Focusing on the mesocorticolimbic DA system makes sense not only because it is well established to be a major site of action of addictive drugs but also because it has long been considered a structure that is essential for translating motivations into goal-directed actions (Phillips et al., 2003; Zweifel et al., 2009). The synaptic adaptations within this system that occur in response to addictive drugs and how these may contribute to addiction-related behaviors in rodent models have been the subject of a number of recent reviews (Kauer and Malenka, 2007; Thomas et al., 2008; Russo et al., 2010; Kalivas et al., 2009; Schmidt and Pierce, 2010; Wolf and Ferrario, 2010; Bowers et al., 2010). Rather than comprehensively reviewing this same material, we will instead highlight some of the most salient findings with an emphasis on the most recent results that point to important avenues of future research. We will also exhibit the strong bias that changes in synaptic function can best be assayed using electrophysiological techniques. Biochemical and imaging based measurements certainly provide important information that is critical for understanding
