[Cerebral Function Monitor and responses to stimuli]

Sudden changes in cerebral activity occurring in response to controlled stimuli or resulting from surgery were recorded with the Monitor of Cerebral Function in an appreciable number of cases. The fluctuations in activity that were observed lasted for various lengths of time and consisted mainly of an elevation of the trace associated with cortical excitation. These fluctuations occurred in various different clinical situations such as under general anaesthesia or under er the effect of barbiturate poisoning. Once we eliminate the possibility that the fluctuations are simply recording artiefacts, then it would seem that their order of magnitude reflects the intensity of the somato-sensory cortical responses that are evoked by a nociceptive stimulus. If this is confirmed, then the M.C.F. would be capable of furnishing a great deal of new knowledge regarding the state of "reactivity" of the cerebral cortex, which is quite distinct from the monitoring of the depressive cortical state.