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Primate rubromotoneuronal cells: parametric relations and contribution to wrist movement
1Department of Physiology, University of Kansas Medical Center, Kansas City 66160.
Journal of Neurophysiology
|July 1, 1994
Summary
Rubromotoneuronal (RM) cells exhibit distinct discharge patterns during wrist movements, with many cells firing before or during target muscle activation. RM cells show tonic activity related to static torque, but with lower slopes than corticomotoneuronal cells.
Area of Science:
- Neuroscience
- Motor Control
- Primate Motor System
Background:
- Rubromotoneuronal (RM) cells play a role in motor control.
- Understanding their discharge properties is crucial for deciphering motor commands.
Purpose of the Study:
- To characterize the discharge patterns of RM cells during voluntary wrist movements in rhesus monkeys.
- To investigate the relationship between RM cell activity and movement parameters like torque and velocity.
Main Methods:
- Identified 59 RM cells using postspike facilitation (PSpF) of electromyographic (EMG) activity in rhesus monkeys.
- Recorded neuronal discharge during ramp-and-hold wrist tracking tasks with auxotonic loads and isometric conditions.
Main Results:
- Observed four main RM cell activity patterns: phasic-tonic (44%), pure phasic (22%), pure tonic (2%), and unmodulated (24%).
- RM cell phasic discharge preceded target muscle EMG onset by ~88 ms.
- 53% of RM cells showed tonic activity during static holds, with activity positively correlated to static torque, albeit at lower rates than corticomotoneuronal cells.
Conclusions:
- RM cells contribute to both the dynamic and static aspects of motor control.
- Their discharge patterns suggest a role in modulating muscle activity and force production during voluntary movements.