1. From the Imaging of Dementia and Aging Laboratory (P.M., E.F., S.N.L., A.E.R., B.R., D.M., C.D., O.T.C.), Department of Neurology (P.M., E.F., B.R., D.M., C.D., O.T.C.), and Center for Neuroscience (S.N.L., A.E.R., C.D.), University of California, Davis.