Robustness tuning: mechanisms of acclimation-driven plasticity in a central pattern generator

Abstract

Temperature influences neuronal and circuit output and extreme temperatures can disrupt neuronal performance. Acclimation invokes a form of neuronal plasticity that we call robustness tuning, that preserves nervous system performance during seasonal alterations in environmental conditions. The stomatogastric nervous system (STNS) of the American lobster, Homarus americanus, produces stereotyped rhythmic motor patterns that are maintained over a range of acute temperature changes, but lost under more extreme conditions. In the wild, H. americanus experience water temperatures from [~]2{degrees}C to 25{degrees}C during the course of a year. We acclimated lobsters to 18{degrees}C versus 4{degrees}C for [~]3 weeks, and found that the pyloric rhythm from warm-acclimated animals maintained its characteristic properties over an extended temperature range, when compared to those recorded from cold-acclimated animals. There were acclimation and temperature dependent differences in the responses of pyloric neurons to the neuropeptide, Crustacean Cardioactive Peptide (CCAP). Computational models suggest that pyloric neuron morphology and neuromodulator conductance distribution play a role in robustness tuning, the reversible changes that allow animals to repeatedly adapt to seasonal change.