|"...certain unique features of the metabolism of the central nervous system amplify the importance of in vivo studies. Its normal functions are completely dependent on the obligatory consumption of oxygen and glucose, and its metabolic rate is normally very great, particularly in relation to its stores of these essential nutrients. It is, therefore, dependent on a continuously adequate renewal of these nutrient materials by means of a relatively enormous blood flow, approximately 55ml per 100gm per minute, and interruption of these supplies rapidly leads to impairment of function and irreversible changes. In these circumstances, metabolism
does not cease."