This study explores brain-network differences between the intrinsic and extrinsic motor coordinate frames. A connectivity model showing the coordinate frames difference was obtained using brain fMRI data of right wrist isometric flexions and extensions movements, performed in two forearm postures. The connectivity model was calculated by machine-learning-based neural representation and effective functional connectivity using psychophysiological interaction and dynamic causal modeling analyses. The model indicated the network difference wherein the inferior parietal lobule receives extrinsic information from the rostral lingual gyrus through the superior parietal lobule and transmits intrinsic information to the Handknob, whereas extrinsic information is transmitted to the Handknob directly from the rostral lingual gyrus. A behavioral experiment provided further evidence on the difference between motor coordinate frames showing onset timing delay of muscle activity of intrinsic coordinate-directed wrist movement compared to extrinsic one. These results suggest that, if the movement is externally directed, intrinsic coordinate system information is bypassed to reach the primary motor area.

中文翻译：

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手腕运动中内在坐标与外在坐标的差分处理：连接性和计时学角度

这项研究探讨了内在和外在运动坐标系之间的大脑网络差异。使用以两种前臂姿势进行的右手腕等距屈曲和伸展运动的大脑功能磁共振成像数据获得了显示坐标系差异的连接模型。连接模型是通过基于机器学习的神经表示和使用心理生理学相互作用和动态因果建模分析的有效功能连接来计算的。该模型表明了网络差异，其中顶下小叶通过顶上小叶从舌回接收外在信息并将内在信息传输到手旋钮，而外在信息直接从舌回传递到手旋钮。一项行为实验提供了关于运动坐标系之间差异的进一步证据，表明与外在坐标系相比，内在坐标引导的手腕运动的肌肉活动的起始时间延迟。这些结果表明，如果运动是外部引导的，则内在坐标系信息将被绕过到达主要运动区域。