Cognitive Processing And The Neural Mechanisms Of Reward Feedback In Depressed Status Individuals

Depression is a common psychiatric disorder that causes suffering to patients and great economic loss to society.It was found that depressed individuals have impaired cognitive function,as evidenced by executive function and processing speed.In addition,depressed individuals have abnormalities in reward processing,producing smaller RewP amplitudes and fb-P3 amplitudes in response to rewards.However,previous studies have focused on clinically diagnosed depressed individuals,and little attention has been paid to the depressed status individuals.Whether the cognitive function is impaired in depressed status individuals even if they can participate normally in daily life,and whether the neural mechanisms of reward feedback processing are altered in depressed status individuals compared to healthy individuals are the main questions of interest in the present study.In this study,the Beck Depression Inventory and the depression sub-scale of the Hospital Anxiety and Depression Inventory were administered to the students.The questionnaire scores were used to screen the depressed status individuals and healthy individuals.The criteria for the depressed status individuals group were Beck Depression Inventory scores ≥13 and the depression sub-scale of the Hospital Anxiety and Depression Inventory scores ≥ 11.Then,the cognitive performance of depressed status individuals and the neural responses of depressed status individuals to reward feedback processing were examined.There were two studies.Study 1: Cognitive processing performance in depressed status individuals.The purpose of the study was to investigate the performance of depressed status individuals on cognitive tasks after passively viewing pictures of different valences and whether they differ from healthy individuals.A 2（group: depressed status individual group,healthy individual group）× 3（picture emotional valence: positive,neutral,negative）mixed experimental design was used,with the group as a between-subjects variable and picture emotional valence as a withinsubjects variable.In the experiment,participants were first asked to view pictures and then determine whether the words that followed were true words or false words,and we recorded the reaction time and accuracy rate of the cognitive task.The results found that depressed status individuals had longer reaction time and lower accuracy rate on the cognitive task than healthy individuals.Study 2: Neural mechanisms of reward feedback processing in depressed status individuals.The aim of the study was to investigate whether the neural responses to reward and loss feedback processing in depressed status individuals differ from those in healthy individuals.A 2（group: depressed status individual group,healthy individual group）× 2（feedback type: reward,loss）mixed experimental design was used,with group as a betweensubjects variable and feedback type as a within-subjects variable.First,the screen presents pictures of two identical doors,and participants select one of them according to their expectation of the reward,thus gaining reward or loss feedback,and subsequently determining whether an equation is correct or wrong.Behavioral data and EEG data at the time the feedback presented were recorded.The results showed that depressed status individuals had longer reaction time than healthy individuals,and both groups exhibited higher correctness after loss feedback than that after reward feedback.The EEG results revealed that reward feedback evoked larger RewP amplitudes than loss feedback;depressed status individuals elicited smaller RewP and fb-P3 amplitudes compared to healthy individuals;from an experimental process perspective,reward feedback produced larger RewP amplitudes than loss feedback in the former part of the data,and depressed status individuals produced both fb-P3 and RewP amplitudes than healthy individuals in the latter data.This study draws the following conclusions: Not only depressed individuals,but also individuals in depressive status show impaired cognitive function;Individuals in depressive status have abnormal reward processing,as evidenced by insensitivity to both reward and loss feedback,which supports the Emotion Context-Insensitivity Hypothesis.