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. 2017 Nov 28;11:378. doi: 10.3389/fncel.2017.00378

FIGURE 2.

FIGURE 2

Insulin modulates the first latency and ISI of pyramidal neurons in current-evoked APs. (A1,B1,C1) Raw traces showing a depolarizing step of 0.2 nA was repeated in the control condition (black trace) and during insulin (red trace), under current-clamp mode. The bottom panel shows the enlarged time windows of the raw traces within dashed boxes in the top panel. (A2,B2,C2) Cumulative probability of the ISI of APs in control condition (black) and during insulin (red) for the representative neurons shown in (A1,B1,C1), respectively. Insulin significantly decreases ISI (A2, within-cell Kolmogorov–Smirnov test, n = 38 and 62 ISIs for control and insulin, respectively, P < 0.001), increases ISIs (B2, n = 59 and 49, P = 0.003) or causes no significant effect (C2, n = 51 and 56, P = 0.34) on the three representative neurons. (D1,E1) Comparison of the current-evoked latency (D1)/ISI (E1) of APs between the control condition and during insulin for all 38 neurons. Dark red, latency/ISI during insulin is significant longer than control (mean value of latency / ISI during insulin is larger than control with a p-value smaller than 0.05 for a given neuron); blue, latency/ISI during insulin is significant shorter than control (mean value of latency/ISI during insulin is shorter than control with a p-value smaller than 0.05 for a given neuron); gray, no signifiant difference. The pink line shows the diagonal, where latency/ISI in control is equal to insulin. (D2,E2) Percent of neurons showing increased (dark red), decreased (blue), and no significant effect (gray) of insulin on latency (D2) and ISI (E2). (D3,E3) Comparsion of latency [D3, paired t-test, n = 38, t(37) = 4.64, P = 4.23∗e-5]/ISI [E3, paired t-test, n = 38, t(37) = 3.00, P = 0.005] in control and insulin conditions across the group of neurons recorded. The error bars represent mean ± SE. (D4,E4) Relationship between normalized change of latency (D4)/ISI (E4) induced by insulin and the latency/ISI in control condition. The significance of correlation was tested by liner regression, n = 38 for both latency (D4) and ISI (E4), the r and P-values are indicated in the plots.