title: Computational Methods for Tracking, Quantitative Assessment, and Visualization of C. elegans Locomotory Behavior.
abstract: The nematode Caenorhabditis elegans provides a unique opportunity to interrogate the neural basis of behavior at single neuron resolution. In C. elegans, neural circuits that control behaviors can be formulated based on its complete neural connection map, and easily assessed by applying advanced genetic tools that allow for modulation in the activity of specific neurons. Importantly, C. elegans exhibits several elaborate behaviors that can be empirically quantified and analyzed, thus providing a means to assess the contribution of specific neural circuits to behavioral output. Particularly, locomotory behavior can be recorded and analyzed with computational and mathematical tools. Here, we describe a robust single worm-tracking system, which is based on the open-source Python programming language, and an analysis system, which implements path-related algorithms. Our tracking system was designed to accommodate worms that explore a large area with frequent turns and reversals at high speeds. As a proof of principle, we used our tracker to record the movements of wild-type animals that were freshly removed from abundant bacterial food, and determined how wild-type animals change locomotory behavior over a long period of time. Consistent with previous findings, we observed that wild-type animals show a transition from area-restricted local search to global search over time. Intriguingly, we found that wild-type animals initially exhibit short, random movements interrupted by infrequent long trajectories. This movement pattern often coincides with local/global search behavior, and visually resembles Lévy flight search, a search behavior conserved across species. Our mathematical analysis showed that while most of the animals exhibited Brownian walks, approximately 20% of the animals exhibited Lévy flights, indicating that C. elegans can use Lévy flights for efficient food search. In summary, our tracker and analysis software will help analyze the neural basis of the alteration and transition of C. elegans locomotory behavior in a food-deprived condition.
authors.affiliation: School of Computing, College of Computing and Digital Media, DePaul University, Chicago, Illinois, United States of America.
authors.forename: Kyle
authors.initials: K
authors.lastname: Moy
authors.affiliation: School of Computing, College of Computing and Digital Media, DePaul University, Chicago, Illinois, United States of America.
authors.forename: Weiyu
authors.initials: W
authors.lastname: Li
authors.affiliation: School of Computing, College of Computing and Digital Media, DePaul University, Chicago, Illinois, United States of America.
authors.forename: Huu Phuoc
authors.initials: HP
authors.lastname: Tran
authors.affiliation: School of Computing, College of Computing and Digital Media, DePaul University, Chicago, Illinois, United States of America.
authors.forename: Valerie
authors.initials: V
authors.lastname: Simonis
authors.affiliation: School of Computing, College of Computing and Digital Media, DePaul University, Chicago, Illinois, United States of America.
authors.forename: Evan
authors.initials: E
authors.lastname: Story
authors.affiliation: Department of Cell Biology and Anatomy, Chicago Medical School, Rosalind Franklin University, North Chicago, Illinois, United States of America.
authors.forename: Christopher
authors.initials: C
authors.lastname: Brandon
authors.affiliation: School of Computing, College of Computing and Digital Media, DePaul University, Chicago, Illinois, United States of America.
authors.forename: Jacob
authors.initials: J
authors.lastname: Furst
authors.affiliation: School of Computing, College of Computing and Digital Media, DePaul University, Chicago, Illinois, United States of America.
authors.forename: Daniela
authors.initials: D
authors.lastname: Raicu
authors.affiliation: Department of Cell Biology and Anatomy, Chicago Medical School, Rosalind Franklin University, North Chicago, Illinois, United States of America.
authors.forename: Hongkyun
authors.initials: H
authors.lastname: Kim
mesh_terms: D000465:Algorithms; D000818:Animals; D001522:Behavior, Animal; D017173:Caenorhabditis elegans / Q000235:genetics / Q000502:physiology*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics; D005502:Food; D008124:Locomotion; D009154:Mutation; D011381:Programming Languages
chemical_list: D029742:Caenorhabditis elegans Proteins