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- Title
Modulating the Rate and Rhythmicity of Perceptual Rivalry Alternations with the Mixed 5-HT<sub>2A</sub> and 5-HT<sub>1A</sub> Agonist Psilocybin.
- Authors
Carter, Olivia L.; Pettigrew, John D.; Hasler, Felix; Wallus, Guy M.; Liu, Guang B.; Hell, Daniel; Vollenweider, Franz X.
- Abstract
Binocular rivalry occurs when different images are presented simultaneously to corresponding points within the left and right eyes. Under these conditions, the observer's perception will alternate between the two perceptual alternatives. Motivated by the reported link between the rate of perceptual alternations, symptoms of psychosis and an incidental observation that the rhythmicity of perceptual alternations during binocular rivalry was greatly increased 10 h after the consumption of LSD, this study aimed to investigate the pharmacology underlying binocular rivalry and to explore the connection between the timing of perceptual switching and psychosis. Psilocybin (4-phosphoryloxy-N,N-dimethyltryptamine, PY) was chosen for the study because, like LSD, it is known to act as an agonist at serotonin (5-HT) PA and 5-HT2A receptors and to produce an altered state sometimes marked by psychosis-like symptoms. A total of 12 healthy human volunteers were tested under placebo, low-dose (115 µg/kg) and high-dose (250 µg/kg) PY conditions. In line with predictions, under both low- and high-dose conditions, the results show that at 90 mm postadministration (the peak of drug action), rate and rhythmicity of perceptual alternations were significantly reduced from placebo levels. Following the 90 mm testing period, the perceptual switch rate successively increased, with some individuals showing increases well beyond pretest levels at the final testing, 360 mm postadministration. However, as some subjects had still not returned to pretest levels by this time, the mean phase duration at 360 mm was not found to differ significantly from placebo. Reflecting the drug-induced changes in rivalry phase durations, subjects showed clear changes in psychological state as indexed by the 5D-ASC (altered states of consciousness) rating scales. This study suggests the involvement of serotonergic pathways in binocular rivalry and supports the previously proposed role of a brainstem oscillator in perceptual rivalry alternations and symptoms of psychosis.
- Publication
Neuropsychopharmacology, 2005, Vol 30, Issue 6, p1154
- ISSN
0893-133X
- Publication type
Academic Journal
- DOI
10.1038/sj.npp.1300621