Short-term neuroplastic effects of brain-controlled and muscle-controlled electrical stimulation

Functional electrical stimulation (FES) has been shown to facilitate the recovery of grasping function in individuals with incomplete spinal cord injury. Neurophysiological theory suggests that this benefit may be further enhanced by a more consistent pairing of the voluntary commands sent from the user's brain down their spinal cord with the electrical stimuli applied to the user's periphery. The objective of the study was to compare brain-machine interfaces (BMIs)-controlled and electromyogram (EMG)-controlled FES therapy to three more well-researched therapies, namely, push button-controlled FES therapy, voluntary grasping (VOL), and BMI-guided voluntary grasping.

Ten able-bodied participants underwent one hour of each of five grasping training modalities, including BMI-controlled FES (BMI-FES), EMG-controlled FES (EMG-FES), conventional push button-controlled FES, VOL, and BMI-guided voluntary grasping. Assessments, including motor-evoked potential, grip force, and maximum voluntary contraction, were conducted immediately before and after each training period.

Motor-evoked potential-based outcome measures were more upregulated following BMI-FES and especially EMG-FES than they were following VOL or FES. No significant changes were found in the more functional outcome measures.

These results provide preliminary evidence suggesting the potential of BMI-FES and EMG-FES to induce greater neuroplastic changes than conventional therapies, although the precise mechanism behind these changes remains speculative. Further investigation will be required to elucidate the underlying mechanisms and to conclusively determine whether these effects can translate into better long-term functional outcomes and quality of life for individuals with spinal cord injury.