Effects of arterial and cardiopulmonary baroreceptor activation on simple and choice reaction times.

Variations in simple reaction time over the cardiac cycle could be due to cortical inhibition associated with activation of the arterial baroreceptors. It has been proposed that higher order cognitive processing may also be modulated and, moreover, that cardiopulmonary baroreceptors may have similar inhibitory effects. This study examined arterial and cardiopulmonary baroreceptor effects on simple and choice reaction times by presenting visual stimuli at one of six intervals after the R-wave of the electrocardiogram (0, 150, 300, 450, 600, 750 ms) while participants lay supine with their legs raised or lowered. Reaction times were slower early in the cardiac cycle compared to later whereas reaction time slopes were not different. No cardiopulmonary baroreceptor effects were found. Cardiac cycle effects on reaction time are consistent with the arterial baroreceptor hypothesis and appear to be confined to lower order sensory-motor processing.