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

doi:10.1016/j.heliyon.2021.e06871

No evidence for theta power as a marker of hypnotic state in highly hypnotizable subjects

Heliyon. 2021 Apr 29;7(4):e06871. doi: 10.1016/j.heliyon.2021.e06871. eCollection 2021 Apr.

Authors

Seppo Hiltunen^{1

2}, Maria Karevaara², Maarit Virta², Tommi Makkonen^{2

3}, Sakari Kallio^{4

5}, Petri Paavilainen^{2

3}

Affiliations

¹ Teaching and Learning Services, University Services, University of Helsinki, Finland.
² Department of Psychology and Logopedics, Faculty of Medicine, University of Helsinki, Finland.
³ Cognitive Brain Research Unit, Department of Psychology and Logopedics, University of Helsinki, Finland.
⁴ Department of Cognitive Neuroscience and Philosophy, School of Bioscience, University of Skövde, Sweden.
⁵ Centre for Cognitive Neuroscience, University of Turku, Finland.

Abstract

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.

Keywords: Brain oscillations; EEG; Hypnosis; Hypnotic suggestion; Spectral-power density.