Cisler Josh M, Bush Keith, James G Andrew, Smitherman Sonet, Kilts Clinton D
Brain Imaging Research Center, Department of Psychiatry, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America.
Department of Computer Science, University of Arkansas at Little Rock, Little Rock, Arkansas, United States of America.
PLoS One. 2015 Aug 4;10(8):e0134717. doi: 10.1371/journal.pone.0134717. eCollection 2015.
Posttraumatic Stress Disorder (PTSD) is characterized by intrusive recall of the traumatic memory. While numerous studies have investigated the neural processing mechanisms engaged during trauma memory recall in PTSD, these analyses have only focused on group-level contrasts that reveal little about the predictive validity of the identified brain regions. By contrast, a multivariate pattern analysis (MVPA) approach towards identifying the neural mechanisms engaged during trauma memory recall would entail testing whether a multivariate set of brain regions is reliably predictive of (i.e., discriminates) whether an individual is engaging in trauma or non-trauma memory recall. Here, we use a MVPA approach to test 1) whether trauma memory vs neutral memory recall can be predicted reliably using a multivariate set of brain regions among women with PTSD related to assaultive violence exposure (N=16), 2) the methodological parameters (e.g., spatial smoothing, number of memory recall repetitions, etc.) that optimize classification accuracy and reproducibility of the feature weight spatial maps, and 3) the correspondence between brain regions that discriminate trauma memory recall and the brain regions predicted by neurocircuitry models of PTSD. Cross-validation classification accuracy was significantly above chance for all methodological permutations tested; mean accuracy across participants was 76% for the methodological parameters selected as optimal for both efficiency and accuracy. Classification accuracy was significantly better for a voxel-wise approach relative to voxels within restricted regions-of-interest (ROIs); classification accuracy did not differ when using PTSD-related ROIs compared to randomly generated ROIs. ROI-based analyses suggested the reliable involvement of the left hippocampus in discriminating memory recall across participants and that the contribution of the left amygdala to the decision function was dependent upon PTSD symptom severity. These results have methodological implications for real-time fMRI neurofeedback of the trauma memory in PTSD and conceptual implications for neurocircuitry models of PTSD that attempt to explain core neural processing mechanisms mediating PTSD.
创伤后应激障碍(PTSD)的特征是对创伤记忆的侵入性回忆。虽然众多研究已经调查了PTSD患者在创伤记忆回忆过程中所涉及的神经处理机制,但这些分析仅集中在组水平的对比上,几乎没有揭示所确定脑区的预测有效性。相比之下,采用多变量模式分析(MVPA)方法来识别创伤记忆回忆过程中所涉及的神经机制,将需要测试一组多变量脑区是否能够可靠地预测(即区分)个体是在进行创伤记忆还是非创伤记忆回忆。在此,我们使用MVPA方法来测试:1)在与攻击性暴力暴露相关的PTSD女性患者(N = 16)中,是否可以使用一组多变量脑区可靠地预测创伤记忆与中性记忆回忆;2)优化特征权重空间图分类准确性和可重复性的方法学参数(例如,空间平滑、记忆回忆重复次数等);3)区分创伤记忆回忆的脑区与PTSD神经回路模型预测的脑区之间的对应关系。对于所有测试的方法学排列,交叉验证分类准确性均显著高于机遇水平;对于选择为效率和准确性最佳的方法学参数,参与者的平均准确率为76%。相对于受限感兴趣区域(ROI)内的体素,基于体素的方法的分类准确性显著更好;与随机生成的ROI相比,使用与PTSD相关的ROI时分类准确性没有差异。基于ROI的分析表明,左侧海马体在区分参与者的记忆回忆中可靠地发挥作用,并且左侧杏仁核对决策功能的贡献取决于PTSD症状的严重程度。这些结果对PTSD创伤记忆的实时功能磁共振成像神经反馈具有方法学意义,对试图解释介导PTSD的核心神经处理机制的PTSD神经回路模型具有概念意义。