1. Department of Animal Physiology, University of Tübingen, Auf der Morgenstelle 28, 72076 Tübingen, Germany;
2. INSERM, Cognitive Neuro-Imaging Unit, IFR 49, Gif sur Yvette, France, CEA, NeuroSpinCenter, IFR 49, Gif sur Yvette, France, Collège de France, Paris, France;