PyFibers: An open-source NEURON-Python package to simulate responses of model nerve fibers to electrical stimulation
Fig 2
Simulation results generated by the code in Box 2; code for recording state variables, calculating the single fiber action potential, and generating plots is not included in Box 2, but can be found in the dataset associated with this manuscript. Stimulation of a 10 μm diameter MRG fiber with a length of 25 nodes (27 mm). The extracellular potentials were calculated using a point source of current located halfway along the fiber at an electrode-fiber distance of 250 μm in an isotropic, homogeneous medium with a conductivity of 10 S/m. The stimulation was a 0.15 ms, monophasic rectangular pulse (from t = 0.1 to 0.25 ms) delivered at threshold amplitude (−0.766 mA). A) Transmembrane potential plotted for all fiber nodes. Vm = −80 mV (white) is the resting transmembrane potential. B) Transmembrane potential recorded at node 11 (“center”) and node 23 (“end”, i.e., second-to-last since the end nodes are passive). C) Gating variables for the center node. D) Single fiber action potential recorded from a point electrode at 90% of the fiber length with a 250 μm electrode-fiber distance in an isotropic medium with conductivity of 10 S/m. Vm = transmembrane voltage (mV).