Basic Characteristics of the Electromagnetic Field at Discharge of the Synaptic Transmitter

Abstract

To clarify the mechanism of signal transmission in nerve systems is one of the most important problems in both medicine and physiology. Until now, many studies and analyses have been done by means of electric circuit theory and cable theory, but the systematic electromagnetic characteristics are not clearly known. In synaptic transmission, electromagnetic and chemical phenomena are closely connected, but their relationship has not been completely explained. In this study, the electromagnetic characteristics of synaptic transmission are analyzed. Every phenomenon that has been explained separately, namely, the propagation of an action potential, the discharge of synaptic transmitter, the reaction of a receptor to transmitter, etc., are connected theoretically so that the characteristics of the spatiotemporal distribution of electric field and ion current are systematically clarified. A 3-dimensional model of single synapse having half-spherical synaptic knob and flat, parallel pre-and postsynaptic membranes is presented. The electric field is separated into three types-intracellular, extracellular and membrane field, and boundary conditions are regarded on the boundary area between which the material constants differ discontinuously. The analysis starts from the Maxwell's equations, to derive the expressions of the Hodgkin-Huxley's equations in vector field instead of scalar field. The cable equations in vector field are also derived from them, and they are connected to expresses the relationship between transmembrane current and propagation-directional current.