Contemporary Neuroscientists – serie

Psychologists and philosophers have grappled unsuccessfully through the ages with the ultimal mysteries of the mind. How is consciousness generated by the brain? What unique cerebral processes accoun for mental events among the myriad of brain activities? How does the brain generate and process mental activity - thought, learning, and memory-when this is unconscious, and how does this differ for conscious mental events? Collected here for the first time and annotated by the author are the key publications of Dr. Benjamin Libet, whose work during thirty years of exploring the human brain has helped estabush a new basis for studying subjective mental phenomena-a basis for clarifying the mysteries of mind / brain relationships with hard experimental investigations. The papers herein present the results of experiments with awake human patients undergoing therapeutic surgical procedures. Intracranial electrodes were placed in the brains of these petients to monitor electrophysiological concomitants and to alter mental activity. The dramatic results reported in these classic papers establish a new field of study and a new scientific basis for understanding the workings of the human mind.This fascinating collection win be invaluable to psychologists, psychiatrists, and neuroscientists, as well as those interested in the philosophy of consciousness.

and made insignificant in practice, by selecting for study simple kinds of ex­ periences which are devoid of emotional content and which can be tested for reliability. A simple somatosensory ''raw feel" fulfills these characteristics (see papers nos. 2,5). In any case, if we fail to find ways to use introspective reports in convincingly acceptable studies we would give up the ability to investigate the relation between conscious experience and neural activity, something warned against by William James (Krech, 1969). Another factor in the dearth of direct experimental studies is, of course, the comparative inaccessibility of the human brain for such purposes. Meaningful investigations of the issue in question requires simultaneous study of brain events and introspective reports of experiences in an awake, cooperative human subject. Analysis by neuropsychologists of pathological lesions in the brain and the related disturbances of conscious functions have contributed much to mapping the pos­ sible representations of these functions. The non-invasive recording of electrical activity with electrodes on the scalp, starting from Berger's initial EEG record­ ings in 1929, has contributed much to the problems of states of consciousness and to various cognitive features associated with sensory inputs, but not as much to the specific issue of conscious experience.

I received my first introduction to the brain sciences in 1936 and 1937, for me the second and third years of the 7-year medical school curriculum at the University of Leiden. During those years my interest in the subject was aroused in particular by the brilliant lectures of the physiologist G. C. Rademaker - a prominent former member of the Rudolf Magnus school - and the neurohistologist S. T. Bok, noted especially for his histometric studies of the cerebral cortex. Fascinated as I was by everything I learned about the brain from these outstanding teachers, toward the end of their courses I began to notice conspicuous gaps that separated neurophysiology from neuroanatomy. In fact, I could (or thought I could) detect a reasonable concordance between the two sciences only in case of some sensory and somatic-motor systems. For most other functions anatomical substrates seemed either poorly defined or, as in the case of the central viscero-endocrine system, hardly recognized at all. With all the arrogance of which a 20-year old student is capable I concluded that what the brain sciences needed was a new and more complete anatomy that emphasized in particular the continuity of, and convergences or interconnections between individual conduction systems. And I wistfully mused that perhaps at some time in the future I could make such an endeavour part of my own career.