Departments of Psychiatry and Behavioral Sciences, Stanford University, 401 Quarry Road, Stanford, CA 94305, USA; Wu Tsai Neuroscience Institute, 290 Jane Stanford Way, Rm E152, Stanford, CA 94305, USA; Veterans Affairs Palo Alto Healthcare System, and the Sierra Pacific Mental Illness, Research, Education, and Clinical Center (MIRECC), 3801 Miranda Ave, Palo Alto, CA 94304, USA. Electronic address: tcaudle@stanford.edu.