ISOLATING HEARTBEAT-EVOKED RESPONSES FROM THE MOTHER AND FETUS IN THE MATERNAL BRAIN USING OPTICALLY PUMPED MAGNETOMETRY

Heartbeat-Evoked Responses (HERs) provide a window into cortical processing of interoceptive signals, but to date have been studied almost exclusively using electroencephalography or conventional cryogenic magnetoencephalography, where the signal-to-noise ratio (SNR) is constrained by sensor distance and fixed sensor geometry. Optically Pumped Magnetometers (OPMs) allow recordings to be made from sensors placed directly on the body, yielding high SNR measurements of both neural and physiological signals. The aim of this work is to establish OPM-based mapping of maternal HERs during pregnancy and to extend this framework to investigate maternal cortical responses to fetal cardiac activity. Simultaneous cortical and abdominal OPM recordings from pregnant participants (n=20) were acquired in a magnetically shielded room. An adapted MNE-Python Independent Component Analysis pipeline was used to isolate distinct maternal and fetal cardiac components from abdominal recordings, rather than remove them as artefacts. Maternal R-peak cardiac events derived from these components were used to epoch the mothers' cortical OPM data, revealing robust maternal HERs in maternal brain recordings. To our knowledge, this constitutes the first demonstration of maternal HERs measured using OPM. Initial analysis also supports the presence of a fetal cardiac component from the abdominal OPM data. Ongoing analyses aim to use fetal R-peaks to compute fetal heartbeat-locked maternal HERs, mapped to the mothers' brain data, providing a novel approach to studying maternal-fetal physiological coupling. Together, these findings highlight the unique advantages of OPMs for high SNR brain-body recordings and open a new avenue for investigating interoception and maternal-fetal interactions and clinical applications.