Department of Molecular, Cellular, and Developmental Biology and Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA 93106, USA.
Department of Molecular, Cellular, and Developmental Biology and Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA 93106, USA.
Curr Biol. 2020 Mar 23;30(6):988-1001.e4. doi: 10.1016/j.cub.2020.01.045. Epub 2020 Mar 5.
Animals integrate information from different sensory modalities, body parts, and time points to inform behavioral choice, but the relevant sensory comparisons and the underlying neural circuits are still largely unknown. We use the grooming behavior of Drosophila melanogaster as a model to investigate the sensory comparisons that govern a motor sequence. Flies perform grooming movements spontaneously, but when covered with dust, they clean their bodies following an anterior-to-posterior sequence. After investigating different sensory modalities that could detect dust, we focus on mechanosensory bristle neurons, whose optogenetic activation induces a similar sequence. Computational modeling predicts that higher sensory input strength to the head will cause anterior grooming to occur first. We test this prediction using an optogenetic competition assay whereby two targeted light beams independently activate mechanosensory bristle neurons on different body parts. We find that the initial choice of grooming movement is determined by the ratio of sensory inputs to different body parts. In dust-covered flies, sensory inputs change as a result of successful cleaning movements. Simulations from our model suggest that this change results in sequence progression. One possibility is that flies perform frequent comparisons between anterior and posterior sensory inputs, and the changing ratios drive different behavior choices. Alternatively, flies may track the temporal change in sensory input to a given body part to measure cleaning effectiveness. The first hypothesis is supported by our optogenetic competition experiments: iterative spatial comparisons of sensory inputs between body parts is essential for organizing grooming movements in sequence.
动物整合来自不同感觉模态、身体部位和时间点的信息，以告知行为选择，但相关的感觉比较和潜在的神经回路在很大程度上仍然未知。我们使用黑腹果蝇的梳理行为作为模型，研究控制运动序列的感觉比较。果蝇会自发地进行梳理动作，但当它们被灰尘覆盖时，它们会按照从前到后的顺序清洁身体。在研究了可以检测灰尘的不同感觉模态之后，我们专注于机械感觉刚毛神经元，其光遗传学激活会诱导类似的序列。计算模型预测，头部更高的感觉输入强度将导致首先进行前部梳理。我们使用光遗传学竞争测定来测试这个预测，其中两个靶向光束独立地激活不同身体部位的机械感觉刚毛神经元。我们发现，梳理运动的初始选择取决于不同身体部位的感觉输入的比值。在被灰尘覆盖的果蝇中，由于成功的清洁运动，感觉输入会发生变化。我们的模型模拟表明，这种变化会导致序列的进展。一种可能性是，果蝇会频繁地在前后感觉输入之间进行比较，而不断变化的比值会导致不同的行为选择。或者，果蝇可能会跟踪给定身体部位的感觉输入的时间变化，以衡量清洁效果。第一个假设得到了我们的光遗传学竞争实验的支持：身体部位之间感觉输入的迭代空间比较对于组织梳理运动的序列是必不可少的。
