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Automatic avoidance of obstacles is a dorsal stream function: evidence from optic ataxia
Igor Schindler1, Nichola J Rice, Robert D McIntosh
1Department of Psychology, Wolfson Research Institute, University of Durham, Queen's Campus, Stockton-on-Tees, TS17 6BH, UK.
Nature Neuroscience
|June 23, 2004
Summary
Patients with dorsal stream damage struggle to adjust reaching movements around obstacles. The dorsal stream is crucial for automatically guiding movements to avoid obstacles and reach targets.
Area of Science:
- Neuroscience
- Cognitive Psychology
- Motor Control
Background:
- Visuomotor networks in the cortical dorsal stream guide reaching movements towards targets.
- Reaching trajectories can be influenced by non-target objects, acting as potential obstacles.
Purpose of the Study:
- To investigate the role of the dorsal stream in obstacle avoidance during reaching movements.
- To determine if dorsal stream damage impairs the ability to adjust reach trajectories around obstacles.
Main Methods:
- Two patients with bilateral dorsal-stream lesions (optic ataxia) participated.
- Participants reached between two cylinders with varying locations (potential obstacles).
- A control task involved pointing midway between the cylinders.
Main Results:
- Patients' reaches were invariant to changes in obstacle location.
- In the control task, responses shifted predictably with object placement.
- This suggests a deficit in automatic obstacle avoidance, not general spatial processing.
Conclusions:
- The dorsal stream is essential for the automatic visual guidance of movements to avoid obstacles.
- This pathway also contributes to guiding movements to ensure target arrival.