Memory specificity is linked to repetition effects in event-related potentials across the lifespan

The specificity with which past experiences can be remembered varies across the lifespan, possibly due to differences in how precisely information is encoded. Memory formation can be investigated through repetition effects, the common finding that neural activity is altered when stimuli are repeated. However, whether differences in this indirect measure of memory formation relate to lifespan differences in memory specificity has not yet been established. In the present study, we examined repetition effects in event-related potentials and their relation to recognition. During incidental encoding, children (aged 7–9 years), young adults (18–30 years), and older adults (65–76 years) viewed repeated object images from different categories. During subsequent recognition, we distinguished memory for the specific items versus the general categories. We identified repetition suppression in all age groups, and repetition enhancement for adults. Furthermore, individual item recognition performance comprising lure discrimination was positively associated with the magnitude of the neural repetition effects, which did not differ between groups, indicating common neural mechanisms of memory formation. Our findings demonstrate that neural repetition effects reflect the formation of highly specific memory representations and highlight their significance as a neural indicator of individual differences in episodic memory encoding across the lifespan.     

Why women may live longer than men do? A telomere-length regulated and diet-based entropic assessment

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Mitochondria in the signaling pathways that control longevity and health span

Genetic and pharmacological intervention studies have identified evolutionarily conserved and functionally interconnected networks of cellular energy homeostasis, nutrient-sensing, and genome damage response signaling pathways, as prominent regulators of longevity and health span in various species. Mitochondria are the primary sites of ATP production and are key players in several other important cellular processes. Mitochondrial dysfunction diminishes tissue and organ functional performance and is a commonly considered feature of the aging process. Here we review the evidence that through reciprocal and multilevel functional interactions, mitochondria are implicated in the lifespan modulation function of these pathways, which altogether constitute a highly dynamic and complex system that controls the aging process. An important characteristic of these pathways is their extensive crosstalk and apparent malleability to modification by non-invasive pharmacological, dietary, and lifestyle interventions, with promising effects on lifespan and health span in animal models and potentially also in humans.     

Relationship between lifespan and somatic mutation in D. melanogaster after treatment with chlorophyllin

Sodium copper chlorophyllin (SCC) has a genetic damage inhibitory capacity due to its antioxidant action. For this reason, it was considered to investigate its role in the life span of Drosophila melanogaster and its relationship with the frequency of somatic mutation induced by gamma rays. Results indicated that SCC alone prolonged the lifespan only in females, but in combination with 20 Gy of gamma rays, the aging delay in both sexes was significant. In addition to confirming that the porphyrin reduces the frequency of mutation, the individuals with the highest mutation load are the individuals who die more quickly, and once they are eliminated, the survivor individuals treated with 20 Gy or with SCC + 20 Gy, died at the same rate. The results together indicate that SCC not only inhibits induced genetic damage, but it also has beneficial effects that probably cause an aging delay of the treated population that need to be investigated.     

基于多模态神经影像学的人海马毕生变化曲线

研究背景近20年来,越来越多的研究者采用fMRI技术研究海马结构与功能,以揭示海马功能与记忆力之间的关系。对正常人海马结构与功能毕生变化曲线的研究和建模,是监测个体发育情况和辅助预测相关疾病的关键环节,能够反映正常人脑自然变化的普适性结构变量(即体积),以及反映功能活动的指标低频振荡振幅、分数低频振荡振幅和局部功能一致性。方法采用fMRI技术,通过连接组计算机系统对125例7~85岁正常个体的海马体积、低频振荡振幅、分数低频振荡振幅和局部功能一致性进行评价。结果双侧海马体积随年龄的增长而显著减小(校正后Ps=0.000),左侧海马低频振荡振幅(校正后P=0.034,β=-0.314)、分数低频振荡振幅(校正后P=0.059,β=-0.687)和局部功能一致性(校正后P=0.005,β=-0.330)与年龄呈显著负相关及负相关趋势。结论从一个侧面揭示了人毕生发展过程中海马结构与功能之间的相互关系。     

