The Study Of Contingent Negative Variation Induced By Emotional Faces In Patients With Depression

Major Depressive Disorder (MDD) is one of the commonly occurring mental disorders, primarily characterized by persistent low mood, recurrent negative thoughts and anhedonia, and it with a lifetime prevalence of 16%. The World Health Organization (WHO) predicted that depression would become the second pathogen of death and deformity by 2020. The dysfunction of emotional material has been identified as core features of MDD, which is not only characterized by deficits in the activation of negative cognitions, but also by an impaired ability to disengage from negative stimuli. The reasons as to why abnormal cognitive process is exerted by MDD patients during the fore period are not entirely clear yet at this stage. However, the specific functional significance and underlying neural correlates of these deficits remain largely unexplored. Therefore, it remains unclear whether abnormalities in recruitment of neural resources during sustained processing of emotional information in MDD are specific to any particular stage of processing. This study examines the deficit in cognitive of brain activity during sustained processing of emotional stimuli in individuals with MDD and nondepressed (ND) participants. Based on these studies, we expected sad faces elicit smaller ERP amplitudes in the MDD group relative to the control group. And an increased response time of MDD on sad stimulate relative to neutral and happy.In this paper, The contingent negative variation induced by emotional faces will be applied in patients with depression and control individuals, the Behavioral data and the Event-Related Potential Data to be compared. The study will investigate differences of cognitive neuroscience between two groups. The contingent negative variation (CNV) is the first cognitive potential to be discovered. The classic experimental paradigm that generates the CNV has been defined by Walter. It occurs when people are warned by a stimulus about an upcoming task. Contingent negative variation (CNV) components of the event-related brain potential (ERP) were recorded from 19 ND participants and 19 participants with MDD. The experimental procedure involved presenting three blocks of stimuli. Each block consisted of 30 S1-S2 trials, with happy, neutral, and sad face presented in randomized order. The S1 (warning stimulus) was presented on a computer screen for 500ms. After a 1-sec interval, a randomly chosen face S2 (imperative stimuli) was presented. Participants were asked to hold each S1, following the S2, to press a button to respond as quickly as possible, S2-S1 interval was 4 sec. The computer recorded the latency of each response. In addition to behavioral measures, event-related potentials (ERPs) were recorded.In the response time data MDD show the slower RT on trials that required a response to a sad face compared with trials that required a response to a happy or neutral face. The difference between-group observed in this study. MDD participants had smaller CNV amplitudes in response to negative relative to both positive and neutral stimuli, The CNV amplitudes were smaller and the latencies were longer in MDD than ND in processing of emotional stimuli. ERP amplitudes revealed main effects, which show significant differences between groups.This study results suggest that MDD have the features of inhibition deficiencies and excessive facilitations to negative stimuli. The present study highlights a selective deficit in cognitive control over negative stimuli in individuals with MDD. This deficit was evident in slow response time and decreased CNV amplitudes. These findings promote the further understanding of brain processes associated with abnormal cognitive functioning in individuals with MDD and suggest that a potential mechanism of abnormalities lies in the dysfunctional sustained brain response to negative information. This result would support the hypothesis of diminished cognitive control in response to sad information in individuals with MDD. The reduced cognitive control over negative responses might represent a vulnerability factor in people with depression will be clinical importance.