1. K. A. Osborne, E. Burgess, S. Butland, R. A. Shaw, A. Coulthard, H. S. Pereira, M. B. Sokolowski, Department of Biology, York University, 4700 Keele Street, North York, Toronto, Ontario, Canada, M3J 1P3.
2. A. Robichon and R. J. Greenspan, Department of Biology and Center for Neural Science, 1009 Main Building, New York University, New York, NY 10003, USA.