![]() It seems that neurogenesis facilitates the forgetting of remote memories and enhances recent memories. They suggested that neurogenesis-induced forgetting would benefit reducing proactive interference (PI) from previous memory traces, therefore further facilitate the following memory encoding with conflict information ( Epp et al., 2016). (2016) partially explained these conflicting results on exercise-induced effects on memories through neurogenesis. However, numerous studies have shown that exercise could improve memory encoding and consolidation, and this beneficial effect was partially mediated by neurogenesis ( Kronenberg et al., 2006 Ahlskog et al., 2011 Alomari et al., 2013 Pontifex et al., 2016 Sakalem et al., 2017). Studies showed that exercise could also facilitate the forgetting of previous memory traces through neurogenesis in adult mice, and when exercise-induced neurogenesis is blocked using genetic techniques, exercise-induced forgetting is simultaneously diminished ( Akers et al., 2014 Epp et al., 2016). The number of adult-born neurons in DG can be enhanced by the external environment, such as enriched environment and exercise ( Nokia et al., 2016 Diederich et al., 2017 Sakalem et al., 2017 Tharmaratnam et al., 2017). Hippocampal DG is one of the brain regions maintaining continuous newborn neurons generation after animals matured ( Alvarez-Buylla and Lim, 2004). Animal studies gave the evidence that infantile rodents had poorer memory retention than adult ones, and this different ability in memory retention was related to the number of newborn neurons in the dentate gyrus (DG) of the hippocampus ( Akers et al., 2014 Guskjolen et al., 2016). This kind of forgetting was discovered in the phenomenon of “infantile amnesia.” As we all experienced, it is hard for an adult to recall experiences that happened during their infancy, and memories during infancy are more fragile than those during adulthood. Furthermore, newborn neurons equally participated in similar and novel memory acquisition.Īlthough neurogenesis is one of the primary mechanisms whereby exercise benefits cognitive enhancement, neurogenesis-induced forgetting has also been widely shown ( Akers et al., 2014 Gao et al., 2018 Ladron de Guevara-Miranda et al., 2018 Ishikawa et al., 2019). These results indicated that the experience of pre-exercise training equally facilitated new learning in the sedentary and exercise groups, even though significantly lower memory retention was found in the exercise group, suggesting rule-based learning in mice. Although newborn neuron activation between groups that had or had not received prior task training was not different, activation was significantly higher in exercise groups than in sedentary groups after the probe test for reversal learning. Activation of new adult-born neurons was also examined. Compared with mice that received no pre-exercise training, mice that had been previously trained, even those in the exercise group that had decreased recall, showed significantly better performance in the reversal learning test. ![]() We found that exercise significantly facilitated the forgetting of the first platform location (i.e., diminished spatial memory) but also significantly enhanced reversal learning. All mice were then subjected to the task, but the platform was located in a different position (reversal learning for previously trained mice). After 4 weeks of this, previously trained mice were tested for their retention of the platform location. Half the mice in each group then exercised on a running wheel, while the other half remained sedentary in home cages. Another mouse group received no training. Two-month-old male C57BL/6J mice were trained on a spatial memory task using the Morris water maze and tested to determine that they had learned the platform location. Our goals were to determine whether spatial memory is diminished by exercise, and if so, whether the memory is completely gone or whether only the local details disappear but not the acquired strategy. It remains unclear whether the diminished memory traces are completely forgotten. 3Beijing Institute for Brain Disorders, Capital Medical University, Beijing, ChinaĮxercise enhances cognitive function through increased neurogenesis but can also cause neurogenesis-induced forgetting. ![]() ![]() 2Beijing Key Laboratory of Mental Disorders, Beijing Anding Hospital, Capital Medical University, Beijing, China.1Department of Sport Psychology, School of Sport Science, Shanghai University of Sport, Shanghai, China.Cuicui Li 1, Rena Li 2,3* and Chenglin Zhou 1* ![]()
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