The Oscillatory Systems of the Brain and Individual Variability of the Defensive Cardiac Reflex in Humans

Abstract

The defensive cardiac reflex (DCR) is a reaction of the cardiovascular system with a specific profile of short- and long-latency reactivities (mainly of arterial blood pressure (BP) and heart rate (HR)). The DCR reflects activation of the defensive motivational system and defensive coping programs in humans. The aim of the present work was to evaluate the contribution of the brain oscillatory systems to the mechanisms of individual variability of the DCR. The oscillatory dynamics of multichannel (64-channel) electroencephalogram (EEG) were assessed using evoked synchronization/desynchronization in different frequency ranges and hemodynamics were assessed using simultaneously recorded beat-by-beat measures of cardiovascular reactivity (Finapres® technology). This is the first report showing significant linkage between θ2 (6–8 Hz) EEG activity with short-latency DCR reactivity and between α2 (10–12 Hz) activity and long-latency reactivity. Hyperreactivity of the long-latency BP component was shown to be associated with the absence of a concomitant phase α2 synchronization evoked. It is suggested that high-frequency θ EEG oscillations are involved in the central magnitude scaling mechanisms and that α2 oscillations have a role in top-down inhibitory control of short- and long-latency stress reactivity of BP in the DCR.