The results of studies with the [14C]deoxyglucose technique establish that local energy metabolism in cerebral tissues is, as in other tissues, closely coupled to local functional activity. Stimulation of local functional activity increases the local rate of glucose utilization; reduced functional activity depresses it. Local cerebral blood flow is normally distributed among the cerebral structures in almost exact proportion to their rates of glucose utilization and changes together with local glucose consumption in response to altered local functional activity. These results demonstrate that the level of functional activity in the structural and functional components of the central nervous system regulates the local rate of energy metabolism, and local blood flow is adjusted to the local metabolic demand.