Department of Neurobiology, the Hebrew University of Jerusalem, Jerusalem, 91904, Israel.
Department of Circuits-Computation-Models, Max-Planck-Institute of Neurobiology, Am Klopferspitz 18, 82152, Martinsried, Germany.
Sci Rep. 2018 Apr 10;8(1):5787. doi: 10.1038/s41598-018-23998-9.
The fly visual system offers a unique opportunity to explore computations performed by single neurons. Two previous studies characterized, in vivo, the receptive field (RF) of the vertical system (VS) cells of the blowfly (calliphora vicina), both intracellularly in the axon, and, independently using Ca 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 different branchlets to the axon differs 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 fly visual system filter dendritic noise and compute the weighted average of their inputs.
蝇的视觉系统为探索单个神经元所进行的计算提供了一个独特的机会。之前的两项研究分别在活体条件下对黑腹果蝇（Calliphora vicina）的垂直系统（VS）细胞的感受野（RF）进行了细胞内的轴突记录，以及使用 Ca 成像技术在数百个远端树突分支上进行了独立的记录。我们将这些信息整合到 3D 重建的 VS 细胞的详细被动电缆和区室模型中。在给定的 VS 细胞类型中，不同分支到轴突的传递电阻（TR）有很大差异，这表明它们对轴突 RF 的形成贡献不均等。通过各自的 TR 对所有树突分支的局部 RF 进行加权，可以忠实地再现轴突 RF。该模型还预测，各种树突分支彼此之间是电分离的，因此它们作为独立的局部功能子单元发挥作用。该研究表明，果蝇视觉系统中的单个神经元可以滤除树突噪声并计算其输入的加权平均值。
