Example of a worm aborting a turn and reversing when neurons RIV, SMB, and SAA are inhibited and the gentle-touch mechanosenseory neurons are activated (strain name: AML499).

Animals express the inhibitory opsin gtACR2 in RIV, SMB, and SAA and the excitatory opsin Chrimson in the gentle-touch mechanosensory neurons. Blue and red light illumination was delivered upon the onset of a turn in closed loop. Green dot denotes the animal’s head. Green line denotes its centerline. Yellow line shows the trajectory of a point midway along the animal’s centerline over the past 10 s. Purple indicates area illuminated by light. (MP4)