Individual Trial Analysis for 7T fMRI Data by a Data-Driven Multi Scale Approach
Individual Trial Analysis for 7T fMRI Data by a Data-Driven Multi Scale Approach
复制标题
通过数据驱动的多尺度方法对 7T fMRI 数据进行个体试验分析
DOI：
10.1007/s10548-013-0301-2
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发表时间：
2013
期刊：
影响因子：
2.7
通讯作者：
Selene Da Rocha Amaral
中科院分区：
文献类型：
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作者：
Selene Da Rocha Amaral
与事件相关的单次试验功能磁共振成像的一个重要兴趣是研究随时间变化的认知过程（例如学习或适应）的可能性。区域特异性建模和诱发反应的试验间变异性发挥着重要作用。我们展示了如何使用迭代多重网格先验（iMGP）方法（一种先前引入的数据驱动的多尺度贝叶斯迭代方法）来扩展对超高磁场数据的逐项试验分析。我们使用了 7T 的人工（当前真实的生理噪声）和真实的（单侧手指敲击实验）数据，并与其他方法进行了比较。由于 iMGP 不需要对数据进行空间平滑，从而避免了灵敏度损失，因此我们利用了 7T 的高 SNR。对于人工数据，我们显示了通过活动阈值和添加额外热噪声参数化的接收器操作特征曲线，并与相关技术结果进行比较。该方法在高噪声数据的特异性方面表现出非常鲁棒性，并且能够捕获跨区域人为施加的时间变化。对于真实数据，我们检查了四名受试者的试验间空间关系以及 iMGP 跨试验、地区和受试者估计的诱发反应的峰值时间。为了强调 iMGP 在单项试验研究中的可靠性，对单个受试者进行了与变分贝叶斯方法（在非常流行的统计参数映射软件中实现）的说明性比较。尽管血管外信号在 7T 时仍然存在，并且生理噪声和血流动力学变异的混杂影响了单一试验方法，但我们表明，使用 iMGP 方法可以稳健地检测个体 HR。
An important interest in event-related single trial fMRI is the possibility of studying cognitive processes that vary in time (e.g. learning or adaptation). Region-specific modelling and the inter-trial variability of the evoked response play an important role. We showed how the use of the iterated multigrid priors (iMGP) method, a previously introduced data-driven multi scale Bayesian iterative approach, may be extended for a trial-by-trial analysis on ultra-high magnetic field data. We used both artificial (present real physiological noise) and real (unilateral finger tapping experiment) data at 7T and compared to other methods. Since the iMGP does not need to spatially smooth the data, avoiding a loss of sensitivity, we take advantage of the high SNR available at 7T. For artificial data, we showed receiver operating characteristic curves parametrized by the activity threshold and by the addition of extra thermal noise and compared with correlation technique results.The method showed be very robust in terms of specificity for very noisy data and capable of capturing the temporal variability imposed artificially across regions. For real data, we examined the inter-trial spatial relationships for four subjects and the time-to-peak of the evoked response estimated by the iMGP across trials, regions and subjects. To stress the reliability of the iMGP in single trial studies, an illustrative comparison with the variational Bayes approach (implemented in the very popular Statistical Parametric Mapping software) was done for a single subject. Despite the extravascular signals are still present at 7T and the confounds of physiological noise and hemodynamic variability affecting single trial approaches, we showed that with the iMGP method it is possible to detect individual HR robustly.