1 Bernstein Center for Computational Neuroscience Berlin, Philippstr. 13, Haus 2, 10115, Berlin, Germany. bc@bccn-berlin.de.
2 Department of Physics, Humboldt University Berlin, 12489, Berlin, Germany. bc@bccn-berlin.de.
3 Department of Mathematics, Applied Mathematics, and Statistics, Department of Electrical Engineering and Computer Science, Department of Cognitive Science, Department of Biology, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106-7058, USA.
4 Department of Psychology, Biomedical Engineering and Applied Mathematics, University of Arizona, 1503 E. University Blvd., Tucson, AZ, 85721, USA.