[1] Univ Maryland, Sch Med, Dept Pediat, Baltimore, MD 21201 USA
[2] Ecole Polytech Fed Lausanne, Lab Funct & Metab Imaging, Lausanne, Switzerland
[3] VA Med Ctr, Dept Neurol, San Francisco, CA USA
[4] Univ Arkansas Med Sci, Dept Neurol, Little Rock, AR 72205 USA
[5] Wake Forest Univ Hlth Sci, Dept Biochem & Mol Biol, Winston Salem, NC USA