Editorial: Oxytocin's routes in social behavior: into the 21st century

The role of the neuropeptide oxytocin in social behaviors is one of the earliest discoveries in social neuroscience. Influential studies in animal models have delineated many of the neural circuits and genetic components that underlie these behaviors (Insel and Young, 2001; Donaldson and Young, 2008). These discoveries have inspired researchers to investigate the effects of oxytocin on brain and behavior in humans (Kirsch et al., 2005; Kosfeld et al., 2005) and its potential as a treatment for psychiatric disorders (Hollander et al. Several criticisms have been raised lately on the effects of intranasal oxytocin (IN-OT) in humans such as weak effect sizes, lack of dose studies and ambiguity about chronic administration. We clearly need more empirical data before drawing conclusions on IN-OT. Yet, how do we approach these needs and how are we making progress with IN-OT or other oxytocin-targeted drugs? Increasing the sample size and performing replications are important factors (Walum et al., 2015), but are only part of the answer. We cannot minimize the importance of innovative medium-sized studies that are based on theoretical frameworks or constructive hypotheses (or even chance observations) that form the foundation of seminal discoveries. Even single-case studies have advanced the field of neuroscience dramatically. Combining large data sets without a theory-based approach and meticulous view of behavior and symptoms can lead to a dilution of important findings and to misleading conclusions. Recent meta-analyses of the effects of IN-OT across all psychiatric disorders and healthy subjects show that the overall effect sizes are low (Bakermans-Kranenburg and Van, 2013; Walum et al., 2015), which some have interpreted to mean that all the effects of IN-OT in humans are likely to be false positives and not true effects (Walum et al., 2015). However, the effects on specific disorders (such as Autism Spectrum or ASD) are medium to high, which indicates that IN-OT can be more beneficial for ASD than for psychiatric disorders in general (Bakermans-Kranenburg and Van, 2013; Young and Barrett, 2015). Oxytocin's role in ASD is further supported by a seminal study showing that chronic IN-OT early in life restored later social behavior in a mouse model of autism (Penagarikano et al., 2015). Other disorders, such as PTSD (Post Traumatic Stress Disorder), might need further investigation. It has been recently observed that IN-OT facilitates extinction of conditioned fear in healthy subjects (Eckstein et al., 2015). Also, IN-OT is more beneficial for some individuals than others …