Abstract
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 large-scale 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 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 wild-isolated 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.
Highlights
In introducing his four questions of ethology [1], Tinbergen emphasized that observation shapes how mechanistic and evolutionary questions are answered
The importance of understanding how animals structure their behaviour was recognized in part by the example set by genetics [2], in which many of the principles of inheritance were elucidated through careful observation and experimentation long before the physical nature of genes was known
We study the full structure and complexity of a behavioural repertoire in a simpler environment and focus on the spontaneous crawling of the nematode worm Caenorhabditis elegans confined to the two-dimensional surface of an agar plate
Summary
In introducing his four questions of ethology [1], Tinbergen emphasized that observation shapes how mechanistic and evolutionary questions are answered. What we choose to measure determines the causal units that will form our explanations. By this reasoning, exploring new ways of quantifying behaviour may identify new phenomena that were not apparent in previous representations. These new phenomena can become the subject of mechanistic studies to dissect their genetic or neural implementation. The importance of understanding how animals structure their behaviour was recognized in part by the example set by genetics [2], in which many of the principles of inheritance were elucidated through careful observation and experimentation long before the physical nature of genes was known. The analogous long-term goal is to generate or constrain hypotheses on the genetic and neural control of behaviour from the structure of behaviour itself
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
