Department of Theoretical Neuroscience, Bernstein-Center for Computational Neuroscience, Central Institute of Mental Health, Medical Faculty Mannheim of Heidelberg University, Mannheim, Germany.|Modelling of Cognitive Processes, Berlin Institute of Technology and Bernstein Center for Computational Neuroscience Berlin, Germany.|Department of Theoretical Neuroscience, Bernstein-Center for Computational Neuroscience, Central Institute of Mental Health, Medical Faculty Mannheim of Heidelberg University, Mannheim, Germany.