Fig. 2

Sex and subregional differences in the excitability of insular cortex pyramidal neurons. A, B As indicated by the response of action potentials to progressive depolarizing current injection, pyramidal neurons exhibit a notably higher level of excitability in the pIC compared to the aIC, and this trend is consistent across both sexes. (500 ms, ranging from 0 to 600 pA in 50 pA steps). C Representative voltage traces evoked by the injection of hyper- and depolarizing current steps (500 ms, ranging from − 150 to 250 pA in 50 pA steps) in both anterior and posterior IC pyramidal neurons of both sexes. D During physiological depolarizing current stages, neurons from the aIC displayed less frequent firing compared to those from the pIC. Additionally, male pIC neurons showed a higher level of excitability than those of their female counterparts. E An example of firing patterns triggered by the injection of + 150 pA depolarizing currents for each group is provided. Data are presented as mean ± SEM in XY plots for (A, B), and as box-and-whisker plots (minimum, maximum, median) for (C). Mann-Whitney U test was applied for (A, B), and two-way ANOVA followed by Šídák's multiple comparison test was performed for (C). P-values < 0.05 are depicted in the graphs. The sample sizes for aIC male and female were 14/10 and 14/6, respectively, and for pIC male and female were 20/15 and 16/12, respectively