Age Differences In Activity Research Articles

Differential Functional Connectivity in Anterior and Posterior Hippocampus Supporting the Development of Memory Formation.

Neuroimaging evidence suggests that the development of the hippocampus, a brain structure critical for memory function, contributes to the improvements of episodic memory between middle childhood to adulthood. However, investigations on age differences in hippocampal activation and functional connectivity and their contributions to the development of memory have yielded mixed results. Given the known structural and functional heterogeneity along the long axis of the hippocampus, we investigated age differences in the activation and functional connectivity in hippocampal subregions with a cross-sectional sample of 96 participants ages 8–25 years. We found that anterior and posterior hippocampus supported memory formation, and there was overall stability in memory-related hippocampal activation with age. Without taking account of memory outcome, direct contrast between subregions showed higher functional connectivity of anterior, compared to the posterior hippocampus, with regions in the inferior frontal and lateral temporal lobes, and higher functional connectivity of posterior, compared to the anterior hippocampus, with regions in the medial and superior frontal, inferior parietal, and occipital lobes. A direct contrast between the memory-related connectivity patterns of anterior and posterior hippocampus identified a region in the medial frontal cortex, with which anterior and posterior hippocampus was differentially functionally connected. Finally, we identified age differences in memory-related differential hippocampal functional connectivity with several frontal and visual/sensory cortices, underscoring the importance of examining age differences in the patterns of hippocampal connectivity. Moreover, the specific patterns of differential anterior and posterior functional connectivity indicate an increase in the functional specialization along the long axis of the hippocampus and a dynamic shift in hippocampal connectivity patterns that supports memory development.

Fos activation patterns related to acute ethanol and conditioned taste aversion in adolescent and adult rats.

Studies in rats have revealed marked age differences in sensitivity to the aversive properties of ethanol, with a developmental insensitivity to ethanol aversion that is most pronounced during pre- and early adolescence, declining thereafter to reach the enhanced aversive sensitivity of adults. The adolescent brain undergoes significant transitions throughout adolescence, including in regions linked with drug reward and aversion; however, it is unknown how ontogenetic changes within this reward/aversion circuitry contribute to developmental differences in aversive sensitivity. The current study examined early adolescent (postnatal day [P]28-30) and adult (P72-74) Sprague-Dawley male rats for conditioned taste aversion (CTA) after doses of 0, 1.0, or 2.5g/kg ethanol, and patterns of neuronal activation in response to ethanol using Fos-like immunohistochemistry (Fos+) to uncover regions where age differences in activation are associated with ethanol aversion. An adolescent-specific ethanol-induced increase in Fos+ staining was seen within the nucleus accumbens shell and core. An age difference was also noted within the Edinger-Westphal nucleus (EW) following administration of the lower dose of ethanol, with 1g/kg ethanol producing CTA in adults but not in adolescents and inducing a greater EW Fos response in adults than adolescents. Regression analysis revealed that greater numbers of Fos+ neurons within the EW and insula (Ins) were related to lower consumption of the conditioned stimulus (CS) on test day (reflecting greater CTA). Some regionally specific age differences in Fos+ were noted under baseline conditions, with adolescents displaying fewer Fos+ neurons than adults within the prelimbic (PrL) cortex, but more than adults in the bed nucleus of the stria terminalis (BNST). In the BNST (but not PrL), ethanol-induced increases in Fos-immunoreactivity (IR) were evident at both ages. Increased ethanol-induced activity within critical appetitive brain regions (NAc core and shell) supports a role for greater reward-related activation during adolescence, possibly along with attenuated responsiveness to ethanol in EW and Ins in the age-typical resistance of adolescents to the aversive properties of ethanol.

Choosing Solitude: Age Differences in Situational and Affective Correlates of Solitude-Seeking in Midlife and Older Adulthood.

Despite a basic need for social connection, individuals across the adult lifespan sometimes seek solitude-a phenomenon that is not well understood. This study examined situational and affective correlates of solitude-seeking and how they may differ between middle-aged and older adults. One hundred community-dwelling adults aged 50-85 years (64% female, 56% East Asian, 36% European, 8% other) completed approximately 30 electronic daily life assessments over 10 days regarding their current location, affect, activities, and current and desired social context. Solitude was common; 86% of solitude instances happened by individuals' own choosing. When desiring solitude, older adults were more likely to be at home and less likely to be outdoors, compared to other locations. Middle-aged adults showed no such solitude-location associations. Among middle-aged adults, desire for solitude was associated with decreased positive affect. Older adults experienced no such dip in affect. Findings suggest that compared to middle-aged adults, older adults are more likely to go to locations that match their desired social context, and also that solitude-seeking has more positive ramifications for older adults. Findings are discussed in the context of age differences in activities, social preferences, and emotion regulation.

Performance level modulates adult age differences in brain activation during spatial working memory

Working memory (WM) shows pronounced age-related decline. Functional magnetic resonance imaging (fMRI) studies have revealed age differences in task-related brain activation. Evidence based primarily on episodic memory studies suggests that brain activation patterns can be modulated by task difficulty in both younger and older adults. In most fMRI aging studies on WM, however, performance level has not been considered, so that age differences in activation patterns are confounded with age differences in performance level. Here, we address this issue by comparing younger and older low and high performers in an event-related fMRI study. Thirty younger (20-30 years) and 30 older (60-70 years) healthy adults were tested with a spatial WM task with three load levels. A region-of-interest analysis revealed marked differences in the activation patterns between high and low performers in both age groups. Critically, among the older adults, a more "youth-like" load-dependent modulation of the blood oxygen level-dependent signal was associated with higher levels of spatial WM performance. These findings underscore the need of taking performance level into account when studying changes in functional brain activation patterns from early to late adulthood.

