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Studies of the human stretch reflex
1Department of Neurology, School of Medicine, University of California, San Francisco, California 94143-0114, USA.
Muscle & Nerve. Supplement
|January 3, 2001
Summary
Late electromyographic responses are influenced by brain mechanisms during limb movements. These suprasegmental (brain) controls help manage limb stiffness and return limbs to their intended positions.
Area of Science:
- Neuroscience
- Motor Control
- Biomechanics
Background:
- Understanding the neural control of limb movements is crucial for diagnosing and treating motor disorders.
- Electromyographic (EMG) responses reflect muscle activity during movement, but the influence of higher brain centers is not fully elucidated.
Purpose of the Study:
- To investigate the role of suprasegmental (cerebral) mechanisms in modulating late electromyographic (EMG) responses.
- To determine if these cerebral mechanisms influence limb stiffness control and limb repositioning during movement.
Main Methods:
- Simultaneous recording of electromyographic (EMG) responses and cerebral activity.
- Applying predictable and unpredictable stretches to wrist flexor and extensor muscles during ballistic movements and isometric contractions.
Main Results:
- Late EMG responses were modulated by cerebral activity during both predictable and unpredictable limb perturbations.
- Evidence suggests a dual role for these suprasegmental mechanisms in controlling limb stiffness and executing limb repositioning.
Conclusions:
- Suprasegmental (cerebral) phasic mechanisms significantly influence late EMG responses.
- These brain-involved mechanisms play a critical role in both maintaining limb stability and correcting limb displacement during motor tasks.