A neuron that extracts directionally selective motion information from upstream signals lacking this selectivity must compare visual responses from spatially offset inputs. Distinguishing among prevailing algorithmic models for this computation requires measuring fast neuronal activity and inhibition. In the Drosophila melanogaster visual system, a fourth-order neuron-T4-is the first cell type in the ON pathway to exhibit directionally selective signals. Here we use in vivo whole-cell recordings of T4 to show that directional selectivity originates from simple integration of spatially offset fast excitatory and slow inhibitory inputs, resulting in a suppression of responses to the nonpreferred motion direction. We constructed a passive, conductance-based model of a T4 cell that accurately predicts the neuron's response to moving stimuli. These results connect the known circuit anatomy of the motion pathway to the algorithmic mechanism by which the direction of motion is computed.

中文翻译：

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快速激发和偏移的简单集成，延迟抑制计算果蝇的方向选择性。

从缺乏这种选择性的上游信号中提取方向选择性运动信息的神经元必须比较来自空间偏移输入的视觉响应。区分这种计算的流行算法模型需要测量快速神经元活动和抑制。在果蝇视觉系统中，四级神经元 T4 是 ON 通路中第一个表现出定向选择性信号的细胞类型。在这里，我们使用 T4 的体内全细胞记录来表明方向选择性源于空间偏移的快速兴奋性和慢速抑制性输入的简单整合，从而抑制对非首选运动方向的反应。我们构建了一个被动的、基于电导的 T4 细胞模型，可以准确预测神经元对移动刺激的反应。这些结果将运动路径的已知电路解剖结构与计算运动方向的算法机制联系起来。