基于认知环路的HD-tDCS调控脑小血管病患者步行功能的脑网络机制研究

The walking disorder caused by (SVD) increases the risk of fall and death in the elderly. Its behavioral characteristics and mechanism of brain networks are unclear. SVD is still lack of effective treatment. There is a common anatomical structure and neural circuits mechanism between cognitive impairment and walking disorder in SVD. Can gait be improved by cognitive ability? We also found, in another pre-experiment applied functional resting-state MRI (rs-MRI) to investigate the connectivity of motor executive brain networks induced by high definition transcranial direct current stimulation(HD tDCS), that functional connectivity of motor executive brain networks had been improved significantly .Therefore, we deduced that it could be a new promising mechanism to the motor function recovery of subjects in SVD. With such synchronization of brain structural network dynamics, we assume that the HD tDCS treatment through frontal-subcortical circuit could facilitate the brain networks more effectively to improve gait recovery. All patients in this study will be assigned randomly to 1 of 2 groups for 2 weeks’ treatments.Before and after treatment, the clinical neural evaluation and kinematics assessment of gait and balance combined with magnetic resonance Imaging(MRI) were applied on each subject to compare the differences within each group and between the two groups. The brain structural and functional networks will be also built up in multi-modal neuroimaging of T1, DTI and Rest-state. Our attention will be put on the coupling with the analysis of structural connectivity and functional connectivity. In the response to this new treatment of HD tDCS , we aim to explore the brain structure and functional data, and to find the relationship between improvements of walking ability and brain network’s topology changes. Meanwhile, Based on biological image markers above, results of this study will show more scientific evidence to form a new and efficient treatment with subjects in SVD.

脑小血管病（SVD）引起的步行障碍，增加老人跌倒和致死风险，其行为学特点、脑网络机制不明确、治疗方法匮乏。SVD的认知障碍和步行障碍存在共同的解剖结构和环路机制，能否通过干预认知能力而改善步态？课题组前期发现HDtDCS可以增强患者磁共振静息态（RS）运动执行功能有关的网络连接，推测可能是改善运动功能的新机制。由此假设脑HDtDCS可能通过额叶-皮层下认知环路使脑结构网络动力学同步化，或许在时空上形成有效的动态功能网络，促进步行改善。本课题拟将SVD患者随机分为2组，治疗2周，治疗前后采用T1、DTI、RS多模态磁共振成像技术，构建全脑结构和功能网络，耦合分析结构和功能连接，并结合步行与平衡的运动学分析及神经功能学评估，探讨HDtDCS刺激DLPFC存在脑结构与功能网络的重塑，可能通过改变脑拓扑网络而起到临床疗效，为SVD步行障碍形成一种全新、有效治疗方案提供生物影像学标记

脑小血管病引起的步行障碍，增加跌倒和致死风险，其行为学特点、脑网络机制不明确、治疗方法匮乏。目前相关研究认为认知障碍和步行障碍存在共同的解剖结构和环路机制，能否通过干预认知能力而改善步态？课题组前期发现tDCS可以增强患者磁共振静息态（RS）运动执行功能有关的网络连接，推测可能是改善运动功能的新机制。由此假设脑tDCS可能通过额叶-皮层下认知环路使脑结构网络动力学同步化，或许在时空上形成有效的动态功能网络，调控步态。本课题引入“双任务步行”模式，即步行过程中执行认知任务，探究tDCS调控运动认知任务的可能机制。将健康青年人纳入试验，受试者随机接受tDCS、伪tDCS刺激，tDCS阳极置于健康青年人左前额叶背外侧脑区（DLPFC），刺激时间20分钟，刺激前后令受试者随机进行单任务、双任务步行。单任务：受试者以最适速度步行，双任务：受试者按最适速度步行，同时执行认知任务，包括计算与工作记忆能力。在干预前、干预后的单、双任务步行过程中，对受试者同时进行三维步态分析，并评估认知任务能力。三维步态评估包括步行周期、步速、步频、步长、单双支撑相时间，认知任务评估包括认知任务的完成率、正确率，研究发现tDCS阳极刺激DLPFC可能会减慢健康青年人的步速，缩短步长，降低认知任务表现，可能与tDCS阳极刺激占用认知容量有关。同时课题对tDCS刺激DLPFC后静息态脑网络进行了分析，以左扣带回作为感兴趣区域计算全脑功能连接，发现小脑等脑区连接明显增强，可能是tDCS干预认知与步态神经环路的重要脑网络节点。tDCS阳极刺激脑卒中偏瘫患者下肢代表区，刺激同时进行步行训练，随机分为tDCS组，伪刺激tDCS组，通过神经功能学量表、三维步态分析、平衡功能学分析发现tDCS可能通过提高平衡功能改善脑卒中患者的步行能力。本课题探讨了tDCS可改善脑卒中患者的平衡运动功能，tDCS可通过调控认知环路、认知容量改变健康青年人认知步行能力，可能通过改变脑拓扑网络而起到临床疗效，为步行障碍形成一种全新、有效治疗方案提供临床干预方案和生物影像学标记。