Geophysical variables and behavior: LXXIX. Overt limbic seizures are associated with concurrent and premidscotophase geomagnetic activity: synchronization by prenocturnal feeding.

Approximately 35% of the variance (multiple r = 0.59) in the proportion of overt seizures (forelimb clonus) within a group of 35 chronically epileptic male rats during 65, daily 10-min. observation periods was significantly accommodated by the variations in the magnitude of the increased geomagnetic activity at the same time as the seizures and with activity during the previous midscotophase. The results supported the hypothesis that increased geomagnetic activity during specific subintervals of the circadian period suppresses the activity of the endogenous anticonvulsant melatonin and lowers the threshold for paroxysmal electrical seizures. The possibility of employing large populations of (limbic) epileptic patients as a network or a very large array of biomonitors for geomagnetic activity is considered.