1. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA 02129, U.S.A., and Massachusetts Institute of Technology, Department of Brain and Cognitive Sciences, Cambridge, MA 02139, U.S.A.
2. Massachusetts Institute of Technology, Department of Brain and Cognitive Sciences, Cambridge, MA 02139, U.S.A.; Max-Planck Institute for Brain Research, Department of Neurophysiology, 60528 Frankfurt am Main, Germany; and Frankfurt Institute for Advanced Studies, 60438 Frankfurt am Main, Germany
3. Massachusetts Institute of Technology, Department of Brain and Cognitive Sciences, Cambridge, MA 02139, U.S.A., and Massachusetts General Hospital, Department of Anesthesia and Critical Care, Boston, MA 02114, U.S.A.