Identification of Neurophysiological Markers of Interoceptive Signal Processing Using Event-Related Potentials

This paper presents and evaluates an algorithm for extracting cerebral evoked potentials associated with the heartbeat (heartbeat-evoked potentials, HEP) using the independent components method. The algorithm includes simultaneous recording of the electroencephalogram (EEG) and photoplethysmogram (PPG), with extraction of EEG fragments corresponding to PPG pulse wave peaks, removal of cardiogenic activity from the resulting fragments by independent components analysis (ICA), and synchronization of the fragments with the cardiogram R-wave. The locations of sources of recorded potentials were clarified by applying a “current source density” (CSD) spatial filter. The algorithm was tested on 21 experimental participants and demonstrated a characteristic increase in the amplitude of the potential in the interval 0–400 msec after the heartbeat, i.e., the HEP. Thus, application of independent components analysis and spatial filtration to PPG-synchronized EEG fragments can isolate cerebral evoked potentials associated with heartbeats independently of the actual cardiac activity recorded by scalp leads.