How a lateralized brain supports symmetrical bimanual tasks.
How a lateralized brain supports symmetrical bimanual tasks.
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DOI：
10.1371/journal.pbio.0040158
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发表时间：
2006-06
期刊：
影响因子：
9.8
通讯作者：
Nyberg L
中科院分区：
文献类型：
--
作者：
Johansson RS;Theorin A;Westling G;Andersson M;Ohki Y;Nyberg L
大量的自然物体操作任务需要双手在单个物体上精确地耦合对称的相反力。我们问的是，侧化的大脑如何处理空间和时间协调的基本问题。我们表明，大脑始终任命一只手作为主要演员，而其他协助，但代理手的选择是灵活的。当研究参与者通过操纵双手之间自由握着的工具来控制光标时，如果光标随着左手力的方向移动，则左手成为主要行为者，而如果右手随着相反的右手力移动，则右手主要起作用。在神经生理学（肌电图，经颅磁脑刺激）和功能磁共振脑成像实验中，我们证明，手分配的变化平行于中线移位的偏侧活动在远端的手肌肉，皮质脊髓通路，和初级感觉运动和小脑皮质区。我们的结论是，双手可以很容易地交换角色，占主导地位的演员在双手的任务。手的力量和目标运动之间的空间关系决定手的分配，而不是习惯性的偏手性。最后，手的灵活角色分配在运动系统的多个层面上表现出来，从皮层区域一直到特定的肌肉。Johansson和他的同事们将联合收割机与神经生理学和脑成像实验结合起来，研究了在物体操作过程中灵活的手协调的神经基础和动力学。
A large repertoire of natural object manipulation tasks require precisely coupled symmetrical opposing forces by both hands on a single object. We asked how the lateralized brain handles this basic problem of spatial and temporal coordination. We show that the brain consistently appoints one of the hands as prime actor while the other assists, but the choice of acting hand is flexible. When study participants control a cursor by manipulating a tool held freely between the hands, the left hand becomes prime actor if the cursor moves directionally with the left-hand forces, whereas the right hand primarily acts if it moves with the opposing right-hand forces. In neurophysiological (electromyography, transcranial magnetic brain stimulation) and functional magnetic resonance brain imaging experiments we demonstrate that changes in hand assignment parallels a midline shift of lateralized activity in distal hand muscles, corticospinal pathways, and primary sensorimotor and cerebellar cortical areas. We conclude that the two hands can readily exchange roles as dominant actor in bimanual tasks. Spatial relationships between hand forces and goal motions determine hand assignments rather than habitual handedness. Finally, flexible role assignment of the hands is manifest at multiple levels of the motor system, from cortical regions all the way down to particular muscles. Johansson and colleagues combine the use of a novel bimanual task with neurophysiological and brain imaging experiments to examine the neural basis and dynamics of flexible hand coordination during object manipulation.
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