Caenorhabditis elegansrequires a gradual regulation of behaviours for spatial navigation, as well as for fine tuned modulation of multiple sensory-dependent cues from the environment. Food-related behaviours in C. elegansare modulated through signalling molecules and precise neural circuits. Different subsets of complex microcircuits in the nervous system, governs the interplay of locomotion strategies during food searching (1,2). Integration of distinct sensory cues is essential for behavioural decision-making. Thus, decision-making in C.elegans is an extremely coordinated process involving layers of sensory neurons, interneurons and motorneurons in the head and ventral nerve cord to generate an appropriate behaviour driven by output muscles (3). Rhythmic behaviours in C.elegansare relatively easy to conduct and observe. Ideally it requires a video recording in order to identify features within particular behaviours, this is a time consuming process. In view of this, we have developed a freely moving tracking toolbox, TrakBox, enabling a real-time analysis of complex behaviours in C. elegans. As a proof-of-concept we have assessed the ability and effectiveness of TrakBox to extract and analyse behavioural information of C. elegansin freely moving worms, verifying its use by analysing a well defined behavioural signature in mod-1mutant. By comparing with known exploratory features in mod-1previously published findings (extracted 'manually') (4), TrakBox was able to show an accurate annotation of sub-behaviours associated with locomotion and exploration, with high levels of accuracy. We also analysed tracks recorded at different duration due to the flexibility of TrakBox which allows long-term monitoring, illustrating the ability to automatically analyse very long tracks. In addition, we quantified features such as reversal events and fractions of time in dwelling/roaming, in chemotaxis assay to further demonstrate the capabilities of the TrakBox analysis. We found that under different track durations, short and long traces, the analysis showed an effective extraction of sub-behaviours. Thus, with TrakBox, we have been able to show alterations of exploratory behaviours in mod-1mutant as previously described, highlighting its capability for the rapid and effective identification of phenotypes in freely moving C. elegans. 1LeDoux, J. E. (2000). Annu Rev Neurosci 23: 155-184.2Barkus, C., S. B. McHugh, et al. (2010). Eur J Pharmacol 626(1): 49-56.3Shtonda, B. B. and L. Avery (2006). J Exp Biol 209(Pt 1): 89-102. 4Flavell, S. W., N. Pokala, et al. (2013). Cell 154(5): 1023-1035.

Affiliations:
- EMbody Biosignals Ltd. Rugby, United Kingdom
- Warwick Engineering in Biomedicine. University of Warwick, United Kingdom