The neuropeptide oxytocin (OXT) is suggested to exert an important role in human social behaviors by modulating the salience of social cues. To date, however, there is mixed evidence whether a single dose of OXT can improve the behavioral and neural sensitivity for emotional face processing. To overcome difficulties encountered with classic event-related potential studies assessing stimulus-saliency, we applied frequency-tagging EEG to implicitly assess the effect of a single dose of OXT (24 IU) on the neural sensitivity for positive and negative facial emotions. Neutral faces with different identities were presented at 6 Hz, periodically interleaved with an expressive face (angry, fearful, and happy, in separate sequences) every fifth image (i.e., 1.2 Hz oddball frequency). These distinctive frequency tags for neutral and expressive stimuli allowed direct and objective quantification of the neural expression-categorization responses. The study involved a double-blind, placebo-controlled, cross-over trial with 31 healthy adult men. Contrary to our expectations, we did not find an effect of OXT on facial emotion processing, neither at the neural, nor at the behavioral level. A single dose of OXT did not evoke social enhancement in general, nor did it affect social approach-avoidance tendencies. Possibly ceiling performances in facial emotion processing might have hampered further improvement.

Department of Neurosciences Center for Developmental Psychiatry KU Leuven Leuven Belgium

Department of Psychology Faculty of Arts Masaryk University Brno Czech Republic

Department of Rehabilitation Sciences Neurorehabilitation Research Group KU Leuven Leuven Belgium

Institute of Neuroscience Université de Louvain Louvain La Neuve Belgium

Institute of Research in Psychological Sciences Université de Louvain Louvain La Neuve Belgium

Leuven Autism Research KU Leuven Leuven Belgium

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