EEG Oscillations during Prehypnosis and Hypnosis in Subjects with High and Low Dissociative Experiences

Abstract

Aims: Hypnosis is a multifaceted phenomenon and refers to suggestions that are used to create desirable changes in behavior, experience and physiology. Most EEG research in hypnosis have allocated people into two groups of high and low hypnotizables. Hence, the empirical data are somewhat controversial, and there is no general agreement about the neurophysiology of hypnosis. On the other hand, dissociation theory of hypnosis posits that people candidates for hypnosis are typically prone to dissociation and individuals divide into two groups with high dissociative (HD) and low dissociative (LD). If this assumption is true, we can expect such a state should be visible as a distinct pattern of changes in absolute power and functional connectivity between brain districts after a hypnotic induction in high but not low dissociative suggestible. Methods: The final sample consisted of 20 participants who scored six or higher on the SHSS: C. then we completed DES on them. To assess the electrical activity of the brain during hypnosis, nineteen channel EEG was recorded from 10 HD and 10 LD participants with their eyes closed before (baseline) and after the induction of hypnosis. We use EEG to measure absolute power and functional connectivity using coherence (COH). We expected that the two groups would have dissimilar pattern of EEG signals in spite of equivalent hypnotizability. Findings: We found that in in bands of delta, theta, alpha, beta, and gamma, both groups were different from the baseline to hypnosis. In addition, both groups showed different connectivity in hypnosis in four bands (delta, theta, alpha, and beta). Conclusion: These findings indicate that although the two LD low and HD groups had equal hypnotizability, the episodic prospection tasks did not involve the same neural networks in the two groups.