Bernstein Center for Computational Neuroscience, Institute of Physics III - Biophysics, Georg-August Universitxc3xa4t, Gxc3xb6ttingen, Germany. tetzlaff@physik3.gwdg.de|Bernstein Center for Computational Neuroscience, Institute of Physics III - Biophysics, Georg-August Universitxc3xa4t, Gxc3xb6ttingen, Germany. tetzlaff@physik3.gwdg.de|Bernstein Center for Computational Neuroscience, Institute of Physics III - Biophysics, Georg-August Universitxc3xa4t, Gxc3xb6ttingen, Germany. tetzlaff@physik3.gwdg.de|Bernstein Center for Computational Neuroscience, Institute of Physics III - Biophysics, Georg-August Universitxc3xa4t, Gxc3xb6ttingen, Germany. tetzlaff@physik3.gwdg.de|Bernstein Center for Computational Neuroscience, Institute of Physics III - Biophysics, Georg-August Universitxc3xa4t, Gxc3xb6ttingen, Germany. tetzlaff@physik3.gwdg.de