tools in particular provide an extremely powerful means to temporally regulate not only neuronal activity but G-protein-coupled receptor signaling using OptoXRs (Airan et al., 2009), glutamatergic signaling(Volgraf et al., 2006; Numano et al., 2009), GABAergic signaling, and even certain intracellular signaling molecules (Wu et al., 2009; Hahn and Kuhlman, 2010). Ultimately, it may be possible to extend these capabilities to optogenetic regulation of transcriptional activity. Likewise, optogenetic tools are making it possible for the first time to study the influence of specific inputs to striatum and to determine whether such inputs impinge in selective ways on D1+ vs. D2+ MSNs (Higley and Sabatini, 2010). The ability to control such signaling and molecular properties with great temporal resolution will allow major steps to be made toward a more comprehensive understanding of the two MSN subtypes, and other cell subtypes in NAc and dStr, in mediating the time course and different phases of drug addiction.
