A parametric manipulation of factors affecting task-induced deactivation in functional neuroimaging
A parametric manipulation of factors affecting task-induced deactivation in functional neuroimaging
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DOI：
10.1162/089892903321593117
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发表时间：
2003-04-01
影响因子：
3.2
通讯作者：
Binder, JR
中科院分区：
文献类型：
--
作者：
McKiernan, KA;Kaufman, JN;Binder, JR
任务诱发失活（TID）是指相对于“静息”或“被动”基线，在主动任务期间血流的局部减少。我们测试的假设，TID的结果从重新分配的处理资源参数操纵任务难度内的三个因素：目标的可辨别性，刺激呈现率，和短期记忆负荷。受试者在功能性磁共振成像（fMRI）过程中执行所有听觉目标检测任务，对单个目标音或在短期记忆负荷条件下对目标序列做出反应。七个任务条件（一个共同的版本和两个额外的水平，每三个因素），每个交替与“休息”在一个区组设计。协方差分析确定了发生TID的脑区。方差分析确定了七个区域（左前扣带回/上级额回，左额中回，右前扣带回，左，右后扣带回，左后顶枕叶皮质，右楔前叶），TID的大小在一个因素内的任务水平变化。后续测试表明，对于这三个因素中的每一个，TID的幅度增加任务难度。这些结果表明，TID代表的加工资源的重新分配，在TID发生的领域，涉及的任务性能。短期记忆负荷和刺激率也可以预测自发思维的抑制，并且许多显示TID的大脑区域与语义处理有关，支持TID可能部分归因于“休息”期间发生的自发语义处理暂停的说法（Binder等人，1999）。典型的“静息状态”实际上是一种以丰富的认知活动为特征的状态，这一概念对神经影像学研究的设计和分析具有重要意义。
Task-induced deactivation (TID) refers to a regional decrease in blood flow during an active task relative to a "resting" or "passive" baseline. We tested the hypothesis that TID results from a reallocation of Processing resources by parametrically manipulating task difficulty within three factors : target discriminability, stimulus presentation rate, and short-term memory load. Subjects performed all auditory target detection task during functional magnetic resonance imaging (fMRI), responding to a single target tone or, in the short-term memory load conditions, to target sequences. Seven task conditions (a common version and two additional levels for each of the three factors) were each alternated with "rest" ill a block design. Analysis of covariance identified brain regions in which TID occurred. Analyses of variance identified seven regions (left anterior cingulate/superior frontal gyrus, left middle frontal gyrus, right anterior cingulate gyrus, left and right posterior cingulate gyrus, left posterior parieto-occipital cortex, and right precuneus) in which TID magnitude varied across task levels within a factor. Follow-up tests indicated that for each of the three factors, TID magnitude increased with task difficulty. These results suggest that TID represents reallocation of processing resources from areas in which TID occurs to areas involved in task performance. Short-term memory load and stimulus rate also predict suppression of spontaneous thought, and many of the brain areas showing TID have been linked with semantic processing, supporting claims that TID may be due in part to suspension of spontaneous semantic processes that occur during "rest" (Binder et al. 1999). The concept that the typical "resting state" is actually a condition characterized by rich cognitive activity has important implications for the design and analysis of neuroimaging studies.