JNeurosci: Johantges et al. used mice to study excitatory and inhibitory synaptic connections in the CA1 region, creating a circuit map with cell-type resolution that will guide future research on how the hippocampus supports learning and memory.
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In the CA1 hippocampus, pyramidal cells (PCs) can be classified as deep or superficial based on their radial position within the stratum pyramidale. Deep and superficial PCs form biased circuits with perisomatic-targeting PV+ basket cells, but it is unknown if such cell-type–specific circuit motifs extend to dendrite-targeting interneurons. Using male and female mice, we investigated synaptic connectivity and physiology in brain slices from four transgenic lines thought to capture distinct subsets of interneurons: SST-IRES-Cre, Nkx2.1-Cre, Chrna2-Cre, and Htr3a-GFP. First, we found that oriens-lacunosum moleculare (OLM) cells captured by the Chrna2-Cre line are a subset of Htr3a-GFP+ cells in the hippocampus. This novel finding is consistent with previous work showing Nkx2.1-Cre OLM cells are distinct from both Chrna2-Cre and Htr3a-GFP+ OLM cells.
