The entorhinal cortex, in particular neurons in layer V, allegedly mediate transfer of information between the hippocampus and the neocortex, underlying long-term memory. Recently, this circuit has been shown to comprise a hippocampal output recipient layer Vb and a cortical projecting layer Va. With the use of in vitro electrophysiology in transgenic mice specific for layer Vb, we assessed the presence of the thus necessary connection between layer Vb and layer Va in the two functionally distinct medial (MEC) and lateral (LEC) subdivisions; MEC processes allocentric spatial information, whereas LEC represents the content of episodes. Using identical experimental approaches, we show that in LEC, but not in MEC, layer Vb neurons provide substantial direct input to layer Va neurons. This indicates that the hippocampal-cortex output circuit is present only in LEC, suggesting that episodic systems consolidation predominantly uses LEC-derived information and not allocentric spatial information from MEC.
bioRxiv Subject Collection: Neuroscience