Fig. 2: Prelimbic neurons responding to spontaneous pain behaviors.

a Enhanced c-Fos expression of PL neurons in rats with CFA injection (day 3). Left: Representations of immunostaining of the neurons of PL (upper) and IL (bottom) in CFA (right) and Sham groups (left). Right: Statistical results. Three slices from each rat, n = 4 rats for IL-CFA group, n = 5 rats for PL and IL-Sham groups. Scale bars: 250 µm. *p < 0.05, **p < 0.01, two-sided unpaired t-test. b Electrophysiological recording sites and an example of representative high-pass filtered traces. c Bi-modal distribution of spike durations was used to identify cells as putative interneurons (gray) and pyramidal neurons (yellow). d Representative neurons showing excitatory (upper), inhibitory (middle) and neutral (bottom) responses to CFA-induced spontaneous paw lifting. Left: The spike trains were binned at a 10-s window, with episodes of spontaneous paw lifting shaded by red. The averaged firing rate was marked by blue lines. Right: The averaged firing rate during the spontaneous paw lifting were marked by red vertical lines. e The proportion of excitatory responsive neurons in the PL but not in the IL paralleled the level of spontaneous paw lifting. *p < 0.05, Chi-square test. f Schematic illustrating electrophysiological recordings of PL using silicon probes during the ibuprofen administration. g Administration of ibuprofen alleviated spontaneous paw lifting in rats with inflammatory pain. n = 6 rats, ***p < 0.001, two-sided paired t-test. h Normalized firing rate changes of putative pyramidal neurons in PL after ibuprofen administration. n = 51 units from 3 rats. The dashed lines indicated the edges of firing rates with significant increment (red) or reduction (blue). i Proportions of changed firing rates (outer pie charts) in PL neurons responding to spontaneous paw lifting behaviors (inner ring chart) after ibuprofen administration. *p < 0.05, Chi-square test for trend. j Decreased spontaneous firing rates of excitatory responsive to paw lifting neurons after ibuprofen administration. n = 11 units, *p < 0.05, two-sided Wilcoxon signed-rank test. Data for A, E, G, I and J were provided as a Source Data file. The diagrams B and F were created with BioRender.com.