Effective central sensory integration of visual, vestibular, and proprioceptive information is required to promote adaptability in response to changes in the environment during postural control. Patients with a lesion in the posterior parietal cortex (PPC) have an impaired ability to form an internal representation of body position, an important factor for postural control and adaptation. Suppression of PPC excitability has also been shown to decrease postural stability in some contexts. As of yet, it is unknown whether stimulation of the PPC may influence postural adaptation. This investigation aimed to identify whether transcranial direct current stimulation (tDCS) of the bilateral PPC could modulate postural adaptation in response to a bipedal incline postural adaptation task. Using young, healthy subjects, we delivered tDCS over bilateral PPC followed by bouts of inclined stance (incline-interventions). Analysis of postural after-effects identified differences between stimulation conditions for maximum lean after-effect (LAE; p = 0.005) as well as a significant interaction between condition and measurement period for the average position (p = 0.03). We identified impaired postural adaptability following both active stimulation conditions. Results reinforce the notion that the PPC is involved in motor adaptation and extend this line of research to the realm of standing posture. The results further highlight the role of the bilateral PPC in utilizing sensory feedback to update one’s internal representation of verticality and demonstrates the diffuse regions of the brain that are involved in postural control and adaptation. This information improves our understanding of the role of the cortex in postural control, highlighting the potential for the PPC as a target for sensorimotor rehabilitation.

中文翻译：

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后顶叶皮层的非侵入性脑刺激改变姿势适应

需要有效的视觉、前庭和本体感觉信息的中央感觉整合，以提高对姿势控制期间环境变化的适应性。后顶叶皮层 (PPC) 病变的患者形成身体位置内部表征的能力受损，这是姿势控制和适应的重要因素。在某些情况下，抑制 PPC 兴奋性也被证明会降低姿势稳定性。迄今为止，尚不清楚刺激 PPC 是否会影响姿势适应。本研究旨在确定双侧 PPC 的经颅直流电刺激 (tDCS) 是否可以调节姿势适应以响应双足倾斜姿势适应任务。使用年轻、健康的受试者，我们通过双边 PPC 提供 tDCS，然后是倾斜姿势（倾斜干预）。姿势后遗症的分析确定了最大瘦后遗症的刺激条件之间的差异（LAE；p = 0.005）以及平均位置的条件和测量周期之间的显着相互作用（p = 0.03）。我们发现在两种主动刺激条件下姿势适应性受损。结果强化了 PPC 参与运动适应的概念，并将这一研究领域扩展到站立姿势领域。结果进一步突出了双侧 PPC 在利用感觉反馈更新一个人的内部垂直表征方面的作用，并展示了参与姿势控制和适应的大脑扩散区域。