Laboratory of Neuroimaging and Psychophysiology, Department of Radiology, Faculty of Medicine, Federal University of Rio de Janeiro, 255 Rodolpho Paulo Rocco st., Ilha do Fundão, Rio de Janeiro, RJ, 21941-590, Brazil.
Laboratory of Behavioral Neurophysiology, Department of Physiology and Pharmacology, Biomedical Institute, Federal Fluminense University, Niterói, RJ, Brazil.
Brain Imaging Behav. 2020 Dec;14(6):2251-2266. doi: 10.1007/s11682-019-00177-6.
Whether subtle differences in the emotional context during threat perception can be detected by multi-voxel pattern analysis (MVPA) remains a topic of debate. To investigate this question, we compared the ability of pattern recognition analysis to discriminate between patterns of brain activity to a threatening versus a physically paired neutral stimulus in two different emotional contexts (the stimulus being directed towards or away from the viewer). The directionality of the stimuli is known to be an important factor in activating different defensive responses. Using multiple kernel learning (MKL) classification models, we accurately discriminated patterns of brain activation to threat versus neutral stimuli in the directed towards context but not during the directed away context. Furthermore, we investigated whether it was possible to decode an individual's subjective threat perception from patterns of whole-brain activity to threatening stimuli in the different emotional contexts using MKL regression models. Interestingly, we were able to accurately predict the subjective threat perception index from the pattern of brain activation to threat only during the directed away context. These results show that subtle differences in the emotional context during threat perception can be detected by MVPA. In the directed towards context, the threat perception was more intense, potentially producing more homogeneous patterns of brain activation across individuals. In the directed away context, the threat perception was relatively less intense and more variable across individuals, enabling the regression model to successfully capture the individual differences and predict the subjective threat perception.
在威胁感知过程中，情绪背景的细微差异是否可以通过多体素模式分析（MVPA）检测到，这仍然是一个有争议的话题。为了研究这个问题，我们比较了模式识别分析区分威胁刺激与身体配对的中性刺激的大脑活动模式的能力，这两种刺激分别处于两种不同的情绪背景（刺激指向或远离观察者）。众所周知，刺激的方向是激活不同防御反应的一个重要因素。使用多核学习（MKL）分类模型，我们准确地区分了指向和远离方向两种情绪背景下的威胁刺激与中性刺激的大脑活动模式。此外，我们还研究了是否有可能使用 MKL 回归模型，从不同情绪背景下的威胁刺激的全脑活动模式中解码个体的主观威胁感知。有趣的是，我们能够仅在远离方向的背景下，从威胁刺激的大脑活动模式中准确预测主观威胁感知指数。这些结果表明，MVPA 可以检测到威胁感知过程中情绪背景的细微差异。在指向方向的背景下，威胁感知更强烈，可能会在个体之间产生更同质的大脑活动模式。在远离方向的背景下，威胁感知相对较弱，个体之间的差异较大，使回归模型能够成功捕捉个体差异并预测主观威胁感知。
