1 Departments of Neurology, Beth Israel Deaconess Medical Center, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA. Electronic address: sschacht@bidmc.harvard.edu.
2 Physiology Department, Ribeirão Preto School of Medicine, University of São Paulo, Ribeirão Preto, SP, Brazil.
3 Department of Neurology, Miller School of Medicine, University of Miami, Miami, FL, USA.