Meeting Abstract

S1-1.5  Wednesday, Jan. 4  Using frustrated total internal reflection to analyze insect walking MENDES, César S.; BARTOS, Imre; AKAY, Turgay; MARKA, Szabolcs ; MANN, Richard S.*; Columbia University; Columbia University; Columbia University; Columbia University; Columbia University rsm10@columbia.edu

A central question for neuroscientists is the identification of circuits and cellular mechanisms that govern animal behavior, such as walking. Drosophila is an attractive model to address these questions due to its relative neuronal simplicity and increasingly sophisticated genetic tools. However, the lack of a reliable and accurate gait analysis method limits the ability to analyze the circuits and mechanisms that regulate coordinated walking. In order to address this challenge, we developed an optical method, based on frustrated total internal reflection (fTIR) coupled with high-speed imaging, that allows us to unambiguously track a fly’s footprints and body position as it walks freely on a flat surface. A custom analysis software is used to track and quantify many parameters exhibited by walking flies, such as step timings, footprint positions, and intersegmental and left-right coordination. Using this method we characterized the walking behavior of wild-type animals and initiated loss and gain of function studies to assess the role of sensory neuron feedback in fruit fly walking behavior. For this, we established a combinatorial expression system to specifically manipulate neuronal function in different regions of the adult leg, thus targeting specific components of the sensory system. Our results reveal how interactions between central pattern generators and the sensory system modify walking behavior in fruit flies.