Dynamics of functional and effective connectivity within human cortical motor control networks

• The dynamics of causal interactions in the praxis network of normal adult humans is reported for the first time.
• Directionally specific propagation from parietal to frontal regions is seen only in the left hemisphere.
• Our observations may provide physiological evidence of corollary discharge in the human frontal–parietal praxis network.

ObjectivePraxis, 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).MethodWe examined praxis network dynamics by measuring EEG effective connectivity while healthy subjects performed a praxis task.ResultsPropagation 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.ConclusionsThese 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.SignificanceIn addition to bolstering the classic view of praxis network function, these results also demonstrate the relevance of additional information provided by directed connectivity measures.