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要旨:
It is a vital ability of humans to flexibly adapt their behavior to different environmental situations. Constantly, the rules for our sensory-to-motor mappings need to be adapted to the current task demands. For example, the same sensory input might require two different motor responses depending on the actual situation. How does the brain prepare for such different responses? It has been suggested that the functional connections within cortex are biased according to the present rule to guide the flow of information in accordance with the required sensory-to-motor mapping. Here, we investigated with fMRI whether task settings might indeed change the functional connectivity structure in a large-scale brain network. Subjects performed a visuomotor response task that required an interaction between visual and motor cortex: either within each hemisphere or across the two hemispheres of the brain depending on the task condition. A multivariate analysis on the functional connectivity graph of a cortical visuomotor network revealed that the functional integration, i.e., the connectivity structure, is altered according to the task condition already during a preparatory period before the visual cue and the actual movement. Our results show that the topology of connection weights within a single network changes according to and thus predicts the upcoming task. This suggests that the human brain prepares to respond in different conditions by altering its large scale functional connectivity structure even before an action is required.
