Fig. 2

General characteristics of cutaneous C-fiber afferents. a Electrical activation threshold. b Conduction velocity. c Proportion of fibers that exhibit spontaneous (background) activity. d Background discharge rate. e Distribution of receptive fields (RFs, shown in red). f Size of RFs. In a, b, d, and f, individual data are plotted as gray circles and summarized data are represented as medians with interquartile ranges (black lines). Note that there were no significant differences between the CTR (n = 37) and IM (n = 36) groups in any of the general characteristic measures (Mann–Whitney U test for a, b, d and f, and Fisher’s exact probability test for c)