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In recent years, there has been a renewed interest in the conceptual and empirical study of altered states of consciousness (ASCs) induced pharmacologically or otherwise, driven by their potential clinical applications. To draw attention to the rich history of research in this domain, we review prominent classification schemes that have been proposed to introduce systematicity in the scientific study of ASCs. The reviewed ASC classification schemes fall into three groups according to the criteria they use for categorization: (1) based on the nature, variety, and intensity of subjective experiences (state-based), including conceptual descriptions and psychometric assessments, (2) based on the technique of induction (method-based), and (3) descriptions of neurophysiological mechanisms of ASCs (neuro/physio-based). By comparing and extending existing classification schemes, we can enhance efforts to identify neural correlates of consciousness, particularly when examining mechanisms of ASC induction and the resulting subjective experience. Furthermore, an overview of what defining ASC characteristics different authors have proposed can inform future research in the conceptualization and quantification of ASC subjective effects, including the identification of those that might be relevant in clinical research. This review concludes by clustering the concepts from the state-based schemes, which are suggested for classifying ASC experiences. The resulting clusters can inspire future approaches to formulate and quantify the core phenomenology of ASC experiences to assist in basic and clinical research.
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It is increasingly recognized that cognitive control requires integration across large-scale brain networks anchored in frontal and parietal cortices. While the functional role of individual networks has been studied extensively, their cross-network interactions in the service of cognitive control are poorly understood. Beyond in-the-moment regulation of goal-relevant information processing (e.g., of sensory information), cognitive control encompasses preparatory processes in anticipation of upcoming stimuli and actions. Such preparatory control is often endogenous, that is, it is based on internal representations without relying on external cues or events. Here, we assessed network interactions that support such endogenously driven preparatory control. We recorded fMRI (N = 25) during a perceptual decision task with highly variable intertrial intervals. In half of the blocks, trial onset was cued, while in the remaining blocks, participants maintained readiness without relying on cues. We studied endogenous preparatory control in the intertrial period preceding uncued (vs. cued) trials. Behavioral outcomes confirmed heavier cognitive control demands in the uncued condition. Endogenous preparatory control was associated with increased activity of the dorsal attention network (DAN). This contrasted with in-the-moment control over stimulus-response processing during the trial itself, which was supported foremost by the right-hemispheric fronto-parietal network (FPN). Cross-network interactions were strengthened exclusively during endogenous preparatory control; the default mode network (DMN) showed more positive connectivity with the DAN and to a lesser degree the cingulo-opercular network (CON). Our results demonstrate that cross-networks interactions are particularly important for endogenously driven preparatory control. They further suggest that the DMN may be implicated in internally harnessing resources for cognitive control. This notion extends the DMN’s known role in internally-oriented processing to the domain of cognitive control when preparation cannot be aided by external events.
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Team
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Sprache
- Englisch (3)
Thema
- altered states of consciousness (1)
- classification (1)
- phenomenology (1)
- psychedelics (1)