Smith Jo Armour, Albishi Alaa, Babikian Sarine, Asavasopon Skulpan, Fisher Beth E, Kutch Jason J
Division of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, CA, USA.
Department of Physical Therapy, Chapman University, Irvine, CA, USA.
Exp Brain Res. 2017 Sep;235(9):2767-2776. doi: 10.1007/s00221-017-5011-7. Epub 2017 Jun 19.
Functional connectivity patterns of the motor cortical representational area of single muscles have not been extensively mapped in humans, particularly for the axial musculature. Functional connectivity may provide a neural substrate for adaptation of muscle activity in axial muscles that have both voluntary and postural functions. The purpose of this study was to combine brain stimulation and neuroimaging to both map the cortical representation of the external oblique (EO) in primary motor cortex (M1) and supplementary motor area (SMA), and to establish the resting-state functional connectivity associated with this representation. Motor-evoked potentials were elicited from the EO muscle in stimulation locations encompassing M1 and SMA. The coordinates of locations with the largest motor-evoked potentials were confirmed with task-based fMRI imaging during EO activation. The M1 and SMA components of the EO representation demonstrated significantly different resting-state functional connectivity with other brain regions: the SMA representation of the EO muscle was significantly more connected to the putamen and cerebellum, and the M1 representation of the EO muscle was significantly more connected to somatosensory cortex and the superior parietal lobule. This study confirms the representation of a human axial muscle in M1 and SMA, and demonstrates for the first time that different parts of the cortical representation of a human axial muscle have resting-state functional connectivity with distinct brain regions. Future studies can use the brain regions of interest we have identified here to test the association between resting-state functional connectivity and control of the axial muscles.
单块肌肉运动皮质代表区的功能连接模式在人类中尚未得到广泛描绘，尤其是对于轴向肌肉。功能连接可能为具有自主和姿势功能的轴向肌肉的肌肉活动适应提供神经基础。本研究的目的是结合脑刺激和神经成像技术，绘制腹外斜肌（EO）在初级运动皮层（M1）和辅助运动区（SMA）中的皮质代表区，并建立与该代表区相关的静息态功能连接。在包含M1和SMA的刺激部位从EO肌肉引出运动诱发电位。在EO激活期间，通过基于任务的功能磁共振成像（fMRI）确认具有最大运动诱发电位的部位坐标。EO代表区的M1和SMA成分与其他脑区表现出显著不同的静息态功能连接：EO肌肉的SMA代表区与壳核和小脑的连接显著更多，而EO肌肉的M1代表区与体感皮层和顶上小叶的连接显著更多。本研究证实了人类轴向肌肉在M1和SMA中的代表区，并首次证明人类轴向肌肉皮质代表区的不同部分与不同脑区具有静息态功能连接。未来的研究可以使用我们在此确定的感兴趣脑区来测试静息态功能连接与轴向肌肉控制之间的关联。
