Cover image

Schematic representation of the connectivity in the mPFC–RE–HC system. The hippocampus (HC, red) projects directly to the medial prefrontal cortex (mPFC, blue), but there are no direct return projections. The nucleus reuniens of the thalamus (RE, purple) has reciprocal connections with HC and mPFC, and serves as the main link completing a HC–mPFC–RE–HC circuit. In addition, RE innervates the entorhinal cortex (EC, green), which relays spatial (via medial EC) and nonspatial/sensory (via lateral EC) mPFC-processed information to HC. The microphotograph of the background panel contains retrogradely labeled fluorescent RE neurons (unilateral labeling was artificially mirrored to illustrate bilateral labeling). This panel shows two subpopulations of RE neurons; the orange colored RE cells project to the medial EC, the blue ones project to the lateral EC. Via these distinct RE–EC projections, RE has the potential to modulate the mPFC-medial EC–HC and mPFC-lateral EC–HC flow of spatial and nonspatial information, respectively, in many different ways. See Dolleman-van der Weel et al. (LearnMem 26: 191–205) for the full article.