Primary states of consciousness: A review of historical and contemporary developments.

Primary states of consciousness are phylogenetically older than secondary states, which are shaped by sociocultural inhibition. The authors review the concept's history in psychiatry and neurobiology and propose that primary states involve a temporary breakdown of self-control, merging action, communication, and emotion (ACE fusion) that are normally separate in adults. This model relates to neural dedifferentiation, loss of modularity during altered states, and increased corticostriatal connectivity. The article offers a perspective on consciousness as a mechanism of differentiation and control, suggests a gradient from primary to secondary states based on thalamocortical interactions and arousal, and proposes testable hypotheses for their distinct signatures.

Study at a glance

Abstract

Primary states of consciousness are conceived as phylogenetically older states of consciousness as compared to secondary states governed by sociocultural inhibition. The historical development of the concept in psychiatry and neurobiology is reviewed, along with its relationship to theories of consciousness. We suggest that primary states of consciousness are characterized by a temporary breakdown of self-control accompanied by a merging of action, communication, and emotion (ACE fusion), ordinarily segregated in human adults. We examine the neurobiologic basis of this model, including its relation to the phenomenon of neural dedifferentiation, the loss of modularity during altered states of consciousness, and increased corticostriatal connectivity. By shedding light on the importance of primary states of consciousness, this article provides a novel perspective on the role of consciousness as a mechanism of differentiation and control. We discuss potential differentiators underlying a gradient from primary to secondary state of consciousness, suggesting changes in thalamocortical interactions and arousal function. We also propose a set of testable, neurobiologically plausible working hypotheses to account for their distinct phenomenological and neural signatures.