Learned oxytocin responses

Preliminary evidence suggests that endogenous hormone secretion, such as cortisol or insulin, might be behaviourally conditionable in humans. Whether other neuroendocrine hormones such as oxytocin can be conditioned as well is currently unclear and no studies focused on possible neural mechanisms of conditioning yet. The primary objective of the current study is to investigate the effect of conditioning with exogenous oxytocin on endogenous oxytocin release in a two-phase (acquisition and evocation) randomized placebo-controlled conditioning paradigm. Additionally, during the evocation phase (1st and 2nd evocation days), psychophysiological state and task-related assessments will be measured. On the third evocation day, resting state and task-related brain activity will be measured.

The aim of the study is to investigate the effect of conditioning with exogenous oxytocin on endogenous oxytocin release in healthy participants. We hypothesize that conditioning will lead to altered oxytocin levels.

The study consists of 7 sessions during the course of 3 weeks. In the first week, participants will be screened for medical and psychological conditions. In the second week, the acquisition phase - consisting of 3 sessions on 3 consecutive days - takes place and in the final week during the evocation phase - again consisting of 3 consecutive sessions - the conditioned responses will be tested.

The design used in this study is based on a widely used randomized placebo-controlled conditioning paradigm, consisting of two phases (acquisition phase & evocation phase). During the acquisition phase, an association between a conditioned stimulus (CS, a distinctive odor) and an unconditioned stimulus (US, oxytocin) is established by repeated paired administration of both stimuli. In the evocation phase, it is tested whether exposure to the conditioned stimulus alone leads to the conditioned response. Participants will be randomly assigned to three groups. In the experimental group, participants will receive a 24 IU dose of oxytocin via a nasal spray during the acquisition phase and an identically looking placebo nasal spray during the evocation phase. In the placebo group, participants will receive a placebo in both phases. In the drug-control group, 24 IU of oxytocin will be administered in both phases.