Function Of Adult Age Research Articles

Aging and Visual Attention

Older adults are often slower and less accurate than are younger adults in performing visual-search tasks, suggesting an age-related decline in attentional functioning. Age-related decline in attention, however, is not entirely pervasive. Visual search that is based on the observer's expectations (i.e., top-down attention) is relatively preserved as a function of adult age. Neuroimaging research suggests that age-related decline occurs in the structure and function of brain regions mediating the visual sensory input, whereas activation of regions in the frontal and parietal lobes is often greater for older adults than for younger adults. This increased activation may represent an age-related increase in the role of top-down attention during visual tasks. To obtain a more complete account of age-related decline and preservation of visual attention, current research is beginning to explore the relation of neuroimaging measures of brain structure and function to behavioral measures of visual attention.

Efficiency of route selection as a function of adult age

Two tasks hypothesized to assess the efficiency of route selection were administered to 328 adults ranging from 18 to 93 years of age. Increased age was associated with slower completion of mazes, even after adjusting for differences in perceptual-motor speed, and with longer and less accurate routes in a task in which participants were asked to visit designated exhibits in a zoo. The route selection measures were correlated with measures hypothesized to represent executive functioning, such as the number of categories in the Wisconsin card sorting test and the number of words generated in a category fluency test. However, most of the age-related influences on the measures from the route selection tasks were shared with age-related effects on established cognitive abilities, which implies that the same mechanisms may account for the relations of age on both sets of variables.

Adult Age Differences in the Implicit and Explicit Components of Top-Down Attentional Guidance During Visual Search.

Two experiments investigated adult age differences in the explicit (knowledge-based) and implicit (repetition priming) components of top-down attentional guidance during discrimination of a target singleton. Experiment 1 demonstrated an additional contribution of explicit top-down attention, relative to the implicit effect of repetition priming, which was similar in magnitude for younger and older adults. Experiment 2 examined repetition priming of target activation and distractor inhibition independently. The additional contribution of explicit top-down attention, relative to the repetition priming of distractor inhibition, was greater for older adults than for younger adults. The results suggest that some forms of top-down attentional control are preserved as a function of adult age and may operate in a compensatory manner.

Ovarian physiology and age-grading in the rice weevil, Sitophilus oryzae (Coleoptera: Curculionidae)

Physiological and morphological changes in the ovarian system in rice weevils, Sitophilus oryzae (L.) (Coleoptera: Curculionidae), reared on wheat seeds were studied as a function of adult age, mating status, and nutrient availability. X-ray analysis was used to determine time of adult eclosion and the duration of development of pre-emergent weevils within the seeds, a process that lasted almost 4 days at 25°C and 60% r.h. There was no follicular differentiation in pre-emergent weevils. Oocyte maturation began after adults emerged from the seeds and started to feed. There was a significant increase in mean germarium length and the size of proximal follicles within the first 5 days when newly emerged weevils were mated and fed ad lib. Maximum number of follicles and mature eggs per ovariole in mated females occurred at 5–30 days of age. The number of mature eggs decreased in 60-days-old weevils, at the same time that adult mortality increased. Development of the ovarian system was much slower in unmated females than in mated females. Although there was follicle development in unmated females, ovulation never occurred and no eggs were laid. Starvation of mated females resulted in a rapid reduction in numbers of follicles and mature eggs, probably as a result of oosorption. Females were categorized into two nulliparous and three parous stages according to ovarian development and the degree of accumulation of follicular relics. Parity was directly correlated with both weevil age and the number of progeny produced and was the physiological basis used to construct an age-grading model for this species. The method will be useful for determining the age structure and reproductive potential of rice weevil populations in the field.

Enzyme profiles in two wing polymorphic soapberry bug populations ( Jadera haematoloma: Rhopalidae)

Wing-polymorphic insects are excellent models for asking questions about trade-offs in physiology and life-history because of the existence of multiple morphs exhibiting numerous strategies living in one environment. We measured activities of select key enzymes in oxidative metabolism (citrate synthase), glycolysis (hexokinase, pyruvate kinase) and fatty acid oxidation (ß-hydroxyacyl CoA dehydrogenase, HOAD) in flying and non-flying long-winged bugs from two populations (ancestral and derived) of the wing-polymorphic soapberry bug ( Jadera haematoloma). In the ancestral population, flyers had significantly greater activities of citrate synthase, hexokinase, pyruvate kinase, and HOAD than non-flyers. In contrast, in the derived population, flyers and non-flyers showed no significant differences in the activities of any of the enzymes tested. There were no significant differences in activities of citrate synthase as a function of adult age (3–20 d) for either population. Short-winged bugs in the derived population had significantly lower citrate synthase activities than either of the two derived, long-winged morphs, however, they were analogous to the ancestral long-winged non-flyer. These results suggest an evolution of alternative flight strategies between the two populations.

