[1] Johns Hopkins Univ, Dept Neurol, Baltimore, MD 21287 USA
[2] Natl Inst Neurol Disorders & Stroke, Anim Care Div, NIH, Baltimore, MD USA
[3] Natl Inst Neurol Disorders & Stroke, Neurogenet Branch, NIH, Bethesda, MD USA
[4] Off Res Serv, Div Vet Resources, NIH, Bethesda, MD USA