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Published on: August 25, 2020
Temporal development of anticipatory reflex modulation to dynamical interactions during arm movement
Toshitaka Kimura1, Hiroaki Gomi
1NTT Communication Science Laboratories, Nippon Telegraph and Telephone Corporation, Kanagawa, Japan. t-kimura@idea.brl.ntt.co.jp
Journal of Neurophysiology
|August 7, 2009
Summary
Somatosensory reflex amplitude during voluntary arm movement is adjusted based on the estimated time until encountering force fields, not just the movement
Area of Science:
- Neuroscience
- Motor Control
- Human Movement Science
Background:
- Somatosensory reflexes are modulated during voluntary arm movements.
- The precise timing and coding (temporal vs. spatial) of this reflex modulation remain unclear.
Purpose of the Study:
- To investigate when and how reflex amplitude is set during voluntary arm movements.
- To determine if reflex modulation is preparatory or continuous.
- To differentiate between temporal and spatial coding of reflex amplitude.
Main Methods:
- Subjects performed planar reaching movements towards predictable force fields.
- Somatosensory reflex responses in shoulder muscles were measured following small perturbations.
- Reflexes were evaluated at various points before force field interaction.
- An additional experiment assessed temporal vs. spatial distance effects.
Main Results:
- Reflex amplitude varied with the direction of the upcoming force field (e.g., higher flexor response for rightward fields).
- This modulation intensified closer to the force fields, indicating continuous adjustment.
- Reflex modulation was primarily dependent on the temporal distance to the force field, not spatial distance.
Conclusions:
- Somatosensory reflex amplitude during voluntary movement is modulated anticipatorily.
- Modulation is based on an estimation of time-to-contact with dynamic interactions, rather than spatial position.
- This suggests a time-based predictive control mechanism for motor reflexes.
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