INTERFACING CULTURED NEURONS TO PLANAR SUBSTRATE MICROELECTRODES - CHARACTERIZATION OF THE NEURON-TO-MICROELECTRODE JUNCTION

This paper focuses on the characterization of the bioelectrochemical i nterface that develops whenever neurons are cultured directly on top o f planar arrays of noble metal microelectrodes. The characterization i s based on the equivalent circuit analysis of a neuron membrane couple d to a metallic planar microelectrode. The membrane is described accor ding to the Hodgkin-Huxley model, using a set of equations specialized for the description of action potentials generated by chick embryo do rsal root ganglia (DRG) neurons. An ad-hoc modified version of the cir cuit analysis program SPICE allows one to simulate the signal correspo nding to an action potential as it should result from the microelectro de transduction. By varying the membrane-to-electrode coupling and oth er biophysical parameters, simulation signals of different durations, intensities and shapes are generated. The appropriateness of the model is verified by adapting simulation signals to experimental ones, obta ined by preliminary experiments with DRG neurons cultured on a microel ectrode array. The potentialities and limitations of the equivalent ci rcuit approach as a tool for the characterization of a long-term (i.e. days) coupling of neurons to planar microelectrodes are discussed.