Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA.
Nat Neurosci. 2018 Feb;21(2):250-257. doi: 10.1038/s41593-017-0046-4. Epub 2018 Jan 8.
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.
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反应。要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。在黑腹果蝇的视觉系统中，第四阶神经元 T4 是第一个表现出方向选择性信号的 ON 通路中的细胞类型。在这里，我们使用 T4 的体内全细胞膜片钳记录来表明，方向选择性源自于空间偏移的快速兴奋性和缓慢抑制性输入的简单整合，导致对非首选运动方向的反应抑制。我们构建了一个 T4 细胞的被动、基于电导率的模型，该模型可以准确预测神经元对运动刺激的反应。这些结果将运动通路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。
