ELECTRICAL ACTIVITY OF SINGLE SPINAL CORD ELEMENTS

Abstract

Using KC1-filled capillary ultramicroelectrodes with tip diameters less than 0.5 microns (Ling and Gerard, 1949), resting and action potentials of single units in cat spinal cord have been recorded. In curarized, decapitate cats, stimulating electrodes were applied to L6DR and L7DR or to gastrocnemius nerves and recording lead placed on L7VR. Spine and pelvis were firmly clamped and movement of the cord due to respiration was minimized by bilateral pneumothorax. The microelectrode was advanced slowly through the spinal cord until it recorded a suddenly appearing, sustained negative potential of 40–100 mv. If afferent or VR stimulation then elicited a monophasic, positive-going action potential superimposed on this resting potential, the electrode tip was adjudged to be within a neuron.