SchizophreniaCreativityMedicinal Chemistry & Drug DevelopmentPsilocybin

Increased Activation of Indirect Semantic Associations under Psilocybin

This early double-blind, placebo-controlled study (1995, n=8) suggests that psilocybin increased indirect semantic priming. The authors add, however, that the setting alone led to a similar effect.

Authors

  • Spitzer, M.
  • Thimm, M.
  • Hermle, L.

Published

Biological Psychiatry
individual Study

Abstract

Hypothesized that psilocybin might exert a defocusing effect on semantic networks (i.e., decrease the signal-to-noise ratio), which should lead to an increased indirect semantic priming effect. A double-blind, placebo-controlled study was conducted on the effects of psilocybin on semantic and indirect semantic priming with 8 normal males (mean age 39.4 yrs). The finding that psilocybin increases indirect semantic priming in normal Ss adds to the general understanding of the effects of hallucinogenic agents on cognitive functions. Data indicate that indirect semantic priming is a highly sensitive measure that appears to respond not only to pharmacologic intervention, but also to the psychological effects of the setting.

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Research Summary of 'Increased Activation of Indirect Semantic Associations under Psilocybin'

Introduction

Semantic and indirect semantic priming in lexical decision tasks provide a measure of how activation spreads through semantic networks. Earlier work has shown that thought-disordered schizophrenia is associated with a faster and wider spread of activation, producing increased direct and indirect priming; this pattern has been interpreted as a reduced signal-to-noise ratio in cortical networks that process meaning. Dopaminergic modulation appears to focus semantic processing (increasing the signal-to-noise ratio and reducing spread), whereas psilocybin acts primarily on the serotonin (5-HT) system and is reported anecdotally to ‘‘broaden’’ conscious experience and enhance creativity, suggesting it might have the opposite, defocusing effect on semantic activation. Spitzer and colleagues therefore tested whether psilocybin increases the spread of activation as measured by indirect semantic priming. They conducted a double-blind, placebo-controlled experiment using a lexical decision paradigm to compare direct and indirect semantic priming under psilocybin versus placebo, as part of a larger project on the behavioural and pharmacokinetic effects of the drug.

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Study Details

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