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. 2023 Apr 19;129(5):1237–1248. doi: 10.1152/jn.00016.2023

Figure 3.

Figure 3.

The firing patterns of Phasic and Tonic neurons are maintained in the absence of synaptic inputs. A: representative traces of a recording from a Phasic ventrolateral periaqueductal gray (vlPAG) neuron from a naive rat in response to 120-pA current injections before (top) and after (bottom) synaptic blockers for glutamate [2,3-dioxo-6-nitro-7-sulfamoyl-benzo[f]quinoxaline (NBQX) 5 µM] and GABA (gabazine 10 µM). B: compiled data showing the firing frequency of all Phasic neurons for current steps ranging from 0 pA to 120 pA in 20-pA increments before (white bars) and after (black bars) synaptic blockers (2-way ANOVA, effect of synaptic blockers, F1,18 = 0.002, P = 0.96; n = 10). Individual experiments from the 0-pA step, showing the effect of synaptic blockers on spontaneous firing frequency (white squares are baseline and black squares are after blockers), are shown on left (Wilcoxon test, P = 0.8125). C: representative traces of a recording from a Tonic vlPAG neuron from a naive rat in response to 120-pA current injections before (top) and after (bottom) synaptic blockers. D: compiled data showing the firing frequency of all Tonic neurons for all current steps before and after synaptic blockers (2-way ANOVA, effect of synaptic blockers, F1,20 = 0.0007, P = 0.98; n = 11). Individual experiments from the 0-pA step, showing the effect of synaptic blockers on spontaneous firing frequency, are shown on left (Wilcoxon test, P = 0.85).