%0 Journal Article
%T Transcranial Magnetic Stimulation with the Maximum Voluntary Muscle Contraction Facilitates Motor Neuron Excitability and Muscle Force
%A Tetsuo Touge
%A Yoshiteru Urai
%A Kazuyo Ikeda
%A Kodai Kume
%A Kazushi Deguchi
%J Neurology Research International
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/847634
%X Three trials of transcranial magnetic stimulation (TMS) during the maximum voluntary muscle contraction (MVC) were repeated at 15-minute intervals for 1 hour to examine the effects on motor evoked potentials (MEPs) in the digital muscles and pinching muscle force before and after 4 high-intensity TMSs (test 1 condition) or sham TMS (test 2 condition) with MVC. Under the placebo condition, real TMS with MVC was administered only before and 1 hour after the sham TMS with MVC. Magnetic stimulation at the foramen magnum level (FMS) with MVC was performed by the same protocol as that for the test 2 condition. As a result, MEP sizes in the digital muscles significantly increased after TMS with MVC under test conditions compared with the placebo conditions ( ). Pinching muscle force was significantly larger 45 minutes and 1 hour after TMS with MVC under the test conditions than under the placebo condition ( ). FMS significantly decreased MEP amplitudes 60 minutes after the sham TMS with MVC ( ). The present results suggest that intermittently repeated TMS with MVC facilitates motor neuron excitabilities and muscle force. However, further studies are needed to confirm the effects of TMS with MVC and its mechanism. 1. Introduction Transcranial magnetic stimulation (TMS) is a noninvasive method of stimulating cortical neurons; that is, electrical currents in axons of interneurons stimulated by TMS activate cortical neuron cell bodies via synaptic transmission [1]. Single TMS or repetitive TMS (rTMS) can transiently inhibit or facilitate cortical neuron excitabilities for a prolonged period following stimulation [2¨C5]. According to these lines of evidence, many studies have tested whether TMSs or rTMS accelerates functional recovery in patients with motor disability [6¨C11]. A previous study reported that only three single TMS during the maximum voluntary muscle contraction (MVC) in patients with weakness of the thigh muscles transiently, but significantly, enhanced muscle strength compared with TMS during muscle relaxation [12]. Nevertheless, the effects of TMS with MVC have not yet been established, and its mechanism still remains unknown. In the present study, we investigated the effects of TMS with MVC on motor neuron excitability by recording motor evoked potentials (MEPs) with MVC, using a modified protocol of TMS with MVC to induce more prolonged and robust effects on motor neuron function. Furthermore, we stimulated the corticospinal tract at the foramen magnum level to detect the functional mechanism of TMS with MVC. Preliminary results of the present
%U http://www.hindawi.com/journals/nri/2012/847634/