Physiology in Drosophila motion-sensitive neurons during walking and flight behavior

Abstract

Event Abstract Back to Event Physiology in Drosophila motion-sensitive neurons during walking and flight behavior Johannes D. Seelig1*, Eugenia M. Chiappe1, Gus K. Lott1, Michael B. Reiser2 and Vivek Jayaraman1 1 HHMI, Janelia Farm Research Campus, United States 2 Janelia Farm Research Campus , United States Drosophila melanogaster is a genetic model organism with many experimental advantages, including the ability to genetically manipulate specific sub-populations of neurons. Selected neurons in the fruit fly central brain can also be targeted for in vivo electrophysiology and two-photon calcium imaging. This powerful combination of physiology and genetic tools-such as cell-type-specific labeling, activity sensing, light-activation and silencing-is increasingly being applied to questions in systems neuroscience [1]. Our goal is to understand circuit computations underlying sensory-motor transformation in the fly brain. This requires recording not just neural activity but also the fly's behavior. Towards this end, we will present two novel experimental setups that we have developed: (i) Two-photon calcium imaging while the fly is walking on an air-supported 'Buchner' ball [2, 3] in a virtual arena [4]. (ii) Two-photon calcium imaging when the tethered fly is flying in a virtual arena. In order to assess the quality of behavior in our imaging preparation, we focused on a well-known behavior, the optomotor response. This turning response to visual motion can be induced by presenting a large field vertical grating moving horizontally in front of the fly. We show that tethered walking and flying flies reliably perform optomotor behavior during two-photon imaging. To assess the quality of the calcium imaging, we investigated calcium responses in lobula plate tangential cells (LPTCs). This small group of neurons has been exhaustively studied in fixed preparations in larger flies, and their responses to large-field stimuli (such as those that induce the optomotor response) have been carefully characterized [5]. In blowflies, LPTCs respond to large field motion stimuli with strong calcium responses, making these cells ideal candidates to test the capabilities of the behaving Drosophila preparation. Recording from Horizontal System (HS) LPTCs, we find reliable calcium responses in behaving fruit flies using a new genetically encoded calcium indicator, GCaMP3.0 [6]. HS neurons show strong (~150±/F) and stable responses to motion in their preferred direction. These calcium responses correlate with the fly's own walking optomotor response in that direction. Do responses of HS neurons change depending on the behavioral state of the animal? We will present results that compare responses in walking flies to those in flying flies. In our poster, we will describe the details of setups that allow us to perform stable recordings from identified motion-sensitive interneurons in the visual system of walking and flying Drosophila. These recordings represent the first physiological recordings in behaving Drosophila and provide a platform for future explorations of decision-making and sensory-motor transformations in this powerful genetic model organism.