The Impact Mechanism Of Reinforcement Sensitivity On Self-harm Among College Student

Non-suicidal self-injury(NSSI)refers to direct,deliberate destruction of one’s own body tissue with the lack of an intention to die.NSSI is an important risk factor for suicide and various psychological/mental disorders.Individuals who may engage in NSSI present 17 times more risk of death from suicide and 35 times more risk of death from drug or alcohol abuse compared to non-exposed populations.College students are one of the high-risk groups of NSSI.The prevalence of NSSI among college students in China is about 16%.However,due to shame,stigma and other reasons,college students tend to hide NSSI.Therefore,it is urgent to find objective,effective and symbolic predictive indicators of NSSI among college students.Theories such as the benefits and barriers model of NSSI emphasized the positive and negative reinforcement characteristics of NSSI,which correspond to the reward sensitivity and punishment sensitivity in the reinforcement sensitivity theory.Previous studies have also supported the role of personality characteristics related to reward sensitivity and punishment sensitivity in NSSI.Rumination,depression,and impulsivity,as risk factors for self-injury,are also closely related to reinforcement sensitivity,and there may be an important mediating effect.In addition,distinguishing different characteristics of NSSI(such as frequency and severity)may help to fully reveal the mechanism of it.However,there is still a lack of research to directly investigate the influence of the neuro characteristics of the reinforcement sensitive nervous system on the NSSI among college students and its mechanism.This paper explored the predictive effects and mechanisms of multimodal reinforcement sensitivity indicators on the frequency,severity,and behavior of NSSI among college students,through three studies and six sub-studies.The first study was designed to explore the effects of reinforcement sensitivity as a personality trait on NSSI(the frequency,severity,and behavior)among college students.And the mediation effects of rumination,depression,and impulsivity were also examined.This study consisted of 2 sub-studies.The results emphasized the important influence of reinforcement sensitivity on NSSI among college students,and further revealed the mechanism.Sub-study 1,based on the cross-sectional study design and questionnaire method among 1939 college students,investigated the predictive effect and mechanism of reward sensitivity(reward responsiveness,drive,and fun seeking)and punishment sensitivity on the frequency,severity,and behavior of NSSI among college students.The results showed that the three dimensions of reward sensitivity significantly predicted college students’ NSSI.Punishment sensitivity significantly predicted the frequency and severity of NSSI among college students.Rumination had mediating effects on reward sensitivity and frequency/behavior of NSSI,as well as punishment sensitivity and frequency of NSSI among college students.Rumination and depression had mediating effects on punishment sensitivity and frequency of NSSI among college students.Impulsivity had mediating effects on punishment sensitivity and severity of NSSI among college students.Sub-study 2,based on the longitudinal study design and questionnaire method among 767 college students,investigated the longitudinal predictive effect and mechanism of reward sensitivity(reward responsiveness,drive,and fun seeking)and punishment sensitivity on NSSI among college students by constructing cross-lag model and inter-temporal mediation model.The results showed that reward sensitivity and punishment sensitivity at time point 1 can predict NSSI at time point 2 among college students.NSSI at time point 1 can predict punishment sensitivity at time point 2 among college students.Depression has an inter-temporal mediating effect between punishment sensitivity and the severity of NSSI among college students.These findings suggested that with the development of time,punishment sensitivity and the severity of NSSI have a strong reciprocal prediction,which can also be achieved through the inter-temporal mediation of depression.The second study,the task-state f MRI,resting-state f MRI,and the structural MRI were used to investigate the neural mechanism of the effect of reinforcement sensitivity on NSSI among college students.The results revealed that abnormal task-state,resting-state brain function and brain structure characteristics were the neural mechanisms that reinforcement sensitivity predicting NSSI among college students.This study consisted of three sub-studies.Sub-study 3,based on task-state functional magnetic resonance imaging(f MRI)combined with Monetary Incentive Delay(MID)task,investigated the relationship between reinforcement sensitivity-related brain activation and network and college students’ NSSI in anticipation and feedback stage through