Allen Paul, Mechelli Andrea, Stephan Klaas E, Day Fern, Dalton Jeffery, Williams Steven, McGuire Philip K
Division of Psychological Medicine and Psychiatry, Institute of Psychiatry, King's College London, London, UK.
J Cogn Neurosci. 2008 Sep;20(9):1656-69. doi: 10.1162/jocn.2008.20107.
The Hayling Sentence Completion Task (HSCT) is known to activate left hemisphere frontal and temporal language regions. However, the effective connectivity between frontal and temporal language regions associated with the task has yet to be examined. The aims of the study were to examine activation and effective connectivity during the HSCT using a functional magnetic resonance imaging (fMRI) paradigm in which participants made overt verbal responses. We predicted that producing an incongruent response (response suppression), compared to a congruent one (response initiation), would be associated with greater activation in the left prefrontal cortex and an increase in the effective connectivity between temporal and frontal regions. Fifteen participants were scanned while completing 80 sentence stems. The congruency and constraint of sentences varied across trials. Dynamic Causal Modeling (DCM) and Bayesian Model Selection (BMS) were used to compare a set of alternative DCMs of fronto-temporal connectivity. The HSCT activated regions in the left temporal and prefrontal cortices, and the cuneus. Response suppression was associated with greater activation in the left middle and orbital frontal gyri and the bilateral precuneus than response initiation. Left middle temporal and frontal regions identified by the conventional fMRI analyses were entered into the DCM analysis. Using a systematic BMS procedure, the optimal DCM showed that the connection from the left middle temporal gyrus, which was driven by verbal stimuli per se, was significantly increased in strength during response suppression compared to initiation. Greater effective connectivity between left temporal and prefrontal regions during response suppression may reflect the transfer of information from posterior temporal regions where semantic and lexical information is stored to prefrontal regions where it is manipulated in preparation for an appropriate response.
海林句子完成任务（HSCT）已知会激活左半球额叶和颞叶语言区域。然而，与该任务相关的额叶和颞叶语言区域之间的有效连接尚未得到研究。本研究的目的是使用功能磁共振成像（fMRI）范式，在参与者做出明显言语反应的情况下，检查HSCT过程中的激活情况和有效连接。我们预测，与一致反应（反应启动）相比，产生不一致反应（反应抑制）将与左侧前额叶皮质更大的激活以及颞叶和额叶区域之间有效连接的增加相关。15名参与者在完成80个句子主干时接受了扫描。句子的一致性和约束在不同试验中有所变化。使用动态因果模型（DCM）和贝叶斯模型选择（BMS）来比较一组额叶-颞叶连接的替代DCM。HSCT激活了左侧颞叶、前额叶皮质和楔叶区域。与反应启动相比，反应抑制与左侧额中回和眶额回以及双侧楔前叶更大的激活相关。通过传统fMRI分析确定的左侧颞中回和额叶区域被纳入DCM分析。使用系统的BMS程序，最优DCM显示，由言语刺激本身驱动的来自左侧颞中回的连接在反应抑制期间的强度与启动相比显著增加。反应抑制期间左侧颞叶和前额叶区域之间更强的有效连接可能反映了信息从存储语义和词汇信息的后颞叶区域转移到在其中进行操作以准备适当反应的前额叶区域。
