Electroencephalographic frequencies associated with heart changes in RR interval variability during paradoxical sleep.

Brain stem autonomic oscillators, hypothalamic and cortico-frontal centre, entrained by baroreceptor input, have been proposed as the control system of the heart rhythm. Recent reported results in animals suggested that the hippocampal theta waves might also participate as a heart rate modulator. A temporal correlation among the firing of neurons in the medulla, the R-wave of the electrocardiogram, hippocampal units, and theta rhythm was reported in guinea pigs.