FIGURE 8.

PCs and interneurons form subtype specific microcircuits in both the hippocampus and cortex. A: paired whole cell recordings in hippocampal CA1 between a PVBC (black) and a neighboring deep PC (green) and superficial PC (blue). The probability of observing a connection from a PVBC to either a deep or superficial PC is the same; however, deep PCs demonstrate larger amplitude inhibitory currents. This finding is consistent along the entire axis of the hippocampus (septal to temporal poles). B: in prefrontal cortex, PVBCs connect to PT-type pyramidal cells with greater probability than neighboring IT type. C: in somatosensory cortex, SST+ Martinotti cells mediate disynaptic inhibition between neighboring recurrently connected PT type PCs. D: in medial entorhinal cortex, CCKBCs selectively target PCs that project to the contralateral entorhinal cortex but not neighboring PCs that project to the dentate gyrus of the hippocampus. E, left: in CA1 hippocampus, PVBCs evoke larger amplitude inhibitory currents in PCs that project to the amygdala (AMG) vs. the media prefrontal cortex (mPFC). Right: PCs projecting to the mPFC are more likely to provide synaptic input to neighboring PVBCs than PCs projecting to the AMG or medial entorhinal cortex (MEC). [A and E from Lee et al. (656) modified with permission from Neuron. B from Lee et al. (650) modified with permission from Neuron. C from Silberberg and Markram (1015) modified with permission from Neuron. D from Varga et al. (1162) modified with permission from Nature Neuroscience.]