Hartwigsen Gesa, Weigel Anni, Schuschan Paul, Siebner Hartwig R, Weise David, Classen Joseph, Saur Dorothee
Language and Aphasia Laboratory, Department of Neurology, University of Leipzig, D-04103 Leipzig, Germany.
Max Planck Institute for Human Cognitive and Brain Sciences, D-04103 Leipzig, Germany.
Cereb Cortex. 2016 Jun;26(6):2590-2601. doi: 10.1093/cercor/bhv092. Epub 2015 May 7.
Left posterior inferior frontal gyrus (pIFG) and supramarginal gyrus (SMG) are key regions for phonological decisions, whereas angular gyrus (ANG) and anterior IFG (aIFG) are associated with semantics. However, it is less clear whether the functional contribution of one area changes in the presence of a dysfunctional area within the network. Using repetitive transcranial magnetic stimulation (rTMS), we first tested whether perturbing one area would disrupt behavior. Second, we applied a condition-and-perturb approach, combining parietal offline rTMS with frontal online rTMS to investigate how the functional contribution of a frontal region changes in the presence of a dysfunctional parietal region. We found that rTMS over SMG or pIFG delayed phonological decisions, but this was not enhanced by combining supramarginal rTMS with pIFG rTMS. In contrast, semantic decisions were only impaired when angular rTMS was combined with aIFG rTMS. We infer that offline rTMS caused a dysfunction of ANG which increased the functional relevance of aIFG for semantic decisions and sensitized this network to the disruptive effects of aIFG rTMS. The results provide causal evidence that ANG and aIFG contribute to semantics and that the functional significance of one area within this network depends on the functional integrity of the other.
左后下额回（pIFG）和缘上回（SMG）是语音决策的关键区域，而角回（ANG）和额下回前部（aIFG）与语义相关。然而，在该网络中一个区域功能出现障碍时，另一个区域的功能贡献是否会发生变化尚不清楚。我们使用重复经颅磁刺激（rTMS），首先测试干扰一个区域是否会扰乱行为。其次，我们采用了一种条件与干扰相结合的方法，将顶叶离线rTMS与额叶在线rTMS相结合，以研究在顶叶区域功能障碍的情况下额叶区域的功能贡献如何变化。我们发现，对SMG或pIFG进行rTMS会延迟语音决策，但将缘上回rTMS与pIFG rTMS相结合并不会增强这种延迟。相反，只有当角回rTMS与aIFG rTMS相结合时，语义决策才会受损。我们推断，离线rTMS导致ANG功能障碍，这增加了aIFG对语义决策的功能相关性，并使该网络对aIFG rTMS的干扰效应更加敏感。这些结果提供了因果证据，表明ANG和aIFG对语义有贡献，并且该网络中一个区域的功能意义取决于另一个区域的功能完整性。
