Sensory integration of a light touch reference in human standing balance.
Sensory integration of a light touch reference in human standing balance.
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DOI：
10.1371/journal.pone.0197316
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发表时间：
2018
期刊：
影响因子：
3.7
通讯作者：
Reynolds RF
中科院分区：
文献类型：
--
作者：
Assländer L;Smith CP;Reynolds RF
在直立的立场，轻触空间静止的触摸参考减少自发摇摆。移动参考唤起摇摆反应，表现出非线性行为，这归因于感官重加权。重加权指的是在相对贡献的变化，感觉线索表明身体在空间上的摇摆和轻触线索表明手指的位置相对于身体。在这里，我们测试了一个假设，即感觉融合过程包括将轻触信号转换为与其他编码身体摆动的感官输入相同的参考框架，反之亦然。八名受试者轻轻地抓住一个围绕踝关节作圆弧运动的机器人操纵杆。在三个振幅下应用具有广谱特征的伪随机运动序列。刺激呈现在两个不同的高度，因此不同的径向距离，这在角运动方面是匹配的。然而，高刺激引起的摇摆反应明显更大，表明响应与刺激的角运动不匹配。相反，身体摇摆反应与操纵杆的水平平移密切相关。结果表明，轻触被整合为身体COM和手指之间的水平距离。数据很好地解释了一个模型，一个反馈回路最小化水平com手指距离的变化。该模型还包括第二个反馈回路，估计手指的水平运动，并在触摸参考移动时纠正第一个回路。第二个循环包括感官信号的预测转换到相同的参考框架和一个非线性阈值元素，该元素再现了非线性摇摆响应，从而提供了一种可以解释权重调整的机制。
In upright stance, light touch of a space-stationary touch reference reduces spontaneous sway. Moving the reference evokes sway responses which exhibit non-linear behavior that has been attributed to sensory reweighting. Reweighting refers to a change in the relative contribution of sensory cues signaling body sway in space and light touch cues signaling finger position with respect to the body. Here we test the hypothesis that the sensory fusion process involves a transformation of light touch signals into the same reference frame as other sensory inputs encoding body sway in space, or vice versa. Eight subjects lightly gripped a robotic manipulandum which moved in a circular arc around the ankle joint. A pseudo-randomized motion sequence with broad spectral characteristics was applied at three amplitudes. The stimulus was presented at two different heights and therefore different radial distances, which were matched in terms of angular motion. However, the higher stimulus evoked a significantly larger sway response, indicating that the response was not matched to stimulus angular motion. Instead, the body sway response was strongly related to the horizontal translation of the manipulandum. The results suggest that light touch is integrated as the horizontal distance between body COM and the finger. The data were well explained by a model with one feedback loop minimizing changes in horizontal COM-finger distance. The model further includes a second feedback loop estimating the horizontal finger motion and correcting the first loop when the touch reference is moving. The second loop includes the predicted transformation of sensory signals into the same reference frame and a non-linear threshold element that reproduces the non-linear sway responses, thus providing a mechanism that can explain reweighting.