1. From the Department of Mechanical Engineering, Massachusetts Institute of Technology (C.J.L.)
2. Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School (M. Selim)
3. Department of Orthopedics, Brigham and Women’s Hospital, Harvard Medical School; Tissue Engineering and Regenerative Medicine, VA Boston Healthcare System (M. Spector)
4. Departments of Radiology and Neurology, Massachusetts General Hospital, Harvard Medical School (E.H.L.).