THE INFLUENCE OF STEADY MAGNETIC-FIELDS ON THE MOUSE HIPPOCAMPAL EVOKED-POTENTIALS IN-VITRO

Direct current-generated EM fields modulated evoked potentials recorde d from hippocampal slices. Both the synaptic efficiency represented by the slope of EPSP and the number of activated pyramidal cells represe nted by the population spike were modified by EM fields. While the wea k EM fields (2-3 mT) exerted a biphasic effect observed as a transient small depression followed by a long-lasting amplification of the pote ntials, stronger EM fields (8-10 mT) depressed these potentials. This depression could be partially reversed by increasing the strength of t he stimulation. It is suggested that EM-induced fluctuations in the in tracellular Ca2+ concentration are responsible for the observed effect .