Brain blood flow and metabolism are vital to the normal mammalian nervous system and provide the basis of functional brain imaging. Over the last decade, dramatic progress has been made in molecular biology, biophysics and genetics that impact on the understanding of brain energy metabolism, neural organization, cell signaling and vascular regulation. In addition, new technologies now enable measures to be made of blood flow and metabolism in the brain with high spatial and temporal resolutions. The stage is set for the use of the methodological progress to address fundamental issues related to the organization of brain function, blood flow, and metabolic activity. We strongly believe that progress in this field will drive new discoveries in the experimental and clinical neurosciences and impact on the diagnosis and treatment of stroke and other neurodegenerative disorders. Every second year, the Gordon research conferences on Brain Energy Metabolism and Blood Flow are devoted to presentations of frontline research of brain metabolism, cell signaling, cell-cell interactions and vascular regulation in the neurovascular unit of normal and injured brains. This 4th conference provides a unique opportunity for experts and novices alike to exchange state-of-the-art experiences with methods, concepts and issues, and to outline collaborative approaches to their resolution. Among these important issues the mechanisms underlying consciousness remain at the forefront of neuroscience. For the 4th GRC on Brain Energy Metabolism and Blood Flow, the general theme is the experimental examination of the relations between oxygen, blood flow, and mitochondrial regulation of brain functions in health and aging.