Consistency and variability in functional localisers.
Consistency and variability in functional localisers.
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DOI：
10.1016/j.neuroimage.2009.03.014
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发表时间：
2009-07-15
期刊：
影响因子：
5.7
通讯作者：
Devlin JT
中科院分区：
文献类型：
--
作者：
Duncan KJ;Pattamadilok C;Knierim I;Devlin JT
使用功能定位器扫描的关键假设是，被识别为功能感兴趣区域（fROI）的体素基本上与主要实验操作激活的体素相同。fROI位置的受试者内变异性违反了这一假设，降低了分析的灵敏度并使结果产生偏差。在这里，我们调查了一组45名志愿者的fROI的一致性和可变性。他们进行了两次功能定位器扫描，以分别识别腹侧和侧枕颞皮层的单词敏感区和物体敏感区。在主要分析中，fROI被定义为每个区域中的类别选择性体素，一致性被测量为扫描之间的空间重叠。当使用最小选择性阈值来定义“活性”体素时（p < 0.05未校正），一致性最大，表明大约65%的体素通常被两次扫描激活。相比之下，高选择性阈值（p < 10− 4至10− 6）产生的一致性值最低，两次扫描中活动体素的重叠小于25%。换句话说，受试者内变异性惊人地高，给定fROI中三分之一到四分之三的体素与主任务中激活的体素不对应。这种水平的变异性与视网膜定位定义区域中的一致性形成鲜明对比，并且对于设计鲁棒但有效的功能定位器扫描具有重要意义。
A critical assumption underlying the use of functional localiser scans is that the voxels identified as the functional region-of-interest (fROI) are essentially the same as those activated by the main experimental manipulation. Intra-subject variability in the location of the fROI violates this assumption, reducing the sensitivity of the analysis and biasing the results. Here we investigated consistency and variability in fROIs in a set of 45 volunteers. They performed two functional localiser scans to identify word- and object-sensitive regions of ventral and lateral occipito-temporal cortex, respectively. In the main analyses, fROIs were defined as the category-selective voxels in each region and consistency was measured as the spatial overlap between scans. Consistency was greatest when minimally selective thresholds were used to define “active” voxels (p < 0.05 uncorrected), revealing that approximately 65% of the voxels were commonly activated by both scans. In contrast, highly selective thresholds (p < 10− 4 to 10− 6) yielded the lowest consistency values with less than 25% overlap of the voxels active in both scans. In other words, intra-subject variability was surprisingly high, with between one third and three quarters of the voxels in a given fROI not corresponding to those activated in the main task. This level of variability stands in striking contrast to the consistency seen in retinotopically-defined areas and has important implications for designing robust but efficient functional localiser scans.
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