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FlyLight’s goal is to generate, with the help of collaborators, a set of split-GAL4 lines that specifically express in the vast majority of cell types of the fly nervous system.
At Janelia, we believe that the unparalleled experimental versatility of Drosophila provides an opportunity for an intellectual approach to understanding neuronal circuits not now feasible in vertebrate systems. The modest size of the fly’s nervous system—100,000 neurons in the adult and 10,000 in the larva—allows a systematic approach to understanding the complete nervous system of an organism that exhibits a fascinating repertoire of behaviors. A detailed wiring diagram is essential, but not sufficient, to understand the function of a neural network. We need to be able to point to any node in that wiring diagram and be able to silence or activate that node or more subtly modify its properties—for example, by inactivating a particular neuromodulator receptor in just that node. We need to be able to measure the effects of those manipulations on the behavior of the animal, the ensemble activity of the local neural network and the activity of individual neurons—a neuron or a network that can be reliably identified in a different animal, tomorrow or a year from now.
FlyLight plays a key role in this strategy by providing the bridge from electron-microscopic-level anatomical studies to behavioral and physiological functional studies. Cell-type-specific GAL4 drivers can be used to characterize the morphology of individual cells using the stochastic labeling methods we developed for this project. Matching the shape of a neuron determined in this way to a cell reconstructed from serial electron micrographs can reliably establish the correspondence between a node in the connectome and driver lines that can be used to express indicators and modifiers of function specifically in that node.
At the heart of the FlyLight project are large-scale data production processes that enable us to highlight and study cells at various points in the life of the fruit fly. We have developed and implemented a number of novel methods for brain dissection, optical clearing of tissue, labeling and automated microscopy. We have also developed computational tools for stitching together multi-stack images, aligning brain images into a common framework, annotating expression patterns, separating individual neurons from multicolor images containing several neurons, and for displaying and manipulating image stacks and other anatomical data.
To establish this functional bridge between the EM-level anatomy and cell-type-specific manipulation and analysis, we:
- Image and annotate several thousand GAL4 and LexA driver lines that label different sets of neurons (Generation 1 lines) in the adult Drosophila and the third instar larva
- Collaborate with world-class anatomical experts to generate a comprehensive library of split-GAL4 driver lines to reproducibly target neurons with cell-type specific resolution.
- Image those lines at high resolution to assemble a complete catalog of single neuron morphologies of the larval and adult Drosophila central nervous system by stochastic labeling of neurons and by imaging reporters targeted to synapses.
- Produce stable fly stocks for further analysis in well-controlled behavioral assays
To find out more, please visit our Research page.