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Humans use continuous visual feedback from the hand to control fast reaching movements.
Jeffrey A Saunders1, David C Knill
1Center for Visual Science, University of Rochester, Meliora Hall 246, NY 14627-0270, Rochester, USA. saunders@cvs.rochester.edu
Experimental Brain Research
|August 9, 2003
Summary
Visual feedback continuously guides fast reaching movements. Even with perturbations, the brain adjusts hand trajectories in real-time, demonstrating ongoing visual control throughout movement.
Area of Science:
- Neuroscience
- Motor Control
- Human Movement Science
Background:
- The role of visual feedback in controlling fast reaching movements is debated.
- It is unclear if visual feedback is used continuously or only during the final movement phases.
Purpose of the Study:
- To investigate the continuous use of visual feedback during fast reaching movements.
- To determine the timing and influence of visual feedback on motor control.
Main Methods:
- A perturbation technique was used to assess visual feedback's influence.
- Subjects performed reaching movements in a virtual 3D space with visual fingertip feedback.
- Perturbations were introduced at 25% and 50% of movement extent.
Main Results:
- Hand trajectories showed smooth and accurate corrections following perturbations.
- Responses to perturbations were detected within 160 ms, indicating rapid processing.
- Correction latencies remained constant regardless of perturbation timing or movement speed.
Conclusions:
- The human brain continuously uses visual feedback to guide fast reaching movements.
- A fixed sensorimotor delay appears to be the primary limitation in response time.
- These findings resolve the debate on the continuous nature of visual feedback in motor control.