The nervous principle: active versus passive electric processes in neurons

Abstract

This essay presents in the first section a comprehensive introduction to classical electrodynamics. The reader is acquainted with some basic concepts like right-handed coordinate system, vector calculus, particle and field fluxes, and learns how to calculate electric and magnetic field strengths in different neuronal compartments. Then the exposition comes to explain the basic difference between a passive and an active neural electric process; a brief historical perspective on the nervous principle is also provided. A thorough description is supplied of the nonlinear mechanism generating action potentials in different compartments, with focus on dendritic electroneurobiology. Concurrently, the electric field intensity and magnetic flux density are estimated for each neuronal compartment. Observations are then discussed, succinctly as the calculated results and experimental data square. Local neuronal magnetic flux density is less than 1/300 of the Earth’s magnetic field, explaining why any neuronal magnetic signal would be suffocated by the surrounding noise. In contrast the electric field carries biologically important information and thus, as it is well known, acts upon voltage-gated transmembrane ion channels that generate neuronal action potentials. Though the transmembrane difference in electric field intensity climbs to ten million volts per meter, the intensity of the electric field is estimated to be only ten volts per meter inside the neuronal cytoplasm.