Mapping and Modeling the Spatial Topography of Tactile Neural Circuits in Drosophila - Project Summary The ability to produce spatially and contextually dependent motor responses depends on the nervous system’s capacity to spatially localize tactile signals. How these computations are accomplished and how the diversity of neuronal cell-types contribute to network function is not well understood. This project will investigate how patterns of synaptic connectivity between diverse cell-types in the nervous system contribute to the spatial localization of tactile stimuli. The Tuthill lab is a collaborative and multifaceted team studying proprioception and sensorimotor processing in Drosophila melanogaster. This project will integrate information from different parts of the sensorimotor pathway while focusing on neural circuits involved in tactile information processing. Specifically, it will investigate how tactile sensory information from the leg is represented topographically in the ventral nerve cord (VNC) of the fly. This will be done by mapping the morphologies and projection patterns of tactile mechanosensory neurons using spatially selective genetic labeling techniques. Moreover, the fine morphology and synaptic connectivity patterns of individual sensory neuron axons will be reconstructed using volumetric electron microscopy image data. To characterize important cell-types in the tactile circuit, interneurons in the VNC that receive synaptic input from the tactile mechanosensory neurons will also be reconstructed. This will involve predicting the cell-type identity of these cells based on morphology, synaptic connectivity, and local shape features, all of which can be derived from large scale electron microscopy. This will shed light on the diverse neuronal types involved in tactile sensory networks as well as the anatomical features that define such types. Finally, theoretical modeling techniques will be applied to elucidate how the architecture of tactile circuits define the spatial representation of tactile sensation and how that may predict the spatial acuity of the fly in response to stimulation. This involves developing a model that represents tactile mechanosensory neurons from different areas on the leg and their downstream partners in the VNC. Constrained by the synaptic connectivity, this model will predict the spatial resolution with which flies can distinguish tactile stimulation on the leg. Overall, this project will examine how individual connections between neurons contribute to tactile sensory encoding and elucidate how deficits in the tactile circuit may affect spatial localization.
