Phd in PHD PROGRAM IN BEHAVIORAL NEUROSCIENCE

Thesis title: THE COMPASSIONATE BRAIN MAKES SENSE OF THE COMPLEXITY BY COMPUTATIONS OF THE HEART. A HIERARCHICAL INTEROCEPTIVE INFERENCE PERSPECTIVE

Background In the past few years, the health promoting influences of compassion have stimulated the investigation of its underlying mechanisms. The psychophysiological perspective emphasized the link between compassion and cardiac vagal tone. At a brain level, compassion has been demonstrated to activate the salience network (SN) suggesting a key role of the insula, a region important for the integration of interoceptive states, emotions, and cognition and for generating motivated responses. However, there is still no consensus on the processes involved in compassion. To elucidate the mechanisms generating and sustaining compassion motivation, we adopted an evolutionary perspective framing it within an interoceptive active inference (IAI) account, which emphasizes the anticipatory dynamics of physiological regulation that enable the individual to proactively adapt to environmental change. Methods In Study 1, we meta-analyzed available studies on the association between compassion and heart rate variability (HRV), as an index of parasympathetic control of the heart. In Study 2, the association between HRV and each component of compassion, namely ‘empathic sensitivity’ and ‘action’, were investigated in a sample of university students. In Study 3, we examined whether anodal transcranial direct current stimulation (tDCS) over the insula would modulate the engagement in compassion in healthy individuals. Dispositional measures and affective, behavioral and physiological outcomes were assessed in studies 2 and 3. Results The results highlight the connection between compassion and cardiac vagal tone and indicate that such association is not linear. Moreover, they suggest the modulatory effect of anodal tDCS over right temporal lobe (which includes the insula region) on compassion, mediated by an IAI process. Epistemological reflections on the complex nature of compassion may arise from the current findings and clinical implications for a better understanding of mechanisms underlying dysregulated functioning in clinical populations, as well as the potential of tDCS treatment in psychiatry.