Microcircuits, functional modules that act as elementary processing units bridging single cells to systems and behavior, could provide the link between neurons and global brain function. Microcircuits are designed to serve particular functions; examples of these functional modules include the cortical columns in sensory cortici, glomeruli in the olfactory systems of insects and vertebrates, and networks generating different aspects of motor behavior. In this Dahlem Workshop volume, leading neuroscientists discuss how microcircuits work to bridge the single cell and systems levels and compare the intrinsic function of microcircuits with their ion channel subtypes, connectivity, and receptors, in order to understand the design principles and function of the microcircuits.The chapters cover the four major areas of microcircuit research: motor systems, including locomotion, respiration, and the saccadic eye movements; the striatum, the largest input station of the basal ganglia; olfactory systems and the neural organization of the glomeruli; and the neocortex. Each chapter is followed by a group report, a collaborative discussion among senior scientists.Contributors: Lidia Alonso-Nanclares, Hagai Bergman, Maria Blatow, J. Paul Bolam, Ansgar Büschges, Antonio Caputi, Jean-Pierre Changeux, Javier DeFelipe, Carsten Duch, Paul Feinstein, Stuart Firestein, Yves Frégnac, Rainer W. Friedrich, C. Giovanni Galizia, Ann M. Graybiel, Charles A. Greer, Sten Grillner, Tadashi Isa, Ole Kiehn, Minoru Kimura, Anders Lanser, Gilles Laurent, Pierre-Marie Lledo, Wolfgang Maass, Henry Markram, David A. McCormick, Christoph M. Michel, Peter Mombaerts, Hannah Monyer, Hans-Joachim Pflüger, Dietmar Plenz, Diethelm W. Richter, Silke Sachse, H. Sebastian Seung, Keith T. Sillar, Jeffrey C. Smith, David L. Sparks, D. James Surmeier, Eörs Szathmáry, James M. Tepper, Jeff R. Wickens, Rafael Yuste