Cortical Discontinuity and Propagation of Spreading Depression

¹ From the Kerckhoff Laboratories of the Biological Sciences, California Institute of Technology, Pasadena, California

The transmissibility of spreading depression across a cut severing all layers of the cortex was investigated in preparations in which 3 weeks to 3 months was allowed for healing of such an injury. No unequivocal signs of transmission of the spreading depression across the scar were observed, although in some instances the scar was less than 0.1 mm wide. In some experiments a small slow potential change was led off from the cortex on the nonstimulated side by an electrode placed in the immediate vicinity of the scar. This potential was considered as evidence for the physical spread across the scar of the potential field produced by the slow potential change which accompanies the spreading depression on the stimulated side. The failure of transmission of spreading depression across a scar does not support the concept that the slow potential change is the agent involved in the propagation of this phenomenon.