Spike-Conducting Integrate-and-Fire Model

Abstract

Modeling is a useful tool for investigating various biophysical characteristics of neurons. Recent simulation studies of propagating action potentials (spike conduction) along axons include the investigation of neuronal activity evoked by electrical stimulation from implantable prosthetic devices. In contrast to point-neuron simulations, where a large variety of models are readily available, Hodgkin–Huxley-type conductance-based models have been almost the only option for simulating axonal spike conduction, as simpler models cannot faithfully replicate the waveforms of propagating spikes. Since the amount of available physiological data, especially in humans, is usually limited, calibration, and justification of the large number of parameters of a complex model is generally difficult. In addition, not all simulation studies of axons require detailed descriptions of nonlinear ionic dynamics. In this study, we construct a simple model of spike generation and conduction based on the exponential integrate-and-fire model, which can simulate the rapid growth of the membrane potential at spike initiation. In terms of the number of parameters and equations, this model is much more compact than conventional models, but can still reliably simulate spike conduction along myelinated and unmyelinated axons that are stimulated intracellularly or extracellularly. Our simulations of auditory nerve fibers with this new model suggest that, because of the difference in intrinsic membrane properties, the axonal spike conduction of high-frequency nerve fibers is faster than that of low-frequency fibers. The simple model developed in this study can serve as a computationally efficient alternative to more complex models for future studies, including simulations of neuroprosthetic devices.

Recording Saltatory Conduction Along Sensory Axons Using a High-Density Microelectrode Array

“…The first possibility that it represented conduction in an unmyelinated axon is unlikely for the following reason. Numerical calculations show that conduction velocity of 2 m/s occurs in unmyelinated axons with diameters of approximately 20 μm ( Ashida and Nogueira, 2018 ). Contrastingly, the diameter of unmyelinated axons was around 0.3 μm, and the maximum diameter of unmyelinated axons was 0.58 μm, as noted from TEM observations.…”

A phenomenological computational model of the evoked action potential fitted to human cochlear implant responses

“…Our model fits the clinical data of a specific patient. The prototype consists of a set of line sources, the virtual neurons (VNs), propagating the membrane currents given by Hodgkin-Huxley-type (H-H) models, (see e.g., [ 33 – 35 ]). The extracellular potential generated by the VN is calculated by FEM.…”

“…In this case, we can consider each VN as a line current source with a spatio-temporal dependence given by λ( t , s ) = λ( t − v −1 s ), where s is the arc length of VN and v is the conduction velocity in the ANF. The line current density λ( t ) is inferred from the Hodgking-Huxley model for an ANF from [ 35 ]. The determination of λ( t − v −1 s ) will be detailed in a subsection below.…”

Effect of Channel Interaction on Vocal Cue Perception in Cochlear Implant Users

“…An electrode carrier with 16 half-band electrode contacts modeling the HiFocus 1 J was created, as shown by the blue array in the left panel of Figure 4 . The physiology of the auditory nerve fiber was modeled as in Ashida and Nogueira (2018) . The voltage distribution from the FEM, as shown in the right panel of Figure 4 , was sampled at the most peripheral node of the nerve section.…”