Ewen Joshua B, Lakshmanan Balaji M, Hallett Mark, Mostofsky Stewart H, Crone Nathan E, Korzeniewska Anna
Department of Neurology and Developmental Medicine, Kennedy Krieger Institute, 707 N. Broadway, Baltimore, MD 21205, USA; Department of Neurology, Johns Hopkins University School of Medicine, 600 N. Wolfe Street, Baltimore, MD 21287, USA.
Department of Neurology and Developmental Medicine, Kennedy Krieger Institute, 707 N. Broadway, Baltimore, MD 21205, USA.
Clin Neurophysiol. 2015 May;126(5):987-96. doi: 10.1016/j.clinph.2014.09.006. Epub 2014 Sep 18.
Praxis, the performance of complex motor gestures, is crucial to the development of motor and social/communicative capacities. Praxis relies on a network consisting of inferior parietal and premotor regions, particularly on the left, and is thought to require transformation of spatio-temporal representations (parietal) into movement sequences (premotor).
We examined praxis network dynamics by measuring EEG effective connectivity while healthy subjects performed a praxis task.
Propagation from parietal to frontal regions was not statistically greater on the left than the right. However, propagation from left parietal regions to all other regions was significantly greater during gesture preparation than execution. Moreover, during gesture preparation only, propagation from the left parietal region to bilateral frontal regions was greater than reciprocal propagations to the left parietal region. This directional specificity was not observed for the right parietal region.
These findings represent direct electrophysiological evidence for directionally predominant propagation in left frontal-parietal networks during praxis behavior, which may reflect neural mechanisms by which representations in the human brain select appropriate motor sequences for subsequent execution.
In addition to bolstering the classic view of praxis network function, these results also demonstrate the relevance of additional information provided by directed connectivity measures.
运用，即复杂运动手势的执行，对运动及社交/交流能力的发展至关重要。运用依赖于一个由顶下小叶和运动前区组成的网络，尤其是左侧的这些区域，并且被认为需要将时空表征（顶叶）转化为运动序列（运动前区）。
我们通过测量健康受试者执行运用任务时的脑电图有效连接性，来研究运用网络动力学。
从顶叶到额叶区域的传播在左侧并不比右侧在统计学上更显著。然而，在手势准备期间，从左侧顶叶区域到所有其他区域的传播显著大于执行期间。此外，仅在手势准备期间，从左侧顶叶区域到双侧额叶区域的传播大于向左侧顶叶区域的反向传播。右侧顶叶区域未观察到这种方向特异性。
这些发现代表了在运用行为期间，左额叶 - 顶叶网络中方向占优传播的直接电生理证据，这可能反映了人类大脑中表征为后续执行选择合适运动序列的神经机制。
除了支持运用网络功能的经典观点外，这些结果还证明了定向连接性测量所提供的额外信息的相关性。
