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Characteristics of motor programs underlying arm movements in monkeys
Journal of Neurophysiology
|January 1, 1979
Summary
Sensory feedback is crucial for monkeys to adapt arm movements, even in practiced tasks. Deafferented monkeys struggle with accuracy when their body
Area of Science:
- Neuroscience
- Motor Control
- Primate Studies
Background:
- Understanding the neural mechanisms of voluntary arm movements.
- Investigating the role of sensory feedback in motor learning and execution.
Purpose of the Study:
- To identify processes underlying arm movements in monkeys.
- To determine the role of afferent feedback in learned motor tasks.
Main Methods:
- Trained adult monkeys to perform a pointing task.
- Conducted experiments before and after bilateral dorsal rhizotomy (deafferentation).
- Assessed arm movement accuracy with and without visual arm guidance, including unexpected limb displacements.
Main Results:
- Both intact and deafferented monkeys accurately reached targets when the body-apparatus relationship was fixed.
- Deafferented monkeys showed significant inaccuracy when the spatial relationship between body and apparatus changed.
- Intact monkeys compensated for positional variations, highlighting the importance of afferent feedback for adaptation.
Conclusions:
- Motor commands may control an equilibrium point, not specific joint angles.
- Afferent feedback is essential for adapting learned motor programs in visually guided movements.
- Deafferentation dramatically impairs motor performance in novel postural settings.