The multimodal Ganzfeld-induced altered state of consciousness induces decreased thalamo-cortical coupling

Abstract

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.

Altered states phenomena induced by visual flicker light stimulation

“…Overall, findings are in accordance with Zakay and Block [74], as well as a metaanalytic review of Block et al [75], proposing an attentional allocation to the prospective time estimation task to result in higher time estimations. Furthermore, our results are consistent with those of former studies in which participants reported a faster passage of time during multimodal Ganzfeld-induced states [15,76], which were shown to be characterized by a similar vigilance reduction to the study at hand [15,54].…”

“…In line with our data, participants gave comparably low ratings for experiences of ego dissolution or mystical-type experiences. To directly compare the obtained 11-ASC ratings for FLS with ratings reported in studies where other methods were applied to induce ASCs, we provide a descriptive comparison in Fig 4 . As a comparison with other non-pharmacological methods, we included ratings obtained for multimodal Ganzfeld exposure, comprising visual homogenous light stimulation and auditory stimulation [15,54]. Comparable ratings were reported for the 5D-ASC/11-ASC dimensions Visionary Restructuralization, indicative of perceptual and imaginational alterations (M Ganzfeld = 14.03 ± SD = 12.67), as well as Vigilance Reduction, reflecting sleepiness or drowsiness (M Ganzfeld = 27.12 ± SD = 15.78), and Complex Imagery, indicating the experience of concrete visual impressions of scenes or pictures like e.g., faces (M Ganzfeld = 22.36 ± SD = 20.09) [15].…”

Bridging the Gap? Altered Thalamocortical Connectivity in Psychotic and Psychedelic States

“…but even those that are present, are markedly reduced in comparison to the psychedelicinduced effects (118). Furthermore, the perceptual changes following perceptual deprivation techniques have not yet been associated with altered thalamocortical connectivity (in contrast to psychedelic-induced effects) and might rather reflect an imbalance between typical top-down signaling and atypical (i.e., unstructured) bottom-up input (117).…”

Altered states of Ganzfeld: A systematic review

“…Prolonged exposure to the Ganzfeld experiment induces altered states of consciousness resulting from sensory deprivation (Ben-Soussan et al, 2019;Glicksohn et al, 2019;Kübel et al, 2020;Pütz et al, 2006;Schmidt & Prein, 2019;Schmidt et al, 2020;Wackermann et al, 2008). Research shows that dissociative imagery (Ben-Soussan et al, 2019;Miskovic et al, 2019), hallucination-like symptoms (Rogers et al, 2020;Voges et al, 2015;Wackermann et al, 2008), and thalamocortical decoupling that provokes alpha band brainwaves (Schmidt et al, 2020;Sumich et al, 2018) are common characteristics of Ganzfeld. However, the relationship between mental imagery and the frequency of hallucinations remains unclear (Sumich et al, 2018).…”

“…This review further explores Ganzfeld because the development of visual imagery can be a powerful tool for exposing underlying mechanisms within the visual environment (Yu et al, 2015). In the apparatus, red light is reportedly emitted on the cavities of Ping-Pong balls over the eyes to facilitate immersion (Kübel et al, 2020;Miskovic et al, 2019;Pütz et al, Altered states of Ganzfeld: A systematic review 2 2006; Schmidt & Prein, 2019;Schmidt et al, 2020;Wackermann et al, 2002). The static sound of a waterfall (Pütz et al, 2006;Wackermann et al, 2002), pink noise (Miskovic et al, 2019), or a related frequency (white/violet/brown noise; Schmidt & Prein, 2019) played through headphones may be used in combination to achieve sensory deprivation.…”