1. Dear Drugs-Forum readers: We are a small non-profit that runs one of the most read drug information & addiction help websites in the world. We serve over 4 million readers per month, and have costs like all popular websites: servers, hosting, licenses and software. To protect our independence we do not run ads. We take no government funds. We run on donations which average $25. If everyone reading this would donate $5 then this fund raiser would be done in an hour. If Drugs-Forum is useful to you, take one minute to keep it online another year by donating whatever you can today. Donations are currently not sufficient to pay our bills and keep the site up. Your help is most welcome. Thank you.

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

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

  1. Metomni
    Psychopharmacology (Berl). (http://javascript:AL_get(this, 'jour', 'Psychopharmacology (Berl).');) 2007 Dec;195(3):415-24. Epub 2007 Sep 14

    Carter OL (http://www.ncbi.nlm.nih.gov/sites/e...bmed_ResultsPanel.Pubmed_RVAbstractPlusDrugs1), Hasler F (http://www.ncbi.nlm.nih.gov/sites/e...bmed_ResultsPanel.Pubmed_RVAbstractPlusDrugs1), Pettigrew JD (http://www.ncbi.nlm.nih.gov/sites/e...bmed_ResultsPanel.Pubmed_RVAbstractPlusDrugs1), Wallis GM (http://www.ncbi.nlm.nih.gov/sites/e...bmed_ResultsPanel.Pubmed_RVAbstractPlusDrugs1), Liu GB (http://www.ncbi.nlm.nih.gov/sites/e...bmed_ResultsPanel.Pubmed_RVAbstractPlusDrugs1), Vollenweider FX (http://www.ncbi.nlm.nih.gov/sites/e...bmed_ResultsPanel.Pubmed_RVAbstractPlusDrugs1)

    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 microg/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.

    Discussion Thread