Neurology Unit, Department of Clinical Neurosciences, University of Cambridge, UK.
Neuroimage. 2010 Mar;50(1):1-6. doi: 10.1016/j.neuroimage.2009.12.012. Epub 2009 Dec 11.
Not only finger tapping speed, but also tapping regularity can be impaired after stroke, contributing to reduced dexterity. The neural substrates of impaired tapping regularity after stroke are unknown. Previous work suggests damage to the dorsal premotor cortex (PMd) and prefrontal cortex (PFCx) affects externally-cued hand movement. We tested the hypothesis that these two areas are involved in impaired post-stroke tapping regularity. In 19 right-handed patients (15 men/4 women; age 45-80 years; purely subcortical in 16) partially to fully recovered from hemiparetic stroke, tri-axial accelerometric quantitative assessment of tapping regularity and BOLD fMRI were obtained during fixed-rate auditory-cued index-thumb tapping, in a single session 10-230 days after stroke. A strong random-effect correlation between tapping regularity index and fMRI signal was found in contralesional PMd such that the worse the regularity the stronger the activation. A significant correlation in the opposite direction was also present within contralesional PFCx. Both correlations were maintained if maximal index tapping speed, degree of paresis and time since stroke were added as potential confounds. Thus, the contralesional PMd and PFCx appear to be involved in the impaired ability of stroke patients to fingertap in pace with external cues. The findings for PMd are consistent with repetitive TMS investigations in stroke suggesting a role for this area in affected-hand movement timing. The inverse relationship with tapping regularity observed for the PFCx and the PMd suggests these two anatomically-connected areas negatively co-operate. These findings have implications for understanding the disruption and reorganization of the motor systems after stroke.
不仅手指敲击速度，而且敲击的规律性在中风后也会受损，导致灵巧度降低。中风后敲击规律性受损的神经基础尚不清楚。先前的工作表明，背侧运动前皮层 (PMd) 和前额叶皮层 (PFCx) 的损伤会影响外部提示的手部运动。我们测试了以下假设，即这两个区域参与了中风后敲击规律性的受损。在 19 名右侧偏瘫中风后部分或完全恢复的患者（15 名男性/4 名女性；年龄 45-80 岁；16 名纯皮质下）中，在中风后 10-230 天内，在单次会议中，通过三轴加速计对敲击规律性进行定量评估，并进行 BOLD fMRI，同时进行固定速率听觉提示索引-拇指敲击。在对侧 PMd 中发现了敲击规律性指数和 fMRI 信号之间的强烈随机效应相关性，即规律性越差激活越强。在对侧 PFCx 中也存在相反方向的显著相关性。如果将最大索引敲击速度、瘫痪程度和中风时间添加为潜在混杂因素，则可以维持这两个相关性。因此，对侧 PMd 和 PFCx 似乎参与了中风患者跟随外部提示进行指尖敲击的能力受损。PMd 的发现与中风后的重复 TMS 研究一致，表明该区域在手部运动定时中起作用。PFCx 和 PMd 观察到的与敲击规律性的反向关系表明这两个解剖连接的区域负性合作。这些发现对理解中风后运动系统的中断和重组具有意义。
