Fig. 1: Age- and species-dependent changes in neuronal excitability.
From: Phylogenetic divergence of GABAB receptor signaling in neocortical networks over adult life
A Example reconstructions of L2/3 and L5 neurons from rat and human neocortex. Inset, voltage response of example cells in response to −500 to +500 pA current injections (100 pA steps, 500 ms duration). B Current-voltage responses of L2/3 (black) and L5 (blue) neurons from 1-month-old (left; L2/3: 25 cells from 14 rats, L5: 25 cells from 13 rats), 6–8-month-old (middle left; L2/3: 35 cells from 20 rats, L5: 31 cells from 20 rats), and 12–14-month-old rats (middle right; L2/3: 13 cells from 5 rats, L5: 11 cells from 5 rats), and human neocortex (right; L2/3: 37 cells from 20 cases, L5: 16 cells from 9 cases). C The slope of the current-frequency (FI) plot between 0 and 500 pA from recorded neurons between layers and age of the same rats (L2/3 vs. L5: p = 2.6 × 10−9 (1-month), 2.55 × 10−9 (6–8 months), 0.599 (12–14 months), L2/3: P = 0.0004 (1 vs. 12–14 months), 0.0335 (1 vs. 6–8 months), 0.0191 (6–8 vs. 12–14 months); Tukey post hoc tests). C’ Comparison of FI slopes of L2/3 and L5 PCs in adult rats (6–14 months) and humans. D Membrane capacitance of recorded neurons in rats for the same age groups (L2/3 vs. L5: p = 0.0025 (1-month), 0.0006 (6–8-month), 0.0364 (12–14 months), L2/3: P = 0.0729 (1 vs. 12–14 months), 0.0029 (1 vs. 6–8 months), 0.834 (6–8 vs. 12–14 months); Tukey post hoc tests). D’ Comparison of membrane capacitance L2/3 and L5 PCs in adult rats (6–14 months) and humans. All data is shown as either mean ± SEM (B) or boxplots (25–75% range) with the median indicated and whiskers indicating maximum/minimum ranges (C and D). All data are overlain by responses of individual cells (circles). Statistical test results are shown above graphs from 2-way ANOVA (2-sided, B) and LMM models (C and D), with results from post-hoc 2-sided Tukey tests: *P < 0.05, **P < 0.01; ***P < 0.001.
