Effects of theta burst stimulation on the interoceptive brain network and cardiac interoception

Interoception, the perception and processing of signals from within the body, plays a central role in various aspects of human cognition, affect, and behavior. This study investigates the effects of theta burst stimulation (TBS) on cardiac interoception, focusing on modulation of activity of the interoceptive brain network (IBN). Twenty-two participants underwent three stimulation protocols: an inhibitory (continuous TBS, cTBS), a facilitatory (intermittent TBS, iTBS), and an ineffective control (intermediate TBS, imTBS) protocol, targeting the right supramarginal gyrus (rSMG). Stimulation of the rSMG allows, thanks to its strong functional connectivity with the right anterior insula, an indirect modulation of the activity of the IBN. We observed an increase in heartbeat-evoked potentials following facilitatory stimulation (iTBS), suggesting increased activity within the interoceptive network. In contrast, we found no effects of inhibitory (cTBS) or ineffective control (imTBS) protocols on HEPs. Furthermore, cardiac interoceptive accuracy (IAc) in a heartbeat perception task was not significantly affected by the different stimulation protocols. In conclusion, the current rSMG facilitation protocol based on iTBS is the first to enhance activity in the IBN. The result that only HEPs, but not cardiac IAc was affected, suggests that rSMG stimulation selectively enhances cardiac interoceptive attention.