John W. Krakauer is John C. Malone Professor and Professor of Neurology, Neuroscience, and Physical Medicine and Rehabilitation at the Johns Hopkins University School of Medicine.

S. Thomas Carmichael is Professor and Chair and Frances Stark Endowed Chair in the Department of Neurology at the David Geffen School of Medicine at the University of California, Los Angeles, and Codirector of UCLA's Broad Stem Cell Center.