Analogous to synapses in other brain regions, excitatory synapses in the NAc can express several different forms of synaptic plasticity including NMDAR-dependent LTD and LTP, endocannabinoid-dependent LTD (eCB LTD) as well as a presynaptic form of mGluR-triggered LTD (for reviews see Thomas and Malenka, 2003; Surmeier et al., 2007; Lüscher and Huber, 2010). Similar to the VTA, evidence is accumulating that, in vivo, drugs of abuse can activate or “hijack” some of these synaptic plasticity mechanisms as well as influence the subsequent generation of synaptic plasticity in slices prepared from animals with a history of drug intake. Assuming that plasticity at NAc excitatory synapses has evolved to serve adaptive behavioral functions, drug-induced synaptic adaptations will have important influences on subsequent behaviors.
