School of Life Science and Technology, Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, 210096, China.
Key Laboratory of Medical Electrophysiology of Ministry of Education and Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, Sichuan 646000, China
J Neurosci. 2021 Mar 10;41(10):2164-2176. doi: 10.1523/JNEUROSCI.2388-20.2021. Epub 2021 Jan 19.
Appropriate termination of the photoresponse in image-forming photoreceptors and downstream neurons is critical for an animal to achieve high temporal resolution. Although the cellular and molecular mechanisms of termination in image-forming photoreceptors have been extensively studied in , the underlying mechanism of termination in their downstream large monopolar cells remains less explored. Here, we show that synaptic ACh signaling, from both amacrine cells (ACs) and L4 neurons, facilitates the rapid repolarization of L1 and L2 neurons. Intracellular recordings in female flies show that blocking synaptic ACh output from either ACs or L4 neurons leads to slow repolarization of L1 and L2 neurons. Genetic and electrophysiological studies in both male and female flies determine that L2 neurons express ACh receptors and directly receive ACh signaling. Moreover, our results demonstrate that synaptic ACh signaling from both ACs and L4 neurons simultaneously facilitates ERG termination. Finally, visual behavior studies in both male and female flies show that synaptic ACh signaling, from either ACs or L4 neurons to L2 neurons, is essential for the optomotor response of the flies in high-frequency light stimulation. Our study identifies parallel synaptic ACh signaling for repolarization of L1 and L2 neurons and demonstrates that synaptic ACh signaling facilitates L1 and L2 neuron repolarization to maintain the optomotor response of the fly on high-frequency light stimulation. The image-forming photoreceptor downstream neurons receive multiple synaptic inputs from image-forming photoreceptors and various types of interneurons. It remains largely unknown how these synaptic inputs modulate the neural activity and function of image-forming photoreceptor downstream neurons. We show that parallel synaptic ACh signaling from both amacrine cells and L4 neurons facilitates rapid repolarization of large monopolar cells in and maintains the optomotor response of the fly on high-frequency light stimulation. This work is one of the first reports showing how parallel synaptic signaling modulates the activity of large monopolar cells and motion vision simultaneously.
适当终止成像光感受器和下游神经元的光反应对于动物实现高时间分辨率至关重要。虽然成像光感受器中终止的细胞和分子机制已经在[物种名称]中得到了广泛研究，但它们下游大型单极细胞中终止的潜在机制仍未得到充分探索。在这里，我们表明来自无长突细胞 (ACs) 和 L4 神经元的突触 ACh 信号有助于 L1 和 L2 神经元的快速复极化。在雌性果蝇中的细胞内记录显示，阻断来自 ACs 或 L4 神经元的突触 ACh 输出会导致 L1 和 L2 神经元的复极化缓慢。在雄性和雌性果蝇中的遗传和电生理研究确定 L2 神经元表达 ACh 受体并直接接收 ACh 信号。此外，我们的结果表明，来自 ACs 和 L4 神经元的突触 ACh 信号同时促进 ERG 终止。最后，在雄性和雌性果蝇中的视觉行为研究表明，来自 ACs 或 L4 神经元到 L2 神经元的突触 ACh 信号对于苍蝇在高频光刺激下的光运动反应是必不可少的。我们的研究确定了 L1 和 L2 神经元复极化的平行突触 ACh 信号，并表明突触 ACh 信号促进了 L1 和 L2 神经元的复极化，以维持苍蝇在高频光刺激下的光运动反应。成像光感受器的下游神经元从成像光感受器和各种类型的中间神经元接收多个突触输入。这些突触输入如何调节成像光感受器下游神经元的神经活动和功能在很大程度上仍然未知。我们表明，来自无长突细胞和 L4 神经元的平行突触 ACh 信号有助于[物种名称]中大型单极细胞的快速复极化，并维持苍蝇在高频光刺激下的光运动反应。这项工作是第一个报告之一，展示了平行突触信号如何同时调节大型单极细胞的活动和运动视觉。
