No evidence for theta power as a marker of hypnotic state in highly hypnotizable subjects
Seppo Hiltunen,
Maria Karevaara,
Maarit Virta,
Tommi Makkonen,
Sakari Kallio,
Petri Paavilainen
Affiliations
Seppo Hiltunen
Teaching and Learning Services, University Services, University of Helsinki, Finland; Department of Psychology and Logopedics, Faculty of Medicine, University of Helsinki, Finland; Corresponding author.
Maria Karevaara
Department of Psychology and Logopedics, Faculty of Medicine, University of Helsinki, Finland
Maarit Virta
Department of Psychology and Logopedics, Faculty of Medicine, University of Helsinki, Finland
Tommi Makkonen
Department of Psychology and Logopedics, Faculty of Medicine, University of Helsinki, Finland; Cognitive Brain Research Unit, Department of Psychology and Logopedics, University of Helsinki, Finland
Sakari Kallio
Department of Cognitive Neuroscience and Philosophy, School of Bioscience, University of Skövde, Sweden; Centre for Cognitive Neuroscience, University of Turku, Finland
Petri Paavilainen
Department of Psychology and Logopedics, Faculty of Medicine, University of Helsinki, Finland; Cognitive Brain Research Unit, Department of Psychology and Logopedics, University of Helsinki, Finland
EEG spectral-power density was analyzed in a group of nine highly hypnotizable subjects via ten frontal, central, parietal, and occipital electrodes under four conditions: 1) wake state, 2) neutral hypnosis, 3) hypnotic suggestion for altering perception of tones, and 4) post-hypnosis. Results indicate no theta-power changes between conditions, challenging previous findings that increased theta power is a marker of hypnosis. A decrease in gamma power under hypnotic suggestion and an almost significant decrease under neutral hypnosis were observed, compared to post-hypnosis. Anteroposterior power distribution remained stable over all conditions. The results are discussed and compared to earlier studies, which report heterogenous findings.
