Combining Automated Behavioral Assays And Neuronal Imaging To Understand Foraging Behavior In C. Elegans

Jun Liu1, Nicolina Zjacic*1, Monika Scholz1

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The ability to effectively forage is essential for the survival of an animal. Foraging involves two behaviors, locomotion and food intake, which need to be temporally coordinated. Due to its small nervous system and tractable genetics, the nematode C. elegans is an ideal model system to study foraging behavior. C. elegans takes in bacterial food particles through the pharynx, which undergoes rhythmic contractions called pumping that transport bacteria into the intestine. Pumping had previously been tracked in immobilized C. elegans fed a liquid bacterial suspension, due to the difficulty of observing pumping in moving animals. To study motor coordination during foraging, we are developing high-throughput behavior assays to automatically measure pumping and locomotion in free-moving worms. Prior studies showed that C. elegans “samples” its environment via slow, regular pumping, then increases its pumping rate upon encounter with a substantial food source. However, we observe that C. elegans already begins rapid pumping before encountering a high concentration of food, such as a bacterial lawn. We hypothesize that smell plays a role in priming C. elegans for the intake of food by increasing pharyngeal pumping pre-emptively. To understand the neural computations underlying these behaviors, we are combining high-throughput behavior assays with targeted neuronal manipulations. C. elegans has a simple neuronal network consisting of ~300 neurons with a fully mapped connectome, only 20 of which are located in the pharynx. We will present our progress in creating a toolbox that targets individual pharyngeal neurons and subsets of neurons with GCaMP and optogenetic activators.

* equal contribution