Figure 4. A posture-based analysis of locomotion responses to weak and strong mechanical stimuli.
(A) A weak mechanical stimulus (0.4 s of 1 kHz vibrations) produced a reversal followed by a small elevation of forward locomotion in L4int larvae (left) and a brief reversal followed by enhanced quiescence during L4leth (right). Inset: the first quiescence bout after the stimulus was longer than subsequent bouts (p < 0.05). (B) A strong mechanical stimulus (15 s of 1 kHz vibrations) produced reversals followed by a prolonged (10 min) elevation of forward locomotion in L4int larvae (left) and a brief reversal followed by elevated levels of directed motion for 4–5 min during L4leth (right). Notably, quiescence returned to its baseline value without transiently exceeding it. (C) Mean baseline fraction of quiescence was measured during the baseline period (see Figure 3A). The baseline fraction of quiescence was significantly higher in strongly stimulated animals as compared to unstimulated and weakly stimulated animals. Weak light I and II labels refer to stimulus strengths of 20 and 40 mW/cm2 blue light, respectively. Plots in panels (A, B) depict mean ± s.e.m and the error bars in panel (C) depict ±s.e.m and asterisks denote p < 0.05. The number of stimuli assayed is noted in parentheses for each condition.