1. Biobehavioral Imaging and Molecular Neuropsychopharmacology Unit, National Institute on Drug Abuse (NIDA) Intramural Research Program, Baltimore, MD 21224, USA.
2. Department of Radiology, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA.
3. Optogenetics and Transgenic Technology Core, NIDA Intramural Research Program, Baltimore, MD 21224, USA.
4. Synaptic Plasticity Section, NIDA Intramural Research Program, Baltimore, MD 21224, USA.
5. Department of Psychiatry, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA.