[1] Massachusetts Gen Hosp, Athinoula A Martinos Ctr Biomed Imaging, Charlestown, MA 02129 USA
[2] Harvard Univ, Sch Med, Dept Radiol, Boston, MA 02115 USA
[3] Katholieke Univ Leuven, Lab Neuroen Psychofysiol, Sch Med, B-3000 Louvain, Belgium
[4] MIT, McGovern Inst, Dept Brain & Cognit Sci, Cambridge, MA 02139 USA
[5] MIT, Media Lab, Synthet Neurobiol Grp, Cambridge, MA 02139 USA
[6] MIT, Dept Biol Engn, Cambridge, MA 02139 USA