behaviors is not surprising considering both TrkB mRNA and protein are enriched in D2+ MSNs (Lobo et al., 2010; Baydyuk et al., 2011). The behavioral changes observed in these mice were accompanied by enhanced neuronal activity in the D2+ MSNs upon a selective knockout of TrkB. These findings prompted us to use optogenetic technology to selectively manipulate MSN activity in cocaine reward (see below).
