Electric field distribution within normal cat spinal cord.

Electric currents of small magnitude have been used successfully to induce 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 microA DC current was applied epidurally to the spinal cord using two different electrode configurations. The two electrode configurations studied were: anode and cathode dorsal (D-D) and anode ventral and cathode dorsal (V-D). Two types of recording electrodes were used to map the potentials on the surface and within the spinal cord. The recording system consisted of glass microelectrodes connected to differential amplifiers. The output was recorded on a polygraph. The current density was more localized on the dorsal surface 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 was a more uniform current density distribution within the spinal cord.