Dual epileptic foci in a single patient express distinct temporal patternsdependent on limbic versus nonlimbic brain location

How timing information is transferred from the suprachiasmatic nucleus to o ther regions of the brain to mediate activity, either physiological or path ological, is largely unclear. A patient with medically refractory epilepsy and a well-documented, long-term seizure diary provided a unique means to d emonstrate how susceptibility to chronobiological modulation varies with br ain region. Evaluation for epilepsy surgery disclosed two independent epile ptic foci, one limbic and the other nonlimbic. Seizures from both foci occu rred periodically with a dominant period of 24 hours but were out off phase with each other. Temporal lobe seizures occurred maximally in the light po rtion of the daily light-dark cycle, and parietal lobe seizures occurred no cturnally and out of phase with limbic seizures. These data suggest that ne uronal excitation and inhibition, depending on the anatomical system involv ed in epilepsy, may be differently affected by circadian modulation.