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Front. Neurosci. | doi: 10.3389/fnins.2019.00149

Effects of Leg Motor Imagery Combined with Electrical Stimulation on Plasticity of Corticospinal Excitability and Spinal Reciprocal Inhibition

 Yoko Takahashi1, 2,  Michiyuki Kawakami1*,  Tomofumi Yamaguchi1, 3, Yusuke Idogawa2, Shigeo Tanabe4, Kunitsugu Kondo2 and Meigen Liu1
  • 1School of Medicine, Keio University, Japan
  • 2Tokyo Bay Rehabilitation Hospital, Japan
  • 3Yamagata Prefectural University of Health Sciences, Japan
  • 4Faculty of Rehabilitation, School of Health Sciences, Fujita Health University, Japan

Motor imagery (MI) combined with electrical stimulation (ES) enhances upper-limb corticospinal excitability. However, its after-effects on both lower limb corticospinal excitability and spinal reciprocal inhibition remain unknown. We aimed to investigate the effects of MI combined with peripheral nerve ES (MI + ES) on the plasticity of lower limb corticospinal excitability and spinal reciprocal inhibition. Seventeen healthy individuals performed the following three tasks on different days, in a random order: 1) MI alone; 2) ES alone; and 3) MI + ES. The MI task consisted of repetitive right ankle dorsiflexion for 20 min. ES was percutaneously applied to the common peroneal nerve at a frequency of 100 Hz and intensity of 120% of the sensory threshold of the tibialis anterior (TA) muscle. We examined changes in motor-evoked potential (MEP) of the TA (task-related muscle) and soleus muscle (SOL; task-unrelated muscle). We also examined disynaptic reciprocal inhibition before, immediately after, and 10, 20, and 30 min after the task. MI + ES significantly increased TA MEPs immediately and 10 min after the task compared with baseline, but did not change the task-unrelated muscle (SOL) MEPs. MI + ES resulted in a significant increase in the magnitude of reciprocal inhibition immediately and 10 min after the task compared with baseline. MI and ES alone did not affect TA MEPs or reciprocal inhibition. MI combined with ES is effective in inducing plastic changes in lower limb corticospinal excitability and reciprocal Ia inhibition.

Keywords: Motor Imagery, Motor-evoked potential, H-Reflex, Disynaptic reciprocal inhibition, Peripheral nerve electrical stimulation

Received: 12 Oct 2018; Accepted: 08 Feb 2019.

Edited by:

Younbyoung Chae, Kyung Hee University, South Korea

Reviewed by:

Junsuk Kim, Max Planck Institute for Biological Cybernetics, Germany
Kyungmo Park, Department of Biomedical Engineering, Kyung Hee University, South Korea  

Copyright: © 2019 Takahashi, Kawakami, Yamaguchi, Idogawa, Tanabe, Kondo and Liu. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Michiyuki Kawakami, School of Medicine, Keio University, Tokyo, Japan, michiyukikawakami@hotmail.com