Are Cardiac Waves Relevant to Epileptic Wave Propagation?
The mechanisms of cardiac fibrillation and of the epilepsies differ markedly. Also, there are many kinds of fibrillation and many epilepsies. Yet some collective parallels stand out. Their tissue substrates (heart muscle, brain neocortex and sub-cortical nuclei) both involve electrically active cells connected to neighbors, and both aberrations are electrical modes that seem alternative to the normal modes in the same tissue without change of parameters. The onset and offset of each is an abrupt switch from or back to the normal mode, both can be evoked by electrical stimulation at 10–100 Hz and current density around 20 mA/cm2, and both can be terminated by a brief stimulus. In the case of fibrillation a single harsh direct-current shock of several milliseconds’ duration is in fact the only known acute therapy. In the case of epilepsy, Gluckman et al.  report prompt suppression of epileptiform activity in hippocampal slices using much smaller 60 Hz AC fields, and it is well known that a single brief sensory stimulus given close to seizure onset often appears to abort it . Both fibrillation and epilepsy look quite irregular electrically, yet both have dominant periodicities in the 3 to 10 Hz range, and both processes seem to be determined at least in part by propagation geometry on the scale of centimeters.
KeywordsPropagation Speed Heart Muscle Refractory Period Migraine With Aura Excitable Medium
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