Preliminary evidence for altered brain-heart coherence during anxiogenic movies

During states of anxiety, fundamental threat circuitry in the brain can increase heart rate via alterations in autonomic balance (increased sympathetic activity and parasympathetic withdrawal) and may serve to promote interoceptive integration and awareness of cardiac signals. Moreover, evidence indicates pathological anxiety could be associated with increased communication between the brain and the heart. Yet, this phenomenon remains not well understood. For instance, studies in this area have been conducted within the confines of tightly controlled experimental paradigms. Whether anxiety impacts brain-heart communication outside of such experimental settings, and in relatively more naturalistic contexts, is less clear. Here, we used a suspenseful movie fMRI paradigm to study induced anxiety (n = 29 healthy volunteers; Caltech Conte dataset;Kliemann et al., 2022). We predicted that brain responses across an anxiety-relevant "defensive response network" (amygdala, hypothalamus, periaqueductal gray, bed nucleus of the stria terminalis, dorsomedial prefrontal cortex, ventromedial prefrontal cortex, subgenual anterior cingulate, and anterior insula;Abend et al., 2022) would show increased coherence with heart rate as participants watched a suspenseful movie clip compared to a non-suspenseful movie clip. Counter to our predictions, we found decreased coherence between heart rate and brain responses during increased anxiety, namely in amygdala-prefrontal circuitry. We suggest these alterations may be underpinned by parasympathetic withdrawal and/or decreased interoceptive awareness during suspenseful movie-watching.