C. elegans becomes habituated to repetitive mechanical stimuli. We compared the habituated states induced by three types of mechanical stimuli: touch on the head (head-touch), touch on the anterior body (body-touch), and mechanical tapping of the Petri dish, all of which evoke backward movement. The habituation patterns were similar, but differed in retention period and/or the rate of recovery. We found a hierarchy between the habituated states induced by the three types of mechanical stimuli

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... the decreasing order of head-touch, body-touch, and tap stimulus. Evidence is presented that the hierarchy is brought out by the magnitude of stimuli rather than by independent neural pathways.