There is a tradition of theoretical brain science which started in the forties (Wiener, McCulloch, Turing, Craik, Hebb). This was continued by a small number of people without interruption up to the present. It has definitely provided main guiding lines for brain science, the devel­ opment of which has been spectacular in the last decades. However, within the bulk of experimental neuroscience, the theoreticians some­ times had a difficult stand, since it was felt that the times were not ripe yet and the methods not yet available for a development of a true theoretical speciality in this field. Thus theory remained in the hands of a fairly small club which recruited its members from theoretical physicists, mathematicians and some experimentalists with amateurish theoretical leanings. The boom of approaches which go by the name of 'computational neuroscience', 'neuronal networks', 'associative mem­ ory', 'spinglass theory', 'parallel processing' etc. should not blind one for the fact that the group of people professionally interested in real­ istic models of brain function up to the present date remains rather small and suffers from a lack of professional organization. It was against this background that we decided to organize a meet­ ing on Theoretical Brain Science. The meeting was held April 18 - 20, 1990 and took place at Schloss Ringberg, West-Germany, a facility sponsored by the Max-Planck-Society.