Attempts to simulate the association between geomagnetic activity and spontaneous seizures in rats using experimentally generated magnetic fields.

In three separate experiments, chronic epileptic male rats (ns = 24, 24, and 4) were exposed to experimental magnetic fields whose intensities were either constant or varied. The ripple frequency was always 7 Hz. Only exposure to a field with a constant intensity (700 nT) appeared to inhibit occurrence of the seizures. Although exposure to a field configuration whose strength increased and decreased by fixed increments during the hour before feeding did not affect the incidence of seizures, exposure to these fields for 5 min, only once per hour (increments of 15 to 20 nT for 30 sec. to a maximum of 70 nT) during the previous night between midnight and 0800 hr. increased the proportion of seizures following the presentation of food. An explanation is given for the persistent antithetical effects of experimental magnetic fields and geomagnetic activity upon seizure phenomena.