Dopamine D2 receptor-knockout changed accumbens neural response to prediction of reward associated with place in mice

The amygdala (AM) and hippocampal formation (HF) play important roles in stimulus-affect association and episodic memory, respectively. The prefrontal cortex (PFC) encodes the prediction of reward or aversion. The nucleus accumbens (NAc) receives converging inputs from these areas, and also mesolimbic dopamine (DA) input originated from the ventral tegmental area (VTA) to predict reward or aversion; this is an essential determinant for learning approach behaviors. However, the involvement of dopamine receptor subtypes in assessing reward information and in learning still remains to be specified. In the present study, we examined the specific role of dopamine D2 receptor (D2R) subtype in mediating associative learning, in regulating NAc neural responses and locomotor activity, using new genetic tool: D2R-knockout mice. The specific contribution of the D2R to reward process and associative learning at neural and behavioral levels is discussed in this article.