Influences of object weight and instruction on grip force adjustments.
Influences of object weight and instruction on grip force adjustments.
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物体重量和指令对握力调整的影响。
DOI：
10.1007/bf00231864
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发表时间：
1991
影响因子：
2
通讯作者：
Petashnick,D
中科院分区：
文献类型：
--
作者：
Winstein,CJ;Abbs,JH;Petashnick,D
本研究探讨了物体重量和指令对人类握力反应的影响。使用精确的抓握，受试者将一个小型仪器测试对象举起到预定的高度。在每组40次试验之前，受试者被口头指示“握住”或“放开”物体以响应重量的任何变化。在一些试验中（< 20%），不可预测地，垂直载荷突然持续增加（载荷）或减少（卸载）施加到物体上。通过测量握力、物体位置和相关的肌电图（EMG）活动来评估对这些诱导的体重变化的抓握反应。加载时的夹持力变化比卸载时的夹持力变化大三倍以上。这种不对称性可能反映了在受重力影响的世界中的日常把握和操纵。平均而言，“保持”指令后对负载的夹持力调整略大于“放手”指令后的夹持力调整，但指令对卸载反应没有影响。这些研究结果与更强大的影响，口头指令的自动姿势和近端上肢的反应，也可能表明，握力调整的影响在更大程度上由内在的任务变量比外在的意志意图。这样的组织似乎是针对自然环境中的功能任务要求而设计的。
This study investigated the influence of object weight and instructions on grip force responses in humans. Using a precision grip, subjects lifted a small instrumented test object to a predetermined height. Prior to each set of 40 trials, subjects were verbally instructed to either “hold” or “let go” of the object in response to any change in weight. Unpredictably on some trials (< 20%), a sudden sustained increase (load) or decrease (unload) in vertical load was applied to the object. Grip responses to these induced weight changes were evaluated by measuring grip force, object position, and associated electromyographic (EMG) activity. Grip force changes for a load were over three times greater than those for an unload. Such asymmetry may reflect everyday grasp and manipulation in a gravity-influenced world. Grip force adjustments to loads following “hold” instructions were on the average somewhat larger than those following “let go” instructions, but there was no influence of instructions on responses to unloads. These findings contrast with more robust influences of verbal instruction on automatic postural and proximal upper limb responses and also may suggest that grip force adjustments are influenced to a greater extent by intrinsic task variables than by extrinsic volitional intent. Such organization appears tailored to functional task requirements in natural environmental contexts.