The fy visual system ofers a unique opportunity to explore computations performed by single neurons. Two previous studies characterized, in vivo, the receptive feld (RF) of the vertical system (VS) cells of the blowfy (calliphora vicina), both intracellularly in the axon, and, independently using Ca2+ imaging, in hundreds of distal dendritic branchlets. We integrated this information into detailed passive cable and compartmental models of 3D reconstructed VS cells. Within a given VS cell type, the transfer resistance (TR) from diferent branchlets to the axon difers substantially, suggesting that they contribute unequally to the shaping of the axonal RF. Weighting the local RFs of all dendritic branchlets by their respective TR yielded a faithful reproduction of the axonal RF. The model also predicted that the various dendritic branchlets are electrically decoupled from each other, thus acting as independent local functional subunits. The study suggests that single neurons in the fy visual system flter dendritic noise and compute the weighted average of their inputs.
Non-uniform weighting of local motion inputs underlies dendritic computation in the fly visual system
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