A new way to describe intra- and extra-cellular electrical potentials and their generation by excitable cells

A fundamental aspect of bioelectricity studies is the process by which activation of an excitable cell results in the generation of atransmembrane voltage (the intracellular action potential) and an extracellular electrical potential in the surrounding medium.Traditional methods for teaching how to calculate the potentials do to provide biomedical engineering students with a means toappreciate the progressive nature of the generation of the extracellular potential as the intracellular potential propagates along thefiber. The objective of this paper is to propose a new approach, based on electrostatic theory, to teach students the basics of theformation of the intra- and extra-cellular potential around a fiber. The paper reports on the application and testing of thisapproach, which is demonstrated to enhance the ability of students to predict the shape (waveform) of the extracellular potential atdifferent electrode positions relative to the fiber. In addition, the new approach helps students to create a mental picture ofbioelectrical potentials in the context of the biological structures in which they occur and interact. The paper also emphasizes thenecessity of considering the spatial profile of the intracellular potential, in conjunction with its temporal profile, for a correctinterpretation of the amplitude and temporal characteristics of extracellular potentials.