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

Carter, Olivia L. and Hasler, Felix and Pettigrew, John D. and Wallis, Guy M. and Liu, Guang B. and Vollenweider, Franz X. (2007) Psilocybin links binocular rivalry switch rate to attention and subjective arousal levels in humans. Psychopharmacology, 195 (3). pp. 415-424. ISSN 0033-3158


[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-HT2A 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-HT2A receptor. The effects of psilocybin (215 μg/kg) were considered alone and after pretreatment with the selective 5-HT2A 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-HT2A receptor.

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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Deposited in accordance with the copyright policy of the publisher. The original publication is available at
Faculty / Department / School: Historic - Faculty of Sciences - Department of Biological and Physical Sciences
Date Deposited: 02 Nov 2007 00:52
Last Modified: 02 Jul 2013 22:50
Uncontrolled Keywords: psilocybin; binocular; ketanserin; mushroom; 5-HT2A
Fields of Research : 11 Medical and Health Sciences > 1115 Pharmacology and Pharmaceutical Sciences > 111504 Pharmaceutical Sciences
11 Medical and Health Sciences > 1113 Ophthalmology and Optometry > 111303 Vision Science
11 Medical and Health Sciences > 1117 Public Health and Health Services > 111714 Mental Health
Socio-Economic Objective: E Expanding Knowledge > 97 Expanding Knowledge > 970111 Expanding Knowledge in the Medical and Health Sciences
Identification Number or DOI: 10.1007/s00213-007-0930-9

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