黄连-吴茱萸不同比例配伍水提物对线虫的毒性效应评价

目的：评价不同比例黄连-吴茱萸配伍提取物对秀丽隐杆线虫的毒性效应。方法：以秀丽隐杆线虫为模式生物,制备不同比例黄连-吴茱萸配伍水提物,测定各水提物对秀丽隐杆线虫寿命、体长及运动行为的影响。每组30条线虫观察存活率,每天在相同时间观察线虫数量,以最后一条线虫死亡时间作为最长寿命;每组40条线虫观察体长,用Image J软件测量死亡线虫虚拟体长;每组30条线虫观察头尾摆动和身体弯曲频率,测定1 min内线虫头部摆动的次数（从一侧摆向另一侧再摆回来）和20 s内身体弯曲的次数（认为线虫相对于身体的长轴移动一个正弦周期的波长为1次身体弯曲）。结果：与黄连组比较,随吴茱萸相对比例增加,秀丽隐杆线虫的死亡率显著降低（P<0.01）;体长显著减少（P<0.01）;对秀丽隐杆线虫的运动行为没有明显的抑制作用。结论：吴茱萸在一定程度上能够降低黄连对秀丽隐杆线虫的毒性,延长其寿命;在生长发育和神经方面影响较小,本研究为黄连和吴茱萸的配伍与炮制减毒研究提供了新的方法。     

Low resting metabolic rate is associated with greater lifespan because of a confounding effect of body fatness

A negative association between resting metabolic rate (RMR) and lifespan is the cornerstone of the rate of living and free-radical damage theories of aging. Empirical studies supporting a negative association of RMR to lifespan may arise from the correlation between RMR and both daily energy expenditure (DEE) and thermoregulatory activity energy expenditure (TAEE). We screened 540 female mice for higher and lower DEE and measured RMR in the resulting 324 (60 %). We then selected 92 mice in which there was no link between residual from the regression of RMR against body mass (BM) and residual of DEE against BM to separate the effects of these traits. Lifespan was not significantly related to body mass, DEE and TAEE, but significantly negatively related to RMR. Fat-free mass (FFM) and fat mass (FM) were both significantly positively related to RMR. After removing the effect of FFM on RMR, the association between RMR and lifespan remained significantly negative; however, after statistically removing the effect of FM on RMR, the significant association between RMR and lifespan disappeared. We conclude that the negative association between RMR and lifespan is primarily due to the effect of FM, with FM positively related to both RMR and mortality and hence RMR negatively to lifespan. In 40 additional screened mice, greater FM was also associated with greater oxidative damage to DNA.     

Metformin reduces all-cause mortality and diseases of ageing independent of its effect on diabetes control: A systematic review and meta-analysis

This systematic review investigated whether the insulin sensitiser metformin has a geroprotective effect in humans. Pubmed and Embase were searched along with databases of unpublished studies. Eligible research investigated the effect of metformin on all-cause mortality or diseases of ageing relative to non-diabetic populations or diabetics receiving other therapies with adjustment for disease control achieved. Overall, 260 full-texts were reviewed and 53 met the inclusion criteria. Diabetics taking metformin had significantly lower all-cause mortality than non-diabetics (hazard ratio (HR) = 0.93, 95%CI 0.88–0.99), as did diabetics taking metformin compared to diabetics receiving non-metformin therapies (HR = 0.72, 95%CI 0.65–0.80), insulin (HR = 0.68, 95%CI 0.63–0.75) or sulphonylurea (HR = 0.80, 95%CI 0.66–0.97). Metformin users also had reduced cancer compared to non-diabetics (rate ratio = 0.94, 95%CI 0.92–0.97) and cardiovascular disease (CVD) compared to diabetics receiving non-metformin therapies (HR = 0.76, 95%CI 0.66–0.87) or insulin (HR = 0.78, 95%CI 0.73–0.83). Differences in baseline characteristics were observed which had the potential to bias findings, although statistical adjustments were made. The apparent reductions in all-cause mortality and diseases of ageing associated with metformin use suggest that metformin could be extending life and healthspans by acting as a geroprotective agent.