Neural Mechanisms Underlying Effortful Control

Effortful control(EC),as one component of temperament,describes an individual's capacity for self-regulation and is defined as “the efficiency of executive attention--including the ability to inhibit a dominant response and/or to activate a subdominant response,to plan,and to detect errors”.EC includes the abilities to voluntarily manage attention and inhibit or activate behaviors as needed to adapt,especially when an individual does not particularly want to do so.EC reflects the component of temperament that is related to self-regulation and executive function.EC is one of the key components of temperament and plays an important role in the development of individuals.Previous researches about EC mostly had explored the correlation between EC and the interpersonal relationships,academic performance,or emotions of infants and adolescents,which indicated that EC was closely related to the individual's academic performance,interpersonal relationships and emotions.For example,studies found that individuals with high EC level had better academic performance,healthy emotion state,and show less aggressive behaviors.These behavioral studies showed that the level of EC was critical to the development of individuals.Therefore,it is of great significance for us to explore the neural mechanisms of EC.Some researchers believed that the neural mechanisms of EC consist of dorsal prefrontal cortex,anterior cingulate cortex,parietal lobe,and supplemently motor area.The activation of these brain regions has also been observed in tasks involving EC,which providied evidences for our understanding of the neural mechanisms of EC.However,most previous studies on EC have focused on adolescents,and the brain of adolescence was still in the process of maturation.It is uncertain for us whether the neural mechanisms of EC develops with the grow up of adolescents.So it is essential for us to explore the neural mechanisms of EC in adult.Therefore,a group of college students in early adulthood was studied in the present research.We explored the brain structures bases and brain connections bases of EC controlling irrelevant variables.This research might provide us more knowledge about EC.In the first study,we used a large sample of healthy young adults and performed whole brain voxel-wise multiple regression analysis to determine whether GM volumes in ACC and lateral PFC were related to individual difference in EC,given that previous adolescent studies highlighted the two regions involved in EC.Firstly,the statistic analysis of EC score showed that there was no significant difference between males and females in EC scores.The results of whole brain voxel-wise multiple regression analysis showed that EC scores were negatively correlated with GM volumes in the right dorsal anterior cingulate cortex(dACC)and adjacent presupplementary motor area(pre-SMA).Furthermore,to ensure the accuracy of multiple regression analysis,permutations testing and cross-validation(CV)were performed to predict EC with GM volumes by multivariate regression approach.And the generalizability of the above brain marker for EC was tested by internal cross validation.Result showed that the predicted EC scores were positively correlated with the actual EC scores in all 3-folds.These findings had demonstrated the executive attention system involved in the temperamental dimension of EC,in accordance with previous adolescents' results,providing evidence for the neuroanatomical neural substrates of EC in young adulthood.Based on the results of the first study,the second study analyzed the brain functional connectivity of EC.Firstly,we took the dorsal anterior cingulate cortex as a region of interest(ROI),then the method of searching the whole brain based on the ROI was used to explore the correlation between resting state functional connectivity strength and effort control scores.Finally,a one-sample T-test was performed on the EC score and resting state functional connectivity strength,and found the areas that were significantly related to the EC scores.The results showed that the functional connectivity between the anterior cingulate cortex and the midcingulate cortex was significantly positively associated with EC scores,and the functional connectivity between the anterior cingulate cortex and the right superior frontal gyrus was also significantly positively correlated with EC scores.These results may indicate that although the gray matter volume of midcingulate cortex is not significant correlated with EC scores in VBM analysis,the functional connectivity between the anterior cingulate cortex and the midcingulate cortex was significantly positively associated with EC scores.Midcingulate cortex might influences the level of EC through functional integration with the anterior cingulate cortex.Similarly,the right superior frontal gyrus also contributed to the development of EC through functional integration with the anterior cingulate cortex.The results of the functional connectivity enriched our knowledge of EC.In summary,we found that the gray matter volume of the right dorsal anterior cingulate cortex and the pre-supplementary motor area was related to the EC scores,suggesting that these two brain regions were the neural basis of EC.And the results of permutations testing and cross-validation(CV)verify the results of VBM above.The second study revealed that the functional connectivity between the anterior cingulate cortex and the midcingulate cortex was significantly positively correlated with EC scores.And the functional connectivity between the anterior cingulate cortex and the right superior frontal gyrus was also significantly positively correlated with EC scores.This result suggested that the strength of the functional connectivity between the anterior cingulate cortex played a vital role in the development level of EC.And the strength of the functional connectivity between the midcingulate cortex and the right superior frontal gyrus also played a vital role in the development level of EC.