[1] Univ Michigan, Dept Radiol, Ann Arbor, MI 48105 USA
[2] Univ Michigan, Funct Neuroimaging Cognit & Mobil Lab, Dept Radiol, 24 Frank Lloyd Wright Dr,Box 362, Ann Arbor, MI 48105 USA
[3] Univ Michigan, Dept Neurol, Funct Neuroimaging Cognit & Mobil Lab, Ann Arbor, MI 48105 USA
[4] Univ Michigan, Morris K Udall Ctr Excellence Parkinsons Dis Res, Ann Arbor, MI 48105 USA
[5] Chulalongkorn Univ, Fac Med, Dept Rehabil Med, Bangkok, Thailand
[6] Univ Michigan, Parkinsons Fdn Res Ctr Excellence, Ann Arbor, MI 48105 USA
[7] VA Ann Arbor Healthcare Syst, Neurol Serv, Ann Arbor, MI USA
[8] VA Ann Arbor Healthcare Syst, GRECC, Ann Arbor, MI USA
[9] Univ Michigan, Dept Neurol, Ann Arbor, MI 48105 USA
[10] Univ Michigan, Sch Kinesiol, Ann Arbor, MI 48105 USA