Experimental Assessment of Epileptogenesis in the Monkey Cerebral Cortex

Introduction In previous studies French, Gernandt, and Livingston¹¹observed that upon direct repetitive stimulation different areas of the monkey's cerebral cortex displayed different thresholds for the induction of electrical after-discharges. The motor cortex had the lowest and the occipital the highest threshold for seizure induction with this technique. A subsequent study by Eidelberg, Konigsmark, and French⁹revealed that this differential susceptibility to seizure induction was paralleled by differences in the amplitude of the direct cortical responses (DCR) to single-shock local electrical stimulation. The maximum amplitudes were encountered in the motor cortex, while minimum deflections were found in the occipital cortex; intermediate values were present in other areas of the convexity. Recently Kandel, Spencer, and Brinley¹⁸have reported very large responses to be elicited by a similar technique on the dorsal hippocampal surface, one of the most epileptogenic structures. Chang,⁵,⁶Clare and Bishop,⁷and others have