Oxytocin Differentially Modulates the Early Neural Responses to Faces and Non-Social Stimuli.

Oxytocin alters social cognition partly through effects on the processing and appraisal of faces. It is debated whether the hormone also impacts the processing of other, non-social, visual stimuli. To this end, we conducted a randomized, counter-balanced, double-blind, placebo-controlled within-subjects EEG study with cismale participants (to control for gender dimorphic hormonal effects; n=37). Participants received intranasal oxytocin (OT; 24 IU) and completed a one-back task viewing emotional (fearful/ happy) and neutral faces, and threat (snakes/spiders) and non-threat (mushrooms/flowers) non-social stimuli. OT differentially impacted ERPs to faces and non-social stimuli. For faces regardless of emotion, OT evoked greater occipital N1 and anterior P1 amplitudes at ~155ms than after PL, and lead to sustained differences over anterior, bilateral parietal, and occipital sites from 205ms onwards. For all non-social stimuli OT evoked greater right parietal N1 amplitudes, and later only impacted threat stimuli over right parietal and occipital sites. None of these OT-induced modulations were related to individual anxiety levels. This pattern of results indicates that OT differentially modulates the processing of faces and non-social stimuli, and that the hormone's effect on visual processing and cognition does not occur as a function of non-clinical levels of anxiety.