Effects of chronic oxytocin on attention to dynamic facial expressions in infant macaques

• Type of Material: Article
• Authors: Lisa Parr, Emory University; Jenna M. Brooks, Emory University; Trina Jonesteller, Emory University; Shannon Moss, Emory University; James O. Jordano, Emory University; Thomas R. Heitz, Emory University
• Language: English
• Date: 2016-12-01
• Publisher: Elsevier
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2016 Elsevier Ltd.
• Final Published Version (URL): http://dx.doi.org/10.1016/j.psyneuen.2016.08.028
• Title of Journal or Parent Work: Psychoneuroendocrinology
• ISSN: 0306-4530
• Volume: 74
• Start Page: 149
• End Page: 157
• Grant/Funding Information: Additional support was provided by the National Center for Research Resources P51RR000165 to the Yerkes National Primate Research Center, currently the Office of Research Infrastructure Programs / OD P51OD011132.; This project was funded by the National Institutes of Health MH104534 to L.A. Parr.
• Keywords: Facial expression; Infant macaque; Oxytocin; Eye-tracking; Gaze; Development
• Research Categories: Psychology, Behavioral; Biology, Neuroscience

Abstract

Studies in a variety of species have reported enhanced prosocial effects after an acute administration of the neuromodulating hormone, oxytocin (OT). Although the exact mechanisms underlying these effects are not fully understood, there is broad interest in developing OT into a treatment for social deficits. Only a few studies, however, have examined the effects of OT if given repeatedly during early development, the period when early intervention is likely to have the greatest benefits for reversing the progression towards social impairment. Those studies, exclusively in rodents, report mixed results. Some have shown enhancement of prosocial behavior, including increased social exploration, but others have shown anti-social effects, including increased aggression. In the present study, infant rhesus macaques were treated with a high-frequency (3× per week) or low-frequency (1× per week) dose of intranasal oxytocin (IN-OT) or placebo (IN-saline) between two and six months of age, after which their reactions to dynamic facial expressions (neutral, lipsmacking and threats) were measured. Results showed that IN-OT, compared to placebo, increased the time monkeys spent viewing the expression videos, but selectively reduced attention to the eyes in neutral faces in a dose dependent manner. The mechanism for this non-prosocial effect may be that repeated IN-OT administration down-regulates the expression of OT receptors in brain regions important for regulating social attention. Consequently, our results raise questions about the efficacy of implementing chronic IN-OT as a pharmacotherapy for the treatment of social deficits, particularly if given early in development. More work is needed, not only to identify optimal treatment schedules, but also to understand how IN-OT exerts its influences on the brain and behavior.