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Modeling an auditory stimulated brain under altered states of consciousness using the generalized Ising model

Sivayini Kandeepan, Jorge Rudas, Francisco Gómez, Bobby Stojanoski, Andrea Soddu

Neuroimage September 12, 2020 DOI: 10.1016/j.neuroimage.2020.117367 (opens in new tab)

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Study at a glance

AI-extracted from the abstract
Characteristics Experimental study with repeated measures across consciousness states Peer reviewed
Population Healthy subjects
Intervention Propofol
Topics Altered states of consciousness
Key findings The generalized Ising model, modified to incorporate naturalistic external stimuli, successfully fitted empirical task fMRI data across awake, mild sedation, deep sedation, and recovery states.

Abstract

Propofol is a short-acting medication that results in decreased levels of consciousness and is used for general anesthesia. Although it is the most commonly used anesthetic in the world, much remains unknown about the mechanisms by which it induces a loss of consciousness. Characterizing anesthesia-induced alterations to brain network activity might provide a powerful framework for understanding the neural mechanisms of unconsciousness. The aim of this work was to model brain activity in healthy brains during various stages of consciousness, as induced by propofol, in the auditory paradigm. We used the generalized Ising model (GIM) to fit the empirical fMRI data of healthy subjects while they listened to an audio clip from a movie. The external stimulus (audio clip) is believed to be at least partially driving a synchronization process of the brain activity and provides a similar conscious experience in different subjects. In order to observe the common synchronization among the subjects, a novel technique called the inter subject correlation (ISC) was implemented. We showed that the GIM-modified to incorporate the naturalistic external field-was able to fit the empirical task fMRI data in the awake state, in mild sedation, in deep sedation, and in recovery, at a temperature T* which is well above the critical temperature. To our knowledge this is the first study that captures human brain activity in response to real-life external stimuli at different levels of conscious awareness using mathematical modeling. This study might be helpful in future to assess the level of consciousness of patients with disorders of consciousness and help in regaining their consciousness.

Comparable studies

Other experimental studies on altered states of consciousness, most cited first.

Study Year Design Participants
The Standardized Psychometric Assessment of Altered States of Consciousness (ASCs) in Humans Healthy subjects in six countries 1998 Experimental and field study n = 1,133
TMS-EEG and resting-state EEG applied to altered states of consciousness: oscillations, complexity, and phenomenology. 2023 Experimental study
A Test of the Psychedelic Model of Altered States of Consciousness 1976 Experimental study with comparison groups
Neural Correlates of Non-ordinary States of Consciousness in Pranayama Practitioners: The Role of Slow Nasal Breathing Experienced meditators 2022 Within-subjects comparison n = 12
Increased spontaneous EEG signal diversity during stroboscopically-induced altered states of consciousness Healthy adults 2019 Experimental study

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Altered states of consciousness Philosophy of mind