Department of Neuroscience, Section of Neurology, University of Padova, Padua, Italy.
Padova Neuroscience Center, University of Padova, Padua, Italy.
Cerebellum. 2024 Oct;23(5):1848-1858. doi: 10.1007/s12311-024-01678-x. Epub 2024 Mar 5.
The overlap between motor and cognitive signs resulting from posterior parietal cortex (PPC) and cerebellar lesions can mask their relative contribution in the sensorimotor integration process. This study aimed to identify distinguishing motor and cognitive features to disentangle PPC and cerebellar involvement in two sensorimotor-related functions: gait and body schema representation. Thirty healthy volunteers were enrolled and randomly assigned to PPC or cerebellar stimulation. Sham stimulation and 1 Hz-repetitive-Transcranial-Magnetic-Stimulation were delivered over P3 or cerebellum before a balance and a walking distance estimation task. Each trial was repeated with eyes open (EO) and closed (EC). Eight inertial measurement units recorded spatiotemporal and kinematic variables of gait. Instability increased in both groups after real stimulation: PPC inhibition resulted in increased instability in EC conditions, as evidenced by increased ellipse area and range of movement in medio-lateral and anterior-posterior (ROMap) directions. Cerebellar inhibition affected both EC (increased ROMap) and EO stability (greater displacement of the center of mass). Inhibitory stimulation (EC vs. EO) affected also gait spatiotemporal variability, with a high variability of ankle and knee angles plus different patterns in the two groups (cerebellar vs parietal). Lastly, PPC group overestimates distances after real stimulation (EC condition) compared to the cerebellar group. Stability, gait variability, and distance estimation parameters may be useful clinical parameters to disentangle cerebellar and PPC sensorimotor integration deficits. Clinical differential diagnosis efficiency can benefit from this methodological approach.
顶叶后部皮层（PPC）和小脑损伤导致的运动和认知症状重叠，可能掩盖了它们在感觉运动整合过程中的相对贡献。本研究旨在确定区分运动和认知特征的方法，以区分 PPC 和小脑在两种感觉运动相关功能中的参与：步态和身体图式表示。30 名健康志愿者被纳入并随机分配到 PPC 或小脑刺激组。在平衡和步行距离估计任务之前，分别对 P3 或小脑进行假刺激和 1Hz 重复经颅磁刺激。每个试验均在睁眼（EO）和闭眼（EC）条件下重复。八个惯性测量单元记录了步态的时空和运动学变量。真实刺激后两组的不稳定性均增加：PPC 抑制导致 EC 条件下不稳定性增加，表现为中侧和前后（ROMap）方向的椭圆面积和运动范围增加。小脑抑制影响 EC（ROMap 增加）和 EO 稳定性（质心位移更大）。抑制性刺激（EC 与 EO）还影响步态时空变异性，两组的踝关节和膝关节角度变化较大且模式不同（小脑与顶叶）。最后，PPC 组在真实刺激后（EC 条件）高估距离，而小脑组则没有。稳定性、步态变异性和距离估计参数可能是区分小脑和 PPC 感觉运动整合缺陷的有用临床参数。这种方法可以提高临床鉴别诊断的效率。
