[1] Univ Maryland, Sch Med, Dept Physiol, Baltimore, MD 21201 USA
[2] Univ Maryland, Sch Med, Dept Neurol, Baltimore, MD 21201 USA
[3] Univ Maryland, Sch Med, Program Neurosci, Baltimore, MD 21201 USA
[4] Univ Maryland, Inst Biotechnol, Ctr Med Biotechnol, Baltimore, MD 21201 USA
[5] Baltimore VA Med Ctr, Neurol Serv, Baltimore, MD 21201 USA