[1] Univ Med & Dent New Jersey, Robert Wood Johnson Med Sch, Dept Neurosci & Cell Biol, Piscataway, NJ 08854 USA
[2] Virginia Commonwealth Univ, Dept Anat & Neurobiol, Richmond, VA USA
[3] Harvard Med Sch, Dept Pathol, Boston, MA USA
[4] Max Planck Inst Expt Med, Dept Neurogenet, D-37075 Gottingen, Germany