Figure 1. Somatosensory Neurons Retain Action Potential Electrogenesis during Hibernation.

(A) Thirteen-lined ground squirrel in the active and torpid state (courtesy of the Gracheva lab).

(B) Diameter of DRG neurons from active and torpid squirrels. NS, not significant; p > 0.05; Mann-Whitney U test. Data are shown as mean ± SEM; n ≥ 32 cells.

(C–E) RMP (C), input resistance (D), and current threshold (E). NS, not significant; p > 0.05; unpaired t test (C) and Mann-Whitney U test (D and E). Data are shown as mean ± SEM; n ≥ 30 cells.

(F) Action potential (AP) firing rate at increasing current injections from 0 to 100 pA. Ordinary two-way ANOVA with Bonferroni correction is shown; ****p < 0.0001 main effect between species; *p < 0.05. Data are shown as mean ± SEM; n ≥ 30 cells.

(G) Exemplar traces of tonic, irregular, single, and phasic firing patterns.

(H) Distribution of firing patterns in active and torpid DRG neurons. Number of cells in each group is indicated.

(I) Firing rate of tonically firing cells at increasing current injections from 0 to 100 pA. Ordinary two-way ANOVA with Bonferroni correction is shown; ****p < 0.0001 main effect between species; *p < 0.05. Data are shown as mean ± SEM; n ≥ 7 neurons.

(J) Half-width of action potentials grouped by firing pattern. NS, not significant; p > 0.05; *p < 0.05, regular two-way ANOVA with Bonferroni correction. Data are shown as mean ± SEM; n ≥ 7 tonic, n ≥ 8 irregular, n ≥ 3 phasic, and n ≥ 4 single.

See also Figures S1–S3.