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    【6h】Sensitivity of motor adaptation to the statistical properties of an environmental load.

    机译电机对环境负荷统计特性的适应性敏感性。

    【摘要】Linear, limited-memory models capture many important features of adaptive motor performance during reaching, stepping and pointing. A recent study in our lab found that a model fitted to data obtained from subjects reaching against elastic loads which varied from trial-to-trial later failed to fit the steady-state response behavior of subjects exposed to deterministic, step changes in load. Does motor adaptation depend on statistical properties of the environment (eg. mean load strength and variability)? Neurologically intact volunteers (n=14) made 6 blocks of 100 planar, ballistic, 10cm, out-and-back reaching movements against spring-like loads having equilibrium positions at the hand's starting point. View of the limb was not allowed. Load stiffness varied trial-by-trial, and each block of movements differed in mean and/or variance such that three, 3-block contrasts were evaluated: increasing standard deviation (VAR), increasing mean (MEAN), and proportionally increasing standard deviation and mean (WEBER). In the VAR and MEAN contrasts, either the mean or the standard deviation of the load stiffness sequence was held constant while the other parameter varied systematically. In WEBER contrast, mean and standard deviation scaled proportionally over the contrast. The zero location of the transfer function moved toward the origin as variability increased. This trend in the zero location was the result of an unbalance in the decrease in the influence of previous load and the decrease of effective limb compliance with increasing variability. Specifically, the decrease in the influence of prior load was greater than the decrease in effective limb compliance. Effective limb compliance decreased to a larger extent in the MEAN and WEBER contrasts, which both presented an increase in mean load. In the MEAN contrast, the decrease in effective limb compliance with increasing mean load was balanced by an equivalent decrease in the influence of prior load, resulting in no significant change in the transfer function zero location. No changes in the influence of prior errors were observed in any of the contrasts. Thus, motor adaptation adjusts in two ways: the influence of prior load on subsequent movements decreases both when the environment is more variable and when effective limb compliance decreases with the mean load.

    【摘要机译】线性有限内存模型在到达,步进和指向过程中捕获了自适应电机性能的许多重要特征。我们实验室中的一项最新研究发现,一个模型拟合了从受试者承受的弹性载荷中获得的数据,该弹性载荷随试验的不同而变化,但未能适应暴露于确定性载荷阶跃变化的受试者的稳态响应行为。电机适应性是否取决于环境的统计特性(例如,平均负载强度和可变性)?神经功能完好的志愿者(n = 14)针对100个平面弹道,10厘米,前后移动的方块进行了6次锻炼,以对抗像弹簧一样的载荷,这些运动在手的起点具有平衡位置。不允许查看肢体。负载刚度因试验而异,并且每个运动块的均值和/或方差均不同,因此评估了三个,三个块的对比:增加标准差(VAR),增加均值(MEAN)和按比例增加标准差并表示(WEBER)。在VAR和MEAN对比中,载荷刚度序列的平均值或标准偏差保持恒定,而其他参数则系统地变化。在WEBER对比中,平均值和标准偏差在对比上成比例缩放。随着变异性的增加,传递函数的零位置移向原点。零位位置的这种趋势是先前负荷影响的降低和有效肢体顺应性的降低(随着变异性增加)不平衡的结果。具体而言,先前负荷影响的降低大于有效肢体顺应性的降低。在MEAN和WEBER对比中,有效肢体顺应性在很大程度上降低了,这两者均显示了平均负荷的增加。在MEAN对比中,有效肢体顺应性随平均负荷的增加而降低,而在先负荷的影响也相应降低,从而使传递函数零位没有明显变化。在任何对比中都没有观察到先验误差影响的变化。因此,运动适应性有两种调整方式:当环境变化更大时,以及当有效肢体顺应性随平均负荷而降低时,先前负荷对后续运动的影响会减小。

    【作者】Goetz-Haswell, Timothy M.;

    【作者单位】Marquette University.;

    【年(卷),期】2010(),

    【年度】2010

    【页码】69 p.

    【总页数】69

    【原文格式】PDF

    【正文语种】eng

    【中图分类】;

    【关键词】

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