Individual differences in activity predict locomotor activity and conditioned place preference to amphetamine in both adolescent and adult rats

Individual and developmental differences in novelty seeking have been implicated in differential sensitivity to psychostimulants in rodents, but findings are mixed. The extent to which age differences in activity in a novel arena depended on test duration was examined by comparing adolescent and adult rats after 5 and after 60 min of testing (session 1). Rats were tested again after amphetamine or saline administration 24 h later (session 2) to examine whether activity in a novel arena predicts sensitivity to locomotor-activating effects of amphetamine. Data from two experiments were used to examine consistency of the findings. Only activity in 60 min sessions produced a consistent age difference (adolescent < adult) and predicted activity after amphetamine in session 2. Session 1 activity also predicted saline activity in session 2, indicating that individual differences in activity is a stable trait. A third data set was used to determine whether general (saline) and amphetamine-induced activity predicted magnitude of conditioned place preference (CPP) in late-adolescent and adult rats. Age was not a significant predictor, but CPP was positively associated with amphetamine activity and negatively associated with saline activity. Thus, in contrast to enhanced psychostimulant sensitivity in high novelty-seekers, rats higher in general activity are less sensitive to amphetamine conditioned place preference.

Overweight Children Reduce Their Activity Levels Earlier in Life Than Healthy Weight Children

To determine differences in the time overweight and nonoverweight youth spend on light, moderate, hard, and very hard activity plus gender and age differences in activity patterns. This study was a cross-sectional design in a primary care hospital. A total of 197 children and adolescents (4-16 years) participated. The overweight group (n = 107) were on a waiting list for an obesity treatment program and were defined as overweight, with a body mass index >95th percentile, and the nonoverweight group (n = 90) were volunteers recruited via advertisements and had a body mass index <75th percentile. INTERVENTIONS AND OUTCOME MEASUREMENTS: To determine activity patterns and perception of activity level, an interview was conducted with the child and a parent using a validated 7-day recall. Body fat was measured with bioelectrical impedance. There was a negative correlation between adiposity and total amount of activity performed, with the amount of moderate activity the best predictor of obesity. Girls did less activity than boys whether overweight or not. Between the ages of 4 and 7 years, overweight and nonoverweight subjects did similar amounts of activity. In the older subjects, the activity of the overweight was less than in nonoverweight. The overweight subjects perceived themselves to be just as active as others their same age and sex. Clinicians need to be aware that overweight children and adolescents are less active than nonoverweight children at an earlier age, particularly females, but feel that their activity level is similar to that of nonobese children.

Adult age differences in attention: filtering or selection?

We examined the effect of target letter redundancy for target-only (TO) and target-plus-noise (TPN) trials on a visual search, divided attention task where target letters were presented in one or two corners of a two-corner display. Half of the two-letter displays also included a noise letter. In both Experiment 1 (two-choice vs go/no-go) and Experiment 2 (all go/no-go), older adults showed larger redundancy gains than did young adults, and this effect did not interact with task type or visual similarity. However, for the "no-go" trials in both experiments, there were no age differences in overall errors. These results suggest that there are age differences in the activation of selective attention rather than age differences in inhibitory control. In Experiment 2, young adults under lower-luminance presentation conditions (18 cd/m2) showed a smaller redundancy gain than did older adults under higher-luminance presentation conditions (40 cd/m2). These results provided further support of the age differences in activation interpretation, as well as indicating that older adults' larger redundancy gain was not due to an age decrement in retinal illuminance.

Tool use by captive chimpanzees at an artificial termite mound

AbstractThis study examines tool use by a colony of captive chimpanzees at an artificial termite mound. The mound, constructed of concrete, simulates the termite mounds which are used as food sources by wild chimpanzees who extract the termites using grass or twig‐type tools. In the present study, tool availability was manipulated, specifically the type of tool, and the distance of tool material from the mound. The type of food available in the mound was also varied. Tool‐making and tool‐using behavior was examined in relation to individual, age, and sex differences.The artificial mound proved to be a viable simulation of the naturally occurring mounds, with most of the chimpanzees exploiting the food in the mound by using tools over the period of study. Interesting individual differences emerged in the way that the chimpanzees selected and used tools, some preferring to move some distance from the mound to collect “off‐the‐peg” tools, others preferring to sit and fashion a tool from material available nearer the mound. Also, some chimpanzees used both ends of a tool, while others used only one end. There were significant age differences in activity at the mound, the younger chimpanzees spending more time at the mound, using tools previously used by others, and manipulating the mound holes manually. Sex differences, although not significant, were apparent. The artificial mound provides the chimpanzees with a stimulating and rewarding activity, interest and enjoyment for the public, and an opportunity for researchers to study tool use under more controlled conditions than are possible in the field.

Evidence for sex and age difference in human Aspirin metabolism.

Based on reports elucidating sex differences in the prophylactic effects of aspirin against thromboembolism, sex and age differences in the activity of serum aspirin esterase (AE), the enzyme hydrolyzing aspirin, found predominantly in the liver, were measured in healthy persons of various age groups. In randomized healthy subjects, serum AE activity (μg of hydrolysed salicylic acid/30 min/ml) in females (average age 37.4±19.4, n=83) was significantly lower than in males (average age 40.2±18.2, n=81), While serum AE activity in males declined with increasing age, no age differences were found in females. Consequently, while men recorded higher activity than women in the younger age groups, the level of activity in men was lower than women in the older age groups. These sex and age differences in serum AE activity may be responsible in part for the sex differences in the efficacy of aspirin.