Influencing Factors And Neural Correlates Of Old Adults' Event-based Prospective Memory

Prospective memory(PM), in contrast to retrospective memory(RM), is defined as remembering to carry out an or several intended actions at an appropriate moment or phase in the future. It is so common in our everyday life, e.g. remembering to post a letter when you pass the post office on the way to work. And sometimes the failures of PM would lead to serious results. So the research on PM seems so necessary and important to everybody, especially to those aged people whose cognition function thought to be declined. And better prospective memory performance would help them to maintain their independent lives and improve their living qualities. So this research focused on the performance and neural correlates of old people's event-based prospective memory, which is one main kind of PM.In Chapter 1-Introduction, the author reviewed the not long history of this domain involved prospective memory, and gave the definitions and classifications of PM. The author also introduced the main experimental paradigms and processing theories, as well as some influencing factors on the PM performance.In Chapter 2, the author discussed the aspects such as aging, neural mechanisms etc., which are more concerned by the prospective memory researchers. All these led to the purpose of this dissertation that the author tried to find if PM declined with age and what were involved with the brain in this cognitive process.Chapter 3 is the most important part of this dissertation, which included 5 experiments. The first one is a behavior measurement experiment. The second to the fourth experiments used event-related potentials (ERPs) technique. The last one is an additional experimental to the former ERPs experiments.Experiment 1 compared the older adults with the younger adults and the schizophrenia both in PM task and ongoing task performance. The correlations between PM and participants' gender, education, familiarity to the cue and preference to the experiment material were verified. The results showed that the aged participants' performance on PM were significantly lower than the younger people, but higher than the schizophrenia. And only preference to the material had significant effect on the PM performance.Experiment 2 compared the PM task, RM task and ongoing task performance between older adults and younger adults with both behavioral data and physiological data. The result showed that both the accuracy and response time of PM and RM had a significant decline in the older adults' related to the younger ones. The neural correlates revealed that 3 modulations which were associated with the prospective memory (i.e. P2, N300, prospective positivity), and the prospective positivity which thought to be associated to the intention retrieval showed a significant decline in older adults.Experiment 3 compare the PM performance under 4 different task load (change the complexity of PM task and ongoing task) conditions between the older adults and the younger adults. The results showed that the complexity of PM led to an obvious age-related decline on the PM performance (both in accuracy and rat). With the increase of the task complexity, the main 2 modulations of ERP(e.g. N300, prospective positivity) showed an phenomena that older adults presented a consistency in the process resources on cue detection and intention retrieval, whereas the younger group presented an balance between the resources on cue detection and intention retrieval.Experiment 4 compared the age differences between older and younger adults on the PM hit, PM false and PM omission. The results showed great increase of PM false in older adults related to younger ones. And the associated modulations showed little difference between the two groups.Experiment 5 gave more concern on related quantitive analyses. We inquired several questions involved in their mental activities during the cognitive actions ASAP the participants finished their test, which is used as a compensation to increase the ecological validity of ERPs study. We also gave a questionnaire about the daily PM performance as an self-estimate evidence. Then we gave a natural PM task to all the participants. The results showed that there were some differences in the process of intention formation or intention retrieval between younger and older adults, and their self-estimate had no significant difference. Both older and younger adults reported using external aids to help performing PM tasks in their daily lives.In the Summary, the author concluded the theories and methods involved in above studies. Further study will be more extended in both participants and PM types (e.g. time-based PM), more elaborate design and high ecological validity.