Figure 6.

Possible circuit implementing gating of medial prefrontal activity by the entorhinal cortex. Axons (labeled “*”) projected by neurons in the hippocampus carry information to up/down neurons in the medial prefrontal cortex. Axons (labeled “G”) originating in entorhinal cortex influence the state of the up/down neurons, and their ability to relay information to other cortical regions. The firing order for the cells is indicated by small numbers: active cells in the hippocampus (0) can only activate medial prefrontal cells (2) once entorhinal neurons have first fired (1). The location of the cells and the connections in the cortical layers were selected using data published in Valenti and Grace (2009) and Dégenètais et al. (2003).