European and American biological scientists offer 13 papers on such aspects as functional modules in biological signalling networks, controlling the immune system with diffuse feedback through a diffuse informational network, humoral coding and decoding, designing immune- based interventions in autoimmunity and viral infections, the development of high-throughput tools to unravel the complexity of gene expression patterns in the mammalian brain, efficiency and complexity in neural coding, and the predictive learning of temporal sequences in recurrent neocortical circuits. Summaries are included for discussions following each paper and for three general discussions.