Olfactory Navigation: Analysis of Simple Strategies and Animal Behavior

Navigation is one of the most essential behaviors for animal survival. To navigate their worlds, animals use sensory cues that provide them with spatial information about their current location, and the direction and distance they should choose to travel to the next location. Information from olfactory cues and how they guide animal navigation remain a challenging problem to be studied. This is due to a dificulty in characterizing the physical properties of odor plumes that are temporally complicated and turbulent. Also, the neural circuits implicated in odor perception and its translation into olfactory driven motor behavior are still unclear and not easily understood. Studies have shown that animals employ different strategies to localize odor sources and follow odor trails. In this thesis, we study how animals use bilateral olfactory information in navigating their environment. We start by a mathematical analysis of the dynamics of a bilateral model that depends on the simultaneous comparison between odor concentrations detected by left and right sensors. We show that the animal has to be in an attraction region around the odor source in order to navigate towards the point source or follow the trail. We then introduce stochasticity into the bilateral model and study the effect of noise on the probability of finding an odor source. We ?find that constant noise is more successful when paired with a nonlinear function applied either to the concentration detected by the left and right sensors or to the difference in concentrations. We also show that concentration dependent noise improves performance for a spot source. Finally, we examine behavioral patterns of mice following odor trails in an attempt to assess whether bilateral olfactory cues are utilized by mice for navigation.