Do fish have necks: measuring 3D motion of the vertebrae and axial muscle dynamics in suction-feeding fishes.

我将通过研究鱼隐藏的“脖子”，展示肌肉和骨骼如何协同工作，使人类和动物的脖子变得灵活。颈部允许头部三维运动，独立于四肢和身体。它在人类中的重要性从颈部疾病造成的功能缺陷得到了鲜明的说明，它的起源是一次重大转变，刺激了陆栖脊椎动物的进化。然而，我们对颈部骨骼和肌肉如何相互作用来提供这些基本功能知之甚少，因为它们的结构和运动很复杂，不可能直接可视化，也不可能与头部和身体的运动分开。有了新的成像技术，现在可以在3D中测量骨骼和肌肉的运动，而FISH为研究这些问题提供了一个有趣的模型系统。尽管鱼没有真正的解剖学脖子，但对它们摄食的研究表明，脊椎可以通过向上弯曲将头部抬离身体来发挥颈部的作用。如果鱼确实有一个隐藏的“脖子”，它是由身体肌肉提供动力的，这些肌肉在一个复杂的肌肉纤维结构中从头延伸到尾。所有肌肉都需要在缩短的速度和产生的力量之间进行权衡。身体肌肉纤维的方向和缩短时的变化方式可以让肌肉以不同的速度“换档”并缩短，这取决于所需的力量。这种动态的平衡可以发生在人的肌肉中，并可能导致与年龄相关的肌肉表现的变化。直接测量动态纤维取向和缩短一直是非常具有挑战性的，但可视化肌肉纤维和测量其运动的新方法可能提供对肌肉功能的关键见解。我将测量鱼的脊椎的3D弯曲，以及它在独立于肩、腰带和身体三维移动头部时的作用。我还将研究这一颈部区域身体肌肉的结构和动态调整，以确定纤维重新定向如何影响肌肉性能。我将在利物浦大学进行这项研究，使用新的基于X射线的可视化技术来测量三种鱼的3D骨骼和肌肉运动，这些鱼具有一系列脊椎形状和假想的“颈部弯曲”。这项工作建立在我使用和开发这种3D成像工具的经验基础上，并利用了大学世界级的X射线拍摄设备。每条鱼的头部、肩带和脊椎的X射线视频将与这些骨骼的3D模型相匹配，这些骨骼是通过CT扫描建立的，以创建准确的3D动画，从中我可以测量每块骨骼的运动。从这些X光视频中，我还将测量身体肌肉在颈部运动时如何改变长度和形状。通过向内森·杰弗里博士学习对比度增强的微CT扫描技术，我可以可视化身体肌肉纤维的3D排列。与卡尔·贝茨博士和克里斯·达奥特博士合作，我将使用这些图像将虚拟肌肉纤维添加到骨骼动画中：创建一个纤维方向和肌肉形状变化如何影响肌肉缩短的模型。这项拟议的研究将改变我们对颈部起源的看法，并为肌肉动力学提供见解。通过将活体鱼类脊椎的解剖和运动联系起来，这项研究将为了解颈部可能的进化奠定基础。它还将帮助水产养殖者了解和改善商业鲑鱼的饲养性能。我关于鱼肌肉的形状变化、纤维旋转和缩短的数据可以用来理解人类肌肉是如何经历这些同样的动态的--以及这些动态在衰老过程中的变化可能如何影响健康和表现。最后，我将在利物浦世界博物馆和当地科学俱乐部的外展项目中使用这项研究的引人入胜的3D模型、动画和X射线视频来激励下一代科学家和创新者。

I will demonstrate how muscles and bones work together to give humans and animals a flexible neck, by studying the hidden "neck" of fish. A neck allows the head to move three-dimensionally, and independently of the limbs and body. Its importance in humans is starkly illustrated by the functional deficits imposed by disorders of the neck, and its origin was a major transformation that spurred the evolution of land-dwelling vertebrates. Yet we know relatively little of how the bones and muscles of the neck interact to provide these essential functions, because their structure and motions are complex and have been impossible to directly visualize or separate from motions of the head and body. With new imaging techniques it is now possible to measure bone and muscle motion in 3D, and fish offer anintriguing model system for investigating these questions. Although fish lack a true, anatomical neck, studies of their feeding suggest the backbone could function as a neck by bending upwards to lift the head away from the body. If fish do have a hidden "neck", it is powered by the body muscles, which extend from head to tail in a complex architecture of muscle fibres. All muscles have a trade-off between how fast they can shorten and how much force they can produce. The orientation of the body muscle fibres and the way that changes as they shorten could allow the muscle to "shift gears" and shorten at different speeds, depending on the force required. This dynamic gearing can occur in human muscles, and may contribute to age-related changes in muscle performance. Directly measuring dynamic fibre orientation and shortening has been very challenging, but new methods for visualizing muscle fibres and measuring their motion may provide key insights into muscle function. I will measure the 3D bending of the backbone in fish and its role in moving the head three-dimensionally and independently of the shoulder girdle and body. I will also examine the architecture and dynamic gearing of the body muscles in this neck region to establish how fibre re-orientation impacts muscle performance. I will carry out this research at the University of Liverpool, using new, X-ray based visualizations to measure 3D bone and muscle motion in three fish with a range of vertebral shapes and hypothesized "neck bending". This work builds on my experience using and developing such 3D imaging tools, and utilizes the University's world-class X-ray filming facility. X-ray video of each fish's head, shoulder girdle, and backbone will be matched with 3D models of these bones, built from CT scans, to create an accurate 3D animation from which I can measure each bone's motion. From these X-ray videos, I will also measure how the body muscles change length and shape during neck motion. By learning contrast-enhanced micro-CT scanning techniques from Dr. Nathan Jeffrey, I can visualize the 3D arrangement of the body muscle fibres. Working with Dr. Karl Bates and Kris D'Aout, I will use these images to add virtual muscle fibres to the bone animations: creating a model of how fibre orientation and muscle shape change affects muscle shortening. The proposed research will change our perspective on the origin of the neck, and provide insights into muscle dynamics. By linking the anatomy and motion of the backbone in living fish, this study will lay the foundation for understanding how the neck may have evolved. It will also help aquaculturists understand and improve feeding performance in commercial trout. My data on shape changes, fibre rotation and shortening of fish muscles can be applied to understanding how human muscles undergo these same dynamics-and how changes these dynamics during ageing may impact health and performance. Lastly, I will use the engaging 3D models, animations, and X-ray videos from this research in outreach programs at the World Museum in Liverpool and local science clubs to inspire the next generation of scientists and innovators.