On April 1, 1992, Otto Creutzfeldt would have celebrated his 65th birthday. About a year before, those of us who worked with him in the Department of Neurobiology decided to organize a meeting to honour Otto and his contri butions to neuroscience. Since Otto Creutzfeldt had no intention of retiring before his 67th birthday, this was not to be a "retirement conference" but a celebration on the occasion of a major anniversary. However. events turned out differently. In the spring of 1991, Otto Creutzfeldt became seriously ill, before we could consult with him on his suggestions for such a meeting, and we decided to postpone further dis cussion until his health improved. In the summer, when we talked to him about the meeting, he basically approved of the idea but immediately sug gested our turning it into a proper scientific congress, rather than limiting ourselves to inviting his friends and former co-workers. He had very good friends in many parts of the world and would certainly have liked to see many of them again. However, his interest in science remained the domi nant factor. He proposed the main topics for the conference and suggested several speakers to be invited. Although he knew that his health was crit ical and that his condition could rapidly worsen, we had the feeling that the planning gave him hope and perhaps an opportunity to look forward."

The basic thesis for this study was that the telencephalon is needed to make decisions in new situations. Subsidary hypotheses were that the telencephalon consists of: (a) a sensorimotor system which generates motor activity from sensory input and (b) a selection system which makes choices from possible motor programs. It was postulated that the selection system should fulfil the following requirements: be accessible for past and present events, have the capacity to process this information in a nondetermined way with a possibility for ordering, and have access to motor-affecting systems (the sensorimotor system). The ability of the selection system to correlate information in a nonpredetermined way was considered most important. In short: The selection system should be able to associate any information in any combination, and have the capability for internal control of neuronal activity and external selection of motor programs (see Fig. IA. ) Xenopus laevis was chosen as a subject, since it has a relatively simple tel encephalon, with characteristics that it shares with "primitive" species of different vertebrate classes, and because it is easy to maintain as a laboratory animal. The main method used was the determination of connections with HRP. The pallium was in the focus of attention, since it was considered to be the core of the selection system. Immunohistochemistry was used as an additional parameter to compare Xenopus laevis forebrain with those of other vertebrates.