EEG Microstates in Altered States of Consciousness

Conscious experience feels continuous but actually consists of brief, discrete brain states lasting 60–120 milliseconds, called EEG microstates. These stable scalp electric field patterns, measured with high temporal resolution, may represent the basic building blocks of thought. Altered states of consciousness—including sleep, anesthesia, meditation, and psychiatric conditions—change the dynamics of these microstates. This perspective argues that studying EEG microstates can reveal underlying features of self-consciousness, summarizing recent findings on microstate alterations during mind-wandering, meditation, sleep, and anesthesia.

Study at a glance

Abstract

Conscious experiences unify distinct phenomenological experiences that seem to be continuously evolving. Yet, empirical evidence shows that conscious mental activity is discontinuous and can be parsed into a series of states of thoughts that manifest as discrete spatiotemporal patterns of global neuronal activity lasting for fractions of seconds. EEG measures the brain’s electrical activity with high temporal resolution on the scale of milliseconds and, therefore, might be used to investigate the fast spatiotemporal structure of conscious mental states. Such analyses revealed that the global scalp electric fields during spontaneous mental activity are parceled into blocks of stable topographies that last around 60–120 ms, the so-called EEG microstates. These brain states may be representing the basic building blocks of consciousness, the “atoms of thought.” Altered states of consciousness, such as sleep, anesthesia, meditation, or psychiatric diseases, influence the spatiotemporal dynamics of microstates. In this brief perspective, we suggest that it is possible to examine the underlying characteristics of self-consciousness using this EEG microstates approach. Specifically, we will summarize recent results on EEG microstate alterations in mind-wandering, meditation, sleep and anesthesia, and discuss the functional significance of microstates in altered states of consciousness.