Extracellular electrical signals in a neuron-surface junction: model of heterogeneous membrane conductivity |
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Authors: | Email author" target="_blank">Pavel?M?BulaiEmail author Pavel?G?Molchanov Andrey?A?Denisov Taras?N?Pitlik Sergey?N?Cherenkevich |
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Institution: | (1) Department of Biophysics, Physics Faculty, Belarusian State University, Nezavisimosty Av. 4, 220050 Minsk, Belarus |
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Abstract: | Signals recorded from neurons with extracellular planar sensors have a wide range of waveforms and amplitudes. This variety
is a result of different physical conditions affecting the ion currents through a cellular membrane. The transmembrane currents
are often considered by macroscopic membrane models as essentially a homogeneous process. However, this assumption is doubtful,
since ions move through ion channels, which are scattered within the membrane. Accounting for this fact, the present work
proposes a theoretical model of heterogeneous membrane conductivity. The model is based on the hypothesis that both potential
and charge are distributed homogeneously on the membrane surface, concentrated near channel pores, as the direct consequence
of the inhomogeneous transmembrane current. A system of continuity equations having non-stationary and quasi-stationary forms
expresses this fact mathematically. The present work performs mathematical analysis of the proposed equations, following by
the synthesis of the equivalent electric element of a heterogeneous membrane current. This element is further used to construct
a model of the cell-surface electric junction in a form of the equivalent electrical circuit. After that a study of how the
heterogeneous membrane conductivity affects parameters of the extracellular electrical signal is performed. As the result
it was found that variation of the passive characteristics of the cell-surface junction like conductivity of the cleft and
the cleft height could lead to different shapes of the extracellular signals. |
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