The Neural Basis Of Trait Self-control

In order to achieve one’s goal successfully, one has to control his attention effectively and eliminate the adverse impact of stimulus unrelated to one’s long-term goals, and also properly regulate his emotion and behavior. The ability to regulate oneself to achieve his long-term goals is termed self-control. Self-control is an important function of self. It is the key factor of successful life, and good for mental health, personal achievements, subjective well-being, as well as social acceptance and social adaption. Just because of this, it is well studied in various subjects, such as sociology, economics, criminology and psychology. However, existing research in psychology mainly focus on the study of state self-control, such as how to solve the cognitive conflict in the face of current stimulus, how to regulate negative emotion, or resist harmful temptation. These studies tried to discover the dynamic process of self-control. However, self-control is quite stable to some extent. It reflects the stable tendency that one often interacts with the environment. Moreover, this tendency varies between different individuals. Therefore, it is necessary to study the neural correlates of stable self-control from the perspective of personality and cognitive neuroscience. The present study aims to investigate the neural basis of inter-individual differences on trait self-control, using the technique of Magnetic Resonance Imaging(MRI).Firstly, we used structural MRI and resting state fMRI to investigate the brain structural basis on trait self-control and resting state neural activities(Study 1). Given that the core processes of trait self-control include cognitive control and emotion regulation, we then tried to investigate the specific process and neural correlates of cognitive control(Study 2) and emotion regulation(Study 3) for individuals with high and low trait self-control, respectively.There are two experiments in study 1. Experiment 1 investigated the relationship between trait self-control and brain regional gray matter volume. The results showed that in contrast to individuals with low trait self-control, individuals with high trait self-control had bigger gray matter volume in the right dorsal medial prefrontal cortex(dMPFC), left inferior frontal gyrus(IFG) and left middle cingulate cortex(MCC). Experiment 2 tried to explore the relations between trait self-control and the intensity of spontaneous brain activity(Amplitude of Low Frequency Fluctuation, ALFF) and resting state functional connectivity(RSFC). The results showed that individuals with high trait self-control had lower spontaneous brain activity in key nodes of cognitive control network and emotion regulation network(left inferior frontal gyrus and dorsal medial prefrontal cortex); in contrast, they showed higher spontaneous brain activity in striatum, which contributes to the process of motivation. Furthermore, these brain regions functionally interacted with each other as a network to predict trait self-control.On the basis of Study 1, study 2 tried to investigate the neural correlates of inter-individual differences on trait self-control from the perspective of cognitive control and emotion regulation, respectively. There are two experiments in study 2. Experiment 3 used the popular AX version of Continuous Performance Task(AX-CPT) to study the two types of cognitive control: proactive control and reactive control. This is a task-based fMRI experiment. We found that individuals with high trait self-control tend to use the strategy of proactive control, maintaining stable information related to long-term goals in the working memory before explicit responses. For individuals with high trait self-control, bilateral inferior frontal gyrus/doral lateral prefrontal cortex, bilateral inferior parietal lobule, right supplemental motor area, right insula, left thalamus and right brainstem activated stronger than that of individuals with low trait self-control in the process of practive control. Experiment 4 adopted the paradigm of attention network test(ANT) to discuss the differences on the efficiency of the three attention sub-networks for high and low trait self-control groups. The results showed that there were no significant differences in the three attention networks.Study 3 aims to investigate the inter-individual differences of the processes and neural correlates of emotion regulation between high and low trait self-control groups. Emotion regulation is a stable ability, and reflects the common style to process emotional information and regulate negative emotion. It is often assessed by the emotion regulation scales or emotion intelligence scales. Therefore, the two experiments in study 3 probed into the resting state tendency of emotion regulation and dynamic processes when regulating negative emotions for high and low trait self-control groups. Experiment 5 adopted emotional intelligence scale to measure the ability of emotion regulation, then investigated the differences on spontaneous brain activity between high and low trait self-control groups. The results indicated that individuals with high emotion regulation ability had high spontaneous activities in regions of cognitive control network and default mode network, such as supplemental motor area, precuneus, inferior parietal lobule, and posterior cingulate cortex. By contrast, the spontaneous activities in emotion processing network, such as temporal pole, orbitofrontal cortex and cerebellum were very weak. These findings advance our understanding of the nature of emotion disorders or depression. Experiments 6 adopted task-based fMRI emotion regulation paradigm to investigate the differences in regulating negative emotions for high and low trait self-control groups. The results showed that when purely viewing the negative emotional pictures, individuals with high trait self-control experienced stronger negative emotion than individuals with low trait self-control. And bilateral dorsal lateral prefrontal cortex and right inferior frontal gyrus activated greater accordingly. However, when they were instructed to regulate negative emotions, individuals with low trait self-control showed better regulation effect and activated greater in core nodes of cognitive control network(such as dorsal lateral prefrontal cortex, inferior frontal gyrus, inferior parietal lobule, middle cingulate cortex and precuneus) compared to individuals with high trait self-control. These results indicated that individuals with high trait self-control tend to regulate bad emotion expierences automatically and showed less sensitive to negative pictures than individuals with low trait self-control. However, they are not good at regulating negative emotion compared to individuals with low trait self-control.In the current study, we investigated the brain structural basis and functional networks of trait self-control by means of multiple modes MRI. We found that individuals with high trait self-control have bigger regional gray matter volume in some regions of cognitive control and emotion regulation networks, indicating that trait self-control has certain material base. In addition, individuals with high trait self-control showed lower spontaneous brain activity in regions of cognitive control network, but higher spontaneous brain activity in regions that contribute to process motivations. These results indicated that individuals with high trait self-control in daily life are good at maintaining certain self-control motivation level and adopt economic and effective strategies to allocate the scarce self-control resources. Study 2 and study 3 further confirmed this speculation form two aspects of cognitive control and emotion regulation, respectively, and found that individuals with high trait self-control tended to adopt proactive control strategy to process information, but they did not showed better attention network efficiency compared to low trait self-control group. Additionally, individuals with high trait self-control tend to regulate poor emotion expierences automatically and showed less sensitive to negative pictures; however, they are not good at regulating negative emotion compared to individuals with low trait self-control.These findings deepened our understanding on the nature of trait self-control, and discovered the neural correlates of inter-individual differences on trait self-control for the first time. Furthermore, it has important meaning on the understanding the development of self-control and could provide valuable suggestions on the counseling for the adolescent with low self-control in school education. On the other hand, these findings may provide directions for clinical treatment for some mental disease in the medical intervention.