Research article summary (published 30 Oct 2002):

Brain electrical activity and subjective experience during altered states of consciousness: ganzfeld and hypnagogic states.

Full Abstract

Manifestations of experimentally induced altered states of consciousness in the brain's electrical activity as well as in subjective experience were explored via the hypnagogic state at sleep onset, and the state induced by exposure to an unstructured perceptual field (ganzfeld). Twelve female paid volunteers participated in sessions involving sleep onset, ganzfeld, and eyes-closed relaxed waking, and were repeatedly prompted for recall of their momentary mentation, according to a predefined schedule. Nineteen channel EEG, two channels EOG and EMG were recorded simultaneously. The mentation reports were followed by the subjects' ratings of their experience on a number of ordinal scales. Two-hundred and forty-one mentation reports were collected. EEG epochs immediately preceding the mentation reports were FFT-analysed and the spectra compared between states. The ganzfeld EEG spectrum, showing no signs of decreased vigilance, was very similar to the EEG spectrum of waking states, even showed a minor acceleration of alpha activity. The subjective experience data were reduced to four principal components: Factor I represented the subjective vigilance dimension, as confirmed by correlations with EEG spectral indices. Only Factor IV, the 'absorption' dimension, differentiated between the ganzfeld state (more absorption) and other states. In waking states and in ganzfeld, the subjects estimated elapsed time periods significantly shorter than in states at sleep onset. The results did not support the assumption of a hypnagogic nature of the ganzfeld imagery. Dream-like imagery can occur in various global functional states of the brain; hypnagogic and ganzfeld-induced states should be conceived as special cases of a broader class of 'hypnagoid' phenomena.

Author information

Author/s: Wackermann, Jiri (J); Pütz, Peter (P); Büchi, Simone (S); Strauch, Inge (I); Lehmann, Dietrich (D);

Affiliation: Department of Empirical and Analytical Psychophysics, Institute for Frontier Areas of Psychology, i Br, Freiburg, Germany. jw(-atsign-)igpp.de

Journal and publication information

Publication Type: Comparative Study; Journal Article

Journal: International journal of psychophysiology : official journal of the International Organization of Psychophysiology (Int J Psychophysiol), published in Netherlands. (Language: eng)

Reference: 2002-Nov; vol 46 (issue 2) : pp 123-46

Dates: Created 2002/11/15; Completed 2003/02/07; Revised 2006/11/15;

PMID: 12433389, status: MEDLINE (last retrieval date: 2/18/2009, IMS Date: )

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Adult Analysis of Variance Brain - physiology Electroencephalography Electromyography Electrooculography Evoked Potentials - physiology Female

Female Humans Perception Relaxation - physiology Sleep Stages - physiology Time Factors Visual Fields - physiology Wakefulness - physiology

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