Fig. 2.

AIB is required for both reversal initiation and pumping inhibition. a Schematic showing the connectivity of ASH and the first layer interneurons (AIA, AIB, AIZ, and AIY). b, c Laser ablation (b) and chemical deletion (c) of AIB exhibited a significantly defect in high-concentration quinine-induced pumping inhibition. For chemical deletion of AIB, CED-3 was transgenetically expressed in AIB driven by the npr-9 promoter. Error bars: s.e.m.. Laser ablation: n ≥ 8 worms; Chemical deletion: n = 16 worms. ***p < 0.001 (t test). d, e Optogenetic stimulation of AIB evoked by either low power (0.28 mW mm⁻²) or high power (1.77 mW mm⁻²) blue light (470 nm; 30 s pulse) triggered reversals, but only by high power blue light-induced pumping inhibition. Worms expressing ChR2 specifically in AIB under the npr-9 promoter were tested. The transgenic animals cultured on ATR-free plates were taken as control. d Reversal behavior. e Pumping behavior. Error bars: s.e.m.. Reversal index, n ≥ 5 groups, and 10 worms/group; Pumping rate, n ≥ 10 worms. ***p < 0.001 (t- test). f Reversal initiation and pumping inhibition triggered by optogenetic activation of AIB. Worms expressed ChR2 in AIB were challenged with varying intensities of blue light to tune the activity of AIB. Reversal initiation and pumping inhibition were plotted as a function of blue light intensities. Lower light intensities were required for triggering reversals. Error bars: s.e.m. n ≥ 10 worms