Figure 3.

DCX⁺ neurons with mature APs have an increased intrinsic excitability after stroke. Intrinsic excitability was analyzed only in those neurons showing mature action potentials (maximum dV/dt ≥ 300 V/s). A, The rheobase (necessary current intensity to evoke an AP) of DCX⁺ cells with mature APs was significantly lower than in their DCX⁻ counterparts in both the sham and MCAO groups, but not within the DCX⁺ or DCX⁻ groups. B, The mean output gain (mean slope of current–frequency curves) was significantly steeper in MCAO DCX⁺ neurons with mature APs than in MCAO DCX⁻ neurons. C, D, Individual input–output curves of recorded granule cells with mature APs are presented in as current-frequency (I–V; C) curves and as the number of action potentials per current step (300 ms; D). Each line represents the response of one neuron. The percentage of cells showing mature AP phenotype (AP rise slope > 300 V/s), and the number of cells (n) included in the analysis are presented above the figures. Two cells in the MCAO DCX⁺ group were lost during recording. MCAO DCX⁺ neurons show steeper curves in both output frequency and AP number compared with MCAO DCX⁻ neurons (p < 0.0001 and 0.005, respectively), but also a higher output frequency compared with sham DCX⁺ neurons (p = 0.0004). Mann–Whitney tests in A and B, mixed linear models in C and D. See text and Table 2 for statistical results. dV/dt = rise time of APs.