Fig. 4

Mechanical response of cutaneous C-fiber afferents. a Response patterns to a ramped mechanical stimulus (294 mN in 30 s). Each data point is represented by the mean discharge rate ± its SEM (gray lines). Two-way repeated measures ANOVA with Geisser–Greenhouse correction revealed an insignificant effect of GROUP (F_{(1, 71)} = 3.424, p = 0.068, partial eta squared (η²) = 0.082) but significant effects of TIME (F_{(4.790, 340.1)} = 12.82, p < 0.0001, partial η² = 0.928) as well as GROUP x TIME interaction (F_{(30, 2130)} = 1.573, p = 0.025, partial η² = 0.752). Post-hoc test detected no significant difference in the discharge rate at any timepoint during the stimulation period of 30 s (31 data points every 1 s) between the CTR and the IM groups. b Mechanical response threshold, as measured using a servo-controlled mechanical stimulator. c Response magnitude (total net evoked spikes during the stimulation). No significant differences were observed in the response threshold and magnitude between the CTR (n = 37) and IM (n = 36) groups (Mann–Whitney U test for b and c)