Enhancement of Limbic Seizures by Nocturnal Application of Experimental Magnetic Fields That Simulate the Magnitude and Morphology of Increases in Geomagnetic Activity

Abstract

Over a 200 day period, chronic (limbic) epileptic rats were exposed intermittently, for either one or three nights (00 to 08 hr), once very approximately 10 days to experimental magnetic fields whose morphology (incremental changes in intensity over time) simulated geomagnetic activity. One of two intensities and two ripple frequencies (7 Hz, 45 Hz) was employed. The display of overt seizures following synchronized food presentation significantly increased by a factor 3.1 relative to controls when the fields had been activated for one or two but not three successive nights. The combined effects of the experimental field and ambient geomagnetic activity (>40 nT) explained approximately 12 to 15% of the variance in the daily incidence of seizures. Implications for the transient disinhibition of electrical lability within the limbic system following suppression of nocturnal melatonin are discussed.

Key Words:

• Limbic seizures
• magnetic fields