论文部分内容阅读
Inter-temporal choice involves the tradeoff of small soon reward and larger later reward,which is a unique ability for human beings developed in the long history of evolution and is critical for human survive.Although a large number of imaging studies have examined the neural correlates of inter-temporal choices,it is still unclear how immediate and delayed rewards are represented in the brain,largely due to the fact that few studies have simultaneously and orthogonally manipulation the two type of rewards.To address this issue,the present study used functional magnetic resonance imaging and both univariate and multivoxel pattern analysis techniques to examine how the BOLD responses were modulated by the magnitude of immediate and delayed rewards.We found that activity in the left superior temporal gyrus (STG) was correlated with the magnitude of immediate rewards,whereas a distributed network of brain regions,including the medial prefrontal cortex (MPFC),left superior temporal gyrus (STG),right middle temporal gyrus,right supplementary motor area (SMA),right superior frontal cortex (SFG),left cerebellum,whose activities were correlated with the magnitude of delayed rewards.Multivoxel pattern analysis revealed that the posterior portion of the MPFC represented the immediate rewards whereas the anterior portion of the MPFC represented the delayed rewards.We concluded that there are distinct brain regions that represent immediate rewards and delayed rewards.In particular,the critical role of the anterior MPFC in representing delayed reward provides a neural basis for human’s unique capacity of delayed gratification.