SINCE the original observations of Caton [1875] various workers have recorded changes of electrical potential in the brain. It has been established that active parts become negative to inactive, but it is difficult to say what elements of the central nervous system are responsible for the effect. The action potentials of the nerve fibres will presumably contribute something, though Baglioni's experiments with strychnine [1905] favoured the nerve cells as the most important factor. The structures involved are so complex, however, that in recent years very little has been added to our knowledge of the central nervous system by the investigation of its potential changes'.The present experiments fall into line with earlier work in showing changes which can be localized and related to the normal activity of the brain, and the same difficulty arises when we attempt a further analysis. But a tentative analysis is possible and its results are of some interest.They suggest a type of electrical activity which differs from that of the nerve fibre in its much more gradual rise and decline, and this agrees with what we might expect from entirely different lines of work on the central nervous sytem.METHOD. The preparation employed was the isolated brain stem of the goldfish removed from the skull and placed on a glass slide. Complete isolation may seem an unnecessary precaution, and the damage occurring through manipulation and from loss of the circulation must have accounted for many failures to observe any sort of activity. But in making a preliminary survey we were anxious to avoid all extraneous electric changes such as those due to the heart and the skeletal muscles. With a sensitive 1 A preliminary account of work by Bartley and Newman [1930] promises a fresh development, but details are not yet available. 9 PH. LXXI.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.