Modeling of Electrical Stimulation of Ganglion Cells in Visual Prostheses

In order to properly and effectively perform electrical stimulation in neural prostheses one should understand the effects of stimulation on the operation of the neural system.

To come up with proper physical and electrical stimulation parameters, the first step is to perform mathematical modeling and computer simulations. This paper studies the response of ganglion cells to electrical stimulations in an epiretinal visual prosthesis received from a microelectrode array. The excitation process of the electrically stimulated retinal cells is simulated in a two step procedure. In the first step, the target ganglion cell is represented with all its compartments. In the next step, the resulting extracellular potential is calculated along the neural structure, and finally, the voltage response of the cell membrane to the applied stimulation is analyzed. Unlike the models that have previously appeared in the literature, here the morphology of all compartments of the model cell are considered. Moreover, the electrical potential along all of the three-dimensional compartments is calculated for the duration of the stimulation process. The stimulation source is considered as a point electrode in an infinite and homogenous environment. In the simulations both monophasic and biphasic current pulses are used.

The results show that the responses are in accordance with the values and diagrams of experimental results of previous literature.

The results predicted by the model that is proposed in this work exhibit higher accuracy than the results of other models.