Rupani Mia, Cleland Luke D, Saal Hannes P
Active Touch Laboratory, School of Psychology, University of Sheffield, Sheffield, UK.
Insigneo Institute for in silico Medicine, University of Sheffield, Sheffield, UK.
J R Soc Interface. 2025 Feb;22(223):20240794. doi: 10.1098/rsif.2024.0794. Epub 2025 Feb 19.
Skin stretch, induced by bodily movements, offers a potential source of information about the conformation of the body that can be transmitted to the brain via stretch-sensitive mechanoreceptive neurons. While previous studies have primarily focused on skin stretch directly at joints, here we investigate the extent and complexity of natural skin stretch across various body regions, including the face and trunk. We used a quad-camera set-up to image large ink-based speckle patterns stamped on participants' skin and calculated the resulting stretch patterns on a millimetre scale during a range of natural poses. We observed that skin stretch associated with joint movement extends far beyond the joint itself, with knee flexion inducing stretch on the upper thigh. Large and uniform stretch patterns were found across the trunk, covering considerable portions of the skin. The face exhibited highly complex and non-uniform stretch patterns, potentially contributing to our capacity to control fine facial movements in the absence of traditional proprioceptors. Importantly, all regions demonstrated skin stretch in excess of mechanoreceptive thresholds, suggesting that behaviourally relevant skin stretch can occur anywhere on the body. These signals might provide the brain with valuable information about body state and conformation, potentially supplementing or even surpassing the capabilities of traditional proprioception.
身体运动引起的皮肤拉伸提供了有关身体形态的潜在信息来源，这些信息可通过对拉伸敏感的机械感受神经元传递至大脑。虽然先前的研究主要集中在关节处的直接皮肤拉伸，但在此我们研究了包括面部和躯干在内的身体各个区域自然皮肤拉伸的程度和复杂性。我们使用四摄像头设置对印在参与者皮肤上的大型基于墨水的散斑图案进行成像，并在一系列自然姿势下以毫米尺度计算由此产生的拉伸图案。我们观察到，与关节运动相关的皮肤拉伸远远超出关节本身，膝盖弯曲会导致大腿上部皮肤拉伸。在躯干上发现了大面积且均匀的拉伸图案，覆盖了相当大一部分皮肤。面部呈现出高度复杂且不均匀的拉伸图案，这可能有助于我们在缺乏传统本体感受器的情况下控制精细面部运动的能力。重要的是，所有区域的皮肤拉伸都超过了机械感受阈值，这表明与行为相关的皮肤拉伸可能发生在身体的任何部位。这些信号可能为大脑提供有关身体状态和形态的有价值信息，有可能补充甚至超越传统本体感觉的能力。
