Physiological Changes Exploration During the Hypnotic State

Since the 19th century, the potential changes induced by hypnosis have been investigated. Indeed, hypnosis induces a change on the usual state of conscious awareness. This state is accompanied by physiological changes, as cardiac and cerebral. However, although literature on the neural mechanisms underlying hypnosis increases, no specific activity change has been identified. Only the subjective judgment of hypnotherapist can assume the volunteer state. Considering that the use of hypnosis enhanced in the field of medical care, it is necessary to clarify and define it. This requires a better understanding of its mechanisms through the study of brain, heart and respiratory activities.

The aim of this clinical trial is to assess modifications of physiological signals (cardiac, respiratory and cerebral) before and during a session of hypnosis, to identify some biomarkers of the hypnotic trance. Therefore the cardiac, respiratory and cerebral activities will be recorded during hypnosis sessions and control state to compare the signals.

The MEG will be used to record brain activity due to its sensitivity in the very low and high frequencies, its temporal resolution and its robustness for the localization of neural origins. In accordance with the literature and preliminary results, changes in theta oscillations (4-8 Hz) will be assessed. In fact, these oscillations seem to be increased during the hypnotic state. So, it seems interesting to correlate these oscillations with potential changes in heart and/or respiratory rhythms.

This clinical trial is an open mono-centric study, performed on a cohort of healthy volunteers in which each subject is his own control (intra-subject control). The physiological parameters will be recorded and analyzed during three control states ("subject alone", "subject and hypnotherapist without communication" and "reading a book by the hypnotherapist"), and several blocks of hypnosis interleaved with an attentional task (stroop). All the collected parameters in these different conditions will be compared.

Inclusion criteria

• Healthy volunteers
• Right-handed
• Non-smoking
• Major participants
• Speaking fluent French
• No experience of hypnosis or other forms of meditation and relaxation
• Registered in the French social security scheme
• Signed informed consent

Exclusion criteria

• Contraindication to Magnetoencephalography (MEG) and/or Magnetic resonance imaging (MRI) : implanted material, claustrophobia,…
• Treatment that may impact physiological measures (psychotropic, cardiovascular,…)
• All categories of protected persons (Pregnant or lactating women, persons subject to a legal protection measure, persons deprived of their liberty by judicial or administrative decision)
• Smokers
• Persons with personality disorders or addictions / narcotic use