1. Volen National Center for Complex Systems, Brandeis University, Waltham, MA 02454, USA.
2. Department of Biophysics, Research Institute for Particle and Nuclear Physics, Hungarian Academy of Sciences, H-1121 Budapest, Hungary.
3. Computational and Biological Learning Lab, Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, UK.
4. Department of Psychology and the Neuroscience Program, Brandeis University, Waltham, MA 02454, USA.
5. Collegium Budapest Institute for Advanced Study, Szentháromság utca 2, Budapest H-1014, Hungary.