[1] Washington Univ, Dept Neurosci, Sch Med, St Louis, MO 63110 USA
[2] Brown Univ, Providence, RI 02912 USA
[3] Washington Univ, Dept Dev Biol, Sch Med, St Louis, MO 63110 USA
[4] Washington Univ, Sch Med, Dept Pathol & Immunol, St Louis, MO 63110 USA
[5] Washington Univ, Sch Med, Dept Genet, St Louis, MO USA
[6] Washington Univ, Sch Med, Dept Neurol, St Louis, MO USA