Prudente Cecilia N, Stilla Randall, Buetefisch Cathrin M, Singh Shivangi, Hess Ellen J, Hu Xiaoping, Sathian Krish, Jinnah H A
Department of Neurology.
Departments of Neurology and Rehabilitation Medicine, Emory University, Atlanta, Georgia 30309.
J Neurosci. 2015 Jun 17;35(24):9163-72. doi: 10.1523/JNEUROSCI.0851-15.2015.
The neural systems controlling head movements are not well delineated in humans. It is not clear whether the ipsilateral or contralateral primary motor cortex is involved in turning the head right or left. Furthermore, the exact location of the neck motor area in the somatotopic organization of the motor homunculus is still debated and evidence for contributions from other brain regions in humans is scarce. Because currently available neuroimaging methods are not generally suitable for mapping brain activation patterns during head movements, we conducted fMRI scans during isometric tasks of the head. During isometric tasks, muscle contractions occur without an actual movement and they have been used to delineate patterns of brain activity related to movements of other body parts such as the hands. Healthy individuals were scanned during isometric head rotation or wrist extension. Isometric wrist extension was examined as a positive control and to establish the relative locations of head and hand regions in the motor cortex. Electromyographic recordings of neck and hand muscles during scanning ensured compliance with the tasks. Increased brain activity during isometric head rotation was observed bilaterally in the precentral gyrus, both medial and lateral to the hand area, as well the supplementary motor area, insula, putamen, and cerebellum. These findings clarify the location of the neck region in the motor homunculus and help to reconcile some of the conflicting results obtained in earlier studies.
在人类中，控制头部运动的神经系统尚未得到很好的描绘。目前尚不清楚同侧或对侧的初级运动皮层是否参与头部的左右转动。此外，在运动小人图的躯体定位组织中，颈部运动区的确切位置仍存在争议，而且关于人类其他脑区贡献的证据也很稀少。由于目前可用的神经成像方法通常不适用于绘制头部运动期间的脑激活模式，我们在头部等长收缩任务期间进行了功能磁共振成像扫描。在等长收缩任务期间，肌肉收缩发生但没有实际运动，并且它们已被用于描绘与其他身体部位（如手部）运动相关的脑活动模式。在等长头部旋转或手腕伸展期间对健康个体进行扫描。将等长手腕伸展作为阳性对照进行检查，并确定运动皮层中头部和手部区域的相对位置。扫描期间颈部和手部肌肉的肌电图记录确保了对任务的依从性。在等长头部旋转期间，双侧中央前回、手部区域内侧和外侧以及辅助运动区、岛叶、壳核和小脑的脑活动均增加。这些发现阐明了运动小人图中颈部区域的位置，并有助于调和早期研究中获得的一些相互矛盾的结果。
