Cerebral Metabolism And Neural Function

From the preface: “Neural Metabolism In Vivo aims to provide a comprehensive overview of neurobiology by presenting the basic principles of up-to-date and cutting-edge technology, as well as their application in assessing the functional, morphological and metabolic aspects of the brain. Investigation of neural activity of the living brain via neurovascular coupling using multimodal imaging techniques extended our understanding of fundamental neurophysiological mechanisms, regulation of cerebral blood flow in connection to neural activity and the interplay between neurons, astrocytes and blood vessels. Constant delivery of glucose and oxygen for energy metabolism is vital for brain function, and the physiological basis of neural activity can be assessed through measurements of cerebral blood flow and consumption of glucose and oxygen.... This book presents the complex physiological and neurochemical processes of neural metabolism and function in response to various physiological conditions and pharmacological stimulations. Neurochemical detection technologies and quantitative aspects of monitoring cerebral energy substrates and other metabolites in the living brain are described under the “Cerebral metabolism of antioxidants, osmolytes and others in vivo” section. Altogether, the advent of new in vivo tools has transformed neuroscience and neurobiology research, and demands interdisciplinary approaches as each technology could only approximate a very small fraction of the true complexity of the underlying biological processes. However, translational values of the emerging in vivo methods to the application of preclinical to clinical studies cannot be emphasized enough. Thus, it is our hope that advances in our understanding of biochemical, molecular, functional and physiological processes of the brain could eventually help people with neurological problems, which are still dominated by the unknowns.” -- In-Young Choi and Rolf Gruetter

This volume is concerned with metabolic reactions occurring in the nervous system. Some time ago, it was thought that since most of the intermediary metabolism that can be observed in the brain is not specific to this organ, there is little justification in studying neural metabolism as such. Later it was realized that for an understanding of neural functions, the understanding of metabolism in the brain and its alterations is essential. All aspects of the metabolism of a substrate in brain, or all metabolic reactions of the nervous system, could not be included in this volume; some will be dealt with in other volumes (such as the ones covering metabolic turn over, alterations of metabolism, or pathology). Review of the aspects covered here clearly shows that the study of metabolic reactions in the nervous system is a very active field, producing important results. As in so many areas of research, as we learn more, new aspects become known, new questions emerge, and we see that in solving some problems we open areas with many additional problems to solve. But the accomplishments to date are impressive and indicate further important advances in the future. Brain metabolism is more active, more plastic, and more comprehensive than previously estimated. It is an essential part of brain function, and with its alteration, brain function will be altered. This shows the importance of more knowledge in this area. It is hoped that this volume will be of assistance in such further studies.

When the projected volumes of the Handbook are completed, most of our current knowledge of the biochemistry of nervous systems will have been touched upon. A number of the chapters will have dealt with the correlations of the biochemical findings with morphological and physio logical parameters as well. Considering the abysmal lack of such attempts, even in the recent past, this is a sign of great progress. If the reader's eventual goal is to derive the "laws" that relate various aspects of animal and human behavior to underlying physiological and biochemical function, these admirable volumes will help him to establish a firm biochemical base from which to operate. It is certain that the future approaches to the various problems of the information-processing functions of the nervous system will require an integrated understanding of the essence of all of the scientific disciplines which are grouped under the general name of neuro biology. The rich feast of information offered up in this Handbook will enable those in the non-chemical disciplines to pick and choose those areas of chemical information pertinent to their immediate interests. Similar types of compendia by physiologists, anatomists, cyberneticists, and psychologists have been helpful to chemists and continue to be so.

Regulation of glucose at the biochemical level affects every area of the brain, and has impact from cellular to behavioral brain function. It plays an important role in diseases such as diabetes, stroke, schizophrenia and drug abuse as well as in normal and dysfunctional memory and cognition. This volume represents a thorough examination of all the major issues that are relevant to glucose metabolism by brain cells in relation to disease, combining basic research and clinical findings in a single, indispensable reference. Serves as an essential reference on glucose metabolism in the brain Presents authoritative accounts by leading researchers in the field Includes thorough reviews with provocative sections on future directions

In recent years, there has been rapid growth in knowledge pertaining to the nervous system. This has, in some measure, been due to the development and application of a number of techniques such as the 2-deoxyglucose method and microchemical methods for measuring metabolites and regional cerebral blood flow. Data from the application of these techniques are just beginning to be collected, and the next few years promise to bring many new and exciting findings. The study of energy metabolism in brain is particularly interesting due to the fact that although the brain has scant energy reserves (as compared with the liver), it has one of the highest metabolic rates in the body. Recent studies from several laboratories have shown a surprising divergence of re sponses to metabolic insult in different areas of brain. In this regard, the cer ebellum, for example, may have metabolic features which are uniqve from those of any other region. The high-energy phosphate compounds ATP and phos phocreatine, supplied by the oxidative metabolism of glucose, are necessary for normal cerebral functions such as the maintenance of membrane potentials, transmission of impulses, and synthetic processes. Interruption of substrate or "poisoning" of the system by a variety of means lead to a rapid change in cellular energetics, and ultimately cell death. From the clinical standpoint, an interesting feature of metabolic encephalopathy is that in many cases, early diagnosis and treatment may result in a rapid reversal of symptoms.

This e-book will review special features of the cerebral circulation and how they contribute to the physiology of the brain. It describes structural and functional properties of the cerebral circulation that are unique to the brain, an organ with high metabolic demands and the need for tight water and ion homeostasis. Autoregulation is pronounced in the brain, with myogenic, metabolic and neurogenic mechanisms contributing to maintain relatively constant blood flow during both increases and decreases in pressure. In addition, unlike peripheral organs where the majority of vascular resistance resides in small arteries and arterioles, large extracranial and intracranial arteries contribute significantly to vascular resistance in the brain. The prominent role of large arteries in cerebrovascular resistance helps maintain blood flow and protect downstream vessels during changes in perfusion pressure. The cerebral endothelium is also unique in that its barrier properties are in some way more like epithelium than endothelium in the periphery. The cerebral endothelium, known as the blood-brain barrier, has specialized tight junctions that do not allow ions to pass freely and has very low hydraulic conductivity and transcellular transport. This special configuration modifies Starling's forces in the brain microcirculation such that ions retained in the vascular lumen oppose water movement due to hydrostatic pressure. Tight water regulation is necessary in the brain because it has limited capacity for expansion within the skull. Increased intracranial pressure due to vasogenic edema can cause severe neurologic complications and death.