Goyens Jana, Aerts Peter
Laboratory of Functional Morphology, University of Antwerp, Universiteitsplein 1, 2610 Antwerp, Belgium.
Laboratory of Functional Morphology, University of Antwerp, Universiteitsplein 1, 2610 Antwerp, Belgium; Department of Movement and Sport Sciences, Ghent University, Watersportlaan 2, 9000 Ghent, Belgium.
Zoology (Jena). 2018 Apr;127:114-120. doi: 10.1016/j.zool.2017.11.008. Epub 2017 Nov 29.
The cyclic patterns of terrestrial animal locomotion are frequently perturbed in natural environments. The terrain can be complex or inclined, the substrate can move unexpectedly and animals can misjudge situations. Loosing stability due to perturbations increases the probability of capture by predators and decreases the chance of successful prey capture and winning intraspecific battles. When controlled corrective actions are necessary to negotiate perturbations, animals rely on their exteroceptive and proprioceptive senses to monitor the environment and their own body movements. The vestibular system in the inner ear perceives linear and angular accelerations. This information enables gaze stabilisation and the creation of a stable, world-bound reference frame for the integration of the information of other senses. During locomotion, both functions are known to be facilitated by head stabilisation in several animals with an erect posture. Animals with a sprawled body posture, however, undergo very large body undulations while running. Using high speed video recordings, we tested whether they nevertheless stabilise their head during running, and how this is influenced by perturbations. We found that running Acanthodactylus boskianus lizards strongly stabilise their head yaw rotations when running on a flat, straight runway: the head rotation amplitude is only 4.76±0.99°, while the adjacent trunk part rotates over 27.0±3.8°. Lateral head translations are not stabilised (average amplitude of 7.4±2.0mm). When the lizards are experimentally perturbed by a large and unexpected lateral substrate movement, lateral translations of both the head and the body decrease (on average by 1.52±0.81mm). At the same time, the rotations of the head and trunk also decrease (on average by 1.62°±7.21°). These results show that head stabilisation intensifies because of the perturbation, which emphasises the importance of vestibular perception and balance in these fast and manoeuvrable animals.
陆地动物运动的周期性模式在自然环境中经常受到干扰。地形可能复杂或倾斜，基质可能意外移动，动物可能误判情况。因干扰而失去稳定性会增加被捕食者捕获的概率，并降低成功捕获猎物和赢得种内战斗的机会。当需要采取可控的纠正行动来应对干扰时，动物依靠其外部感知和本体感知来监测环境和自身身体运动。内耳中的前庭系统感知线性和角加速度。这些信息有助于稳定注视，并为整合其他感官信息创建一个稳定的、与世界相关的参考框架。在运动过程中，已知在几种具有直立姿势的动物中，头部稳定有助于这两种功能。然而，具有伸展身体姿势的动物在奔跑时会经历非常大的身体波动。我们使用高速视频记录测试了它们在奔跑时是否仍然能稳定头部，以及这是如何受到干扰影响的。我们发现，奔跑的棘趾蜥在平坦、笔直的跑道上奔跑时能强烈稳定其头部偏航旋转：头部旋转幅度仅为4.76±0.99°，而相邻的躯干部分旋转超过27.0±3.8°。头部的横向平移不稳定（平均幅度为7.4±2.0毫米）。当蜥蜴受到大的、意外的横向基质移动实验性干扰时，头部和身体的横向平移都会减少（平均减少1.52±0.81毫米）。同时，头部和躯干的旋转也会减少（平均减少1.62°±7.21°）。这些结果表明，由于干扰，头部稳定增强，这强调了前庭感知和平衡在这些快速且灵活的动物中的重要性。
