Intrinsic Electromagnetic Noise from Cortical Neurons and its Measurement Ex Vivo

An overview of measurements of intrinsic electromagnetic noise from rat cortical neurons ex vivo is reported here. A series of experiments was conceived around a modified Kerr brain chamber setup with a special vector microelectrode array to measure electromagnetic noise intrinsic to living cells, beyond the Johnson noise limit. Cortical cell sections (mainly neurons) from Wistar rats were obtained and kept in specially developed brain chambers wherein recordings were made under physiological conditions. There were spectra of conspicuous electromagnetic noise measured from living cells distinguishable from Johnson and 1/f noise and from the noise measured from dead cells or medium alone. An exhaustive overview of the experiments and the suggested technique, involving measurements reported here, is presented. A preliminary model is outlined to explain this noise and its origin as well as possible underlying connections with neuronal physiology, especially with intercellular calcium ion flux and waves. This study may have some significance as it may provide possibility of electromagnetic mechanisms playing possible roles in higher functions of the cerebral cortex. In addition, the technique offers promise as a useful new biophysical method in analysis of electromagnetic signals from living cells in vitro or ex vivo.