A scalable method for automatically measuring pharyngeal pumping in C. elegans

•We describe an automated assay for Caenorhabditis elegans pharyngeal pumping; a technical breakthrough as compared to manual assays currently used.•Our method enables prolonged measurements and statistical characterization while minimizing unintentional bias.•Our method enables precise control of feeding conditions, which can be static or dynamic.•Our method is scalable and can affordably provide high throughput.•We demonstrate our method in an oscillating feeding environment and identify the resulting feeding dynamics.

BackgroundThe nematode Caenorhabditis elegans is widely used for studying small neural circuits underlying behavior. In particular, the rhythmic feeding motions collectively termed pharyngeal pumping are regulated by a nearly autonomous network of 20 neurons of 14 types. Despite much progress achieved through laser ablation, genetics, electrophysiology, and optogenetics, key questions regarding the regulation of pumping remain open.New methodWe describe the implementation and application of a scalable automated method for measuring pumping in controlled environments. Our implementation is affordable and flexible: key hardware and software elements can be modified to accommodate different requirements.ResultsWe demonstrate prolonged measurements under controlled conditions and the resulting high quality data. We show the scalability of our method, enabling high throughput, and its suitability for maintaining static and dynamic conditions. When food availability was oscillated, pumping rates were low as compared to steady conditions and pumping activity was not reliably modulated in response to changes in food concentration.Comparison with existing methodThe prevailing method for measuring rates of pumping relies on scoring by visual inspection of short recordings. Our automated method compares well with manual scoring. It enables detailed statistical characterization under experimental conditions not previously accessible and minimizes unintentional bias.ConclusionsOur approach adds a powerful tool for studying pharyngeal pumping. It enhances the experimental versatility of assaying genetic and pharmacological manipulations and the ability to characterize the resulting behavior. Both the experimental setup and the analysis can be readily adapted to additional challenging motion detection problems.