We know more about how hypnosis and consciousness work

Under hypnosis, a very particular area of ​​the brain seems to block the process of becoming aware of certain information, in order to respect the hypnotic suggestion. In a woman hypnotized to be temporarily deaf, auditory stimuli were perceived but blocked before reaching consciousness, French researchers led by Prof Lionel Naccache report in the journal. Frontiers in Neuroscience. Hypnosis could be the ideal tool to explore our consciousness and thus better understand how our brain can self-limit its capabilities, sometimes even a neurological disorder.

Beep beep beep beep beep”, The monitor rings in the ear of the young woman lying down, with her eyes closed. Very sensitive to hypnotic suggestions, he agreed to undergo a very serious experiment. Guided by her hypnotherapist and co-author of this new work, Jean-Marc Benhaiem, she was losing her sense of hearing. With each burst of “beep”, Makes a gesture to indicate that he feels or no longer feels. In the end, the only sound that penetrates his consciousness is the therapist’s voice. The experiment lasts less than half a day, but allows researchers to record the young woman’s brain activity as the sounds reach her, before that during hypnosis. “I believe that altered states of consciousness, such as lucid dreams or hypnosis, can help us better understand the mechanisms of our consciousness.”Explains Esteban Muñoz Musat, the first author of this work.

Consciousness, what is it?

If the question of the definition of consciousness is far from being answered clearly by the scientific community, two main theories clash. The first is “Neural Global To workspace”, Or global neural workspace theory. According to this theory,consciousness would be a late process, reaching between 300 and 400 milliseconds after the unconscious perception of the stimulus.”Explains Esteban Muñoz Musat. At this point, the information (here a sound), initially processed unconsciously by a local neural network (here the auditory cortex), spreads globally to the brain, thanks to the prefrontal and parietal cortex. This global dissemination of information allows it to be processed by other specialized brain circuits (that of memory, for example), giving rise to the subjective impression of being “conscious” of the information. “It is zero or one, a step from unconscious information to information that we can consciously report”Specifies the researcher.

The second theory, that of integrated information, is based on a very different philosophical position. It is assumed that any system capable of integrating information has a consciousness by definition, and that the more complex the system, the more important the consciousness. “According to this theory, even a simple diode has a form of consciousness”, Illustrates Esteban Muñoz Musat.

When the brain inhibits consciousness

Proponents of global neural workspace theory, scientists make two assumptions about their hypnotic patient. “First of all, it is necessary to observe the disappearance of the brain wave P300”, Lists Esteban Muñoz Musat. The P300 is this brain wave that characterizes the consciousness of a stimulus, that is, the moment when it spreads more widely to the brain through the prefrontal cortex. Under hypnosis, the auditory stimulus does not reach the consciousness, as the subject claims not to hear anything. Researchers explain this disruption by a second hypothesis: it is the brain itself that would block the signal. “We assumed that unconscious perception was still occurring, but that another part of the prefrontal cortex would actively inhibit the entry of auditory information into the conscious process.”Explains Esteban Muñoz Musat. And that’s what happened.

When the hypnotherapist finally lifts her patient’s hypnotic suggestion, she immediately regains normal hearing. “He confirmed to us that in a state of advanced hypnosis he could no longer hear, which coincided with the absence of the P300 wave observed on the electroencephalogram.”Says Esteban Muñoz. The first hypothesis is therefore verified, the P300 is well correlated with the transition to consciousness. Second victory: When the P300 was due to arrive, researchers observed a brief activity of the anterior cingulate cortex (below part of the prefrontal cortex). “Hypnosis generates an active mechanism, a kind of filter or counter-order that says that information is blocked and does not go beyond the brain.”Interprets the researcher. If these results are to be replicated to confirm them, they are already paving the way for therapeutic applications.

Use of hypnosis to treat neurological disorders

Functional neurological disorders are neurological symptoms with no associated organic injury, either to the spinal cord or to the brain. Labeled as psychological in origin, some can be unlocked through hypnosis. “When the disorder involves motor paralysis, hypnosis allows many patients to move again. And once out of the hypnotic suggestion, some permanently retain their mobility.”Explains Esteban Muñoz Musat. “Some authors link these mechanisms, saying that in these disorders the subject self-imposes a blockade with a mechanism close to that of hypnotic suggestion.”.

Therefore, understanding the mechanisms of hypnosis is not only about exploring consciousness, but also understanding how to best treat these patients. Knowing which part of the brain is responsible for inhibiting the awareness of information could allow it to be processed. “Our results show the inhibitory role of the anterior cingulate cortex. We think that in these neurofunctional disorders, this active block would go through the same structures. This paves the way for optimized treatment of these disorders by specifically stimulating this area of ​​the brain.”Concludes the researcher.

Leave a Comment