Suppression-burst activity from isolated cerebral cortex in man.

Abstract 1. 1. Direct electrical recording from the cortex of man has been carried out on 34 patients before, throughout and following prefrontal lobotomy. Operations were done under local as well as Pentothal anesthesia, and included the classical or standard “open” prefrontal lobotomy and surgical isolation by undercutting of both superior convexity (partial Brodmann areas 9 and 10) and orbital surfaces. The pial circulation was preserved in all cases. 2. 2. All cases showed a marked decrease in electrical activity from cortex rostral to the section, and all but one showed the development of bursts of fast activity alternating with quiet sections of record. Such bursts were usually superimposed on or followed by high voltage very slow delta activity. 3. 3. This suppression-burst activity was confined to isolated cortex and was not seen from leads lateral and posterior to such cortex. It was characteristically asynchronous from right and left sides. 4. 4. Suppression-burst activity, as judged from its continued presence at the time of repeat operation,persisted for over a year in the electrogram of undercut cortex, but was not detected in the scalp EEG. 5. 5. Suppression-burst activity, while resembling the patterns of barbiturate bursts, does not depend on barbiturate or other anesthesia for it developed in characteristic form in cases operated under local anesthesia. 6. 6. This pattern is probably analogous to that seen in cats following lesions to the basal diencephalon. It is possibly related to the release of cortex from the influence of the reticular activating system. 7. 7. Some of the literature dealing with the relative role of cortex and thalamus is reviewed. It is concluded that there is autochthonous electrocortical activity and that reverberating thalamo-cortical circuits are not necessary for the maintenance of such activity.