Buetefisch Cathrin M, Revill Kate Pirog, Shuster Linda, Hines Benjamin, Parsons Michael
Department. of Neurology, West Virginia University, Morgantown, West Virginia; Department of Physiology, West Virginia University, Morgantown, West Virginia; Department of Neurology, Emory University, Atlanta, Georgia; Department of Rehabilitation Medicine, Emory University, Atlanta, Georgia; and
Center for Advanced Brain Imaging, Georgia State University/Georgia Institute of Technology, Atlanta, Georgia.
J Neurophysiol. 2014 Aug 15;112(4):999-1009. doi: 10.1152/jn.00110.2014. Epub 2014 May 21.
The role of ipsilateral primary motor cortex (M1) in hand motor control during complex task performance remains controversial. Bilateral M1 activation is inconsistently observed in functional (f)MRI studies of unilateral hand performance. Two factors limit the interpretation of these data. As the motor tasks differ qualitatively in these studies, it is conceivable that M1 contributions differ with the demand on skillfulness. Second, most studies lack the verification of a strictly unilateral execution of the motor task during the acquisition of imaging data. Here, we use fMRI to determine whether ipsilateral M1 activity depends on the demand for precision in a pointing task where precision varied quantitatively while movement trajectories remained equal. Thirteen healthy participants used an MRI-compatible joystick to point to targets of four different sizes in a block design. A clustered acquisition technique allowed simultaneous fMRI/EMG data collection and confirmed that movements were strictly unilateral. Accuracy of performance increased with target size. Overall, the pointing task revealed activation in contralateral and ipsilateral M1, extending into contralateral somatosensory and parietal areas. Target size-dependent activation differences were found in ipsilateral M1 extending into the temporal/parietal junction, where activation increased with increasing demand on accuracy. The results suggest that ipsilateral M1 is active during the execution of a unilateral motor task and that its activity is modulated by the demand on precision.
在复杂任务执行过程中，同侧初级运动皮层（M1）在手部运动控制中的作用仍存在争议。在单侧手部运动的功能磁共振成像（fMRI）研究中，双侧M1激活的观察结果并不一致。有两个因素限制了对这些数据的解读。由于这些研究中的运动任务在质量上存在差异，可以想象M1的贡献会因对熟练程度的要求不同而有所差异。其次，大多数研究在采集成像数据时缺乏对运动任务严格单侧执行的验证。在此，我们使用功能磁共振成像来确定同侧M1的活动是否取决于指向任务中的精度要求，在该任务中精度进行了定量变化，而运动轨迹保持不变。13名健康参与者使用与磁共振成像兼容的操纵杆，以区组设计指向四种不同大小的目标。一种集群采集技术允许同时收集功能磁共振成像/肌电图数据，并证实运动是严格单侧的。表现的准确性随着目标大小的增加而提高。总体而言，指向任务显示对侧和同侧M1均有激活，延伸至对侧体感和顶叶区域。在同侧M1延伸至颞叶/顶叶交界处发现了与目标大小相关的激活差异，其中激活随着对准确性要求的增加而增强。结果表明，同侧M1在单侧运动任务执行过程中是活跃的，并且其活动受到精度要求的调节。
