Propagation of Endogenous Electric Fields as a Possible Mechanism of Synchronization of Interictal Spikes in the Rat Neocortex

Abstract

The effects of weak electric fields with parameters close to those of the electrical activity of brain structures on neural networks in the brain have been studied for several decades. Interest in these studies has increased recently in connection with the fact that the treatment of a number of diseases uses transcranial stimulation methods. The present study used linear regression and correlation analysis to establish a relationship between the magnitude of the interictal spike potential and the magnitude of the potential at the cortical point located a few millimeters from the point at which the spike is generated. A link was also found between the occurrence of interictal spikes at one point of the cortex and the synchronous appearance of electric potentials in neighboring areas. Blockade of sodium channels at the recording points was followed by increases in the linear regression coefficient and the correlation coefficient. This indicated that the actions of electric field potentials were more significant. To identify whether this relationship was random, the time sequence of a single channel was shifted in relation to another using the random numbers principle. The magnitudes of the linear regression and correlation coefficients decreased by an order of magnitude. Our results showed that the electric potential of a small interictal spike arising at one point on the cortex propagates to other areas with a short time delay.