Altered electrical properties, but normal spike firing capabilities of pyramidal neurons in Dgcr8+/- mice. (A) Magnified image (20×) of a neurobiotin-labeled L5 mPFC pyramidal neuron filled during whole-cell recording. (B,C) Representative current-clamp recordings from mPFC L5 pyramidal neurons from (B) WT and (C) Dgcr8+/- mice show stereotyped pyramidal neuron firing patterns in both genotypes in response to a series of hyperpolarizing (-200 to -25 pA) and depolarizing (+100 pA) current injections. (D) I-V relationships were assessed in voltage-clamp mode through a series of 5-mV steps and demonstrate increased input resistance (Rin) in Dgcr8+/- neurons. (E) Action potential firing responses in WT and Dgcr8+/- neurons evoked by +75, +125 and +175 pA current injections. (F) The plot of the steady-state firing frequency (ss-ff) as a function of current intensity shows no changes in the input-output response between genotypes (WT n = 17; Dgcr8+/- n = 11). (G) Plot of the interspike interval between spikes of a train of action potentials evoked by +200 pA current injection demonstrates no changes in firing capabilities (WT n = 17; Dgcr8+/- n = 11).