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. 2021 May 25;12:668337. doi: 10.3389/fphar.2021.668337

FIGURE 4.

FIGURE 4

Optogenetic activation of CeA-CRF neurons under normal conditions increases evoked activity of spinal cord neurons. (A) Experimental design. Responses of WDR neurons (n = 15) to brushing the skin (B) and innocuous (C) and noxious (D) compression of the left knee joint were significantly enhanced by optical activation of ChR2 expressing CeA–CRF neurons with blue (473 nm) light (“On”, 20 Hz, 5 mW, 5–10 min) compared to no light (“Off”) values in normal naive rats. (E) Peristimulus time histograms (500 ms bin size) show recordings of an individual WDR neuron recorded before, during and after blue (473 nm) light application (20 Hz, 5 mW, 5–10 min) in a normal naïve rat. Bar histograms show means ± SEM. *, p < 0.05, **, ## p < 0.01, repeated measures one–way ANOVA with Bonferroni posthoc tests. (F–H) Same display as (B–D) but for silencing of eNpHR3.0 expressing CeA–CRF neurons with yellow (590 nm) light (“On”) exposure (n = 5). (I) Same display as (E) but for CeA–CRF neuron silencing. (J–L) Same display as (B–D) but in wild type control rats with blue (473 nm) light (“On”) application (n = 8). (M) Same display as (E) but in a wild type control rat.