1. Department of Biological Sciences, The University of Warwick, Coventry CV4 7AL, UK
2. Centre for Neurobiology and Behavior, Columbia University, 1051 Riverside Drive, NY 10032 USA
3. Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QJ, UK
4. Netherlands Institute for Brain Research, Meibergdreef 33, Amsterdam, 1105 AZ, The Netherlands
5. Glaxo SmithKline Pharmaceuticals, Coldharbour Road, The Pinnack, Harlow, Essex CM19 5AD, UK