Age-related differences in attention to novelty among cognitively high performing adults

Age-related differences in attention to novel events were studied in well-matched, cognitively high performing old, middle-aged and young subjects. Event-related potentials were recorded during a visual novelty oddball task in which subjects controlled viewing durations that served as a behavioral measure of attentional allocation. All age groups had a larger P3 amplitude and longer viewing duration to novel than to standard stimuli, with no age-related differences in the magnitude of these effects, indicating old individuals were as engaged by the processing of novelty as younger adults. Old subjects had a larger, more anteriorly distributed P3 component to novels and standards. The increased P3 amplitude differs from prior reports of a diminished P3 response with processes, including aging, that have a potentially deleterious impact on the brain. We hypothesise that cognitively high performing old individuals successfully manage the task by relying on additional neural resources and perhaps more effortful frontal activity than their younger counterparts.     

Age-related changes in early novelty processing as measured by ERPs

This study investigated age-related changes in the early processing of novel visual stimuli using ERPs. Well-matched old (n = 30), middle-aged (n = 30), and young (n = 32) subjects were presented standard, target/rare, and perceptually novel visual stimuli under Attend and Ignore conditions. Our results suggest that the anterior P2 component indexes the motivational salience of a stimulus as determined by either task relevance or novelty. Its enhancement by focused attention does not decrease with age. Its responsiveness to novel stimuli is particularly striking in older adults. The age-related increase in the anterior P2 to novel visual stimuli does not appear to be due to impaired inhibitory control associated with aging. Rather, the enhanced anterior P2 to novel stimuli in older adults may be linked to age-related changes in the process of matching unusual visual stimuli to stored representations, which is indexed by the temporally overlapping anterior N2 component whose amplitude substantially decreases with age.     

Age-related differences in brain activation during emotional face processing

Advancing age is associated with significant declines on neurobehavioral tasks that demand substantial mental effort. Functional imaging studies of mental abilities indicate that older adults faced with cognitive challenges tend to activate more regions, particularly frontal, than their younger counterparts, and that this recruitment of additional regions may reflect an attempt to compensate for inefficiency in cortical networks. The neural basis of emotion processing in aging has received little attention, and the goal of the present study was to use functional magnetic resonance imaging (fMRI) to examine the influence of age on facial emotion processing and activation in cortical and limbic regions. Participants (eight old and eight young adults) viewed facial displays of happiness, sadness, anger, fear, disgust, and neutrality in alternating blocks of emotion and age discrimination. We predicted that in response to an emotion discrimination task, older adults would demonstrate increased use of frontal regions relative to younger adults, perhaps combined with diminished use of regions recruited by younger adults, such as temporo-limbic regions. During the emotion discrimination task, young participants activated, visual, frontal and limbic regions, whereas older participants activated parietal, temporal and frontal regions. A direct comparison between emotion and age discrimination revealed that while younger adults activated the amygdala and surrounding temporo-limbic regions, older adults activated left frontal regions. The results of this study suggest that older adults may rely on different cortical networks to perceive emotional facial expressions than do their younger counterparts.     

Age-related differences in impulsivity among adolescent and adult Sprague-Dawley rats

Adolescence is an ontogenetic period characterized by numerous hormonal, neural, and behavioral changes. In animal models, adolescents exhibit greater levels of novelty-seeking behavior and risk-taking relative to adults, behaviors associated in humans with increases in impulsivity and elevated propensities to engage in drug and alcohol seeking behaviors. The current series of experiments sought to explore possible age-related differences in impulsivity when indexed using delay discounting in adolescent (postnatal day [P] 25-27) and adult (P68-71) female (Experiment 1) and male (Experiment 2) Sprague-Dawley rats. In both experiments, adolescents exhibited significantly greater levels of impulsive-like behavior in this test relative to adults-even when data were adjusted to account for baseline differences in activity levels (i.e., general nose-poking behavior) across age. Taken together, these results extend to both sexes previous findings of adolescent-associated elevations in impulsivity observed among male mice using delay discounting, as well as among male rats using other procedures to index impulsivity. That these age differences were observed among both male and female rats suggests that impulsivity may be a pervasive feature of adolescence, and contributes to the expression of risky behaviors during this ontogenetic period.     

