Makary Meena M, Eun Seulgi, Soliman Ramy S, Mohamed Abdalla Z, Lee Jeungchan, Park Kyungmo
aDepartment of Biomedical Engineering, Kyung Hee University, Yongin, Republic of Korea bDepartment of Radiology, Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA.
Neuroreport. 2017 Aug 16;28(12):731-738. doi: 10.1097/WNR.0000000000000825.
Controversy exists regarding the involvement of the primary motor cortex (M1) during motor imagery (MI) and also regarding the differential somatotopic representation of motor execution (ME) and mental simulation of movement, that is, MI within M1. Although some research reported clear M1 involvement during MI without overt motor output, others did not. However, possible somatotopic representation between execution and imagery has not been clearly investigated to date. The aim of the present study was to aid in the resolution of this controversy by investigating the possible involvement of M1 during MI, and the differential, within M1, somatotopic representation between execution and imagery by quantitatively assessing different location markers such as activation peak and center of mass as well as intensity differences between the two tasks in case of with and without the overlap between the two representations. Forty-one healthy volunteers participated in two functional MRI runs of mouth-stretching ME and MI tasks. Our findings suggest the clear involvement of M1 (BA 4) during MI with lower signal intensity compared with ME, and further showed distinct centers for each representation along the y-axis (anteroposterior plane), with MI showing more involvement of the anterior sector of M1 (BA 4a), whereas ME recruited more of the posterior sector (BA 4p). These results parallel the pioneering findings of a functional distinction between BA 4a and BA 4p, where BA 4a is more involved in the cognitive aspects of MI, whereas BA 4p is more related to executive function, promoting the idea of distinctive somatotopic mapping between execution and imagery within M1 sectors.
关于运动想象（MI）过程中初级运动皮层（M1）是否参与，以及运动执行（ME）和运动心理模拟（即M1内的MI）的不同躯体定位表征，目前存在争议。尽管一些研究报告称在没有明显运动输出的MI过程中M1有明确参与，但其他研究则未发现。然而，迄今为止，执行和想象之间可能的躯体定位表征尚未得到明确研究。本研究的目的是通过研究MI过程中M1的可能参与情况，以及通过定量评估不同的位置标记（如激活峰值和质心）以及在两种表征存在或不存在重叠情况下两个任务之间的强度差异，来帮助解决这一争议，从而明确M1内执行和想象之间的差异躯体定位表征。41名健康志愿者参与了口部伸展ME和MI任务的两次功能磁共振成像扫描。我们的研究结果表明，MI过程中M1（BA 4区）明显参与，与ME相比信号强度较低，并且进一步显示出沿y轴（前后平面）每种表征有不同的中心，MI显示M1前区（BA 4a）参与更多，而ME募集了更多后区（BA 4p）。这些结果与BA 4a和BA 4p功能差异的开创性发现一致，其中BA 4a更多地参与MI的认知方面，而BA 4p更多地与执行功能相关，这支持了M1各区域内执行和想象之间存在独特躯体定位映射的观点。
