Introduction

The supplementary motor area (SMA) plays an important role in the initiation and coordination of internally and externally cued movements. Such movements include reaching, grasping, speaking, and bilateral hand coordination. While many studies discuss the SMA and its relationship to other parts of the motor network, there is minimal literature examining the connectivity of the SMA outside of the motor network. Using region-based fMRI studies, we built a neuroanatomical model to account for these extra-motor connections.

Methods

Thirty region-based fMRI studies were used to generate an activation likelihood estimation (ALE) using BrainMap software. Cortical parcellations overlapping the ALE were used to construct a preliminary model of the SMA connections outside the motor network. DSI-based fiber tractography was performed to determine the connectivity between cortical parcellations. The resulting connections were described using the cortical parcellation scheme developed by the Human Connectome Project (HCP).

Results

Four left hemisphere regions were found to comprise the SMA. These included areas SFL, SCEF, 6ma, and 6mp. Across mapped brains, these areas showed consistent interconnections between each other. Additionally, ipsilateral connections to the primary motor cortex, left inferior and middle frontal gyri, the anterior cingulate gyrus, and insula were demonstrated. Connections to the contralateral SMA, anterior cingulate, lateral premotor, and inferior frontal cortices were also identified.

Conclusions

We describe a preliminary cortical model for the underlying structural connectivity of the supplementary motor area outside the motor network. Future studies should further characterize the neuroanatomic underpinnings of this network for the purposes of medical application.

中文翻译：

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基于分区的辅助运动区域建模

介绍

运动辅助区（SMA）在内部和外部提示运动的发起和协调中起着重要作用。这些动作包括伸手，抓地，说话和双边手部协调。尽管许多研究都讨论了SMA及其与电机网络其他部分的关系，但很少有文献研究SMA在电机网络外部的连通性。使用基于区域的功能磁共振成像研究，我们建立了一个神经解剖模型来说明这些运动外连接。

方法

使用BrainMap软件，使用了30个基于区域的fMRI研究来生成激活可能性估计（ALE）。与ALE重叠的皮质细胞被用来构建运动网络外部SMA连接的初步模型。进行基于DSI的纤维束成像，以确定皮质细胞间的连通性。使用人类连接基因组计划（HCP）开发的皮质细胞分裂方案描述了产生的连接。

结果

发现四个左半球区域构成了SMA。这些区域包括SFL，SCEF，6ma和6mp。跨制图的大脑，这些区域之间显示出一致的相互联系。此外，还证实了同侧与主运动皮层，左下中额中回，前扣带回和岛状连接。还确定了与对侧SMA，前扣带回，外侧前运动和额叶下皮质的连接。

结论

我们描述了一个初步的皮层模型，用于在电机网络外部的辅助电机区域的基础结构连通性。未来的研究应进一步表征该网络的神经解剖基础，以用于医学应用。