Functional MRI of memory in the hippocampus: Laterality indices may be more meaningful if calculated from whole voxel distributions
Functional MRI of memory in the hippocampus: Laterality indices may be more meaningful if calculated from whole voxel distributions
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DOI：
10.1016/j.neuroimage.2006.04.201
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发表时间：
2006-08-15
期刊：
影响因子：
5.7
通讯作者：
Golby, Alexandra J.
中科院分区：
文献类型：
--
作者：
Branco, Daniel M.;Suarez, Ralph O.;Golby, Alexandra J.
功能性磁共振成像（fMRI）的记忆偏侧化可能有助于与内侧颞叶（MTL）相关的手术计划。大多数功能磁共振记忆研究计算偏侧化指数（LI）的MTL从阈上体素，但阈值的选择仍然是高度任意性的。我们假设可以从包含所有正T统计值的体素分布中可靠地提取LI，每个LI由其自身的统计显著性加权。我们还假设，与对照组平均LI相差两个或更多标准差（SD）的患者LI可能比未与对照组进行比较的LI更具临床相关性。13名健康受试者进行了记忆功能磁共振成像，5名癫痫患者同时进行了功能磁共振成像和颈动脉内异戊巴比妥程序（IAP）。功能磁共振成像任务包括编码模式，场景和单词。我们发现，正常受试者从整体加权统计分布中提取的LI倾向于向左偏置单词，向右偏置模式，中间偏置场景，与以前的研究一致。加权LI的变化小于仅从阈上体素计算的变化。使用这种方法，所有患者的fMRI记忆偏侧与IAP结果一致。与阈上体素计数方法相比，加权LI提供了更明确的患者与正常组的区别（根据组平均值的SD）。我们的研究结果表明，使用加权分布可以是一个有用的策略，在MTL的功能磁共振成像评估记忆偏侧化。(c)2006年爱思唯尔公司All rights reserved.
Lateralization of memory by functional MRI (fMRI) may be helpful for surgical planning related to the medial temporal lobe (MTL). Most fMRI memory studies have calculated lateralization indices (LI) in the MTL from suprathreshold voxels only, but the selection of threshold remains highly arbitrary. We hypothesized that LIs could be reliably extracted from the distribution of voxels encompassing all positive T statistical values, each weighted by their own statistical significance. We also hypothesized that patient LIs that are two or more standard deviations (SD) away from the control group mean LI may be more clinically relevant than LIs that are not compared to control group. Thirteen healthy subjects had memory fMRI, and five epilepsy patients had both fMRI and the intracarotid amobarbital procedure (IAP). The fMRI task consisted of encoding patterns, scenes, and words. We found that normal subjects' LIs extracted from whole weighted statistical distributions tended to lateralize to the left for words, to the right for patterns, and intermediately for scenes, consistent with previous research. Weighted LIs were less variable than those calculated from suprathreshold voxels only. Using this approach, all patients had fMRI memory lateralizations consistent with IAP results. The weighted LIs provided a more clear-cut distinction of patients from the normal group (in terms of SDs from the group mean) than the suprathreshold voxel count approach. Our results suggest that using weighted distributions can be a useful strategy for assessing memory lateralization by fMRI in the MTL. (c) 2006 Elsevier Inc. All rights reserved.