Three-dimensional behavioural phenotyping of freely moving C. elegans using quantitative light field microscopy

Behavioural phenotyping of model organisms is widely used to investigate fundamental aspects of organism biology, from the functioning of the nervous system to the effects of genetic mutations, as well as for screening new drug compounds. However, our capacity to observe and quantify the full range and complexity of behavioural responses is limited by the inability of conventional microscopy techniques to capture volumetric image information at sufficient speed. In this article we describe how combining light field microscopy with computational depth estimation provides a new method for fast, quantitative assessment of 3D posture and movement of the model organism Caenorhabditis elegans (C. elegans). We apply this technique to compare the behaviour of cuticle collagen mutants, finding significant differences in 3D posture and locomotion. We demonstrate the ability of quantitative light field microscopy to provide new fundamental insights into C. elegans locomotion by analysing the 3D postural modes of a freely swimming worm. Finally, we consider relative merits of the method and its broader application for phenotypic imaging of other organisms and for other volumetric bioimaging applications.模式生物（model organisms）的行为表型分型（behavioural phenotyping）已被广泛应用于探究生物体生物学的基础层面——涵盖神经系统功能、基因突变的影响，以及新型药物化合物的筛选。然而，传统显微技术无法以足够高的速率获取三维体积图像信息，这限制了我们观测并量化行为反应的全部范围与复杂程度的能力。本文阐述了将光场显微镜（light field microscopy）与计算深度估计（computational depth estimation）相结合的新方法，可实现对模式生物秀丽隐杆线虫（Caenorhabditis elegans, C. elegans）的三维姿态与运动进行快速、定量评估。我们运用该技术对表皮胶原蛋白突变体（cuticle collagen mutants）的行为开展对比分析，发现其在三维姿态与运动模式上存在显著差异。通过分析自由游动线虫的三维姿态模式，我们证明了定量光场显微镜能够为秀丽隐杆线虫的运动研究提供全新的基础性认知。最后，我们探讨了该方法的相对优势，以及其在其他模式生物的表型成像（phenotypic imaging）及其他三维体积生物成像应用中的拓展前景。