On the state-nonstate theory of hypnosis: network and topological EEG findings.

Hypnosis is a state of consciousness spontaneously occurring or induced through various techniques. Its occurrence is more likely in individuals with high scores of hypnotizability (highs) than in low hypnotizables (lows). The study aimed to assess the topological homogeneity within highs and lows during neutral hypnosis, and the EEG topological characteristics of highs and lows before and after hypnotic induction experienced as an altered state of consciousness only by highs. Sixteen highs and 16 lows were enrolled, informed that they would be submitted to hypnotic induction and studied across a session including open and closed eyes waking rest, hypnotic induction, neutral hypnosis, and post hypnosis open eyes rest. EEG was monitored throughout the session. Network analysis showed greater identifiability (less homogeneity) among lows than among highs. It revealed a similar pattern of changes in functional connectivity and topological properties-homological persistence and persistent entropy, which describe multiscale integration patterns-in the two groups across the session. Findings suggest that neutral hypnosis represents a modulation of the ordinary consciousness within its physiological variability rather than a distinct physiological state. Neither network nor topological differences account for the different subjective experiences of highs and lows.