1Center for Magnetic Resonance Research, School of Medicine, University of Minnesota, Minneapolis, MN, United States, 2Laboratory of Integrative Human Physiology, School of Kinesiology, University of Minnesota, Minneapolis, MN, United States, 3Division of Biostatistics, School of Public Health, University of Minnesota, Minneapolis, MN, United States, 4Berman Center for Clinical Research, Hennepin County Medical Center, Minneapolis, MN, United States