Moulton Eric, Galléa Cécile, Kemlin Claire, Valabregue Romain, Maier Marc A, Lindberg Pavel, Rosso Charlotte
Sorbonne Universits, UPMC Univ Paris 06, Inserm U1127, Centre National de la Recherche Scientifique UMR 7225, UM 75, ICM, Paris, France.
Centre de Neuro-Imagerie de Recherche, CENIR, Paris, France.
Front Hum Neurosci. 2017 Oct 25;11:511. doi: 10.3389/fnhum.2017.00511. eCollection 2017.
Structural and functional differences are known to exist within the cortical sensorimotor networks with respect to the dominant vs. non-dominant hand. Similarly, the cerebellum, a key structure in the sensorimotor network with its cerebello-cortical connections, has been reported to respond differently when using the dominant vs. non-dominant hand. Several groups have already investigated causal interactions during diverse motor paradigms using effective connectivity but few have studied the larger visuomotor network, including key structures such as the parietal cortex and the cerebellum, with both hands. Moreover, the effect of force level on such interactions is still unclear. We therefore sought to determine the hemispheric asymmetries in the cerebello-cortical sensorimotor network in right-handers at two force levels (5% and 10% maximum voluntary contraction) for both hands. Cerebello-cortical modulations were investigated in 28 healthy, right-handed volunteers by determining the effective connectivity during a visuomotor task at two force levels under fMRI. A network was built consisting of the left and right primary motor (M1), ventral premotor (PMv) and posterior parietal cortices (PPC), in addition to the supplementary motor area (SMA), and the ipsilateral cerebellum (Cer) to the hand performing the motor task. Task performance (precision of isometric grip force tracking) did not differ between hands, nor did task-related activations in the sensorimotor areas apart from the contralateral primary motor cortex. However, during visuomotor control of the non-dominant hand, connectivity analysis revealed causal modulations between (i) the ipsilateral cerebellum and SMA, and (ii) the ipsilatearl cerebellum and contralateral PPC, which was not the case when using the dominant hand. These cerebello-cortical modulations for the non-dominant hand were more present at the higher of the two force levels. We conclude that precision force generation executed with the non-dominant hand, compared to the dominant hand, may require enhanced cerebello-cortical interaction to ensure equivalent left-right task performance.
已知在皮质感觉运动网络中，优势手和非优势手之间存在结构和功能差异。同样，小脑作为感觉运动网络中的关键结构，通过其小脑 - 皮质连接，据报道在使用优势手和非优势手时反应不同。已有多个研究小组使用有效连接性研究了不同运动范式中的因果相互作用，但很少有人用双手研究包括顶叶皮质和小脑等关键结构在内的更大的视觉运动网络。此外，力水平对这种相互作用的影响仍不清楚。因此，我们试图确定右利手在两种力水平（最大自主收缩的5%和10%）下双手的小脑 - 皮质感觉运动网络中的半球不对称性。通过在功能磁共振成像（fMRI）下的两种力水平的视觉运动任务中确定有效连接性，对28名健康的右利手志愿者的小脑 - 皮质调制进行了研究。构建了一个网络，该网络由左右初级运动皮层（M1）、腹侧前运动皮层（PMv）和后顶叶皮层（PPC）组成，此外还包括辅助运动区（SMA）以及执行运动任务手的同侧小脑（Cer）。双手之间的任务表现（等长握力跟踪的精度）没有差异，除了对侧初级运动皮层外，感觉运动区域中与任务相关的激活也没有差异。然而，在非优势手的视觉运动控制过程中，连接性分析揭示了（i）同侧小脑与SMA之间以及（ii）同侧小脑与对侧PPC之间的因果调制，而使用优势手时并非如此。非优势手的这些小脑 - 皮质调制在两种力水平中较高的那个水平上更为明显。我们得出结论，与优势手相比，用非优势手进行精确力的产生可能需要增强小脑 - 皮质相互作用，以确保左右任务表现相当。
