[1] Washington Univ, Sch Med, Dept Neurol, St Louis, MO 63131 USA
[2] Vanderbilt Univ, Med Ctr, Dept Pediat, Nashville, TN 37203 USA
[3] Vanderbilt Univ, Med Ctr, Dept Pharmacol, Nashville, TN 37203 USA
[4] Vanderbilt Univ, Med Ctr, Kennedy Ctr Res Human Dev, Nashville, TN 37203 USA
[5] Columbia Univ, Mailman Sch Publ Hlth, Dept Environm Hlth Sci, New York, NY 10032 USA
[6] Purdue Univ, Sch Hlth Sci, W Lafayette, IN 47907 USA