Fig. 5. AIY neurons function to extend food-seeking periods. Trajectory on mediocre food, E. coli DA837, of (A) a ttx-3 mutant and (B) an animal whose AIY neurons have been killed. Compare to wild-type in Fig. 4C. ttx-3 mutant trajectories did not span the whole lawn; and there were far fewer long straight roaming events. Trajectories of AIY worms also had fewer straight long movements than wild-type controls. (C,D) Movement duration distribution of (C) wild type, ttx-3, osm-6, osm-6;ttx-3 and (D) AIY-ablated animals, all tested on E. coli DA837 food. N=10 for WT, 10 for ttx-3, 6 for osm-6, 6 for osm-6;ttx-3, 10 for AIY ablations and 8 for ttx-3p::GFP controls. (E) ttx-3 was defective in the food preference behavior if bacterial foods were located at a small distance from each other. By 3 h, all ttx-3 worms found food, but there was no preference in the harder arrangement. In contrast to ttx-3, osm-6 animals took longer to discriminate between good and bad food, but they finally managed to make the right choice even if foods were located at a distance. Values are means ± s.e.m. ^*Different from the wild type (P<0.01); different from ttx-3 (P<0.01; Student's t-test). (F) Biased food preference for E. coli HB101 over B. megaterium of mutants and animals with laser-ablated neurons. The fraction of animals that reached the central colony of good food, E. coli HB101, was determined. ttx-3 mutants and AIY-ablated animals performed worse than controls. In laser ablation experiments, worms were counted after 20 h. For tests on mutants, the number of assays is 18 for WT, 15-17 for ttx-3 alleles and 6-15 for various mutants tested. For laser ablations, number of worms found in the center and the total number of worms tested is indicated next to the bars. Values are means ± s.e.m. ^*Different from the wild type (P<0.01; Student's t-test); Different from the ablation control (P<0.01; ² test of independence).