Abstract
The somatic marker hypothesis proposes that cortical representation of visceral signals is a crucial component of emotion processing. There has been no previous study investigating the causal relationship among brain regions of visceral information processing during emotional perception. In this magnetoencephalography study of 32 healthy subjects, heartbeat evoked potential (HEP), which reflects cortical processing of heartbeats, was modulated by the perception of sad faces, but not other faces and text-based emoticons. We here provide the first evidence for an increased causal flow of heartbeat information from the right posterior insula to the anterior insula to the anterior cingulate cortex and from the right globus pallidus to the prefrontal cortices by sad faces. Moreover, this effect was not an effect of visual evoked potential, which indicates separate systems of interoceptive and visual processing. These findings provide important progress in the understanding of brain-body interaction during emotion processing.