State-of-the-art potential clamp device for myelinated nerve fibres using a new versatile input probe

A potential clamp device for myelinated axons is presented which, for the first time, systematically optimizes all the methodological parameters that limit the reliability of ionic current measurements. A crucial step toward this end consisted in the development of a new input probe with broad-band, extremely low-capacitance characteristics. In combination with a simple-to-use compensation criterion for optimum positive feedback, based on plausible assumptions, and with additional technological improvements, it enables the measurement of ionic currents with a reliability never previously achieved. The consequences with respect to evaluation of several earlier findings are discussed.