In functional magnetic resonance imaging (fMRI) studies, performance of unilateral hand movements is associated with primary motor cortex activity ipsilateral to the moving hand (M1_ipsi), in addition to contralateral activity (M1_contra). The magnitude of M1_ipsi activity increases with the demand on precision of the task. However, it is unclear how demand-dependent increases in M1_ipsi recruitment relate to the control of hand movements. To address this question, we used fMRI to measure blood oxygenation level-dependent (BOLD) activity during performance of a task that varied in demand on precision. Participants (N = 23) manipulated an MRI-compatible joystick with their right or left hand to move a cursor into targets of different sizes (small, medium, large, extra-large). Performance accuracy, movement time, and number of velocity peaks scaled with target size, whereas reaction time, maximum velocity, and initial direction error did not. In the univariate analysis, BOLD activation in M1_contra and M1_ipsi was higher for movements to smaller targets. Representational similarity analysis, corrected for mean activity differences, revealed multivoxel BOLD activity patterns during movements to small targets were most similar to those for medium targets and least similar to those for extra-large targets. Only models that varied with demand (target size, performance accuracy, and number of velocity peaks) correlated with the BOLD dissimilarity patterns, though differently for right and left hands. Across individuals, M1_contra and M1_ipsi similarity patterns correlated with each other. Together, these results suggest that increasing demand on precision in a unimanual motor task increases M1 activity and modulates M1 activity patterns.

中文翻译：

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随着对精度要求的提高，单手运动期间的初级运动皮层活动。

在功能性磁共振成像 (fMRI) 研究中，除了对侧活动 (M1 _{contra ) 之外，单侧手部运动的表现还与运动手同侧的初级运动皮层活动 (M1 ipsi} ) 相关。_{M1 ipsi}活动的幅度随着任务精度的要求而增加。_{然而，目前尚不清楚 M1 ipsi}的需求依赖性增长如何招募与手部运动的控制有关。为了解决这个问题，我们使用 fMRI 来测量执行一项对精度要求不同的任务期间的血氧水平依赖性 (BOLD) 活动。参与者 (N = 23) 用右手或左手操纵与 MRI 兼容的操纵杆，将光标移动到不同大小（小、中、大、特大）的目标中。性能精度、运动时间和速度峰值的数量随目标大小成比例，而反应时间、最大速度和初始方向误差则没有。在单变量分析中，M1 _contra和 M1 _{ipsi中的 BOLD 激活}移动到较小的目标时更高。对平均活动差异进行校正的代表性相似性分析显示，在向小目标移动期间的多体素 BOLD 活动模式与中等目标最相似，而与特大目标最相似。只有随需求（目标大小、性能准确性和速度峰值数量）变化的模型与 BOLD 差异模式相关，尽管左右手有所不同。在个体之间，M1 _contra和 M1 _ipsi相似性模式相互关联。总之，这些结果表明，在单手运动任务中增加对精度的要求会增加 M1 活动并调节 M1 活动模式。