The Production and Detection of Epileptogenic Lesions in Rat Cerebral Cortex

SUMMARY 1 Epileptogenic lesions have been produced in rat cerebral cortex by the implantation of cobalt but not by glass implants of the same size. 2 The development of the lesion has been monitored by regular recording of the ECoG in the conscious rat. For this purpose specially constructed chronically implanted electrodes have been devised. 3 The effects of implanting cobalt into either parietal or frontal cortex have been studied. Differences in the time of onset, duration and site of origin of the spike discharges have been observed. The discharge is always associated with a motor disturbance consistent with the site of implantation. 4 Evidence that implantation into frontal cortex only results in the development of a secondary focus is presented. The nature of this focus is currently under study. RESUME 1 Des lesions epileptogenes ont ete produites sur le cortex cerebral du rat par implantation de cobalt et non par implants de verre de la meme taille. 2 Le developpement de la lesion a ete regulierement suivi par l'enregistrement de l'ECoG chez le rat conscient. Dans ce but, on a fabrique des electrodes chroniques speciales. 3 On a etudie l'effet de Fimplantation de cobalt dans le cortex parietal et frontal. On a observe des differences en ce qui concerne la duree et le point d'origine des decharges de pointes. Le decharge est toujours associee a un trouble moteur en relation avec le siege de l'implantation. 4 On a mis en evidence que seule l'implantation dans le cortex frontal donne lieu au developpement d'un foyer secondaire. La nature de ce foyer est en cours d'etude.