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Contact-evoked changes in EMG activity during human grasp.
D F Collins1, B Knight, A Prochazka
1Division of Neuroscience, University of Alberta, Edmonton T6G 2S2, Alberta T6G 2B7, Canada.
Journal of Neurophysiology
|May 13, 1999
Summary
Sensory feedback from skin receptors during grasp significantly alters muscle activity. This research shows that touch signals are crucial for regulating electromyography (EMG) responses in human hands.
Area of Science:
- Neuroscience
- Human Motor Control
- Somatosensation
Background:
- Cutaneous receptors in digits generate activity upon object contact during grasp.
- Sensory feedback is essential for precise motor control and task execution.
Purpose of the Study:
- To investigate the role of sensory feedback from digit contact in modulating muscle activity during a precision grasp task.
- To determine the timing and magnitude of electromyography (EMG) changes related to contact-evoked afferent activity.
Main Methods:
- Twelve subjects performed a precision grasp task without vision.
- Electromyography (EMG) activity was recorded and compared between trials with and without object contact.
- Local anesthesia was applied to digits in a subset of subjects to assess the contribution of cutaneous receptors.
Main Results:
- Significant differences in EMG amplitude were observed 50-100 ms after contact, emerging as early as 34 ms.
- EMG responses were typically larger with the object present, but varied in some muscles.
- Local anesthesia reduced or abolished contact-evoked EMG activity, confirming the role of cutaneous feedback.
Conclusions:
- Sensory activity signaling contact, particularly from cutaneous receptors, plays a critical role in regulating EMG during human grasp.
- Both spinal and supraspinal pathways likely mediate these sensory-motor interactions.
- Understanding this feedback mechanism is vital for grasping and manipulation research.