1. C. Ikonomidou, F. Bosch, M. Miksa, P. Bittigau, J. Vöckler, V. Stefovska, Department of Pediatric Neurology, Charité-Virchow Clinics, Humboldt University, Augustenburger Platz 1, 13353 Berlin, Germany. K. Dikranian, T. I. Tenkova, J. W. Olney, Department of Psychiatry, Washington University School of Medicine, 4940 Children's Place, St. Louis, MO 63110, USA. L. Turski, Eisai London Research Laboratories, Bernard Katz Building, University College London, Gower Street, London WC1E 6BT, UK.