ELECTRIC-FIELD DISTRIBUTION WITHIN NORMAL CAT SPINAL-CORD

Electric currents of small magnitude have been used successfully to in duce regrowth of injured spinal cord fibers. The purpose of this study was to determine the potentials and current density distributions on the surface, as well as within the spinal cord, after the application of exogenous electric fields. A 10 mu A DC current was applied epidura lly to the spinal cord using two different electrode configurations. T he two electrode configurations studied were: anode and cathode dorsal (D-D) and anode ventral and cathode dorsal (V-D). Two types of record ing electrodes were used to map the potentials on the surface and with in the spinal cord. The recording system consisted of glass microelect rodes connected to differential amplifiers. The output was recorded on a polygraph. The current density was more localized on the dorsal sur face of the spinal cord for the D-D configuration. In contrast, in the V-D configuration, the current density was greater near the anode on the ventral surface and near the cathode on the dorsal surface of the spinal cord. As a result of the anode being located ventrally, there w as a more uniform current density distribution within the spinal cord.