The origins of EEG
Hans Berger's invention of the electroencephalogram (EEG) is one of the most surprising, remarkable, and momentous developments in the history of clinical neurology. It is a well-known fact that Berger was the first to record the human EEG. Yet the unusual motivation for Berger's psychophysical research program, his eccentric model of cerebral energetics, and the technical, personal, and political obstacles that marked the path of his discovery deserve historical attention. Understanding Berger's work within the context of his own scientific era and life's experiences highlights both the familiar and the foreign in Berger's story, and provides an historical prelude to the modern investigation of the brain and its functions.
As a young man, Berger was involved in a bizarre military accident that almost cost him his life. Thereafter he maintained an unwavering belief in mental telepathy and embraced the philosophical concept of interactionism, arguing for a physical connection between mind and brain at a time when the world of brain research was polarized by recurrent debates between localizationism and holism, having already divorced itself from philosophical speculation. As a former student of the physical sciences Berger adopted a naturwissenschaftlich approach to psychophysical research, applying the most rigorous scientific law of his day - conservation of energy - to the functions of the brain. Indeed, energy conservation was applied for models of brain function by figures as the Gustav Fechner, August Forel, Theodor Meynert, and experimental psychologists Hugo Munsterberg, Oswald Külpe, and Alfred Lehmann.
It was Lehmann's theory of cerebral energetics that clearly identified the boundary conditions for Berger's psychophysical study of brain function: namely, the supply of metabolic energy to the brain and its transformation into heat, electricity, and mental phenomena. He speculated that with reasonable estimates of cortical energy stores and precise measurements of the heat and electricity produced in cortical tissue, it would be possible to calculate the energy converted into thought, feelings and emotions, i.e. psychic energy! Over the next three decades, Berger adopted this thermodynamic model of brain function and pursued each of these lines of investigation. Following the earlier work of Angelo Mosso, Berger first recorded changes in cerebral blood flow in patients with cranial defects with the use of a plethysmograph. Later, Berger turned from recording the energy supply to the brain, to measuring the energy converted into heat and electricity during various mental tasks. It was the last of these challenges, recording the electrical current of the brain from the surface of the scalp, that ultimately Berger led to his Hirnspiegel (brain-mirror), the human EEG.
There were many obstacles to his achievement. Berger had only minimal training in basic electrophysiology and he was constantly operating the most delicate of physiological instruments at the outer limits of their sensitivity. Every improvement in recording technique or apparatus brought its own set of technical difficulties, exacerbating Berger's self critical attitude and bouts of depression. In addition, many of Berger's colleagues at Jena were critical of his work and alienated by his promotion to Professor of Psychiatry, adding to his isolation at Jena. Berger perservered throughout, however, and pioneered the theory and application of EEG in many neurological and psychiatric diseases. When Berger described his technique for recording the electrical activity of the human brain from the surface of the head in 1929, the medical and scientific establishments met him with incredulity and overwhelming skepticism when they did not ignore him altogether, only accepting the human EEG after Berger's discovery was replicated by the Cambridge physiologist Lord Adrian in 1934.
Session VI -- Anatomical and Physiological Models and Techniques
Los Angeles, California, USA