Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany.|Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany.|Department of Biology, Randolph-Macon College, Ashland, Virginia, United States of America.|Department of Orthopaedic Surgery, Duke Institute for Brain Sciences, Duke University, Durham, North Carolina, United States of America.|Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany.