Thomas Adam G, Marrett Sean, Saad Ziad S, Ruff Douglas A, Martin Alex, Bandettini Peter A
Functional MRI Facility, NIMH, Bethesda, MD, USA.
Neuroimage. 2009 Oct 15;48(1):117-25. doi: 10.1016/j.neuroimage.2009.05.097. Epub 2009 Jun 9.
Voxel-Based Morphometry (VBM) has been used for several years to study differences in brain structure between populations. Recently, a longitudinal version of VBM has been used to show changes in gray matter associated with relatively short periods of training. In the present study we use fMRI and three different standard implementations of longitudinal VBM: SPM2, FSL, and SPM5 to assess functional and structural changes associated with a simple learning task. Behavioral and fMRI data clearly showed a significant learning effect. However, initially positive VBM results were found to be inconsistent across minor perturbations of the analysis technique and ultimately proved to be artifactual. When alignment biases were controlled for and recommended statistical procedures were used, no significant changes in grey matter density were found. This work, initially intended to show structural and functional changes with learning, rather demonstrates some of the potential pitfalls of existing longitudinal VBM methods and prescribes that these tools be applied and interpreted with extreme caution.
基于体素的形态测量学（VBM）已被用于研究不同人群之间的脑结构差异数年。最近，纵向版本的VBM已被用于显示与相对较短训练期相关的灰质变化。在本研究中，我们使用功能磁共振成像（fMRI）以及纵向VBM的三种不同标准实现方式：SPM2、FSL和SPM5来评估与一项简单学习任务相关的功能和结构变化。行为和fMRI数据清楚地显示出显著的学习效果。然而，最初得到的正向VBM结果在分析技术的微小扰动下并不一致，最终被证明是人为造成的。当控制了对齐偏差并使用推荐的统计程序时，未发现灰质密度有显著变化。这项工作最初旨在展示学习过程中的结构和功能变化，却反而揭示了现有纵向VBM方法的一些潜在陷阱，并规定使用和解释这些工具时要极其谨慎。
