1. From the Department of Neurology (S.R.Z., E.M.G., M.Y.L., P.F.W., R.J.O.B., J.W.K.) and Department of Neuroscience (P.F.W., J.W.K.), Johns Hopkins University, Baltimore, MD; and Department of Neurology, University of Utah, Salt Lake City, UT (R.E.H.)