Evidence for a Postsynaptic Origin of the Surface-negative Response to Direct Stimulation of the Cat's Cerebral Cortex

Abstract

ADRIAN¹ first demonstrated that a surface-negative potential, lasting approximately 20 msec, is produced by a single brief electrical stimulus of weak intensity applied to the exposed cerebral cortex. This response spreads not more than 10 mm across the cortical surface, conducted along elements confined to the molecular layer (layer I) of the cortex^2–4. There is disagreement as to the nature of this surface-negative response⁵. Some investigators have concluded that this potential is generated by the nervous processes which conduct the response^2–4. Others hold that potentials generated by activity in these elements cannot be recorded at the surface and that the surface-negative response is a postsynaptic potential generated in elements other than those conducting the response⁶.