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Biomedical subjects

R Plonsey

Publications and source records attributed to R Plonsey.

At least 91 records · Page 5Linked to original sources
PubMed1972

Finite difference solution for biopotentials of axially symmetric cells.

The finite difference equations necessary for calculating the three-dimensional, time-varying biopotentials within and surrounding axially symmetric cells are presented. The method of sucessive overrelaxation is employed to solve these equations and is shown to be rapidly convergent and accurate for the exemplary problem of a spheroidal cell under uniform field stimulation.

Cell Membrane↗
PubMed1972

Integral equation solution for biopotentials of single cells.

A Fredholm integral equation of the second type is developed for the biopotentials of single cells. Two singularities arise in the numerical solution of this integral equation and methods for handling them are presented. The problem of a spherical cell in an applied uniform field is used to illustrate the technique.

Cell Physiological Phenomena↗
PubMed1971

Fiber interaction in a nerve trunk.

This paper is concerned with the nature of the transmembrane potential induced in an inactive nerve fiber lying in an impressed potential field within a nerve trunk. The impressed potential field is assumed to be produced by the synchronous activity of other fibers within the trunk; an expression for the induced transmembrane potential is obtained utilizing the principles of electromagnetic field theory. The results strongly indicate that membrane capacitance is the main determinant of the induced transmembrane potential wave form.

Action Potentials↗
PubMed1970

A mathematical study of nerve fiber interaction.

This paper presents a quantitative description of the electric field interaction between two adjacent unmyelinated nerve fibers (one active, the other inactive) for the infinite medium and nerve trunk geometries, and considers their dependence on various electrical and geometrical parameters. Based on the use of synthetic giant axon data, the conclusion of this study is that the cross-sectional area of the nerve trunk and the specific resistivity of the interstitial medium are of particular importance to the degree of fiber interaction. Other factors such as separation distance between fibers, axoplasmic resistivity, membrane resistance, and capacitance of the inactive fiber, are also investigated and found to be of secondary importance.

Action Potentials↗
PubMed1970

Simulation of electrical interaction of cardiac cells.

A model of the electrical activity of excitable membrane was used to simulate action potential propagation in cardiac cells. Using an implicit method for solving finite difference equations, propagation through the intercalated disc region between two abutting cells was studied. A model of interaction was constructed and parameters of the cellular junction determined. Estimates of the intercalated disc resistance were then made from these junction parameters using a field analysis of the junction. Values of approximately 4 Omega-cm(2) were found and correlate well with experimentally measured values.

Action Potentials↗
PubMed1968

The extracellular potential field of the single active nerve fiber in a volume conductor.

The potential field of an active fiber in a uniform medium of infinite extent and within a nerve trunk is calculated from transmembrane potential data. The resulting distributions are given quantitatively. A comparison of both magnitude and field pattern in the nerve trunk and infinite medium environments is made and the effect of interstitial conductivity and nerve trunk diameter on potential magnitudes is considered.

Electrophysiology↗