sub-study 3a and 3b respectively.The results of sub-study 3a showed that under the condition of reward anticipation,orbitofrontal cortex(OFC)-precuneus functional connectivity and OFC-Supplementary Motor Area(SMA)functional connectivity were significantly related to frequency and severity of NSSI among college students.Rumination played a mediation role between brain functional connectivity and frequency and severity of NSSI among college students.The results of sub-study 3b showed that under the condition of reward feedback,the activation of the right dorsolateral prefrontal cortex and the OFC-insula functional connectivity were significantly enhanced.The functional connectivity between middle frontal gyrus and OFC was significantly related to the frequency and behavior of NSSI of college students.Rumination,and depression mediated the relation between the functional connectivity the frequency and behavior of NSSI among college students.These findings suggested that the brain functional characteristics related to reward sensitivity in different stages had a predictive effect on NSSI among college students,and depression and rumination provided a more complete path for the correlation between neural mechanism and NSSI.Sub-study 4,based on resting-state f MRI,investigate the relationship between brain activation and network characteristics related to reinforcement sensitivity and the frequency,severity,and behavior of NSSI among college students.The results showed that the Regional Homogeneity(Re Ho)value of OFC is significantly correlated with college students’ NSSI behavior,and depression plays a mediation role between them.The Amplitude of Low Frequency Fluctuation(ALFF value of the right caudate was significantly correlated with the severity of NSSI.The OFC-cuneus resting-state functional connectivity was significantly related to NSSI behavior.These findings suggested that the spontaneous activity of brain regions related to reinforcement sensitivity in resting-state is also the key to understand the NSSI among college students,and the role of important psychological variables such as depression should also be considered.Sub-study 5,voxel-based morphometry(VBM)analysis was used,which investigated the correlation between the reinforcement sensitivity-related gray matter volume characteristics and the frequency,severity,and behavior of NSSI among college students.The results showed that the gray matter volume of OFC,caudate and SMA is positively correlated with NSSI of college students.And there was a significant positive correlation between the gray matter volume of OFC extracted under different conditions and NSSI.These findings suggested that structure of reinforcement sensitivity-related brain regions was also a key factor to understand college students’ NSSI.The third study,based on the multimodal reinforcement sensitivity index and machine learning method,three support vector regression(SVR)models were constructed for the frequency,severity,and behavior of college students’ NSSI,investigated the prediction effect of multimodal reinforcement sensitivity index on NSSI among college students.The results showed that multimodal reinforcement sensitivity index had significant prediction effect on the frequency and severity of NSSI among college students.The results showed that it is of great significance to investigate the reinforcement sensitivity information of multiple modes to predict the different characteristics of college students’ NSSI and realize personalized prediction.Under the experimental conditions of this paper,the following conclusions can be drawn:(1)Reinforcement sensitivity was an important influencing factor of college students’ NSSI.Reinforcement sensitivity can indirectly affect the frequency,severity,and behavior of NSSI through rumination,depression,and impulsivity among college students.And with the development of time,there was an interactive relationship between punishment sensitivity and the severity of NSSI among college students.(2)Abnormal neural basis of reinforcement sensitivity was the key to the individual differences of college students’ NSSI.Compared with punishment sensitivity,reward sensitivity had a stronger effect on college students’ NSSI in the anticipation and feedback stage.The data of multimodal brain imaging suggested that OFC can be regarded as the core brain region to understand college students’ NSSI.(3)Multimodal reinforcement sensitivity index combined with machine learning method can effectively predicted the frequency and behavior of NSSI among college students.Above all,this paper indicated that reinforcement sensitivity is an important factor predicting NSSI among college students.The multimodal integrated model of ‘psycho-brain’ association of NSSI was constructed based on the results in this paper.This model showed new theoretical and empirical evidence for a comprehensive understanding of the intrinsic motivational mechanism of NSSI.