This double-blind within-subject placebo-controlled study (n=21/drug-condition) investigated the effects of esketamine (38.6mg/70kg) and psilocybin (8.1mg/70kg) concerning brain activity during non-conscious and conscious emotional face processing. Results indicated that both substances impaired the early encoding of fearful face responses, while esketamine also impaired the encoding of happy facial expressions, and these measures were more pronounced during conscious than non-conscious processing.

Abstract of Ketamine & psilocybin produce dissociable effects on the structural encoding of emotional face expressions

“Rationale: Both glutamate and serotonin (5-HT) play a key role in the pathophysiology of emotional biases. Recent studies indicate that the glutamate N-methyl-D-aspartate (NMDA) receptor antagonist ketamine and the 5-HT receptor agonist psilocybin are implicated in emotion processing. However, as yet, no study has systematically compared their contribution to emotional biases.

Objectives: This study used event-related potentials (ERPs) and signal detection theory to compare the effects of the NMDA (via S-ketamine) and 5-HT (via psilocybin) receptor system on non-conscious or conscious emotional face processing biases.

Methods: S-ketamine or psilocybin was administrated to two groups of healthy subjects in a double-blind within-subject placebo-controlled design. We behaviorally assessed objective thresholds for non-conscious discrimination in all drug conditions. Electrophysiological responses to fearful, happy, and neutral faces were subsequently recorded with the face-specific P100 and N170 ERP.

Results: Both S-ketamine and psilocybin impaired the encoding of fearful faces as expressed by a reduced N170 over parieto-occipital brain regions. In contrast, while S-ketamine also impaired the encoding of happy facial expressions, psilocybin had no effect on the N170 in response to happy faces.

Conclusion: This study demonstrates that the NMDA and 5-HT receptor systems differentially contribute to the structural encoding of emotional face expressions as expressed by the N170. These findings suggest that the assessment of early visual evoked responses might allow detecting pharmacologically induced changes in emotional processing biases and thus provides a framework to study the pathophysiology of dysfunctional emotional biases.”

Authors: André Schmidt, Michael Kometer, Rosilla Bachmann, Erich Seifritz & Franz X. Vollenweider

Summary of Ketamine & psilocybin produce dissociable effects on the structural encoding of emotional face expressions

Emotional faces increase neuronal activity in specific brain areas, and this increased activity might correspond to a fundamental regulatory role of basic emotional signals associated with social appraisal and cognition.

Emotional face processing can be modulated by serotonin (5-hydroxytryptamine, 5-HT), and citalopram (an SSRI) may have a mechanism of action that shifts emotional biases in a manner opposite to the negative biases previously described in depression.

A functional imaging study in healthy subjects showed that the visual activity in response to fearful faces is abolished under the influence of the glutamate N-methyl-D-aspartate (NMDA) receptor antagonist ketamine.

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The NMDA antagonist ketamine and the 5-HT agonist psilocybin produce dissociable effects on structural encoding of emotional face expressions

https://doi.org/10.1007/s00213-012-2811-0

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Cite this paper (APA)

Schmidt, A., Kometer, M., Bachmann, R., Seifritz, E., & Vollenweider, F. (2013). The NMDA antagonist ketamine and the 5-HT agonist psilocybin produce dissociable effects on structural encoding of emotional face expressions. Psychopharmacology, 225, 227-239.

Study details

Compounds studied
Psilocybin Ketamine

Topics studied
Neuroscience

Study characteristics
Placebo-Controlled Double-Blind Within-Subject

Participants
42 Humans

Authors

Authors associated with this publication with profiles on Blossom

Franz Vollenweider
Franz X. Vollenweider is one of the pioneering psychedelics researchers, currently at the University of Zurich. He is also the director of the Heffter (sponsored) Research Center Zürich for Consciousness Studies (HRC-ZH).

Institutes

Institutes associated with this publication

University of Zurich
Within the Department of Psychiatry, Psychotherapy and Psychosomatics at the University of Zurich, Dr Mialn Scheidegger is leading team conducting psychedelic research and therapy development.