Olfactory Discrimination in Caenorhabditis elegans

Caenorhabditis elegans (C. elegans) is an organism with only 302 neurons (in the adult hermaphrodite) and only two pairs of (bilaterally symmetrical) neurons detect attractive volatile odourants. Despite its simple neuroanatomy, C. elegans can perform olfactory discrimination between two odourants when both are detected almost exclusively by a single pair of neurons. ARR-1 (Beta-Arrestin) desensitizes the receptors detecting the two odourants in an activity-dependent manner; this allows for odourant-specific adaptation and olfactory discrimination. An arr-1 null strain of C. elegans is unable to discriminate intra-neuronally (when both odours are detected by the same pair of neurons), but is able to discriminate inter-neuronally (when odours are detected by separate pairs of neurons). This work characterizes the mechanism of intra-neuronal olfactory discrimination in C. elegans, which has been mysterious since it was first decribed by Bargmann et al in 1993.M.Sc