Human adaptive behavior in sensorimotor control is aimed to increase the confidence in feedforward mechanisms when sensory afferents are uncertain. It is thought that these feedforward mechanisms rely on predictions from internal models. We investigate whether the brain uses an internal model of physical laws (gravitational and inertial forces) to help estimate body equilibrium when tactile inputs from the foot sole are depressed by carrying extra weight. As direct experimental evidence for such a model is limited, we used Judoka athletes thought to have built up internal models of external loads (i.e. opponent weight management) as compared with Dancers (highly skilled in balance control) and Non-Athlete participants. We compared the amplitude of P1N1 somatosensory cortical potentials evoked by electrical stimulation of the foot sole in participants standing still with their eyes closed. We showed smaller P1N1 amplitudes in the Load compared to No Load conditions in both Non-Athletes and Dancers. This decrease neural response to tactile stimulation was associated with greater postural oscillations. By contrast in the Judokas group, the neural early response to tactile stimulation was unregulated in the Load condition. This suggests that the brain can selectively increase the functional gain of sensory inputs, during challenging equilibrium tasks when tactile inputs were mechanically depressed by wearing a weighted vest. In Judokas, the activation of regions such as the right posterior inferior parietal cortex (PPC) as early as the P1N1 is likely the source of the neural responses being maintained similar in both Load and No Load conditions. An overweight internal model stored in the right PPC known to be involved in maintaining a coherent representation of one’s body in space can optimize predictive mechanisms in situations with high balance constraints.

中文翻译：

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当触觉提示不确定时，可以激活习得的超重内部模型以维持平衡：来自皮质和行为方法的证据


感觉运动控制中的人类自适应行为旨在当感觉传入不确定时增加前馈机制的置信度。人们认为这些前馈机制依赖于内部模型的预测。我们研究了当脚底的触觉输入因承受额外重量而受到抑制时，大脑是否使用物理定律（重力和惯性力）的内部模型来帮助估计身体平衡。由于这种模型的直接实验证据有限，我们使用了被认为已经建立了外部负载（即对手体重管理）内部模型的柔道运动员，与舞者（平衡控制能力很强）和非运动员参与者进行比较。我们比较了闭眼站立的参与者脚底电刺激诱发的 P1N1 体感皮层电位的幅度。我们发现，与非运动员和舞者的无负载条件相比，负载条件下的 P1N1 振幅更小。这种对触觉刺激的神经反应的减弱与更大的姿势振荡有关。相比之下，在柔道运动员组中，神经对触觉刺激的早期反应在负荷条件下不受调节。这表明，在具有挑战性的平衡任务中，当穿着加重背心机械地抑制触觉输入时，大脑可以选择性地增加感觉输入的功能增益。在柔道运动员中，早在 P1N1 阶段右后下顶叶皮层 (PPC) 等区域的激活可能是在负载和无负载条件下保持相似神经反应的根源。 存储在正确的 PPC 中的超重内部模型已知参与维持身体在空间中的连贯表示，可以在具有高平衡约束的情况下优化预测机制。