Neural sources involved in auditory target detection and novelty processing: an event-related fMRI study

We used event-related functional magnetic resonance imaging (erfMRI) techniques to examine the cerebral sites involved with target detection and novelty processing of auditory stimuli. Consistent with the results from a recent erfMRI study in the visual modality, target processing was associated with activation bilaterally in the anterior superior temporal gyrus, inferior and middle frontal gyrus, inferior and superior parietal lobules, anterior and posterior cingulate, thalamus, caudate, and the amygdala/hippocampal complex. Analyses of the novel stimuli revealed activation bilaterally in the inferior frontal gyrus, insula, inferior parietal lobule, and in the inferior, middle, and superior temporal gyri. These data suggest that the scalp recorded event-related potentials (e.g., N2 and P3) elicited during similar tasks reflect an ensemble of neural generators located in spatially remote cortical areas.     

Sex differences in muscular load among house painters performing identical work tasks

Purpose

The present study aimed to estimate possible differences in upper body muscular load between male and female house painters performing identical work tasks. Sex-related differences in muscular load may help explain why women, in general, have more musculoskeletal complaints than men.

Methods

In a laboratory setting, 16 male and 16 female house painters performed nine standardised work tasks common to house painters. Unilateral electromyography (EMG) recordings were obtained from the supraspinatus muscle by intramuscular electrodes and from the trapezius, extensor and flexor carpi radialis muscles by surface electrodes. Relative muscular loads in %EMG_max as well as exerted force in Newton, based on ramp calibrations, were assessed. Sex differences were tested using a mixed model approach.

Results

Women worked at about 50 % higher relative muscular loads than men in the supraspinatus and forearm muscles at all percentiles and in all tasks. Women exerted about 30 % less force in the trapezius muscle at the 50th percentile.

Conclusions

Female house painters had a higher relative muscular load than their male colleagues without exerting more force. The effects of a higher relative muscular load accumulated over years of work may in part explain why musculoskeletal complaints in the upper body occur more frequently among women than men.     

Similarities and differences in sleep-wake patterns among adults and their children

STUDY OBJECTIVE: To determine associations and differences in sleep-wake patterns among children and their parents and to explore the correlates for sleep-wake patterns among adults. DESIGN: A school-based cross-sectional survey. PARTICIPANTS: Sample included 1479 fourth to eighth graders and their parents, using a multistage sampling method. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: Students and their parents completed a Sleep Habit Questionnaire, which included sleep schedules, a mood scale, and the morningness/eveningness scale. Statistical methods included Pearson and Spearman correlations and analysis of variance using a mixed model. Results showed low correlations in sleep schedules and sleep-wake patterns between children and those parents who did not work shifts or have an evening or night job. Compared to their children, parents tended to go to bed and rise later, have shorter nighttime sleep duration, have less weekend compensation of sleep, and have the morning-type sleep profile. In addition, junior-high students (seventh and eight graders) demonstrated different sleep-wake patterns compared to elementary-school students (fourth to sixth graders). Young age, moodiness, and shift work were associated with tendencies to be the evening type among parent participants. CONCLUSIONS: Our findings indicate that age, social demands (school work for children and adolescents and employment type for adults), and mood status are associated with sleep-wake patterns. Future study examining the association between evening-sleep type and neurotic traits and psychopathology in the adult population will be our next step.     

Gender differences in sexual activity among mid-aged adults in Massachusetts

Objectives: The purpose of this study was to determine if self-reported measures of sexual activity differ between aging men and women. Methods: Responses to 12 questions concerning various aspects of sexual activity were compared between 349 women and 589 men aged 51–61, who were participants in two larger community surveys in Massachusetts conducted in 1987 and 1988. Comparisons were made by least squares means adjusted for age, socio-demographic and health-related variables. Analyses were stratified by the presence or absence of one or more current sexual partners. Results: Regardless of partner status, overall satisfaction with sex life did not differ between men and women. For those with partners, the mean frequency of intercourse was somewhat higher for women than men, while mean frequency of sexual desire and fantasies was significantly higher for men. Similar results were seen for those without partners, although frequency was lower and did not differ by gender. Conclusions: We found no gender difference in sexual satisfaction and little difference in frequency in mid-aged adults, but sexual desire and fantasies were more common for men.     

