Spatiotemporal Brain Dynamics of Emotional Face Processing Modulations Induced by the Serotonin 1A/2A Receptor Agonist Psilocybin

Abstract

Emotional face processing is critically modulated by the serotonergic system. For instance, emotional face processing is impaired by acute psilocybin administration, a serotonin (5-HT) 1A and 2A receptor agonist. However, the spatiotemporal brain mechanisms underlying these modulations are poorly understood. Here, we investigated the spatiotemporal brain dynamics underlying psilocybin-induced modulations during emotional face processing. Electrical neuroimaging analyses were applied to visual evoked potentials in response to emotional faces, following psilocybin and placebo administration. Our results indicate a first time period of strength (i.e., Global Field Power) modulation over the 168-189 ms poststimulus interval, induced by psilocybin. A second time period of strength modulation was identified over the 211-242 ms poststimulus interval. Source estimations over these 2 time periods further revealed decreased activity in response to both neutral and fearful faces within limbic areas, including amygdala and parahippocampal gyrus, and the right temporal cortex over the 168-189 ms interval, and reduced activity in response to happy faces within limbic and right temporo-occipital brain areas over the 211-242 ms interval. Our results indicate a selective and temporally dissociable effect of psilocybin on the neuronal correlates of emotional face processing, consistent with a modulation of the top-down control.

Psychedelics

“…In a subsequent study, Bernasconi et al (2014) carried out electrical neuroimaging analyses on visual evoked potentials in response to facial expressions (fearful, happy, and neutral) under placebo and psilocybin treatment. The aim of the study was to identify neurophysiological modulation induced by psilocybin to emotional face processing.…”

Face and emotion expression processing and the serotonin transporter polymorphism 5‐HTTLPR/rs22531

“…Further evidence for the importance of the serotonin metabolism for face cognition abilities has been provided by neuro‐pharmacological studies. Participants under the influence of a 5‐HTT agonist showed a modulated ERP in the inferior temporal cortex, 170 milliseconds after stimuli onset while viewing emotional faces (Bernasconi et al ; Schmidt et al ). This ERP component, known as the N170, is thought to be elicited by structural encoding of facial features – a general step in the processing of faces, independent of the emotional information contained (Bentin & Deouell ; Bentin et al ; Eimer ).…”

Recent advances in the neuropsychopharmacology of serotonergic hallucinogens

“…reduces activation of the amygdala by negative and neutral pictures, and the BOLD signal change was inversely correlated with reports of increased positive mood (Kraehenmann et al, 2014). Likewise, an electrical neuroimaging study conducted by the same group found psilocybin impairs processing of facial expression valence in the amygdala and other limbic regions (Bernasconi et al, 2013). In healthy subjects, there is an inverse correlation between the density of mPFC 5-HT 2A binding and the responsiveness of the amygdala to threatening stimuli (Fisher et al, 2009), suggesting processing in the amygdala is regulated by 5-HT 2A receptors in mPFC.…”

“…In healthy subjects, there is an inverse correlation between the density of mPFC 5-HT 2A binding and the responsiveness of the amygdala to threatening stimuli (Fisher et al, 2009), suggesting processing in the amygdala is regulated by 5-HT 2A receptors in mPFC. Hence, the ability of psilocybin to reduce emotional processing in the amygdala could potentially be a consequence of increased inhibitory top-down control from the PFC (Bernasconi et al, 2013). …”