A, example artistic renderings of light microscopic reconstructions of a pyramidal cell (PC), an oriens-radiatum cell (O-R), an oriens-lacunosum-moleculare cell (OLM), and a fast spiking perisomatic region-targeting interneuron (FS PTI). Dendrites are represented in black and axons in red. Dendritic spines are enhanced for visibility. B, voltage responses to depolarising (200 pA) and hyperpolarising current steps (from −20 to −200 pA in increments of 20 pA). A sag (marked with arrows) indicating the presence of Ih can be seen in PCs, O-R cells and OLM cells. FS PTIs had a small or no sag. s.l-m., stratum lacunosum-moleculare; s.r., stratum radiatum; s.p., stratum pyramidale; s.o., stratum oriens.