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Combining Multiple Data Acquisition Systems to Study Corticospinal Output and Multi-segment Biomechanics
Published on: January 9, 2016
Do corticomotoneuronal cells predict target muscle EMG activity?
D M Griffin1, H M Hudson, A Belhaj-Saïf
1Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, KS 66160-7336, USA.
Journal of Neurophysiology
|December 28, 2007
Summary
Cortical neurons activate in sync with target muscle activity during reach-to-grasp movements. Ensemble activity of these neurons effectively predicts muscle activation patterns, supporting a muscle-based motor control framework.
Area of Science:
- Neuroscience
- Motor Control
- Computational Neuroscience
Background:
- Understanding how the primary motor cortex (M1) controls voluntary movements is crucial.
- Corticospinal pathways, particularly corticomotoneuronal (CM) cells, are key mediators of motor output.
- The precise relationship between individual CM cell activity and specific muscle activation patterns remains an active area of research.
Purpose of the Study:
- To investigate the relationship between cortical cell activation patterns and the electromyographic (EMG) activity of facilitated target muscles during reach-to-grasp movements.
- To determine if CM cells encode movement via muscle-based parameters.
- To examine the contribution of CM cell ensembles to motor control.
Main Methods:
- Recorded activity of M1 cortical neurons and EMG from 22-24 forelimb muscles in two rhesus macaques during reach-to-grasp tasks.
- Identified CM cells using postspike facilitation (PSpF) in spike-triggered averages (SpTAs) of EMG.
- Quantified covariation using peak analysis, timing/overlap assessment, and Pearson correlation between CM cell firing rate and EMG activity.
Main Results:
- Nearly all (95%) tested CM cells showed a firing rate peak coinciding with a target muscle EMG activity peak.
- While some individual CM cells exhibited strong correlations with target muscles, substantial disparities were common.
- Ensemble activity of a small group of CM cells targeting the same muscle yielded a strong match (r ≥ 0.8) to the muscle's EMG pattern.
Conclusions:
- Corticospinal output from M1 appears to encode movement using muscle-based parameters, specifically muscle activation patterns.
- Ensemble coding by CM cells provides a robust representation of muscle activity.
- This study supports the hypothesis that motor cortex utilizes a muscle-centric framework for generating voluntary movements.
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