Journal Article

Effects of repetitive transcranial magnetic stimulation and trans-spinal direct current stimulation associated with treadmill exercise in spinal cord and cortical excitability of healthy subjects: A triple-blind, randomized and sham-controlled study

Campêlo, Mayara, Mendonça, Thyciane, Albuquerque, Plínio Luna, Monte-Silva, Katia, Brito, Rodrigo de Mattos, Fontes, Luís Augusto Mendes

2018

Overview

Repetitive transcranial magnetic stimulation (rTMS) over motor cortex and trans-spinal direct current stimulation (tsDCS) modulate corticospinal circuits in healthy and injured subjects. However, their associated effects with physical exercise is still not defined. This study aimed to investigate the effect of three different settings of rTMS and tsDCS combined with treadmill exercise on spinal cord and cortical excitability of healthy subjects. We performed a triple blind, randomized, sham-controlled crossover study with 12 healthy volunteers who underwent single sessions of rTMS (1Hz, 20Hz and Sham) and tsDCS (anodal, cathodal and Sham) associated with 20 minutes of treadmill walking. Cortical excitability was assessed by motor evoked potential (MEP) and spinal cord excitability by the Hoffmann reflex (Hr), nociceptive flexion reflex (NFR) and homosynaptic depression (HD). All measures were assessed before, immediately, 30 and 60 minutes after the experimental procedures. Our results demonstrated that anodal tsDCS/treadmill exercise reduced MEP's amplitude and NFR's area compared to sham condition, conversely, cathodal tsDCS/treadmill exercise increased NFR's area. High-frequency rTMS increased MEP's amplitude and NFR's area compared to sham condition. Anodal tsDCS/treadmill exercise and 20Hz rTMS/treadmill exercise reduced Hr amplitude up to 30 minutes after stimulation offset and no changes were observed in HD measures. We demonstrated that tsDCS and rTMS combined with treadmill exercise modulated cortical and spinal cord excitability through different mechanisms. tsDCS modulated spinal reflexes in a polarity-dependent way acting at local spinal circuits while rTMS probably promoted changes in the presynaptic inhibition of spinal motoneurons. In addition, the association of two neuromodulatory techniques induced long-lasting changes.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Adolescent / Adult / Analysis / Behavioral sciences / Biology and Life Sciences / Blindness / Brain stimulation / Circuits / Cortex (motor) / Cross-Over Studies / Direct current / Evoked Potentials, Motor / Excitability / Exercise / Exercise - physiology / Female / Fitness equipment / Healthy Volunteers / Humans / Inhibition / Laboratories / Magnetic brain stimulation / Magnetic fields / Male / Medicine and Health Sciences / Mental depression / Motor Cortex - physiology / Motor evoked potentials / Motor neurons / Muscle, Skeletal - physiology / Nervous system / Neurological disorders / Neuromodulation / Neurophysiology / Neurosciences / Pain / Pain perception / Physical exercise / Physical fitness / Physical therapy / Physiological aspects / Polarity / Presynapse / Pyramidal tracts / Randomization / Reflexes / Research and Analysis Methods / Spinal cord / Spinal Cord - physiology / Studies / Transcranial Magnetic Stimulation / Transcutaneous Electric Nerve Stimulation / Treadmills / Walking / Young Adult