Estrogen treatment and age effects on auditory brainstem responses in the post-breeding Long-Evans rat.

The auditory brainstem response (ABR) was recorded from 20-month-old Long Evans hooded female rats to determine if latency reductions occur from estrogen replacement. The ABR in these post-breeding age rats was also examined for reductions in response latencies as a function of adult age. Tone pip stimuli (8 and 40 kHz) were presented at 21, 51, or 81 s(-1). Aging control and ovariectomized animals showed slower response latencies for waves Ib-VI than young adults for 8 and 40 kHz stimulation at 21 s(-1). Increased stimulus rate resulted in longer latencies for all waves at 20 months. In contrast to hormone treatment effects in young adults, ABR latencies in post-breeding age estrogen-treated animals were not reduced, consistent with a general decrease in CNS responsiveness to estrogen steroids associated with age. The results also suggest that sensorineural modifications in the auditory system which prolong ABR latencies can occur early in the aging process of adult female subjects.

Circadian cycling of a PERIOD-beta-galactosidase fusion protein in Drosophila: evidence for cyclical degradation.

The authors analyzed circadian features of two period-lacZ (per-lacZ) fusion genes in transgenic strains of Drosophila. Both genes manifest circadian fluctuations of mRNA levels, but fluctuations of only the larger chimeric protein are apparent. Fusion protein cycling is indistinguishable from the behavior of wild-type per protein (PER), including apparent temporal regulation of phosphorylation state. Several arguments indicate that the difference in the two constructs is proper regulation at the level of protein turnover: the smaller protein has much higher levels; a beta-galactosidase degradation products is visible in both strains but fails to manifest cycling, presumably due to a long half-life; and only the noncycling proteins accumulate as a function of adult age. The large cycling fusion protein also undergoes modest cycling in an arrhythmic per01 background. This is light dependent, resembles the regulation of the timeless protein (TIM) by light, and reflects a documented fusion protein-TIM interaction. The results are discussed with respect to the posttranscriptional regulation that is necessary for proper cycling of both PER and TIM as well as for clock function.

Temporal patterns of gene expression in the antenna of the adult Drosophila melanogaster.

The time course of gene expression in the adult fruit fly has been partially characterized by using enhancer trap and reporter gene constructs that mark 49 different genes. The relative intensity of the reporter protein in individual cells of the antennae was measured as a function of adult age. Most genes showed a graduated expression, and the intensity of expression had a reproducible and characteristic time course. Different genes displayed different temporal patterns of expression and more often than not the pattern of expression was complex. We found a number of genes having patterns that scaled with life span. In these cases the intensity of gene expression was found to be invariant with respect to biological time, when expressed as a fraction of the life span of the line. The scaling was observed even when life span was varied as much as threefold. Such scaling serves to (1) further demonstrate that deterministic mechanisms such as gene regulation act to generate the temporal patterns of expression seen during adult life, (2) indicate that control of these regulatory mechanisms is linked to life span, and (3) suggest mechanisms by which this control is accomplished. We have concluded that gene expression in the adult fly is often regulated in a fashion that allows for graduated expression over time, and that the regulation itself is changing throughout adult life according to some prescribed program or algorithm.

Production Dynamics of Cucujolide Pheromones and Identification of 1-Octen-3-ol as a New Aggregation Pheromone for Oryzaephilus surinamensis and O. mercator (Coleoptera: Cucujidae)

Aggregation pheromone production by Oryzaephilus surinamensis (L.) and O. mercator (Fauvel) was measured as a function of adult age and population density. Porapak Q-captured volatiles were monitored weekly from mixed-sex adults feeding on rolled oats at two different population densities. Macrolide aggregation pheromones (cucujolides) were produced by males of both species by the end of the first week after eclosion and maximum production rates were still maintained more than 3 mo later. For O. mercator , the previously identified cucujolides were 3( Z ),11( R )-dodecen-11-olide and 3( Z ),6( Z ),11( R )-dodecadien-11-olide, and for O. surinamensis , 3( Z ),6( Z ),11( R )-dodecadien-11-olide, 3( Z ),6( Z )-dodecadienolide, and 5( Z ),8( Z ),13( R )-tetradecadien-13-olide. O. surinamensis less than 1 mo after eclosion showed a two- to threefold increase in cucujolide production compared with adults maintained at a fivefold higher population density. In comparison, cucujolide production by young O. mercator was less sensitive to the presence of conspecifics. At the lower population density, adults of both species more than 1 mo after eclosion produced almost optically pure ( R )-(−)-1-octen-3-01. Laboratory bioassays in a two-choice, pitfall olfactometer indicated that l-octen-3-01 alone serves as an aggregation pheromone, and when added to mixtures of cucujolide pheromones, it extends the attractive range of the cucujolides for both Oryzaephilus species.

