1. E. H. Buhl, MRC Anatomical Neuropharmacology Unit, Oxford University, Mansfield Road, Oxford OX1 3TH, UK.
2. T. S. Otis, Department of Neurophysiology, University of Wisconsin Medical School, Medical Sciences Center, 1300 University Avenue, Madison, WI 53706-1532, USA.
3. I. Mody, Department of Neurology RNRC 3-131, UCLA School of Medicine, 710 Westwood Plaza, Los Angeles, CA 90095-1769, USA.