Impulses from Single Nerve Fibres recorded in Man using Microelectrodes

Abstract

OUR knowledge of impulse patterns in the different types of afferent nerve fibres is based chiefly on animal experiments. It is true that Hensel and Boman¹ recorded action potentials from single cutaneous nerve fibres in man using the microdissection method, but this method cannot be used in routine clinical examinations. Moreover, it only allowed investigation of the cutaneous nerves and not of other types of nerve fibres. We therefore considered it of interest to develop a method for recording from single nerve fibres in man using microelectrodes. For this purpose glass-coated platinum-iridium wire electrodes were used, made according to the method described by Wolbarsht and Wagner². The wire had a diameter of 400µ. It was electrolytically polished to a tip of 0.5–1µ As shown by Wolbarsht and Wagner, it is possible to free the metal tip from the glass insulation over a surface of optional size and thereby obtain electrodes of different impedance. In our electrodes the impedance ranged between 40 and 100 kΩ at 1,000 c/s. The electrodes were sterilized by immersion in boiling water for 20 min and then connected to a preamplifier with a cathode follower, the action potentials being displayed on an oscilloscope. A loud-speaker and a tape recorder with a frequency response of 400–19,000 c/s were also used.