Verstynen Timothy, Diedrichsen Jörn, Albert Neil, Aparicio Paul, Ivry Richard B
Deptartment of Psychology, University of California, Berkeley, CA 94720, USA.
J Neurophysiol. 2005 Mar;93(3):1209-22. doi: 10.1152/jn.00720.2004. Epub 2004 Nov 3.
Functional imaging studies have revealed recruitment of ipsilateral motor areas during the production of sequential unimanual finger movements. This phenomenon is more prominent in the left hemisphere during left-hand movements than in the right hemisphere during right-hand movements. Here we investigate whether this lateralization pattern is related specifically to the sequential structure of the unimanual action or generalizes to other complex movements. Using event-related fMRI, we measured activation changes in the motor cortex during three types of unimanual movements: repetitions of a sequence of movements with multiple fingers, repetitive "chords" composed of three simultaneous key presses, and simple repetitive tapping movements with a single finger. During sequence and chord movements, strong ipsilateral activation was observed and was especially pronounced in the left hemisphere during left-hand movements. This pattern was evident for both right-handed and, to a lesser degree, left-handed individuals. Ipsilateral activation was less pronounced in the tapping condition. The site of ipsilateral activation was shifted laterally, ventrally, and anteriorly with respect to that observed during contralateral movements and the time course of activation implied a role in the execution rather than planning of the movement. A control experiment revealed that strong ipsilateral activity in left motor cortex is specific to complex movements and does not depend on the number of required muscles. These findings indicate a prominent role of left hemisphere in the execution of complex movements independent of the sequential nature of the task.
功能成像研究显示，在进行连续的单手手指运动时，同侧运动区会被激活。这种现象在左手运动时左半球比右手运动时右半球更为明显。在此，我们研究这种偏侧化模式是否特定与单手动作的连续结构相关，或者是否能推广到其他复杂运动。使用事件相关功能磁共振成像，我们测量了三种单手运动过程中运动皮层的激活变化：多个手指的一系列动作的重复、由三个同时按键组成的重复“和弦”以及单指的简单重复敲击动作。在序列和和弦运动过程中，观察到强烈的同侧激活，且在左手运动时左半球尤为明显。这种模式在右利手个体中明显，在左利手个体中程度稍轻。在敲击条件下，同侧激活不太明显。同侧激活的部位相对于对侧运动时观察到的部位向外侧、腹侧和前方偏移，激活的时间进程表明其在运动执行而非运动计划中起作用。一项对照实验表明，左运动皮层中的强烈同侧活动特定于复杂运动，并不取决于所需肌肉的数量。这些发现表明，左半球在复杂运动的执行中起重要作用，而与任务的序列性质无关。
