Haller Sven, Klarhoefer Markus, Schwarzbach Jens, Radue Ernst W, Indefrey Peter
Institute of Radiology, Department of Neuroradiology, University Hospital Basel, Petergraben 4, CH 4031 Basel, Switzerland.
Eur J Neurosci. 2007 Oct;26(7):2074-84. doi: 10.1111/j.1460-9568.2007.05816.x.
Written language comprehension at the word and the sentence level was analysed by the combination of spatial and temporal analysis of functional magnetic resonance imaging (fMRI). Spatial analysis was performed via general linear modelling (GLM). Concerning the temporal analysis, local differences in neurovascular coupling may confound a direct comparison of blood oxygenation level-dependent (BOLD) response estimates between regions. To avoid this problem, we parametrically varied linguistic task demands and compared only task-induced within-region BOLD response differences across areas. We reasoned that, in a hierarchical processing system, increasing task demands at lower processing levels induce delayed onset of higher-level processes in corresponding areas. The flow of activation is thus reflected in the size of task-induced delay increases. We estimated BOLD response delay and duration for each voxel and each participant by fitting a model function to the event-related average BOLD response. The GLM showed increasing activations with increasing linguistic demands dominantly in the left inferior frontal gyrus (IFG) and the left superior temporal gyrus (STG). The combination of spatial and temporal analysis allowed a functional differentiation of IFG subregions involved in written language comprehension. Ventral IFG region (BA 47) and STG subserve earlier processing stages than two dorsal IFG regions (BA 44 and 45). This is in accordance with the assumed early lexical semantic and late syntactic processing of these regions and illustrates the complementary information provided by spatial and temporal fMRI data analysis of the same data set.
通过功能磁共振成像（fMRI）的空间和时间分析相结合的方法，对单词和句子层面的书面语言理解进行了分析。空间分析通过一般线性模型（GLM）进行。关于时间分析，神经血管耦合的局部差异可能会混淆不同区域之间基于血氧水平依赖（BOLD）反应估计的直接比较。为避免这个问题，我们对语言任务要求进行参数化变化，并仅比较各区域内任务诱发的BOLD反应差异。我们推断，在一个分层处理系统中，较低处理水平上任务要求的增加会导致相应区域中较高水平处理的延迟启动。激活流因此反映在任务诱发的延迟增加的大小上。我们通过将模型函数拟合到事件相关的平均BOLD反应，来估计每个体素和每个参与者的BOLD反应延迟和持续时间。GLM显示，随着语言要求的增加，激活主要在左侧额下回（IFG）和左侧颞上回（STG）增加。空间和时间分析的结合允许对参与书面语言理解的IFG子区域进行功能区分。腹侧IFG区域（BA 47）和STG比两个背侧IFG区域（BA 44和45）服务于更早的处理阶段。这与这些区域假定的早期词汇语义和晚期句法处理一致，并说明了对同一数据集进行空间和时间fMRI数据分析所提供的补充信息。
