Manipulating the edge of instability
Manipulating the edge of instability
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DOI：
10.1016/j.jbiomech.2007.01.022
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发表时间：
2007-01-01
影响因子：
2.4
通讯作者：
Valero-Cuevas, Francisco J.
中科院分区：
文献类型：
--
作者：
Venkadesan, Madhusudhan;Guckenheimer, John;Valero-Cuevas, Francisco J.
我们研究了视觉和触觉感官输入在动态操作中的整合。我们的实验数据和计算模型表明，时间延迟对于任务最优的多感官整合与感觉运动噪声同样关键。我们关注的是一个“处于不稳定边缘”的动态操作任务。数学分岔理论预测，在这种情况下，该系统将呈现出分类明确的低维动态。任务是用拇指垫尽可能地压缩一个容易弯曲的细长弹簧，但又不至于滑落。正如分岔理论所预期的那样，主成分分析将数据投影到一个低维子空间上，该子空间能捕捉到其91 - 97%的方差。在这个子空间中，我们根据系统已知的机械和神经生理特性，为大脑 + 手 + 弹簧的动态建立了一个低阶模型。通过对12名同意参与的受试者有系统地遮挡视觉以及用麻醉剂阻断拇指垫的感觉，我们发现只有当拇指垫感觉缺失时，视觉才对动态操作有帮助。在感觉通道缺失的情况下，模型系统压缩弹簧的能力下降，这与实验结果非常相似。此外，我们发现只有考虑到时间延迟，模型才能重现视觉在情境中的作用。我们的研究结果揭示了动态操作不同于静态捏合的关键特征，以及当年龄或神经肌肉疾病导致感觉运动整合过程中的噪声和/或时间延迟增加时，可能导致手部灵活性丧失以及对视觉依赖增加的机制。(C) 2007由爱思唯尔有限公司出版
We investigate the integration of visual and tactile sensory input for dynamic manipulation. Our experimental data and computational modeling reveal that time-delays are as critical to task-optimal multisensory integration as sensorimotor noise. Our focus is a dynamic manipulation task "at the edge of instability." Mathematical bifurcation theory predicts that this system will exhibit well-classified low-dimensional dynamics in this regime. The task was using the thumbpad to compress a slender spring prone to buckling as far as possible, just shy of slipping. As expected from bifurcation theory, principal components analysis gives a projection of the data onto a low dimensional subspace that captures 91-97% of its variance. In this subspace, we formulate a low-order model for the brain + hand + spring dynamics based on known mechanical and neurophysiological properties of the system. By systematically occluding vision and anesthetically blocking thumbpad sensation in 12 consenting subjects, we found that vision contributed to dynamic manipulation only when thumbpad sensation was absent. The reduced ability of the model system to compress the spring with absent sensory channels closely resembled the experimental results. Moreover, we found that the model reproduced the contextual usefulness of vision only if we took account of time-delays. Our results shed light on critical features of dynamic manipulation distinct from those of static pinch, as well as the mechanism likely responsible for loss of manual dexterity and increased reliance on vision when age or neuromuscular disease increase noisiness and/or time-delays during sensorimotor integration. (C) 2007 Published by Elsevier Ltd.