1. a Human Cognitive Neurophysiology Laboratory, Veterans Affairs Northern California Health Care System , Martinez, CA, USA
2. b Department of Neurology , University of California at Davis , Davis, CA, USA
3. c Center for Neurosciences, University of California at Davis , Davis, CA, USA
4. d Center for Mind and Brain, University of California at Davis , Davis, CA, USA
5. e Alzheimer's Disease Center, Veterans Affairs Northern California Health Care System , Martinez, CA, USA