
- Catch trials revealed I.G. used memorized visual information for improved grip scaling.
Conclusions:
- Visuomotor guidance for grasping can be supported by networks independent of the PPC.
- The PPC may not be essential for all aspects of off-line visuomotor calibration.
- Suggests distinct neural pathways for real-time versus memory-based visuomotor control.