Carina Soares‐Cunha

The nucleus accumbens (NAc) has been considered a key brain region for encoding reward/aversion and cue–outcome associations. These processes are encoded by medium spiny neurons that express either dopamine receptor D1 (D1‐MSNs) or D2 (D2‐MSNs). Despite the well‐established role of NAc neurons in encoding reward/aversion, the underlying processing by D1‐/D2‐MSNs remains largely unknown. Recent electrophysiological, optogenetic and calcium imaging studies provided insight on the complex role of D1‐ and D2‐MSNs in these behaviours and helped to clarify their involvement in associative learning. Here, we critically discuss findings supporting an intricate and complementary role of NAc D1‐ and D2‐MSNs in associative learning, emphasizing the need for additional studies in order to fully understand the role of these neurons in behaviour.