Khosrowabadi Reza
Institute for Cognitive and Brain Sciences, Shahid Beheshti University, Tehran, Iran.
Basic Clin Neurosci. 2018 Mar-Apr;9(2):107-120. doi: 10.29252/NIRP.BCN.9.2.107.
Long-term stressful situations can drastically influence one's mental life. However, the effect of mental stress on recognition of emotional stimuli needs to be explored. In this study, recognition of emotional stimuli in a stressful situation was investigated. Four emotional conditions, including positive and negative states in both low and high levels of arousal were analyzed.
Twenty-six healthy right-handed university students were recruited within or after examination period. Participants' stress conditions were measured using the Perceived Stress Scale-14 (PSS-14). All participants were exposed to some audio-visual emotional stimuli while their brains responses' were measured using the Electroencephalography (EEG) technique. During the experiment, the subject's perception of emotional stimuli is evaluated using the Self-Assessment Manikin (SAM) questionnaire. After recording, EEG signatures of emotional states were estimated from connectivity patterns among 8 brain regions. Connectivity patterns were calculated using Phase Slope Index (PSI), Directed Transfer Function (DTF), and Generalized Partial Direct Coherence (GPDC) methods. The EEG-based connectivity features were then labeled with SAM responses. Subsequently, the labeled features were categorized using two different classifiers. Classification accuracy of the system was validated by leave-one-out method.
As expected, performance of the system is significantly improved by grouping the subjects to stressed and stress-free groups. EEG-based connectivity pattern was influenced by mental stress level.
Changes in connectivity patterns related to long-term mental stress have overlapped with changes caused by emotional stimuli. Interestingly, these changes are detectable from EEG data in eyes-closed condition.
长期的压力状况会极大地影响一个人的精神生活。然而，精神压力对情绪刺激识别的影响仍有待探索。在本研究中，我们调查了在压力状况下对情绪刺激的识别。分析了四种情绪状况，包括低唤醒水平和高唤醒水平下的积极和消极状态。
在考试期间或考试结束后招募了26名健康的右利手大学生。使用感知压力量表-14（PSS-14）测量参与者的压力状况。所有参与者在接触一些视听情绪刺激的同时，使用脑电图（EEG）技术测量他们的大脑反应。在实验过程中，使用自我评估人体模型（SAM）问卷评估受试者对情绪刺激的感知。记录后，根据8个脑区之间的连接模式估计情绪状态的脑电图特征。使用相位斜率指数（PSI）、定向传递函数（DTF）和广义部分直接相干（GPDC）方法计算连接模式。然后将基于脑电图的连接特征与SAM反应进行标记。随后，使用两种不同的分类器对标记的特征进行分类。通过留一法验证系统的分类准确率。
正如预期的那样，将受试者分为有压力组和无压力组后，系统的性能显著提高。基于脑电图的连接模式受精神压力水平的影响。
与长期精神压力相关的连接模式变化与情绪刺激引起的变化重叠。有趣的是，这些变化在闭眼状态下的脑电图数据中是可检测到的。
