Effects of oxytocin on approach behavior and social action control

Appropriate social behavior is vital for human health and well-being, although
the neurobiological mechanisms which mediate social behavior remain poorly
understood. Oxytocin (OXT) is a neurohypophysial nonapeptide which is
synthesized in the supra-optic (SON) and the parvoventricular (PVN) nuclei of
the hypothalamus and its release is under serotonergic control (Gimpl &
Fahrenholz 2001). Oxytocin has, next to its peripheral effects (i.e. induction
of parturition and lactation), received attention for its role in social
behavior and has been suggested to induce prosocial behavior in animals as well
as in humans, without side effects (Campbell 2007; Domes, Heinrichs et al.
2009; Kosfeld et al., 2005; Young 2002; Zak, Stanton et al. 2007). As these
studies have used a wide variety of tests, from trust games to emotion
detection, the concept of genuine, standardized approach behavior remains
rather vague. The current study aims at employing two paradigms that provide
more concrete manifestations of affiliative behavior and social motivation
which, as widely suggested, ought to be boosted by oxytocin (Depue &
Morrone-Strupinsky, 2005).
Furthermore, the effect of oxytocin on action control in a joint task setting
shall be examined. As Sebanz et al. (2003, 2005) have shown, representing the
other*s action in a joint setting affects one*s own performance in a spatial
(in-) compatibility task (Social Simon Task). During co-acting, low-level
processing of irrelevant cues occurs automatically and leads to longer RTs to
incompatible stimuli. The social context additionally modulates this effect as
the interference is enlarged in the joint setting (Sebanz et al., 2005).
The Ultimatum Game has been shown to be responsive to the pro-social effects of
oxytocin as trusting other people is a precondition of affiliation (Heinrichs
et al., 2009). The administration of oxytocin results in greater risk taking in
social situations (Kosfeld et al., 2005), thus promoting approach behavior.
Conversely, several psychiatric disorders are associated with disturbances in
social motivation and social behavior. Apart from social anxiety, social
deficits also occur in patients with Autism Spectrum Disorders (ASD),
Obsessive-Compulsive Disorder (OCD), Borderline Personality Disorder (BPD) or
Depression.
The current study aims to address abovementioned issues regarding oxytocin
effects on approach behavior and action control in healthy volunteers. Results
of this study will be used to optimize the design of a future study to assess
the effects of oxytocin in patients with depression, which will be separately
communicated to the local ethics committee at that time.

The main objective of the present protocol is to investigate to what extent
oxytocin modulates specific aspects of approach behavior and action control in
healthy volunteers
Results from this study shall give rise to designing a future study on the
effects of oxytocin in patients diagnosed with depression.

This proposal consists of a double-blind, placebo-controlled, two-way
cross-over experiment. 16 volunteers will be randomly assigned to one of two
treatment sequences. Each volunteer will receive a nasal spray containing
oxytocin or placebo with an interval of 14 days between each treatment and
subjects will perform a test battery.

24 intranasal units (IU) of oxytocin, administered via a nasal spray containing
4 IU oxytocin per spray. In total 6 sprays of oxytocin (3 per nostril) will be
administered. Placebo (PLC) will consist of the vehicle fluid contained in the
oxytocin nasal spray without actual oxytocin.

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