<em>C. elegans</em> Tracking and Behavioral Measurement

Abstract

We have developed instrumentation, image processing, and data analysis techniques to quantify the locomotory behavior of C. elegans as it crawls on the surface of an agar plate. For the study of the genetic, biochemical, and neuronal basis of behavior, C. elegans is an ideal organism because it is genetically tractable, amenable to microscopy, and shows a number of complex behaviors, including taxis, learning, and social interaction. Behavioral analysis based on tracking the movements of worms as they crawl on agar plates have been particularly useful in the study of sensory behavior, locomotion, and general mutational phenotyping. Our system works by moving the camera and illumination system as the worms crawls on a stationary agar plate, which ensures no mechanical stimulus is transmitted to the worm. Our tracking system is easy to use and includes a semi-automatic calibration feature. A challenge of all video tracking systems is that it generates an enormous amount of data that is intrinsically high dimensional. Our image processing and data analysis programs deal with this challenge by reducing the worms shape into a set of independent components, which comprehensively reconstruct the worms behavior as a function of only 3-4 dimensions. As an example of the process we show that the worm enters and exits its reversal state in a phase specific manner.

Mechanistic analysis of the search behaviour ofCaenorhabditis elegans

“…The frequency distribution of the time between omegas following reversals was bimodal; therefore, we used the maximum time of the first peak (two frames) as a threshold for the pirouette behaviour. Velocity of the worm's undulatory cycle was measured using eigenworm analysis [31,41] and used to flag reversals and pauses. The behavioural detection algorithm (see electronic supplementary material, figure S1) was applied to the image dataset of 52 individuals, 30 min each (total of 374 400 frames) and, in total, it detected 937 reversals, 1064 omegas, 1125 pirouettes and 387 pauses.…”

Automated Analysis of <em>C. elegans</em> Swim Behavior Using CeleST Software

“…A growing number of trackers have elevated the objectivity, sophistication, and precision of the analysis of C. elegans movement on solid media [14][15][16][17][18] . C. elegans locomotion on plates is mostly restricted to the plane in which the animal makes contact with the solid surface of the media.…”

“…Hardware and software tools designed to track and measure C. elegans locomotion on solid media remove the subjectivity bias and allow for large-scale studies, permitting more sophisticated biological questions to be addressed. The recent behavioral database created by the Schafer lab 16 is an excellent example of the analytical extension and depth that has been achieved with a computational system for locomotion on plates.…”

Agarose Microchambers for Long-term Calcium Imaging of <em>Caenorhabditis elegans</em>

“…Two principal approaches can be used to observe motile animals over long time scales. The first approach is following the animal during movement using an automated stage or camera [2][3][4][5][6][7][8] and the second is to restrict the movement to a range that is at least as small as the field of view of the camera [9][10][11][12][13][14] . Both methods have their advantages.…”