[1] Columbia Univ, Dept Neurol, New York, NY 10032 USA
[2] Hosp Clin Barcelona, Lab Neurol Expt, Fdn Clin, IDIBAPS, E-08036 Barcelona, Spain
[3] Columbia Univ, Dept Pathol, New York, NY 10032 USA
[4] Columbia Univ, Ctr Neurobiol & Behav, New York, NY 10032 USA