[1] Univ So Calif, Keck Sch Med, Zilkha Neurogenet Inst, Los Angeles, CA 90089 USA
[2] Univ So Calif, Keck Sch Med, Dept Physiol & Biophys, Los Angeles, CA 90089 USA
[3] CALTECH, Beckman Inst, Biol Imaging Ctr, Pasadena, CA 91101 USA
[4] Univ So Calif, Dept Neurol, Inst Neuroimaging & Informat, Los Angeles, CA 90089 USA
[5] Univ So Calif, Keck Sch Med, Dept Neurobiol, Los Angeles, CA 90089 USA
[6] Univ So Calif, Keck Sch Med, Neuroradiol Div, Dept Radiol, Los Angeles, CA 90089 USA
[7] Huntington Med Res Inst, Pasadena, CA 91101 USA