Naturalistic use of psychedelics does not modulate processing of self-related stimuli (but it might modulate attentional mechanisms): An event-related potentials study.

Regular naturalistic use of classic psychedelics does not appear to alter long-term neural representations of the self, but it may affect how attentional resources are allocated to task-relevant stimuli. In a cross-sectional study comparing 56 experienced psychedelics users (15 or more lifetime uses) with 57 nonusers, no difference was found in the P300 brain response to hearing one's own name, a stimulus that robustly activates self-representation. However, psychedelics users showed a larger P300 response to other people's names and a smaller increase in P300 amplitude when processing task-relevant target names compared to nonusers. These results suggest that while self-representation remains unchanged, regular psychedelic use might subtly shift attentional processing.

Study at a glance

Abstract

Classic psychedelics are able to profoundly alter the state of consciousness and lead to acute experiences of ego dissolution - the blurring of the distinction between representations of self and the external world. However, whether repeated use of psychedelics is associated with more prolonged and permanent modifications to the concept of self remains to be investigated. Therefore, we conducted a preregistered, cross-sectional study in which experienced psychedelics users (15 or more lifetime experiences with psychedelics; N = 56) were compared to nonusers (N = 57) in terms of neural reactivity to a Self-name (i.e., each participant's own name) stimulus, which is known to robustly activate a representation of self. Two control stimuli were additionally used: an Other-name stimulus, as a passive control condition in which no reaction was required, and a Target-name stimulus, to which participants provided a manual response and which thus constituted an active control condition. Analysis of the amplitude of the P300 ERP component evoked by the Self- or Target-names revealed no difference between the psychedelics users and nonusers. However, psychedelic users exhibited increased P300 amplitude during perception of Other-names. In addition, in comparison to nonusers, psychedelics users exhibited a smaller increase in P300 amplitude when processing the task-relevant Target-names (in relation to both Self- and Other-names). Therefore, our data suggests that regular naturalistic use of psychedelics may not be related to long-term changes in the representation of self, but it might potentially affect the allocation of attentional resources to task-relevant stimuli.