CPM Seminar

Measuring and modeling stochastic behavior of simple organisms: bacterial and worm behavior

William Ryu

Department of Physics
University of Toronto

Sensory processing is a universal, complex function of biological systems, and from a broad perspective, all cells and organisms that can move, search for sensory information. For simple organisms this searching behavior is typically stochastic rather than deterministic and here I will discuss how we measure and model this random behavior by studying two model organisms: the bacterium E. coli and the nematode C. elegans. We are interested in E. coli because it is a model of how single cells process sensory information. The study of how the bacteria performs taxis (movement towards sensory cues) has been instrumental in understanding general principles of sensory networks and here I will discuss how we determine the computation that the bacteria performs when measuring thermal signals. We are interested in C. elegans because it is a model of how small neuronal networks process sensory information. C. elegans poses additional challenges to biophysicists when discussing sensory behavior, because the potential dimensionality of the output is so large. Here I will discuss how we deal with this challenge by showing you examples of how we quantify, parametrize, and model worm behavior.