1. Section on Light and Circadian Rhythms (SLCR), National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA.
2. Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA.
3. Unit on Neuromodulation and Synaptic Integration, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA.
4. Department of Immunobiology, School of Medicine, Yale University, New Haven, CT 06520, USA.