拖延的脑机制:基于大尺度脑网络的分析

The neural basis underlying procrastination: a large-scale study of brain networks

拖延是指个体明知有害却仍自愿推迟执行任务的一种不理智行为.拖延不仅会对人们的情绪、学业表现以及社会成就等产生不利的影响,而且会降低人们的主观幸福感,更有甚者会损害人们的身心健康.关于拖延的神经基础,目前研究只探索了拖延和脑区局部活动及简单的功能连接的关系.然而,拖延行为涉及任务价值表征、认知控制、趋近与回避动机等复杂的心理过程,以单变量和局部的脑活动来对拖延的神经基础进行描述会存在可见的局限.因此本研究采用图论拓扑分析的方法从大尺度脑网络连接角度考察拖延的神经基础.首先,定义Power等人的全脑264个感兴趣区(regions of interest, ROIs)为网络的节点,进一步采用图论分析的方法重构了全脑10个固有大尺度脑网络,结果发现构建的脑网络具有较好的网络拓扑属性(如较高的局部效率和全局效率).其次,采用皮尔逊相关的方法计算了10个脑网络内以及网络间的功能连接的强度.最后,考察了脑网络连接的强度与拖延行为之间的关系.结果发现,拖延与扣带执行网络的内部连接存在显著的负相关,而与皮层下网络的内部连接存在显著的正相关;进一步的网络间的功能连接发现,突显网络与皮层下网络间的功能连接与拖延存在显著的正相关.这些结果表明,皮层下网络和扣带执行网络内的连接以及突显网络对皮层下网络的调节可能是特质性拖延的神经基础.本研究的结果证明了认知控制与冲动性价值表征等认知能力在拖延行为中的重要作用.

Procrastination is a type of irrational behavior during which an individual voluntarily delays the execution of a task despite perceiving such behavior as harmful. Procrastination adversely affects people’s emotions, academic performances, and social achievements;it reduces their subjective well-being, and worse, their physical and mental health. The brain systems that regulate procrastination are still largely undetermined;previous studies have only explored the relationships between procrastination and regional brain activities and cerebral functional connections. Because procrastination involves complex psychological motivations that are dependent on elements such as task value representation, cognitive control, and the approach-avoidance conflict, some limitations to exploring the neural basis of procrastination using univariate and regional brain activities may exist. Therefore, this study used graph-theoretic analysis to investigate the connectivity patterns of large-scale brain networks underlying procrastination. We first defined the 264 regions of interest(ROIs) introduced by Power et al.(2011) as nodes of the network, and then reconstructed the ten intrinsic largescale brain networks using graph-theoretic analysis. The results showed that the constructed brain network had better network topology attributes, such as a higher local and global efficiency. The strength of functional connectivity within each of these ten brain networks and that between them was then calculated using Pearson’s correlation. Finally, the association between procrastination and the functional network connectivity of brain networks was examined. We found that procrastination was negatively associated with the functional connectivity within the cingulo-opercular network(CON), whereas it was positively associated with the functional connectivity within the subcortical network(SCN). We also found a positive correlation between procrastination and the functional connectivity between the salience network(SAN) and the SCN. These results suggest that the functional network connectivity within the CON and the SCN, as well as that between the SAN and the SCN may be the neural basis underlying procrastination, which highlights the critical role of cognitive control and impulsive value representation in procrastination.