NeuroNexus acute 32-channel probes (Iso_3x_tet-A32 and Iso_4x_tet-A32) were used for acute recordings in the lateral entorhinal cortex (LEC) and hippocampal CA1 of awake, behaving, head-fixed rats. The probes were previously custom designed by Yoshikazu Isomura and precisely target each layer of LEC and were used during optogenetic stimulation to identify CA1-projecting neurons and neurons projecting to prefrontal cortex. In this paper by Shogo Soma et al. with Isomura and collaborators, they studied single-unit recordings during behavior and learning. Their results highlight the significance of a hippocampal-entorhinal circuit – not just cortex – in tuning ongoing actions.