Figure 8. Inactivation of lateral PB contralateral to an inflamed paw (1 or 5/6 d) did not attenuate the ON-cell burst evoked by mechanical stimulation of the inflamed or untreated paw. a, ON-cell burst/inflamed paw, 1 d post-CFA administration. Effect of muscimol microinjected into the lateral PB contralateral to stimulated (inflamed) hindpaw on ON-cell activity associated with application of Von Frey probes in the innocuous (4, 8, and 15 g probes) and noxious (60 and 100 g probes) ranges to the inflamed and untreated paws. For the inflamed paw, there was a significant effect of force (innocuous vs noxious, F(1,13) = 8.74, p = 0.011), but no effect of block (F(1,13) = 0.081, p = 0.38) or force × block interaction (F(1,13) = 0.12, p = 0.73). For the untreated paw, ipsilateral to the block, there was a significant effect of force (F(1,13) = 14.06, p = 0.0024), but no effect of block (F(1,13) = 1.19, p = 0.29) or force × block interaction (F(1,13) = 0.045, p = 0.83, n = 14). b, OFF-cell pause/inflamed paw, 1 d post-CFA administration. Effect of muscimol microinjected into the lateral PB contralateral to stimulated (inflamed) hindpaw on OFF-cell pause associated with application of innocuous and noxious Von Frey probes to the inflamed and untreated paws. For the inflamed paw (contralateral to block, 7 cells with full datasets), there was no effect of force (F(1,6) = 1.18, p = 0.32) or block (F(1,6) = 1.11, p = 0.33). Similarly, for the normal paw (ipsilateral to block, eight cells with full datasets), there was no effect of force (F(1,7) = 0.00006, p = 0.99) or block (F(1,17) = 0.34, p = 0.86). c, Ongoing firing of both cell classes was unchanged during PB block 1 d post-CFA administration. (ON-cells: t(13) = 2.44, p = 0.030, n = 14; OFF-cells: t(9) = 1.56, p = 0.15, n = 10). d, ON-cell burst/inflamed paw, 5–6 d post-CFA administration. Effect of muscimol microinjected into the lateral PB contralateral to stimulated (inflamed) hindpaw on ON-cell activity associated with the application of Von Frey probes in the innocuous and noxious ranges to the inflamed and untreated paws. For the inflamed paw, there was a significant effect of force (innocuous vs noxious, F(1,12) = 57.89, p < 0.0001), but no effect of block (F(1,12) = 3.11, p = 0.1030) or force × block interaction (F(1,12) = 0.12, p = 0.73). For the normal paw, ipsilateral to the block, there was a significant effect of force (F(1,12) = 42.22, p < 0.0001), but no effect of block (F(1,12) = 1.94, p = 0.19) or force × block interaction (F(1,12) = 0.034, p = 0.86, n = 13). e, OFF-cell pause/inflamed paw, 5–6 d post-CFA. Effect of muscimol microinjected into the lateral PB contralateral to stimulated (inflamed) hindpaw on OFF-cell pause associated with application of innocuous and noxious Von Frey probes to the inflamed and untreated paws. For the inflamed paw (n = 11), there was a significant effect of force (innocuous vs noxious, F(1,10) = 6.79, p = 0.026) and block (F(1,10) = 7.93, p = 0.018), with no force × block interaction (F(1,10) = 1.6, p = 0.23). For the normal paw, ipsilateral to the block (n = 10 cells with complete datasets), there was no effect of force (F(1,9) = 1.12, p = 0.32) or block (F(1,9) = 4.29, p = 0.068). f, Ongoing firing of both cell classes was unchanged during PB block 5–6 d post-CFA administration (ON-cells: t(12) = 0.72, p = 0.49, n = 13; OFF-cells: t(10) = 1.51, p = 0.16, n = 11). Evoked activity was analyzed using a two-way ANOVA with repeated measures on both stimulus force and block as factors, with Sidak's multiple-comparisons test used to compare responses during block with preblock baseline at each force when effect of block was significant. Spontaneous activity before block was compared with that during block using t tests for correlated means. Cell data are presented as the geometric mean with 95% confidence intervals. *p < 0.05, ***p < 0.001 compared with preblock. Sp/s, Spikes per second; Innoc, Innocuous.