No abstract

Essentially all social species experience social stress which can be a catalyst for detriments in mental and physical health. The neuropeptide oxytocin (OXT) has been shown to produce anxiolytic and antistress effects, thereby qualifying the OXT system as a promising drug target in the treatment of stress-related disorders. However, recently it has been shown that OXT can have anxiogenic effects as well. In the present study, we used functional magnetic resonance imaging to scan the brains of 60 healthy men while they were exposed to social stress after they received either intranasal OXT (24 IU) or placebo treatment. Although OXT administration did not alter salivary cortisol levels as a surrogate marker of stress axis activity, our participants initially reported an increment in perceived social stress. This behavioral effect was paralleled on the neural level by increased activity in the precuneus and cingulate cortex. Taken together, our results support the hypothesis that OXT can induce a self-referential processing bias which facilitates the sensation of social stress in the absence of altered endocrine responses.

No abstract

In human evolution, social group living and Pavlovian fear conditioning have evolved as adaptive mechanisms promoting survival and reproductive success. The evolutionarily conserved hypothalamic peptide oxytocin is a key modulator of human sociality, but its effects on fear conditioning are still elusive. In the present randomized controlled study involving 97 healthy male subjects, we therefore employed functional magnetic resonance imaging and simultaneous skin conductance response (SCR) measures to characterize the modulatory influence of intranasal oxytocin (24 IU) on Pavlovian fear conditioning. We found that the peptide strengthened conditioning on both the behavioral and neural levels. Specifically, subjects exhibited faster task-related responses and enhanced SCRs to fear-associated stimuli in the late phase of conditioning, which was paralleled by heightened activity in cingulate cortex subregions in the absence of changes in amygdala function. This speaks against amygdalocentric views of oxytocin having pure anxiolytic-like effects. Instead, it suggests that the peptide enables extremely rapid and flexible adaptation to fear signals in social contexts, which may confer clear evolutionary advantages but could also elevate vulnerability for the pathological sequelae of interpersonal trauma.