Dual-task performance as a function of adult age and task complexity.

A dual-task procedure was used to examine capacity demands of letter-matching in younger and older adults. Older subjects generally were slower on both tasks than were younger adults, but this difference was especially pronounced for the late stages of category matching, suggesting that retrieval and comparison of category information is particularly demanding for older adults.

Dual-task performance as a function of adult age and task complexity.

Dual-task performance as a function of adult age and task complexity.

Age and sensitivity to oxygen in the flour beetle, Tribolium confusum

Sensitivity of Tribolium confusum males and females to pure oxygen at one atmosphere was measured as a function of adult age. Sensitivity to oxygen increased markedly with age the reciprocal to the LD 50 exposure time was a linear function of age. The sensitivity to oxygen increased more rapidly with age in males than in females; this may be related to the greater longevity of females in this species. Thus the LD 50 exposure time represents an index of physiological age. Sublethal exposure to pure oxygen Unlike equivalent exposure to ionizing radiation, did not affect longevity. This suggests that the age-associated increase in oxygen sensitivity is a non-specific stress effect, rather than additivity of acute oxygen damage with cumulative atmosphere-induced lesions.

Persistence of complementary afterimages as a function of adult age and exposure duration.

The persistence of complementary afterimages was studied in 36 young (X age 18.8 years) and old (X age 62.1 years) male and female subjects. Afterimage persistence was found to be a direct function of exposure duration and to be greater for the older subjects as compared with the younger ones. The interactions between age and duration and between presentation order and duration were also significant. The data extend support for the "stimulus persistence" model to age differences in retinal function.

Attitudes toward youth as a function of adult age: a multivariate study in intergenerational dynamics.

This study explores the social attitudes of three groups of adult males-young adult, middle-aged, and elderly-toward three, present-day youth groups (young people today, our boys in Vietnam, college students). Utilizing a semantic differential measure of attitude and testing for adult age group differences in attitudes toward the young, the study establishes that young adults are least accepting of youth, that elderly males are most accepting, and that middle-aged males assume an intermediate position between the other two age groups. These results suggest that acceptance of youth is a linearly increasing function of age. It was further observed that the subjects of this study, irrespective of their position on the adult age range, are significantly more positively inclined toward the young military in Vietnam than they are toward the generalized young or to college students. The latter receive the least favorable attitudinal ratings. The authors discuss a number of possible interpretations of the results obtained.

Paired-associate learning as a function of adult age and the length of the anticipation and inspection intervals.

Paired-associate learning as a function of adult age and the length of the anticipation and inspection intervals.

A study of some aspects of the physiology of ageing in Drosophila subobscura

1. 1. The ability to acclimatize to temperature was determined in adult h hybrid D. subobscura ( B/ K) males as a function of adult age. 2. 2. The rapid decline in the ability to withstand exposure to 34° in these young flies, which has been reported earlier, is confirmed. It is suggested this decline in physiological performance is not an ageing phenomenon but rather a loss of pre-adult high tolerance. 3. 3. Flies up to the age of 56 days were able to acclimatize to temperature but older flies could not do so. Thus there is no decline in physiological performance during the plateau phase of the life table. 4. 4. The oxygen consumption of hybrid and inbred male D. subobscura was determined, at 25°, as a function of adult age. In the hybrid males and the K inbred males the rate of oxygen consumption was about 4μlO 2/fly/hr; this value declined in old flies to be about 3μlO 2/fly/hr. In the hybrid males the higher level of oxygen consumption was maintained during the plateau phase of the life table and fell only when the rate of mortality was increasing. This was also the case in K males except that the plateau phase of the life table is short. The oxygen consumption of B males is about 3μlO 2/fly/hr and shows no decline with age. 5. 5. This age-dependent decline in oxygen consumption is thought to reflect the lower activity of the older flies. B males being the least vigorous are relatively inactive even as young adults and so it is suggested that 3μlO 2/fly/hr is close to the basal metabolic rate for D. subobscura. 6. 6. The loss of the ability to acclimatize to temperature with increasing age is discussed with regard to age related changes in protein synthetic mechanisms.