Models of interneuron connectivity. (A) Molecular recognition model: SOM interneurons specifically recognize and target distal dendritic trees of PCs, whereas PV axons target somatic compartments. (B) Laminar model: By projecting to layer 1, where only distal dendrites are present, SOM interneurons avoid contacting somata and proximal dendrites of PCs. PV interneurons, on the other hand, project to layer 2/3 and thus avoid contacting distal dendrites.