关键词: 未来时间, 未来思考, 情节式未来思考, 年龄差异, 脑机制

Abstract: Episodic future thinking (EFT) is a projection of the self into the future to pre-experience an event. It plays a significant role in our daily life, especially in the process of planning, problem solving and delay of gratification. The present study explored the age difference and its underlying neural mechanism in EFT. The former part is focused on the occurrence and development of individual and phenomenological characteristics in age-related changes. Specifically, the occurrence of individual EFT was about four years old when children happened to imaging future and showed appropriate behavior according to possible future situations. The ability of individuals’ EFT improved as they grew older. For example, compared with children, adolescents created more episodic and semantic details when imagining future events. The age difference of phenomenal characteristics associated with projecting oneself forward into the future mainly includes the kind of details, the valence and intensity of emotion, temporal distance, novelty and vividness of events. Specifically, for the details, young adults produced more details, whereas children and the old presented more general but not special ones; for emotional valence, old adults showed more positive effect. However, it needs further research to explore whether the effect exists in EFT; for emotional intensity, the old scored higher than youth; for the temporal distance, former researches showed that children and adults generated more specific simulation of the near-future events; For the novelty and vividness of events, the age difference of EFT existed in the number of vivid images that the young produced more vivid image compared to the old. To conclude, there were some age differences in phenomenological characteristics of EFT. Generally speaking, the development of EFT showed an inverted U function, which peaking at adulthood. The latter referred to the brain-related activation of the age difference, which mainly include brain areas such as temporal lobe, precuneus, hippocampus, and frontal lobe. First of all, different cognitive process activate different brain areas. Neuroimaging study showed that the episode of the Old’s EFT depended on frontal lobe and temporal gyrus, which emphasizes specific scene. Secondly, different age groups showed different activation model of hippocampus in EFT. The old tended to activate the right anterior hippocampus, whereas the young activated the left part. It could be speculated that in EFT the elderly occupied more cognitive processes such as spatial memory and visual mental imagery. The youth called for more specific and episodic details about the cognitive processes, which to some extent explains the differences between the two populations’ EFT. Thirdly, age difference existed in frontal lobe in different tasks in EFT. The whole-brain interaction analysis founded the activation of the lateral prefrontal cortex when doing EFT, indicating the role of LPFC. To sum, in EFT the youth and the old activated similar brain areas (e g. temporal lobe, precuneus, hippocampus, and frontal lobe) but differed in the intensity of activation. Future researches should enlarge the age span both normal and special people, pay more attention to the research angle, longitudinal crossover studies of age difference as well as the underlying elaborate neuro-mechanism, which needs combine internal and external factors and would be of vital social implication in the research of cognitive aging.

Key words: future time, future thinking, episodic future thinking, age difference, neural mechanism