Neuromuscular Electrical Stimulation Primes Feedback Control During a Novel Single Leg Task

Abstract

FMRI studies support that neuromuscular electrical stimulation can modulate the excitability of the somatosensory cortex. We studied whether practice and electrical stimulation of the quadriceps would enhance learning during a weight-bearing task. 20 healthy individuals (10 male) and 8 control subjects participated in a 2-day study. Day 1 consisted of a pretest, a training session, and a post-test; day 2 consisted of a pretest, 2 bouts of electrical stimulation to the quadriceps muscles, and a post-test. The single limb squat task was performed at varying knee resistance and target velocities and a random unexpected perturbation was administered. Feedforward error was calculated during a 50 ms time window before the unexpected event. Feedback error was calculated during a 150 ms window after the unexpected event. Peak error score decreased by 2.98 degrees (p < 0.001) immediately following training. Error was improved by 1.78 degrees (p < 0.001) during the feedforward phase and 1.44 degrees (p < 0.001) during the feedback phase. All subjects plateaued after day 1; except for the electrical stimulation group that showed a decrease of 1.206 degrees during the perturbed cycles (p = 0.024). Electrical stimulation triggered additional learning, beyond practice, during the unexpected event at a latency associated with the transcortical reflex.

Keywords:

• motor adaptation
• rehabilitation
• perturbation
• motor learning

Acknowledgments

We acknowledge past and current members from Dr. Shields’ lab including Shauna Dudley-Javoroski, Colleen McHenry, Chu-Ling Yen, Amy Kimball, Jinhyun Lee, Jared Johanns, and Amanda Kockler for their assistance with the data collection during this study.

Author Contributions

Michael Petrie was involved with the design of the study, data collection, data analysis, and writing of the manuscript. Kristin Johnson was involved in data collection, data analysis, and writing of the manuscript. Patrick McCue was involved in writing of the manuscript. Richard K. Shields was involved with the design of the study, funding procurement, data collection, data analysis, and writing of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This study was funded, in part, by the National Center for Medical Rehabilitation Research under grant numbers R01HD084645 and R01 HD082109. REDCap access provided by the University of Iowa Institute for Clinical and Translational Science (NIH UL1TR002537).