Hierarchical compression ofCaenorhabditis eleganslocomotion reveals phenotypic differences in the organization of behaviour

Alex Gomez-Marin, Greg J. Stephens, André E. X. Brown
2016 Journal of the Royal Society Interface  
Regularities in animal behaviour offer insights into the underlying organizational and functional principles of nervous systems and automated tracking provides the opportunity to extract features of behaviour directly from largescale video data. Yet how to effectively analyse such behavioural data remains an open question. Here, we explore whether a minimum description length principle can be exploited to identify meaningful behaviours and phenotypes. We apply a dictionary compression algorithm
more » ... to behavioural sequences from the nematode worm Caenorhabditis elegans freely crawling on an agar plate both with and without food and during chemotaxis. We find that the motifs identified by the compression algorithm are rare but relevant for comparisons between worms in different environments, suggesting that hierarchical compression can be a useful step in behaviour analysis. We also use compressibility as a new quantitative phenotype and find that the behaviour of wildisolated strains of C. elegans is more compressible than that of the laboratory strain N2 as well as the majority of mutant strains examined. Importantly, in distinction to more conventional phenotypes such as overall motor activity or aggregation behaviour, the increased compressibility of wild isolates is not explained by the loss of function of the gene npr-1, which suggests that erratic locomotion is a laboratory-derived trait with a novel genetic basis. Because hierarchical compression can be applied to any sequence, we anticipate that compressibility can offer insights into the organization of behaviour in other animals including humans. rsif.royalsocietypublishing.org J. R. Soc. Interface 13: 20160466
doi:10.1098/rsif.2016.0466 pmid:27581484 pmcid:PMC5014070 fatcat:o2c65zq4gng5xoafxoi5zxbuua