Is the hypnotic state a separate state of consciousness or merely a form of half-sleep? To answer this question, Pierre Rainville, a researcher in neuropsychology at Université de Montréal, subjected some twenty hypnotized subjects to brain imaging tests. The tests revealed many differences between a “normal” waking state and a hypnotic state in the activity of the various mechanisms that control consciousness and attention. It was the first time anyone had analyzed the hypnotic state using brain imaging.

Until now, researchers only had subjective data to describe and understand the hypnotic state, characterized by a loss of self-control and change of consciousness, which appears in different stages of falling asleep. The research done by Pierre Rainville and his team represents a major contribution to the debate, since they show that the subjective changes connected with hypnosis are accompanied by changes in neuronal activity. “We didn't know anything about the neuronal mechanisms underlying the hypnotic state,” added the researcher, who is affiliated with the Department of Stomatology in the Faculty of Dentistry. The only data we had were collected indirectly from electroencephalograms, and remained controversial.”

The observed changes—increase or reduction of activity in different zones of the brain—appeared to correlate with subjective assessments: the more relaxed or concentrated the subject felt, the greater the neuronal changes. The researchers were even surprised to observe increased activity in the frontal lobe, the seat of control of motor functions. This observation contradicts the hypotheses that activity in this zone should be reduced, since in a state of hypnosis a person seems to lose self-control.
The results of Pierre Rainville’s research work appeared last September in the Journal of Cognitive Neuroscience, published by the Massachusetts Institute of Technology. His co-authors included Robert Hofbauer, Catherine Bushnell, Gary Duncan and Donald Price.

Researcher: Pierre Rainville
Telephone: (514) 343-6111, extension 3935
Email: pierre.rainville@umontreal.ca
Funding: Canadian Institutes of Health Reseach, Human Frontier Science Program