Fig. 1

Subregional intrinsic properties of anterior and posterior insular cortex pyramidal neurons in males and females. A, B Representative coronal sections of the brain from the anterior (Bregma + 1.98) and posterior (Bregma − 1.06) regions of the insular cortex (IC) showing recording sites of layer V pyramidal neurons. C, D Quantitative analysis of passive and active membrane properties revealed that anterior IC (aIC) pyramidal neurons are significantly larger (i.e., larger capacitance) and hyperpolarized compared to posterior IC (pIC) neurons, and that this difference is present in both male and female mouse. E, F Subregional differences in the current–voltage relationship between aIC and pIC pyramidal neurons were found in response to current injection steps of 50 pA, ranging from − 400 pA to + 50 pA, in adult females (E), but not in males (F). G An example of an action potential (AP) evoked by increasing current steps is illustrated, with the rheobase indicated. H The results indicated that the minimal current required to trigger an AP (rheobase) was significantly higher in aIC compared to pIC pyramidal neurons. Data are presented as box-and-whisker plots (minimum, maximum, median) for (C-D-H), and as mean ± SEM in XY plots for (E–F). Two-way ANOVA followed by Šídák's multiple comparison test was performed for (C-D-H), and Mann–Whitney U test was applied for (E–F). P-values < 0.05 are depicted in the graphs. The sample sizes for aIC male and female were 14/10 and 13/6, respectively, and for pIC male and female were 28/15 and 20/12, respectively