Deciphering inter-individual response profiles to a Positive Interaction Paradigm (PIP)

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Positive social interactions confer anxiolytic effects and attenuate physiological stress responses. However, these salubrious effects differ between individuals depending on previous bonding experiences. In fact, dysfunctional interpersonal behavior has been identified as a key mediator of the dramatically increased risk for psychopathology after childhood trauma. While there are several tasks to induce negative emotions in social contexts and quantify the stress-induced responses, there is a surprising paucity of validated experimental paradigms to assess inter-individual differences in the neuro-hormonal response profiles to positive social interactions in a controlled setting. The present project was therefore designed to establish a standardized Positive Interaction Paradigm (PIP) and gauge the predictive validity of PIP-induced behavioral, hormonal, psychophysiological and neural changes for social interactions and perceived stress in the following two weeks. Specifically, in Study 1, we plan to examine interpersonal synchrony of response profiles in a naturalistic PIP with two participants (pPIP) and an experimenter-controlled PIP (ePIP) and compare the outcomes to a control condition without social interaction. To probe the long-term effects of early life experiences on the neuro-hormonal response to positive social interactions, healthy participants with varying levels of childhood trauma will be recruited. The impact of different trauma types (intentional vs. accidental), developmental timing, number and duration of traumata will be explored. In Study 2, we will use functional magnetic resonance imaging to examine inter-individual differences in the neural after-effects of the ePIP relative to the control condition. We will focus on two readouts that are known to be altered in individuals with childhood trauma: (i) amygdala activation during an emotional face matching task and (ii) sensory cortical activations in response to interpersonal touch. We hypothesize that the trauma-associated amygdala and sensory hyperreactivity will be alleviated after the positive social interaction experience. Collectively, by providing norm values for response profiles to positive social interactions, the planned project can lay the experimental framework to improve the evaluation of social dysfunctions and novel targeted interventions in patients with psychological disorders.