Oxytocin differentially modulates reward system responses to social and non-social incentives.

Rationale: Oxytocin has been shown to modulate behavior related to processing of monetary incentives and to regulate social and reproductive behavior, yet little is known about how oxytocin differentially influences neural responses to social and non-social incentives.

Objectives: We aimed to evaluate the effects of oxytocin administration on behavioral and neural responses to social and monetary incentives.

Methods: Twenty-eight healthy adults (age 18-45 years) performed both monetary and social incentive tasks during blood oxygenation level dependent (BOLD) imaging. Intranasal oxytocin or placebo was administered before each scan using a double blind, randomized, cross-over design. Task performance and self-reported motivation and mood states were collected. Time-series analysis was conducted to assess the influence of oxytocin on the hemodynamic response in the ventral tegmental area and substantia nigra (VTA/SN) and nucleus accumbens (NAc).

Results: Oxytocin demonstrated a multifaceted effect on VTA/SN and NAc when processing reward incentives, with it increasing BOLD response in VTA/SN and decreasing BOLD response in NAc during social incentive anticipation. A reversal of this was shown with decreased BOLD responses in the VTA/SN and increased BOLD response in the NAc during monetary incentive anticipation.

Conclusions: Our findings suggest a more nuanced purpose of oxytocin when evaluating reward incentive decision making. It is possible that while oxytocin does increase salience to rewards, that it is more important for cognitive control when determining short-term versus long-term benefits in rewards. Future studies should more closely examine the relationship between oxytocin and delay discounting.