The facilitating effect of clinical hypnosis on motor imagery: an fMRI study

Hypnosis is increasingly being employed in therapy of neurologically impaired patients. In fact, reports from neuropsychological practice point out that neurological patients with a loss of motor abilities achieve successful rehabilitation by means of motor imagery during hypnosis. This approach was shown to be effective even if the patients' ability to imagine movements was impaired or lost. The underlying mechanisms of "how" and "where" hypnosis affects the brain, however, are largely unknown. To identify the brain areas involved in motor imagery under hypnosis, we conducted an fMRI study in which we required healthy human subjects either to imagine or to execute repetitive finger movements during a hypnotic trance. We observed fMRI-signal increases exclusively related to hypnosis in the left superior frontal cortex, the left anterior cingulate gyrus and left thalamus. While the superior frontal cortex and the anterior cingulate were active related more to movement performance than to imagery, the thalamus was activated only during motor imagery. These areas represent central nodes of the salience network linking primary and higher motor areas. Therefore, our data substantiate the notion that hypnosis enhances motor imagery.