The roundworm Caenorhabditis elegans is an important model system for understanding the genetics and physiology of touch. Classical assays for C. elegans touch, which involve manually touching the animal with a probe and observing its response, are limited by low their low throughput and qualitative nature. To address these limitations, weWe developed a microfluidic device in which several dozen animals are subject to spatially localized mechanical stimuli with variable amplitude. The device contains 64 sinusoidal channels through which worms crawl, and hydraulic valves that deliver touch stimuli to the worms. We used this assay to characterize the behavioral responses to gentle touch stimuli and the less well studied harsh (nociceptive) touch stimuli. First, we measured the relative response thresholds of gentle and harsh touch. Next, we quantified differences in the receptive fields between wild type worms and a mutant with non-functioning posterior touch receptor neurons. We foundshowed that under gentle touch the receptive field of the anterior touch receptor neurons extends into the posterior half of the body. Finally, we found that the behavioral response to gentle touch does not depend on the locomotion of the animal immediately prior to the stimulus, but does depend on the location of the previous touch. Responses to harsh touch, on the other hand, did not depend on either previous velocity or stimulus location. Differences in gentle and harsh touch response characteristics may reflect the different innervation patterns of the respective mechanosensory cells. Our assay will facilitate studies of mechanosensation, sensory adaptation, and nociception.

中文翻译：

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使用多路液压微流体装置比较秀丽隐杆线虫温和和粗糙的触摸反应行为

线虫秀丽隐杆线虫是了解触觉遗传学和生理学的重要模型系统。线虫触摸的经典检测涉及用探针手动触摸动物并观察其反应，但由于其低通量和定性性质而受到限制。为了解决这些限制，我们开发了一种微流体装置，其中几十只动物受到幅度可变的空间局部机械刺激。该装置包含 64 个供蠕虫爬行的正弦通道，以及向蠕虫提供触摸刺激的液压阀。我们使用这种测定来表征对温和触摸刺激和研究较少的严厉（伤害性）触摸刺激的行为反应。首先，我们测量了轻柔和粗糙触摸的相对响应阈值。接下来，我们量化了野生型线虫和后触觉感受器神经元无功能的突变体之间感受野的差异。我们发现，在轻柔的触摸下，前触觉感受器神经元的感受野延伸到身体的后半部。最后，我们发现对轻柔触摸的行为反应并不取决于动物在刺激前的运动，而是取决于前一次触摸的位置。另一方面，对严厉触摸的反应并不取决于先前的速度或刺激位置。轻柔和粗糙触摸响应特性的差异可能反映了各自机械感觉细胞的不同神经支配模式。我们的测定将促进机械感觉、感觉适应和伤害感受的研究。