1. Centre for Computational, Neuroscience and Robotics (CCNR), Evolutionary and Adaptive Systems Group (EASy), COGS/Informatics, University of Sussex, Brighton BN1 9QH UK
2. Centre for Computational Neuroscience and Robotics (CCNR), Evolutionary and Adaptive Systems Group (EASy), COGS/Informatics, University of Sussex, Brighton BN1 9QH UK and IRIDIA Université Libre de Bruxelles Avenue, Franklin Roosevelt 50, CP 194/6, B-1050 Brussels, Belgium