POTENTIALS RECORDED FROM THE NERVE TRUNK AND THE DORSAL ROOT BY MICRO-ELECTRODES

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Abstract
Micro-electrodes have been used to record potentials from nerve trunks and from dorsal root ganglia. The form of the potentials recorded from the nerve trunk by micro-eleclrodes is the same as that recorded by gross electrodes similarly arranged. Micro-electrodes whose tip-diams. are greater than 15[mu] are not sufficiently selective to record single fiber responses from the nerve trunk when large numbers of the fibers are activated synchronously. Small electrodes (16[mu]) attenuate potentials arising at a distance far more than do large electrodes (42[mu]). The ganglionic potential curve is very complex when recorded by large micro-electrodes within the ganglion. It is composed of waves representing activity of the nerve fibers contained in the ganglion and others representing activity of the cell bodies. In a few instances single cell-body potentials have been recorded from the ganglia. This cell-body spike has a greater latency than can be explained by the conduction time in the nerve fiber and this delay probably represents a slowing of the depolarization wave as it invades the cell body.