FIG. 5.

Acute activation of motor neurons with ChR2 and H134R-ChR2 affects locomotion. A: larval locomotor response to constant illumination in animals expressing ChR2 in motor neurons (blue) and in genetic controls (black and gray). Crawling speeds of ChR2 animals were not significantly different from both controls at any time point. B: same experiment as in A, but with H134R-ChR2 expressed in motor neurons (red). Red asterisks indicate times when H134R-ChR2 expressing animals crawl significantly more slowly than both controls (P < 0.05 for t = 10–70 s). Pink # symbols indicate times when H134R-ChR2 animals crawl slower than animals expressing ChR2 (P < 0.05 for t = 20–130 s). C: response to rhythmic (500 ms on, 500 ms off) illumination in ChR2-expressing motor neurons (light blue) and in genetic controls (black and gray). There were no significant differences in crawling speeds between experimental and control animals throughout the trial. D: same experiment as in C, but with H134R-ChR2 expressed in motor neurons (orange). Experimental animals were not different from both controls at any point. In all experiments, crawling speeds were binned to yield average speed for 10-s intervals. Note that in A and B and again in C and D, GAL4 control data are shown twice, to facilitate comparison. Blue bars represent duration of stimulus. Data are presented as means ± SE. *P < 0.05 (ANOVA with Bonferroni post hoc test).