University of Houston

During exploratory activity, Drosophila adults exhibit positional preference of arena boundary and exhibit a non-linear decay in their activity. Exploratory activity in Drosophila is a complex behavior, because it involves interaction between the environment and their sensory unit . Therefore, deducing rules underlying exploration in Drosophila is a non-trivial task. This thesis provides a quantitative framework for deducing these rules using novel phenomenological models of locomotion of Drosophila in open field arenas.

This thesis presents a novel phenomenological model for simulating Drosophila movement trajectories based on two local rules: directional persistence and local wall attraction. This two-component model , unlike other studies, is arena-independent and reproduces very similar time-averaged positional preferences of Drosophila in a variety of arenas of simple and complex geometries. This thesis also presents a novel model for time-dependent activity in Drosophila which relies on two basic principles: flies form a spatial memory representation of an environment as a set of lattice nodes and repeated exposure to these nodes is necessary for learning the environment. This model accurately predicts the temporal behaviors of movement speed and directional persistence during arena edge exploration.

The phenomenological models implemented in this thesis identify primary factors driving exploratory activity in Drosophila and challenge long-held theories of positional preferences exhibited by Drosophila such as thigmotaxis, centrophobicity and low turning behavior.