Hemispheric Asymmetry of Frequency-Dependent Suppression in the Ipsilateral Primary Motor Cortex During Finger Movement: A Functional Magnetic Resonance Imaging Study
Hemispheric Asymmetry of Frequency-Dependent Suppression in the Ipsilateral Primary Motor Cortex During Finger Movement: A Functional Magnetic Resonance Imaging Study
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DOI：
10.1093/cercor/bhn053
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发表时间：
2008-12-01
期刊：
影响因子：
3.7
通讯作者：
Sadato, Norihiro
中科院分区：
文献类型：
--
作者：
Hayashi, Masamichi J.;Saito, Daisuke N.;Sadato, Norihiro
电生理学研究表明，同侧手运动时初级运动皮质(M1)的活动既反映了同侧的神经支配，也反映了对侧大脑半球初级运动皮质(M1)对同侧初级运动皮质的抑制控制，它们的不对称性可能导致手的支配。为了研究频率应激下单手运动任务中同侧运动皮质受累的不对称性，我们对22名正常右利手受试者进行了区组设计的功能磁共振成像。这项任务包括视觉提示对手的手指以不同的速度移动。对侧M1呈对称性频率依赖性激活。同侧M1呈任务相关去激活，频率低，无偏侧性。随着左手运动频率的增加，左侧M1的失活逐渐减少。这一数据表明，左侧M1参与同侧手控制的频率依赖增加。相反，随着右手运动频率的增加，右侧M1显示出更显著的失活。这表明，在同侧手部运动时，从左侧M1到右侧M1，存在更多的跨痂抑制，这压倒了右侧M1的激活。这些结果表明，在右利手个体中，左侧M1在同侧神经支配和跨痂抑制中占主导地位。
Electrophysiological studies have suggested that the activity of the primary motor cortex (M1) during ipsilateral hand movement reflects both the ipsilateral innervation and the transcallosal inhibitory control from its counterpart in the opposite hemisphere, and that their asymmetry might cause hand dominancy. To examine the asymmetry of the involvement of the ipsilateral motor cortex during a unimanual motor task under frequency stress, we conducted block-design functional magnetic resonance imaging with 22 normal right-handed subjects. The task involved visually cued unimanual opponent finger movement at various rates. The contralateral M1 showed symmetric frequency-dependent activation. The ipsilateral M1 showed task-related deactivation at low frequencies without laterality. As the frequency of the left-hand movement increased, the left M1 showed a gradual decrease in the deactivation. This data suggests a frequency-dependent increased involvement of the left M1 in ipsilateral hand control. By contrast, the right M1 showed more prominent deactivation as the frequency of the right-hand movement increased. This suggests that there is an increased transcallosal inhibition from the left M1 to the right M1, which overwhelms the right M1 activation during ipsilateral hand movement. These results demonstrate the dominance of the left M1 in both ipsilateral innervation and transcallosal inhibition in right-handed individuals.