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Electrophysiological Alterations During Hypnosis for Ego-Enhancement: A Preliminary Investigation

American Journal of Clinical Hypnosis, Apr 2004 by Stevens, Larry, Brady, Brian, Goon, Angela, Adams, Deanna, Et al

EEG activity at the midfrontal (Fz) region was recorded during pre- and postbaselines, live hypnotic induction, arm levitation and progressive relaxation (PNR) deepening, and therapeutic ego-enhancing suggestions among 60 college student volunteers, previously screened with the Stanford Hypnotic Susceptibility Scale, Form C. Comparisons across conditions for delta, theta, alpha, and beta activity were made between low, moderate, high, and very high hypnotizable groups. Results indicated (a) significant increases in theta EEGs across the hypnosis process with a peak at PNR and a drop in theta thereafter to termination, with highs showing significantly more dramatic effects than moderates; (b) a similar inverted U-shaped pattern for beta EEGs across hypnosis conditions, with very highs significantly higher in beta power than moderates and lows, and with highs significantly higher than moderates; (c) general profile differences between the highs for theta and the highs and very highs for beta in comparison to the moderates and lows, with peak theta and beta power occurring during ego-enhancing suggestions for more highly hypnotizable participants; (d) a drop in alpha EEGs across the trance process with a return to baseline after hypnosis, with moderates showing significantly lower alpha power; and (e) an increase in delta power across conditions to PNR and then a decrease to post-hypnosis baseline, with moderates significantly lower than highs.

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Key Words: Clinical hypnosis, EEG, electroencephalograph, electrophysiology

Practitioners of clinical hypnosis have long observed often dramatic emotional, cognitive, behavioral, and physiological changes occurring during and as an apparent consequence of hypnotic trance (Bowers, 1976; Brown & Fromm, 1987; Gorton, 1949). These effects have been reported across virtually all physiological systems of the body and appear to have a profound impact upon emotional and physical functioning, albeit most dramatically for a specific subpopulation of individuals, that is, those highly responsive to hypnotic manipulations in general. These overtly observed consequences of hypnotic interventions have also been associated with more covert changes in brain physiology, as indexed by corresponding changes in regional cerebral blood flow, positron emission tomography, evoked potentials, and electroencephalography (EEG; Barabaszetal, 1999;Crawford & Gruzelier, 1992; DePascalis & Carboni, 1997; Gruzelier, 1988; Kosslyn, Thompson, Costantini-Ferrando, Alpert, & Spiegel, 2000; Meszaros & Banyai, 1978; Tebecis, Provins, Farnbach, & Pentony, 1975). However, the most commonly observed changes in cortical physiology during hypnosis have been observed through the medium of EEG.

Cortical neuroelectrical changes occurring during hypnotic trance states have been studied for over 40 years but only recently have rather reliable correlates of hypnotic trance been established, and this research literature remains in its early childhood. Because initial EEG studies had found the alpha bandwidth (8-12 Hz) associated with relaxation, biofeedback, and meditation-induced altered states, it was originally hypothesized that individuals in hypnotic trance would likewise show enhanced alpha production. Early results were contradictory, however, with some studies reporting enhanced right occipital or occipital-parietal alpha (Crawford, Meszaros, & Szabo, 1989; MacLeod-Morgan, 1982; Ulett, Akpinar, & Itil, 1972), others reporting diminished bilateral occipital alpha (Saletu, 1987), and still others reporting no alpha changes in frontal, parietal, or occipital derivations during hypnosis (Meszaros & Banyai, 1978; Tebecis, Provins, Farnbach, & Pentony, 1975). This research was further confused by similarly contradictory relationships obtained between alpha EEGs and hypnotic susceptibility (Crawford & Gruzelier, 1992; Perlini & Spanos, 1991). In a comprehensive critical review of the literature up to 1990, Perlini and Spanos (1991) found little support for an alpha-hypnotizability relationship, such serious methodological flaws in most of the hypnosis research as to render conclusions untenable, and no alpha differences between hypnotic and non-hypnotic conditions in the few well-designed and controlled studies. These inconsistent outcomes have most often been the result of technological, methodological, and participant differences common to these early studies.

With a more precise screening for level of hypnotic susceptibility, more consistent electrode derivations across studies, enhanced experimental controls, and vast improvements in measurement technology, a more consistently validated "signature" of hypnotic trance has begun to emerge however. And the more reliable characteristics of this signature have been theta EEG frequencies (4-8 Hz), with some recent research also reporting a high frequency gamma characteristic around 40 Hz. For example, Sabourin, Cutcomb, Crawford, and Pribram ( 1990), in a 6-site EEG study of 24 very high and very low susceptible participants, found increased mean theta power, and not alpha or beta power, during a 20-minute tape-recorded hypnotic induction and a 2-minute deepening for both highs and lows across frontal, central, and occipital derivations. Graffin, Ray, and Eundy (1995) obtained increased parietal and occipital theta and beta power and increased frontal, temporal, parietal, and occipital alpha power (although this observed increase in alpha power might have been due to an artifact of the induction process) during a 10-minute eyes-open, eyes-closed recorded relaxation induction in 27 very high and very low hypnotizable participants measuring across 8 EEG sites. Crawford, Clarke, and Kitner-Triola (1996), in an investigation of EEG correlates of self-generated happy and sad emotions during awake and hypnosis conditions in low and highly hypnotizable men, found greater parietal involvement in lows for high theta (5.5-7.45 Hz) during hypnosis. Crawford (1990) also reported increased theta power, particularly in temporal regions but also across all sites measured, in highs compared to lows during pain and hypnotic analgesia. And DePascalis, Ray, Tranquillo, and D'Amico (1998), measuring across 6 sites before and after an approximately 10-minute recorded hypnotic induction in 20 high and low hypnotically susceptible females, reported no significant changes in theta activity but a progressive increase in 40 Hz gamma activity for highly suggestible participants. DePascalis and colleagues (DePascalis, 1993; DePascalis, Marucci, & Penna, 1989; DePascalis & Penna, 1990) had previously found similar 40 Hz increments during hypnosis for very highly hypnotizable participants across multiple experimental contexts.

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Electrophysiological Alterations During Hypnosis for Ego-Enhancement: A Preliminary Investigation

American Journal of Clinical Hypnosis, Apr 2004 by Stevens, Larry, Brady, Brian, Goon, Angela, Adams, Deanna, Et al

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