Type I and type II cells in L5 of the mouse mPFC. A1, A2, Electrophysiological characterization and response to serotonin administration (10 μm) in two L5 pyramidal cells, one classified as a type I and the other as type II by the Bayesian sorter. B, Heat map depicting the probability that each of the 72 cells tested belongs to the type I and type II classes as determined by Autoclass. The probability for each cell is color-coded as depicted in the scale bar. C, Summary graph plotting the amplitude of the peak serotonin-induced currents in the cells sampled. D, Effect of serotonin on IsAHP and IsADP in type I and type II cells. Traces were baseline subtracted for clarity. The type I cell responded to serotonin with a 69-pA outward current and the type II cell with a –24-pA inward current. Overall, in this group of cells, serotonin (10–30 μm) elicited a –14 ± 6.5-pA inward shift in the aftercurrent in type I cells and –27 ± 3.5 pA in type II cells (p < 0.01).