Journal of Cognitive Neuroscience
October 1, 2005
Olivia Carter, David C. Burr, John D. Pettigrew et al.
236 citations
A hallucinogenic drug that activates serotonin receptors, psilocybin, impaired healthy volunteers' ability to track moving objects but did not affect their spatial working memory. Blocking the 5-HT2A receptor with ketanserin before psilocybin did not prevent this attentional deficit, pointing to the 5-HT1A receptor as the likely cause. The authors suggest the impairment may stem from a reduced ability to filter out distractions rather than a loss of attentional capacity. Eight participants completed both tasks under placebo, psilocybin, ketanserin, and the combination.
Psychopharmacology
September 13, 2007
Olivia Carter, Felix Hasler, John D. Pettigrew et al.
150 citations
Binocular rivalry, where each eye sees a different image and perception alternates between them, was slowed by psilocybin (215 µg/kg) in ten healthy adults. Pretreatment with ketanserin (50 mg), a 5-HT2A receptor blocker, prevented most of psilocybin's hallucinogenic symptoms but did not reverse the slowing of rivalry switching or the drug's negative-type symptoms such as reduced arousal and vigilance. These findings link slower binocular rivalry switching to subjective levels of arousal and attention, and suggest that psilocybin's effect on rivalry is not mediated by the 5-HT2A receptor.
Neuropsychopharmacology
January 26, 2005
Olivia Carter, John D. Pettigrew, Felix Hasler et al.
122 citations
Binocular rivalry, where each eye sees a different image and perception alternates between them, is influenced by psilocybin. In 12 healthy volunteers, both low (115 µg/kg) and high (250 µg/kg) doses of psilocybin significantly reduced the rate and rhythmicity of perceptual alternations 90 minutes after administration, compared to placebo. Over time, switch rates increased, with some exceeding pretest levels at 360 minutes, though mean phase duration did not significantly differ from placebo. Drug-induced changes in rivalry phase durations corresponded to altered states of consciousness measured by the 5D-ASC scale. The findings implicate serotonergic pathways and support a brainstem oscillator's role in perceptual rivalry and psychosis symptoms.
Journal of Vision
March 19, 2010
O. Carter, John D. Pettigrew, Felix Hasler et al.
3 citations
Binocular rivalry, the fluctuation in visual awareness when different images are shown to each eye, is slowed by the hallucinogenic compound psilocybin, the active ingredient in magic mushrooms. In ten healthy human subjects, psilocybin reduced the rate of switching between percepts and increased the experience of mixed or transitional percepts. Pretreatment with ketanserin, a selective 5-HT2A receptor antagonist, blocked most of psilocybin's positive psychotic-like symptoms but did not affect the slowing of binocular rivalry switching or negative symptoms related to reduced arousal and vigilance. This suggests that the slowing of binocular rivalry by psilocybin is not mediated by 5-HT2A receptors but may instead involve 5-HT1A receptor activation reducing serotonin release from the brainstem raphe nuclei, linking rivalry switching rate to arousal and attention.