Modeling the neuron-microtransducer junction: from extracellular to patch recording

A detailed characterization of the neuron-to-microtransducer junction, based on the equivalent electric-circuit approach, is provided. The recording of action potentials is then simulated with the general-purpose network-analysis program SPICE. Both noble-metal microelectrodes and insulated-gate FETs are considered. The responses of such devices are characterized as functions of several parameters, e.g. sealing impedance, density of ionic currents in the cell membrane, and spatial discontinuities of the adhesion process. It is shown that the various signal shapes reported in the literature can be reproduced and interpreted in terms of time derivatives of the action potential. In this way, the shape of any experimental signal can be interpreted on the basis of a specific sealing condition. Possible future improvements in microtransducer design, based on the proposed approach, are also suggested.