In visual systems, neurons adapt both to the mean light level and to the range of light levels, or the contrast. Contrast adaptation has been studied extensively, but it remains unclear how it is distributed among neurons in connected circuits, and how early adaptation affects subsequent computations. Here, we investigated temporal contrast adaptation in neurons across Drosophila's visual motion circuitry. Several ON-pathway neurons showed strong adaptation to changes in contrast over time. One of these neurons, Mi1, showed almost complete adaptation on fast timescales, and experiments ruled out several potential mechanisms for its adaptive properties. When contrast adaptation reduced the gain in ON-pathway cells, it was accompanied by decreased motion responses in downstream direction-selective cells. Simulations show that contrast adaptation can substantially improve motion estimates in natural scenes. The benefits are larger for ON-pathway adaptation, which helps explain the heterogeneous distribution of contrast adaptation in these circuits.

中文翻译：

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果蝇方向选择电路中的异质时间对比度适应。

在视觉系统中，神经元既适应平均光照水平，又适应光照水平范围或对比度。对比度适应已被广泛研究，但仍不清楚它如何在连接的电路的神经元之间分布，以及早期适应如何影响后续的计算。在这里，我们研究了果蝇视觉运动电路中神经元的时间对比度适应。随着时间的推移，几个通路神经元显示出对对比度变化的强烈适应。这些神经元之一Mi1在快速时标上显示出几乎完全的适应性，并且实验排除了其适应性的几种潜在机制。当对比度适应降低了ON通路细胞的增益时，伴随着下游方向选择性细胞的运动响应降低。仿真表明，对比度自适应可以大大改善自然场景中的运动估计。沿路径自适应的好处更大，这有助于解释这些电路中对比度自适应的异构分布。