Preface This book describes problems and results of research in the gap between two fields: Human genetics, and clinical neurophysiology. Whenever I talked about my research on the genetics of the EEG, the answer of human geneticists was: "Very interesting, but I do not understand anything about the EEG. " On the other hand, EEG specialists usually remark: "Very interesting, but I do not understand anything about human genetics. " This is why I wrote this book. It tries to summarize results my own and from some others - and to point to problems. In the from researc- light of the recent progress especially in human molecular genetics, this field of research promises deep insights into biological mechanisms of brain function, as well as genetic variation involved in mental performance, and personality of humans. However, the logistic problems of such studies are not easy to overcome: It is necessary to study carefully ascertained population samples either of "normal" persons, or of persons selected for phenotypic characteristics that are not easy to diagnose. Moreover, EEG diagnosis and classification must be very specific, and is not trivial at all. All these problems require careful preparations at various levels, long-lasting efforts, and patience. Of this I am sure, however: The results would justify the efforts. I am too old to plan such a program myself; moreover, as an emeritus professor, I do not have the means for such studies.