Telencephalic outputs from the medial entorhinal cortex are copied directly to the hippocampus

Standard models for memory storage assume that signals reach the hippocampus from superficial layers of the entorhinal cortex (EC) and are returned to the telencephalon by projections from deep layers of the EC. Here we show that telencephalon-projecting cells in Layer 5a of the medial EC send a copy of their outputs back to the CA1 region of the hippocampus. Our results suggest that rather than serving as a relay, deep EC may coordinate hippocampal-neocortical interactions in memory consolidation.