Different pharmacologic agents have been used to investigate the neuronal underpinnings of alterations in consciousness states, such as psychedelic substances. Special attention has been drawn to the role of thalamic filtering of cortical input. Here, we investigate the neuronal mechanisms underlying an altered state of consciousness (ASC) induced by a non-pharmacological procedure. During fMRI scanning, N = 19 human participants were exposed to multimodal Ganzfeld stimulation, a technique of perceptual deprivation where participants are exposed to intense, unstructured, homogenous visual and auditory stimulation. Compared to pre- and post-resting-state scans, the Ganzfeld data displayed a progressive decoupling of the thalamus from the cortex. Furthermore, the Ganzfeld-induced ASC was characterized by increased eigenvector centrality in core regions of the default mode network (DMN). Together, these findings can be interpreted as an imbalance of sensory bottom-up signaling and internally-generated top-down signaling. This imbalance is antithetical to psychedelic-induced ASCs, where increased thalamo-cortical coupling and reduced DMN activity were observed.

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Although sexual intrusive thoughts (SITs) are often studied in combination with other intrusions, little is known about the metacognitive processes that are specific to SITs. The present study evaluated sexual versus non-SIT frequency in relation to two main factors: gender and general negative beliefs (GNB), a component of metacognition involving beliefs about the consequences of failing to control thoughts. A nonclinical sample of 286 undergraduate students completed the Revised Obsessional Intrusions Inventory-Sex Version and the Meta-Cognitions Questionnaire. Results indicated main effects for GNB and a significant interaction between gender and GNB for SITs. More specifically, frequency of SITs was significantly higher for males, as well as for participants with higher GNB. In contrast, analyses for non-SITs revealed a main effect for GNB, but no main effects for gender or a significant interaction. These findings suggest a link between high GNB and increased SIT and non-SIT frequency. Moreover, gender may function as a moderator between GNB and SIT frequency. Further characterizing the effects of gender and GNB may help in form treatments for disorders involving clinically significant SITs.

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