Circuit Robustness to Temperature Perturbation Is Altered by Neuromodulators

In the ocean, the crab Cancer borealis is subject to daily and seasonal temperature changes. Previous work, done in the presence of descending modulatory inputs, had shown that the pyloric rhythm of the crab increases in frequency as temperature increases but maintains its characteristic phase relationships until it “crashes” at extremely high temperatures. To study the interaction between neuromodulators and temperature perturbations, we studied the effects of temperature on preparations from which the descending modulatory inputs were removed. Under these conditions, the pyloric rhythm was destabilized. We then studied the effects of temperature on preparations in the presence of oxotremorine, proctolin, and serotonin. Oxotremorine and proctolin enhanced the robustness of the pyloric rhythm, whereas serotonin made the rhythm less robust. These experiments reveal considerable animal-to-animal diversity in their crash stability, consistent with the interpretation that cryptic differences in many cell and network parameters are revealed by extreme perturbations. •The marine crab Cancer borealis experiences large changes in environmental temperature•The stability of the crab’s pyloric rhythm depends on its modulatory environment•Some modulators increase the pyloric rhythm’s robustness to high temperature•Serotonin decreases the robustness of the pyloric rhythm to high temperature The crab Cancer borealis experiences substantial changes in ocean water temperature both daily and seasonally. Modulatory substances alter the range of temperatures over which one of the crab’s rhythmic motor patterns can function normally.