Heart rate and P300: Integrating peripheral and central indices of cognitive processing.

To assess the integration of peripheral (heart rate, HR) and central (event-related potential, P300) measures of cognition, the present study varied inter-stimulus presentation time (ISI) and employed comparable data reduction methods for the HR and ERP data. Young adults (n=33) performed an auditory oddball count task in which the ISI was varied (short vs. long, to maximize target detection for both measures) and task condition (single stimulus, short-ISI oddball, long-ISI oddball, to assay stimulus presentation condition between HR and P300). The off-line cardiotachometer method parallels signal averaging and was applied to HR data reduction. The main goal was to characterize target vs. standard processing in each measurement type using appropriate recording approaches with respect to differentiating the two stimuli in each task (target vs. silence, target vs. standard short-ISI, target vs. standard long-ISI). Results demonstrated reliable differences between target/standard stimuli for both the biphasic HR (deceleration/acceleration) signal and for P300 amplitude production, with larger amplitudes for target than standard. The short and long ISIs yielded no reliable initial HR deceleration differences, but the late acceleration was observed for the long-ISI condition only. Correlational analysis between HR and P300 measures indicated that people with smaller HR deceleration had larger P300 amplitude suggesting that the larger target/standard differences for HR deceleration and P300 amplitude, observed at an experimental level, are reversed at an individual level. The contributions of simultaneously recording HR and P300 to characterize cognition and theoretical implications are discussed.