Oxytocin reduces top-down control of attention by increasing bottom-up attention allocation to social but not non-social stimuli - A randomized controlled trial

The neuropeptide oxytocin (OXT) may facilitate attention to social stimuli by influencing early stage bottom-up processing although findings in relation to different emotional expressions are inconsistent and its influence on top-down cognitive processing mechanisms unclear. In the current double-blind placebo (PLC) controlled between-subject design study we therefore recruited 71 male subjects (OXT = 34, PLC = 37) to investigate the effects of intranasal OXT (24IU) on both bottom-up attention allocation and top-down attention inhibition using a prosaccade and antisaccade paradigm incorporating social (neutral, happy, fearful, sad, angry faces) and non-social (oval shape) visual stimuli with concurrent eye movement acquisition. Results revealed a marginal significant interaction effect between treatment, condition and task (p = 0.054), with Bonferroni-corrected posthoc tests indicating that OXT specifically increased antisaccade errors for social stimuli (ps < 0.04, effect sizes 0.46-0.88), but not non-social stimuli. Antisaccades are under volitional control and therefore this may indicate that OXT treatment reduced top-down inhibition. However, the overall findings are consistent with OXT acting to reduce top-down control of attention as a result of increasing bottom-up early attentional processing of social, but not non-social, stimuli in situations where the two systems are in potential conflict. Marked deficits in bottom-up attention allocation to social stimuli have been reported in autism spectrum disorder, within this context OXT may have the potential to increase early attention allocation towards social cues.