Effects of psilocybin on time perception and temporal control of behaviour in humans

¹ Generation Research Programme, Human Science Centre, Ludwig-Maximilian University Munich, Bad Tölz, Germany.
² Vision Touch and Hearing Centre, University of Queensland, Brisbane, Australia. Heffter Research Centre, University Hospital of Psychiatry, Zürich, Switzerland.
³ Heffter Research Centre, University Hospital of Psychiatry, Zürich, Switzerland.
⁴ Department of Neurosciences, University of California at San Diego, La Jolla, USA. Heffter Research Centre, University Hospital of Psychiatry, Zürich, Switzerland.
⁵ University Hospital of Psychiatry, Zürich, Switzerland.
⁶ Brain Research Institute, University of Bremen, Bremen, Germany.
⁷ Heffter Research Centre, University Hospital of Psychiatry, Zürich, Switzerland. University Hospital of Psychiatry, Zürich, Switzerland.

^* To whom correspondence should be addressed.

	Abstract

Hallucinogenic psilocybin is known to alter the subjective experience of time. However, there is no study that systematically investigated objective measures of time perception under psilocybin. Therefore, we studied dose-dependent effects of the serotonin (5-HT)_2A/1A receptor agonist psilocybin (4-phosphoryloxy-N,N-dimethyltryptamine) on temporal processing, employing tasks of temporal reproduction, sensorimotor synchronization and tapping tempo. To control for cognitive and subjective changes, we assessed spatial working memory and conscious experience. Twelve healthy human volunteers were tested under placebo, medium (115 µg/kg), and high (250 µg/kg) dose conditions, in a double-blind experimental design. Psilocybin was found to significantly impair subjects' ability to (1) reproduce interval durations longer than 2.5 sec, (2) to synchronize to inter-beat intervals longer than 2 sec and (3) caused subjects to be slower in their preferred tapping rate. These objective effects on timing performance were accompanied by working-memory deficits and subjective changes in conscious state, namely increased reports of 'depersonalization' and 'derealization' phenomena including disturbances in subjective 'time sense.' Our study is the first to systematically assess the impact of psilocybin on timing performance on standardized measures of temporal processing. Results indicate that the serotonin system is selectively involved in duration processing of intervals longer than 2 to 3 seconds and in the voluntary control of the speed of movement. We speculate that psilocybin's selective disruption of longer intervals is likely to be a product of interactions with cognitive dimensions of temporal processing - presumably via 5-HT2A receptor stimulation.

Key Words: psilocybin, 5-HT_2A receptor, temporal processing, sensorimotor synchronization, altered states of consciousness, working memory, human study

First published on May 19, 2006, doi:10.1177/0269881106065859

Journal of Psychopharmacology 2007;21:50.

A more recent version of this article appeared on January 1, 2007


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