Understanding the electrical behavior of the action potential in terms of elementary electrical sources.

A concept of major importance in human electrophysiology studies is the process by which activation of an excitable cell results in a rapid rise and fall of the electrical membrane potential, the so-called action potential. Hodgkin and Huxley proposed a model to explain the ionic mechanisms underlying the formation of action potentials. However, this model is unsuitably complex for teaching purposes. In addition, the Hodgkin and Huxley approach describes the shape of the action potential only in terms of ionic currents, i.e., it is unable to explain the electrical significance of the action potential or describe the electrical field arising from this source using basic concepts of electromagnetic theory. The goal of the present report was to propose a new model to describe the electrical behaviour of the action potential in terms of elementary electrical sources (in particular, dipoles). The efficacy of this model was tested through a closed-book written exam. The proposed model increased the ability of students to appreciate the distributed character of the action potential and also to recognize that this source spreads out along the fiber as function of space. In addition, the new approach allowed students to realize that the amplitude and sign of the extracellular electrical potential arising from the action potential are determined by the spatial derivative of this intracellular source. The proposed model, which incorporates intuitive graphical representations, has improved students' understanding of the electrical potentials generated by bioelectrical sources and has heightened their interest in bioelectricity.

[1]  N. Dimitrova,et al.  Precise and fast calculation of the motor unit potentials detected by a point and rectangular plate electrode. , 1998, Medical engineering & physics.

[2]  Stephen H Wright,et al.  Generation of resting membrane potential. , 2004, Advances in physiology education.

[3]  P. Rosenfalck.  Intra- and extracellular potential fields of active nerve and muscle fibres. A physico-mathematical analysis of different models. , 1969, Acta physiologica Scandinavica. Supplementum.

[4]  R. C. Lennartz,et al.  Electrophysiology of the undergraduate neuroscience student: a laboratory exercise in human electromyography. , 1999, The American journal of physiology.

[5]  M. Taussig.  The Nervous System , 1991 .

[6]  W. Reid.  Skeletal Muscle Structure and Function: Implications for Rehabilitation and Sports Medicine , 1993 .

[7]  E. Stålberg.  Single fibre electromyography , 1979, Trends in Neurosciences.

[8]  Javier Rodriguez,et al.  Teaching a master student how to model the electrical potentials produced by the muscle , 2010 .

[9]  R. Burke.  Motor Units: Anatomy, Physiology, and Functional Organization , 1981 .

[10]  Javier Rodriguez-Falces.  A novel approach to teach the generation of bioelectrical potentials from a descriptive and quantitative perspective. , 2013, Advances in physiology education.

[11]  D. F. Sousa,et al.  Talking about bioelectrical potentials using rings of the mesenteric artery without glass micropipettes. , 2012, Advances in physiology education.

[12]  A. Hodgkin,et al.  A quantitative description of membrane current and its application to conduction and excitation in nerve , 1952, The Journal of physiology.

[13]  S. Andreassen,et al.  Relationship of intracellular and extracellular action potentials of skeletal muscle fibers. , 1981, Critical reviews in bioengineering.

[14]  J. Denton,et al.  A simple, inexpensive method for teaching how membrane potentials are generated. , 1999, The American journal of physiology.

[15]  S. Andreassen,et al.  Quantitative Analysis of Individual Motor Unit Potentials: A Proposition for Standardized Terminology and Criteria for Measurement , 1986, Journal of clinical neurophysiology : official publication of the American Electroencephalographic Society.

[16]  Robert Plonsey,et al.  Bioelectricity: A Quantitative Approach Duke University’s First MOOC , 2013 .

[17]  R. LorentedeNo.  Analysis of the distribution of the action currents of nerve in volume conductors. , 1947 .

[18]  R. Plonsey,et al.  The extracellular potential field of the single active nerve fiber in a volume conductor. , 1968, Biophysical journal.

[19]  S. Yoshida.  Simple techniques suitable for student use to record action potentials from the frog heart. , 2001, Advances in physiology education.

[20]  R. Granit.  THE HEART ( Extract from “ Principles and Applications of Bioelectric and Biomagnetic Fields , 2005 .

[21]  S. Nandedkar,et al.  Simulation of single muscle fibre action potentials , 1983, Medical and Biological Engineering and Computing.

[22]  Armando Malanda-Trigueros,et al.  Influence of the shape of intracellular potentials on the morphology of single-fiber extracellular potentials in human muscle fibers , 2012, Medical & Biological Engineering & Computing.

[23]  F. N. Wilson,et al.  THE DISTRIBUTION OF THE ACTION CURRENTS PRODUCED BY HEART MUSCLE AND OTHER EXCITABLE TISSUES IMMERSED IN EXTENSIVE CONDUCTING MEDIA , 1933, The Journal of general physiology.

[24]  Joseph D. Bronzino,et al.  The Biomedical Engineering Handbook , 1995 .

[25]  H. Helmholtz.  Ueber einige Gesetze der Vertheilung elektrischer Ströme in körperlichen Leitern mit Anwendung auf die thierisch‐elektrischen Versuche , 1853 .

[26]  R Plonsey,et al.  The active fiber in a volume conductor. , 1974, IEEE transactions on bio-medical engineering.

[27]  R. Lorente de Nó,et al.  Analysis of the distribution of the action currents of nerve in volume conductors. , 1947, Studies from the Rockefeller institute for medical research. Reprints. Rockefeller Institute for Medical Research.