en Cognitive Neuroscience Cognitive Neuroscience Original Original <p dir="ltr" style="text-align: justify;"><strong>Introduction: </strong>Long-term stressful situations can drastically influence one&rsquo;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.&nbsp;<br> <strong>Methods:</strong> Twenty-six healthy right-handed university students were recruited within or after examination period. Participants&rsquo; 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&rsquo; were measured using the Electroencephalography (EEG) technique. During the experiment, the subject&rsquo;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.<br> <strong>Results:</strong> 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.&nbsp;<br> <strong>Conclusion: </strong>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.</p> Long-term stress, Effective connectivity, Electroencephalography (EEG), Emotion 107 120 http://bcn.iums.ac.ir/browse.php?a_code=A-10-654-1&slc_lang=en&sid=1 Reza Khosrowabadi r.khosrowabadi@gmail.com 13700319475328460015552 13700319475328460015552 Yes Institute for Cognitive and Brain Sciences, Shahid Beheshti University, Tehran, Iran.