Young David R, Parikh Pranav J, Layne Charles S
Center for Neuromotor and Biomechanics Research, Department of Health and Human Performance, University of Houston, Houston, TX, United States.
Center for Neuro-Engineering and Cognitive Science, University of Houston, Houston, TX, United States.
Front Hum Neurosci. 2020 Jun 26;14:248. doi: 10.3389/fnhum.2020.00248. eCollection 2020.
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; = 0.005) as well as a significant interaction between condition and measurement period for the average position ( = 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.
在姿势控制过程中，为了促进对环境变化做出适应性反应，需要对视觉、前庭和本体感觉信息进行有效的中枢感觉整合。后顶叶皮质（PPC）受损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一个重要因素。在某些情况下，抑制PPC的兴奋性也会降低姿势稳定性。到目前为止，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）是否能调节对双足倾斜姿势适应任务的姿势适应。我们使用年轻健康受试者，在双侧PPC上施加tDCS，然后进行倾斜站立训练（倾斜干预）。对姿势后效应的分析发现，刺激条件之间在最大倾斜后效应（LAE；=0.005）方面存在差异，并且在平均位置上条件与测量期之间存在显著交互作用（=0.03）。我们发现两种主动刺激条件后姿势适应性均受损。结果强化了PPC参与运动适应的观点，并将这一研究方向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个体垂直性内部表征方面的作用，并证明了参与姿势控制和适应的大脑弥散区域。这些信息增进了我们对皮质在姿势控制中作用的理解，突出了PPC作为感觉运动康复靶点的潜力。
