Development of a High-Fidelity Preamplifier for Use in the Recording of Bioelectric Potentials with Intracellular Electrodes

Abstract

In the intracellular recording of action potentials, the fidelity of recording is limited by the resistance and capacitance of the ultramicroelectrode required for making connection to the intracellular contents, and by the characteristics of the input circuit of the amplifier. The cathode follower circuit conventionally used to minimize the time constant of the recording system is discussed and its shortcomings are analyzed. An improved circuit involving positive feedback is presented. The measurement of the recording system time constant is discussed.