Very little is known about differences in the properties of NAc indirect and direct pathway MSNs. Using targeted recordings from BAC transgenic mice that express fluorescent proteins in one or the other MSN populations (Gong et al., 2003; Shuen et al., 2008), it was recently reported that the basal properties of indirect and direct pathway MSNs in the NAc core differ in a manner quite similar to the differences observed in dorsal striatal MSNs (Kreitzer and Malenka, 2008; Grueter et al., 2010). D2 DA receptor-expressing indirect pathway MSNs are more excitable and the excitatory synapses on these cells exhibit a higher probability of release. Furthermore, while NMDAR-dependent LTD can be generated to the same degree in both subtypes of MSNs, as in the dorsal striatum eCB LTD is generated much more robustly in indirect pathway NAc MSNs (Kreitzer and Malenka, 2007; Grueter et al., 2010). This was surprising giving that eCB LTD in the NAc had been reported previously in slices from wildtype mice in which it was not possible to make targeted recordings (Robbe et al., 2002). However, the
