Oxytocin reduces interoceptive influences on empathy-for-pain in the anterior insula

Empathy-for-pain states are underpinned by interoception, i.e the central representation of internal states. Cardiac signals occur in a phasic manner; baroreceptor discharges at systole communicate the heartbeats strength. These signals modulate pain and emotion processing. We tested whether these phasic interoceptive signals modulate empathy-for-pain. As oxytocin (OT) enhances empathy and modulates interoceptive signals precision, we also tested if OT administration impacts empathy-for-pain via interoceptive mechanisms. Male subjects (N=32) attended three sessions to perform psychometric tests and an fMRI empathy-for-pain task, after intranasal administration of OT or placebo (40IU). Pictures of hands in painful or non-painful context were presented at systole or diastole. Effects of drug, emotion and cardiac timing on behaviour and brain activity was tested using general and mixed-effects linear models. Across conditions, activation was observed within regions implicated in pain and empathy-for-pain, with insula activation greater in the right than left hemisphere. OT administration, compared to placebo, attenuated the reactivity of some regions, including anterior cingulate cortex, but presentation of stimuli at systole blocked the OT attenuating effect. Our data suggest that OT alters the processing of motivationally-salient social cues, interacting with interoceptive signals. Our findings may inform targeted use of OT in psychiatric conditions linked to aberrant interoceptive processing.