Fig. 9: Gap junctions between AVAL and AVAR help biased threat-reward decision-making by equilibrating inhibitory synaptic inputs from D-MNs.

a, b UNC-9 innexin is required for equilibrating inhibitory postsynaptic current (PSC) caused by optogenetic activation of D-MNs but not excitatory PSC caused by optogenetic activation of ASH sensory neurons. Top: diagram indicating the numbers of chemical synapses from D-MNs and AHS neurons to AVAL and AVAR, and the neurons for optogenetic stimulation and PSC recording. Middle: sample current traces. AVA were held at −10 mV. The blue lines indicate the times of blue light stimulation. Bottom: comparison of the AVAL/AVAR ratios of peak current and charge transfer, and the total charge transfer (AVAL + AVAR). In a, Compared with wild type (wt), p values of unc-9(fc16), unc-9 RNAi in AVA, and unc-9(fc16) rescue in AVA are 0.000, 0.000, and 0.008 for peak ratio, 0.000, 0.000, and 0.073 for charge transfer ratio, and 0.002, 0.002, and 0.247 for total charge transfer. In b, Compared with wt, the respective p values of unc-9(fc16) and unc-9 RNAi in AVA are 1.000 and 0.998 for evoked PSC of AVAL, 0.923 and 0.628 for evoked PSC of AVAR, 0.912 and 0.658 for peak ratio, 0.888 and 0.979 for charge transfer ratio, and 0.740 and 0.901 for total charge transfer. The p values between wt and wt retinal (−) were 0.000 for evoked PSC of both AVAL and AVAR. c Disruption of AVAL and AVAR electrical coupling reduced escape probability from a hyperosmotic glycerol barrier in a multisensory behavioral assay, in which 10–15 worms were placed inside a glycerol ring (1-cm diameter) on an agar plate (6-cm diameter) with two drops of diacetyl (1:1000 dilution) outside of the ring. The percentage of worms that escaped in 15 min was quantified. Compared with wt, p = 0.253, 0.466, 0.393, 0.544, 0.010, and 0.117 at glycerol concentrations of 0, 0.5, 1, 2, 3, and 4 M, respectively. The asterisk indicate significant differences compared with wt (**p < 0.01, ***p < 0.001) based on either one-way ANOVA with Tukey’s post hoc test (a, b) or unpaired two-sided t-test (c). The numbers inside brackets indicate sample size (n). n = numbers of independently recorded cells in a and b, but numbers of individual worms in c. In c, sample sizes of the wt and unc-9 RNAi groups varied among different glycerol concentrations. For wt, n = 10, 10, 10, 17, 14, and 11 for the concentrations of 0–4 M. For unc-9 RNAi, n = 10, 10, 10, 16, 15, and 16 for the concentrations of 0–4 M. Data are presented as mean values ± SEM. Source data are provided as a Source data file.