Fig. 3.
Neuronal determinants of thermotaxis. (A) Analysis of AFD contributions to negative thermotaxis when T > Ts and to positive thermotaxis when T < Ts. (B) Analysis of other neurons in the proposed circuit for thermotaxis. (C) Analysis of AFD in mutant backgrounds that always crawl up or down temperature gradients. The thermotactic index—the ratio between mean velocity in the gradient direction and mean crawling speed (mean ± 1 SEM)—is calculated over the trajectories of individual worms when started at 20 °C and grown at 25 °C (red, T < Ts) or when started at 20 °C and grown at 15 °C (T > Ts). Salient comparisons between worms with intact neurons or disrupted neurons are shown. *P < 0.05; **P < 0.005; ***P < 0.0005 by Student t test. A total of 40–309 worms were used to calculate each index.