Objective: To study the changes of magnetic evoked potentials by thinking of simple motion without actual muscle action of that motion.

Method: We use H-reflex to test the excitability of relevant pools of spinal motor neurons and Magnetic Evoked Potentials (MEPs) to study the core of brain motor activity. The H-reflex and MEPs were obtained in three different conditions. 1) non-facilitation (NF), that is, resting state without actual motion and without thinking of that motion. 2) volitional-faciliation (VF), with actual motion which is usual manner of facilitation of MEPs. 3) thinking-facilitation (TF), without actual motion but with imaginary thinking of that motion. We evaluate the thresholds, amplitudes and latencies of H-reflex and MEPs in each three condition.

Results: Comparing with the parameters in NF condition as a baseline, there were no significant changes in any parameters of H-reflex in TF condition, but there were significant changes in threshold and amplitude of H-reflex in VF. On the while there were significant changes both in VF and TF of MEPs. The amount of facilitation of MEPs were greater in VF than in TF; the amount threshold decrement, amplitude increment and latency decrement of MEPs were greater in VF than in TF.

Conclusion: Thinking of simple motion without actual muscle action of that motion could facilitate the MEPs, and this facilitation is induced by increasing activity of brain motor cortex not by that of spinal cord level.