Projection neurons from medial entorhinal cortex to basolateral amygdala are critical for the retrieval of morphine withdrawal memory

The medial entorhinal cortex (MEC) is crucial for contextual memory, yet its role in context-induced retrieval of morphine withdrawal memory remains unclear. This study investigated the role of the MEC and its projection neurons from MEC layer 5 to the basolateral amygdala (BLA) (MEC−BLA neurons) in context-induced retrieval of morphine withdrawal memory. Results show that context activates the MEC in morphine withdrawal mice, and the inactivation of the MEC inhibits context-induced retrieval of morphine withdrawal memory. At neural circuits, context activates MEC−BLA neurons in morphine withdrawal mice, and the inactivation of MEC−BLA neurons inhibits context-induced retrieval of morphine withdrawal memory. But MEC−BLA neurons are not activated by conditioning of context and morphine withdrawal, and the inhibition of MEC−BLA neurons do not influence the coupling of context and morphine withdrawal memory. These results suggest that MEC−BLA neurons are critical for the retrieval, but not for the formation, of morphine withdrawal memory.