Brain Dynamics – serie

What is the source of the electroencephalogram, or "EEG", the human electrical brain activity that manifests itself in scalp recordings? Although encephalography is still one of the most widely-used measurement techniques in neurological diagnostics and neurophysiological research, the generators in the brain of the EEG recordings are still widely unknown. This volume, commemorating the discovery of EEG by Hans Berger, brings together the latest ideas and findings of international experts in neurological and neurophysiological research. Combining new scientific findings with thorough state-of-the-art reviews of the basic mechanisms of the EEG, the chapters examine the relationships between cortical single-cell activity and EEG, the significance of subcortical structures and transmitter systems to the dynamics of the EEG, the generation of cortical field potentials, the relevance of glial cell activities and cell metabolism to EEG. These relationships are explored in their neurophysiological, clinical and neuropathological aspects.

This volume is based on selected and updated papers from the symposium on "Basic Mechanisms of the EEG," which was held under the sponsor­ ship of the German EEG Society in Hamburg on September 28-29, 1990. The intention of this symposium was to relate recent experimental, clini­ cal, and neuropathological data on the basic mechanism that underlie the EEG. Although we know much about these mechanisms, there is still much more to be learned. The symposium was partly the continuation of an earlier symposium on "Origin of Cerebral Field Potentials" held in 1979 in Munster under the leadership of one of the present editors (E. -J. Speckmann) and H. Caspers. The present work combines new experimental and clinical results with state-of-the-art reports giving excellent general views. The first chapter presents a historical survey of the roots of current developments in neu­ rophysiology. It seems that in the near future we may decipher the EEG, which we have considered up to now somewhat as a cryptogram (chap­ ter 2). After chapter 3-a chapter concerned with more general points of the generation of cortical field potentials-chapters 4, 5, and 6 deal with several aspects and models of interactions and rhythms of cortical neurons. The role of glial cells in cortical electrical field generation is considered in chapter 7. Chapter 8 emphasizes the significance of brain metabolism.

It is easy to imagine the excitement that pervaded the neurological world in the late 1920's and early 1930's when Berger's first descriptions of the electro­ encephalogram appeared. Berger was not the first to discover that changes in electric potential can be recorded from the surface of the head, but it was he who first systematized the method, and it was he who first proposed that explanatory correlations might be found between the electroencephalogram, brain processes, and behavioral states. An explosion of activity quickly fol­ lowed: studies were made of the brain waves in virtually every conceivable behavioral state, ranging from normal human subjects to those with major psychoses or with epilepsy, to state changes such as the sleep-wakefulness transition. There evolved from this the discipline of Clinical Electroencepha­ lography which rapidly took a valued place in clinical neurology and neuro­ surgery. Moreover, use of the method in experimental animals led to a further understanding of such state changes as attention-inattention, arousal, and sleep and wakefulness. The evoked potential method, derived from electro­ encephalography, was used in neurophysiological research to construct pre­ cise maps of the projection of sensory systems upon the neocortex. These maps still form the initial guides to studies of the cortical mechanisms in sensation and perception. The use of the event-related potential paradigm has proved useful in studies of the brain mechanisms of some cognitive functions of the brain.