Studies of the mechanisms relating blood supply to the brain appeared to be, in some sense, at a deadlock. Despite extensive application of different methodical approaches, no qualitative progress has been observed in these studies at the present time. This is perhaps due to the traditional, but not understandable, separation of neurophysiological and "circulatory" studies. It may seem very paradoxical, but the study of cerebral blood circulation proceeds almost in complete isolation from the knowledge about brain functions and does not take into account the specificity of the working brain as a part of the whole body. This book comprehensively addresses the issues of blood flow regulation. It is well known that the brain belongs to the group of organs having a high level of oxygen consumption. Oxygen consumption by the brain is an average 4.6 ml per 100 g of tissue per minute. In humans, the level of oxygen consumption by the whole brain attains 46 ml/min. This makes up approximately 20% of the total oxygen volume consumed by the organism. Consequently, the cerebral tissue is characterised by highly energetic processes. There is evidence indicating that even in functionally resting conditions, 18% of the entire energy expenditure of the body is utilised by the brain Calculations made by Rushmer indicate that the intensity of energy consumption by the human brain appears to be on average 20 Watt.