Sensitivity Of Depression Inclination Individuals To Social And Monetary Reward

Anhedonia is a core symptom of depression,so depressed people are thought to have a motivational disorder.Several studies have linked depression to decrease neurosensitivity to monetary rewards,but there is no consistent conclusion as to whether reward passivation can be directly generalized to other types of rewards.Social reward,alike monetary reward,is a driving force that shapes behavior and is a typical representation of many rewards.Therefore,this study explores the following two questions:(1)Is there a difference in the behavioral response of depression inclination individuals in social reward tasks and monetary reward tasks?(2)Do social and monetary rewards have different effects on the neural mechanisms of the reward function of depression inclination individuals?Study 1 selected the undergraduates with a Beck Depression Inventory-Ⅱ(BDI-Ⅱ)score <14 and a Self-Rating Depression Scale(SDS)score <0.5 as the healthy group,and undergraduates with a BDI score ≥14 and a SDS score≥0.5 were selected as the depression inclination group.At last,fifty-seven people were recruited into each group.Study 1 use monetary incentive delay(monetary incentive delay task,MID)task and social incentive delay task(social incentive delay task,SID),the successful response of the subjects can get RMB and "thumbs up" as a monetary reward and social reward,hit rate and reaction as behavior indicators.Considering that reward expectation is influenced by reward probability and reward value,the variables of reward probability and incentive type are included in study I to observe the influence of these factors on two groups.The results showed that(1)the hit rate of depression inclination group under incentive conditions was lower than that of healthy group,no between-group effect on incentive condition;(2)the response rate of depression inclination group under high reward probability was longer than that of health group under high reward probability.The above behavioral results suggest that the blunt reward function of depression inclination individuals is universal in monetary reward and social reward,and this bluntness is more obvious under the condition of high reward probability.The screening criteria of study 2 were the same as study 1,with 26 persons in the healthy group and the depression inclination group each.Event-related potentials(ERP),which have a millisecond temporal resolution,can separate the anticipated and consummatory stages of reward processing,and can characterize cognitive processing signals that occur sequentially in a short time.Therefore,study 2 combined ERP technology and behavioral measurement methods to compare the brain electrical activities associated with reward processing in MID and SID tasks of the depression inclination group and the health group,this study focuses on the following electrical activity indicators: cue-P3,CNV,SPN,the three ERP components of reward anticipation stage and FN and fb-P3,the two ERP components of reward consummatory stage.When the reward probability was set to 50%,it was found that(1)the average amplitude of depression inclination group in cue-P300,CNV,FN and fb-P3,regardless of monetary reward or social reward,was significantly smaller than that in the healthy group,indicating that blunt reward sensitivity in individuals with depression inclination generally exist in monetary and social rewards;(2)under the MID task condition,the average amplitude of CNV and SPN in the depression inclination group was significantly lower than that in the healthy group,indicating that the neural response of the depression inclination individuals to the monetary reward was blunt;(3)In addition,in the behavioral results of study 2,it was found that the hit rate of the depressed group was significantly lower than that of the healthy group in the SID task,indicating that the social reward reactivity of the depressed individuals was decreased.The above results show that(1)individuals with depression inclination have deficits in reward function in both anticipation and consummatory stages of monetary rewards and social rewards,especially in the action preparation and outcomes expectation sub-phases of reward anticipation stage when expecting monetary rewards;(2)the reward probability will affect the performance of individuals with depression inclination in different reward types,which may be related to the difficulty of the task and the uncertainty of the reward;(3)When the reward uncertainty is the largest(50%),individuals with depression inclination exhibit specific social reward deficit at the behavioral level.In summary,this research has the following conclusions: the reward dysfunction of individuals with depression inclination is universal both in the processing of monetary rewards and social rewards,and there is also a decline in reward sensitivity in specific domain.