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README.md

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+# Neuron demo file to simulate local field potentials
+
+This Neuron demo file simulates the model of local field potentials (LFP) with variable resistivity, as described in the following paper:
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+Bedard C, Kroger H and Destexhe A. Modeling extracellular field potentials and the frequency-filtering properties of extracellular space. *Biophysical Journal* 86: 1829-1842, 2004.
+
+This paper develops a model of LFP that includes the frequency filtering properties of extracellular space. The paper considers inhomogeneous conductivity and permittivity profiles, which results from the multiple media (fluids, membranes, vessels, ...) composing the extracellular space around neurons. Including non-constant profiles of conductivity enables the model to display frequency filtering properties, ie slow events such as EPSPs/IPSPs are less attenuated than fast events such as action potentials.
+
+The model shown here is a reproduction of Figure 6 of the paper. The source current is monopolar in this simple case and consists of an EPSP/IPSP sequence followed by an action potential (see details in the paper).
+
+The method to calculate the extracellular LFP consists of the following steps:
+
+- read in the source current I from a data file
+- compute the Fourier transform of the source current I
+- compute the impedance Z assuming a non-homogeneous conductivity function (radial symmetry) - this step requires a MOD file with the ImpedanceFM mechanism
+- compute the extracellular voltage by inverse Fourier transform of the product Z(w) * I(w)
+
+Note that this demo file is provided "as is", unfortunately I have no time to help implementing, but feedbacks are always welcome if it has been useful to you. If you use this for your research, please cite the above paper.
+
+Alain Destexhe,  
+CNRS, Gif sur Yvette, France  
+[http://cns.iaf.cnrs-gif.fr](http://cns.iaf.cnrs-gif.fr)
+
+Changelog
+---------
+2022-05: Updated MOD files to contain valid C++ and be compatible with the upcoming versions 8.2 and 9.0 of NEURON.
+
+2025-06-02: Converted README to Markdown.