Cardiac-related cortical activity during variations in mean heart rate

Koriath and Lindholm (Int. J. Psychophysiol., 1986; 4: 183-195) reported cardiac-related cortical inhibition and speculated that cardiovascular events could modulate electrocortical activity by setting constraints on cortical excitability during diastole based on levels of blood pressure during systole. One dimension of this proposal could be supported if the extent of cardiac-related cortical activity (CRCA) varies with changes in heart rate and blood pressure. The current study investigated this dimension of cardio-cortical relationship by having each subject perform a fixed-foreperiod reaction time task while pedalling a bicycle ergometer under three conditions of workload: No Pedal (0 kpm/min), Lo Pedal (150 kpm/min), and Hi Pedal (450 kpm/min). Mean HR increased significantly from No Pedal to Lo Pedal to Hi Pedal. Results confirmed the presence of CRCA during variations in mean HR and indicated that the extent of CRCA increases with increases in mean HR. This investigation reinforces the importance of the extrahomeostatic effects of cardiovascular afferent fibers and supports the importance of psychophysiological measures which integrate the activity of cardiovascular, autonomic, and central nervous systems.