C. Elegans Neuron Tracking: Neuron Dynamics That Drive Behavioral Response to Food

Overview

Several important animal behaviors are stable and persist for long durations, ranging on the scale of minutes to hours. Food exploration and exploitation are discrete long-lasting behavioral states. We attempted to address a fundamental problem in gut-brain signaling in the simple nervous system of Caenorhabditis elegans: how enteric neurons respond to feeding cues and drive complex behavioral responses to food ingestion. Caenorhabditis elegans, also referred to as C. elegans, are a microscopic nematode species, which have been frequently used as model organisms for neuroscience research since they have been diligently studied and literature resources have identified and began to understand much of their nervous system. The Flavell lab has previously characterized a neuromodulatory circuit that generates food-dependent, long-lasting roaming and dwelling states in C. elegans: Serotonin promotes dwelling states, slow and focused locomotive behavior, and an opposing neuromodulatory circuit promotes roaming states, faster and exploratory behavior. In this study, we found that a specific neuron, known as NSM, is an enteric serotonergic neuron whose response to food is mediated by the acid-sensitive ion channels (ASICs), DEL-7 and DEL-3. Through the use of calcium imaging, which allowed us to detect the activity of NSM, we were able to determine that food ingestion, mechanical grinding of the food within the worms pharynx, and the presence of its minor process, its dendrite, are required for NSM response to reach it full potential. The correlation between NSM activity and change in locomotive speeds allowed us to believe that NSM, the serotonin releasing neuromodulatory circuit, is responsible for the alternation and transitions between roaming and dwelling in the C. elegans in the presence of food. Also we were able to identify that the specific ASICs mediated the activity of NSM and are required for it to reach its maximum level of intensity, which would most largely affect the worms’ locomotive speed. Ultimately, this finding allows us to develop a better understanding of the gut-brain interaction and apply it to humans, while also further advancing our knowledge on the nervous system of C. elegans.

Competition history

• AJAS 2019 Category not listed

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