[1] Columbia Univ, Dept Pathol & Cell Biol, Ctr Motor Neuron Biol & Dis, Columbia Stem Cell Initiat,Med Ctr, New York, NY 10032 USA
[2] Columbia Univ, Dept Neurol, Ctr Motor Neuron Biol & Dis, Columbia Stem Cell Initiat,Med Ctr, New York, NY 10032 USA
[3] Columbia Univ, Dept Neurosci, Ctr Motor Neuron Biol & Dis, Columbia Stem Cell Initiat,Med Ctr, New York, NY 10032 USA
[4] MIT, Comp Sci & Artificial Intelligence Lab, Cambridge, MA 02139 USA