EEG Microstates in Altered States of Consciousness

Summary

Our seemingly continuous conscious experience is actually a rapid succession of discrete "atoms of thought." Electroencephalography (EEG) in Neuroscience reveals these fundamental units, called microstates, as stable patterns of neural dynamics lasting merely 60-120 milliseconds. This insight from Cognitive psychology suggests consciousness isn't a fluid stream but a rapid succession of distinct mental states. Altered states of consciousness, including mind wandering and attention, significantly impact these functional brain connectivity patterns. Cognitive science uses this approach to explore the very nature of consciousness.

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.

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