Max-Planck-Institute of Neurobiology, Martinsried, Germany.
Elife. 2017 Aug 22;6:e29044. doi: 10.7554/eLife.29044.
In the fruit fly optic lobe, T4 and T5 cells represent the first direction-selective neurons, with T4 cells responding selectively to moving brightness increments (ON) and T5 cells to brightness decrements (OFF). Both T4 and T5 cells comprise four subtypes with directional tuning to one of the four cardinal directions. We had previously found that upward-sensitive T4 cells implement both preferred direction enhancement and null direction suppression (Haag et al., 2016). Here, we asked whether this mechanism generalizes to OFF-selective T5 cells and to all four subtypes of both cell classes. We found that all four subtypes of both T4 and T5 cells implement both mechanisms, that is preferred direction enhancement and null direction inhibition, on opposing sides of their receptive fields. This gives rise to the high degree of direction selectivity observed in both T4 and T5 cells within each subpopulation.
在果蝇的视神经叶中，T4 和 T5 细胞代表了第一批方向选择性神经元，T4 细胞对移动的亮度增加（ON）有选择性反应，而 T5 细胞对亮度降低（OFF）有选择性反应。T4 和 T5 细胞都包含四个亚型，对四个基本方向中的一个有方向调谐。我们之前发现，对向上敏感的 T4 细胞实现了对最佳方向的增强和对零方向的抑制（Haag 等人，2016 年）。在这里，我们询问这种机制是否适用于 OFF 选择性的 T5 细胞以及这两个细胞类别的所有四个亚型。我们发现，T4 和 T5 细胞的所有四个亚型都在其感受野的相对侧实现了这两种机制，即最佳方向增强和零方向抑制。这导致了在每个亚群中观察到的 T4 和 T5 细胞的高度方向选择性。
