1. Department of Biological Sciences, Lehman College, and The Graduate Center, The City University of New York, 250 Bedford Park Boulevard West, Bronx, New York 10468; Department of Rehabilitation Medicine, College of Physicians & Surgeons, Columbia University, New York, New York 1003; and Department of Neurology, University of Miami School of Medicine, 1501 N.W. 9th Avenue, Miami, Florida 33136