Berger lecture. Is Berger's dream coming true?

In the last quarter of our century technologies have been developed that permit us to measure and localize with previously unknown precision physiological concomitants of mental activities. Human in vivo cerebral psychophysiology has come of age, decades after the discovery of EEG. In part this has come about through the development of PET and most recently dynamic MRI. However, it is hardly known today that the concepts which underlie these modern methods of studying the physiological correlates of human mental activity were the focus of Berger's early research at the onset of his scientific career at the turn of the century. Indeed at that time he attempted to study human mental function through measuring cerebral blood flow by means of plethysmography applied to patients who had pulsating skull defects. He also measured intracerebral temperature changes during neurosurgical procedures in awake, locally anesthetized, patients in a quest of identifying metabolic concomitants of mental activity. He was thus well ahead of his time, but was forced to give up these methods because they were not commensurate to the task. Only at age 50 he turned to electrophysiology and discovered the EEG. At last he was able to identify some electrophysiological facets of human psychophysiology related to attention, sleep, wakefulness and coma. This essay will illustrate some examples of PET, functional MRI, computerized EEG and cerebral electrical stimulation studies that show that Berger's conceptual approaches to human psychophysiology, even though he could not effectively apply them himself, were correct and have become powerful tools of modern neuroscience.