Department of Basic Psychology, Autonoma University of Madrid, 28049 Madrid, Spain.
J Neurosci. 2013 Jul 31;33(31):12679-88. doi: 10.1523/JNEUROSCI.0645-13.2013.
An increasing amount of evidence supports a crucial role for the anterior temporal lobe (ATL) in semantic processing. Critically, a selective disruption of the functional connectivity between left and right ATLs in patients with chronic aphasic stroke has been illustrated. The aim of the current study was to evaluate the consequences that lesions on the ATL have on the neurocognitive network supporting semantic cognition. Unlike previous work, in this magnetoencephalography study we selected a group of patients with small lesions centered on the left anteroventral temporal lobe before surgery. We then used an effective connectivity method (i.e., dynamic causal modeling) to investigate the consequences that these lesions have on the functional interactions within the network. This approach allowed us to evaluate the directionality of the causal interactions among brain regions and their associated connectivity strengths. Behaviorally, we found that semantic processing was altered when patients were compared with a strictly matched group of controls. Dynamic causal modeling for event related responses revealed that picture naming was associated with a bilateral frontotemporal network, encompassing feedforward and feedback connections. Comparison of specific network parameters between groups revealed that patients displayed selective network adjustments. Specifically, backward connectivity from anterior to posterior temporal lobe was decreased in the ipsilesional hemisphere, whereas it was enhanced in the contralesional hemisphere. These results reinforce the relevance of ATL in semantic memory, as well as its amodal organization, and highlight the role of feedback connections in enabling the integration of the semantic information.
越来越多的证据支持前颞叶（ATL）在语义处理中起着关键作用。至关重要的是，已经说明了慢性失语症中风患者左、右 ATL 之间功能连接的选择性破坏。本研究的目的是评估 ATL 病变对支持语义认知的神经认知网络的影响。与以前的工作不同，在这项脑磁图研究中，我们选择了一组手术前病变集中在左前腹侧颞叶的患者。然后，我们使用有效的连通性方法（即动态因果建模）来研究这些病变对网络内功能相互作用的影响。这种方法允许我们评估大脑区域之间因果相互作用的方向性及其相关的连通性强度。行为上，我们发现当患者与严格匹配的对照组进行比较时，语义处理会发生改变。与事件相关反应的动态因果建模表明，图片命名与包括前馈和反馈连接的双侧额颞叶网络有关。对两组特定网络参数的比较表明，患者表现出选择性的网络调整。具体来说，对侧半球的同侧颞叶的向后连接减少，而对侧半球的向后连接增强。这些结果加强了 ATL 在语义记忆中的重要性及其非模态组织，并强调了反馈连接在实现语义信息整合中的作用。
