The Influence of Visual, Vestibular, and Hindlimb Proprioceptive Ablations on Landing Preparation in Cane Toads
The Influence of Visual, Vestibular, and Hindlimb Proprioceptive Ablations on Landing Preparation in Cane Toads
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DOI：
10.1093/icb/icy059
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发表时间：
2018-11-01
影响因子：
2.6
通讯作者：
Gillis, G. B.
中科院分区：
文献类型：
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作者：
Cox, S. M.;Ekstrom, L. J.;Gillis, G. B.
跳跃协调着陆需要做好准备，其中必须包括着陆肢体和身体的适当定位和配置才能成功。在对哺乳动物进行深入研究的同时，我们的实验室一直在使用甘蔗蟾蜍（Rhinella marinus）作为模型来了解无尾目动物受控着陆的生物力学，无尾目动物使用跳跃或跳跃作为其主要运动模式。在本文中，我们报告了实验的新结果，这些实验旨在探索不同的感觉反馈模式如何有助于先前确定的蟾蜍协调着陆特征。更具体地说，视觉、后肢本体感觉或前庭反馈被去除的动物接受了一系列跳跃试验，同时使用高速视频记录和表征肢体运动，并记录主要肘伸肌（肘肌）的肌电图（EMG）活动。结果表明，改变任何感觉系统都会影响着陆行为，但视力丧失的影响最小。相对于对照组，失明动物的肘部肌电图计时存在显着差异，但前肢和后肢运动以及使用前肢成功减速身体的能力不受影响。后肢本体感觉受损导致前肢运动学明显不同。尽管肌电图模式被破坏，但在这种情况下，动物在撞击后也能够减速，尽管控制较少，在着陆过程中经常允许它们的树干接触地面。前庭系统受损的动物在起飞和着陆行为方面表现出最大的缺陷，这些行为变化很大且很少协调。然而，这种情况下的动物表现出与对照动物相似的肌电图模式和前肢运动学。事实上，没有任何消融能够完全消除着陆准备的所有方面，这表明其基础是复杂的，并且没有单一的感官触发因素来启动它。
Coordinated landing from a jump requires preparation, which must include appropriate positioning and configuration of the landing limbs and body to be successful. While well studied in mammals, our lab has been using the cane toad (Rhinella marinus) as a model for understanding the biomechanics of controlled landing in anurans, animals that use jumping or bounding as their dominant mode of locomotion. In this article, we report new results from experiments designed to explore how different modes of sensory feedback contribute to previously identified features of coordinated landing in toads. More specifically, animals in which vision, hindlimb proprioception, or vestibular feedback were removed, underwent a series of hopping trials while high-speed video was used to record and characterize limb movements and electromyographic (EMG) activity was recorded from a major elbow extensor (anconeus). Results demonstrate that altering any sensory system impacts landing behavior, though loss of vision had the least effect. Blind animals showed significant differences in anconeus EMG timing relative to controls, but forelimb and hindlimb movements as well as the ability to successfully decelerate the body using the forelimbs were not affected. Compromising hindlimb proprioception led to distinctly different forelimb kinematics. Though EMG patterns were disrupted, animals in this condition were also able to decelerate after impact, though with less control, regularly allowing their trunks to make ground contact during landing. Animals with compromised vestibular systems showed the greatest deficits, both in takeoff and landing behavior, which were highly variable and rarely coordinated. Nevertheless, animals in this condition demonstrated EMG patterns and forelimb kinematics similar to those in control animals. The fact that no ablation entirely eliminates all aspects of landing preparation suggests that its underpinnings are complex and that there is no single sensory trigger for its initiation.