Hypnotic suggestion alters the state of the motor cortex

•We used TMS of MI to investigate effect of hypnotic suggestion on the motor system.•Corticospinal excitability was enhanced, with increased hand-grip force exertion.•The hypnotic suggestion actually altered the state of M1 and the resultant behavior.

Hypnosis often leads people to obey a suggestion of movement and to lose perceived voluntariness. This inexplicable phenomenon suggests that the state of the motor system may be altered by hypnosis; however, objective evidence for this is still lacking. Thus, we used transcranial magnetic stimulation of the primary motor cortex (M1) to investigate how hypnosis, and a concurrent suggestion that increased motivation for a force exertion task, influenced the state of the motor system. As a result, corticospinal excitability was enhanced, producing increased force exertion, only when the task-motivating suggestion was provided during hypnotic induction, showing that the hypnotic suggestion actually altered the state of M1 and the resultant behavior.