Psilocybin links binocular rivalry switch rate to attention and subjective arousal levels in humans

Abstract

Rationale Binocular rivalry occurs when different images are simultaneously presented to each eye. During continual viewing of this stimulus, the observer will experience repeated switches between visual awareness of the two images. Previous studies have suggested that a slow rate of perceptual switching may be associated with clinical and drug-induced psychosis.Objectives The objective of the study was to explore the proposed relationship between binocular rivalry switch rate and subjective changes in psychological state associated with 5-HT 2A receptor activation. Materials and methods This study used psilocybin, the hallucinogen found naturally in Psilocybe mushrooms that had previously been found to induce psychosis-like symptoms via the 5-HT 2A receptor. The effects of psilocybin (215 μg/kg) were considered alone and after pretreatment with the selective 5-HT 2A antagonist ketanserin (50 mg) in ten healthy human subjects. Results Psilocybin significantly reduced the rate of binocular rivalry switching and increased the proportion of transitional/mixed percept experience. Pretreatment with ketanserin blocked the majority of psilocybin's "positive" psychosis-like hallucinogenic symptoms. However, ketanserin had no influence on either the psilocybin-induced slowing of binocular rivalry or the drug's "negative-type symptoms" associated with reduced arousal and vigilance. Conclusions Together, these findings link changes in binocular rivalry switching rate to subjective levels of arousal and attention. In addition, it suggests that psilocybin's effect on binocular rivalry is unlikely to be mediated by the 5-HT 2A receptor.

Psychedelics

“…Psilocybin dose-dependently increased binocular rivalry phase duration in a manner reflecting subjective changes in state of consciousness, as assessed with the 5D-ASC rating scale developed by Dittrich (1998). Carter et al (2007) explored the proposed relationship between binocular rivalry switch rate and subjective changes in psychologic state associated with 5-HT 2A receptor activation. Ten healthy human subjects were tested after administration of psilocybin (215 mg/kg) and after pretreatment with the selective 5-HT 2A antagonist ketanserin (50 mg).…”

Pupil dilation reflects perceptual selection and predicts subsequent stability in perceptual rivalry

“…Small individual differences in the LC-NE system would explain the fact that individual variation in perceptual switch rates are consistent across different rivalry types (23,24), whereas the distributed release of NE would account for instances of perceptual entrainment arising when multiple ambiguous stimuli are temporally interleaved (25). Given that the LC-NE system is believed to be primarily involved in behavioral orienting (14) and cognitive engagement (13,26), this model can also account for results from a variety of recent studies demonstrating clear links between the selection of dominance during rivalry and the mechanisms driving switches in attentional focus (9,(27)(28)(29)(30). Even Levelt's paradoxical observation that increases in the salience of one rivalry target will lead to an increase in its overall predominance, through reduced suppression durations rather than prolonged dominance durations, can be explained by the fact that NE can lead to increases in responsiveness to subthreshold (nondominant) stimuli, without a corresponding increase in responsiveness to suprathreshold (dominant) stimuli (20).…”

Quantum formalism to describe binocular rivalry

“…Therefore, we conclude that, within the context of our model, the hallucinogenic drug changes the burst frequency and the char-acteristic period T significantly, which places the observing conscious apparatus into a regime where oscillations are transparent. More recent studies on the influence of hallucinogenic drugs (Carter et al, 2007(Carter et al, , 2005 indicate that it might be in the "rebound-phase" (a phase reached several hours after the peak of the drug influence) that a state of the type indicated in Fig. 5 and in Ref.…”