Age-related sex differences in verbal memory

Verbal learning and memory were studied in 196 healthy men and women aged 40 to 89. The Rey Auditory Verbal Learning Task (RAVLT), a 15-word list, was presented over five trials followed by free recall after each trial. A recognition trial of 50 words subsequently was administered. A stepwise regression that examined the contributions of age, sex, and vocabulary on the five trials of the RAVLT showed that age and sex accounted for a significant portion of the variance on each trial. Vocabulary accounted for a significant portion of the variance only on trials 4 and 5. The recognition trial was not affected by age, sex, or vocabulary. Men had lower scores overall as compared to women. In the older age group (ages 66-89), this difference was significant on trials two through five. Possible mechanisms that may underlie these age-related sex differences in learning curves are discussed.     

Age-related changes in cortical swallowing processing

The cortical organization of swallowing has been mainly studied in young and healthy subjects. Aging effects on human deglutition have been found in several behavioral studies and are known to affect both the oral and pharyngeal phases of swallowing. The aim of this study was to evaluate a potential cortical compensation of age-related swallowing impairment. Whole-head MEG was employed in 9 healthy elderly subjects (mean age 71.6 years) and compared to 9 healthy young participants (mean age 23.8 years). Data were analyzed by means of time-frequency plots and synthetic aperture magnetometry (SAM). Group analysis of individual SAM data was performed using a permutation test. The main finding of this study was an increase of somatosensory cortical activation during swallowing execution in elderly subjects compared to the young control group. This effect was present in both hemispheres. These results point to adaptive cerebral changes in response to aging effects on the complex process of swallowing. Our finding underlines the relevance of age matched control groups in neuroimaging studies related to deglutition or other complex sensorimotor processes.     

Age-related differences in corrected and inhibited pointing movements

It has been widely reported that aging is accompanied by a decline in motor skill performance and in particular, it has been shown that older subjects take longer to adapt their ongoing reach in response to a target location shift. In the present experiment, we investigated the influence of aging on the ability to perform trajectory corrections in response to a target jump, but also assessed inhibition by asking a younger and an older group of participants to either adapt or stop their ongoing movement in response to a target location change. Results showed that although older subjects took longer to initiate, execute, correct and inhibit an ongoing reach, they performed both tasks with the same level of accuracy as the younger sample. Moreover, the slowing was also observed when older subjects were asked to point to stationary targets. Our findings thus indicate that aging does not specifically influence the ability to perform or inhibit fast online corrections to target location changes, but rather produces a general slowing and increased variability of movement planning, initiation and execution to both perturbed and stationary targets. For the first time, we demonstrate that aging is not accompanied by a decrease in the inhibition of motor control.

Age-related differences in force variability and visual display

The objective of this study was to determine the importance of every frequency component on total physiological tremor (PT) amplitude. We suspect that since high frequencies of PT are of lower amplitude in displacement, removing them will have little to no impact on PT amplitude. PT of the index finger was measured with a laser displacement sensor while the finger was held horizontally. Amplitude of tremor was calculated in displacement, velocity and acceleration. PT amplitude was also calculated within five frequency bands. Although displacement amplitude of oscillations within the 7.5–12.5 and 16.5–30 Hz frequency bands represent 24 and 10% of total PT oscillation amplitude, respectively, their removal reduced PT amplitude by less than 3%. Conversely, the removal of the oscillations within 1–3.5 Hz band from the PT signal reduced the amplitude of the original PT signal by 56% in displacement. This suggests that when a task to be studied involves the measurement of a reduction in tremor, focus should be on the oscillations in the 1–3.5 Hz band.     

Age-related deficits in mice performing working memory tasks in a water maze

This study determined whether mice exhibit spatial working memory deficits with increased age. C57BL/6JNia mice of 3 different ages were tested in the Morris water maze with 2 protocols designed to assess immediate and delayed working memory abilities. Young mice required multiple trials in order to show improvements in the working memory task. Deficits in immediate working memory were detected in both 10- and 24- to 26-month-old mice. Reference memory deficits and declines in performance in the delayed working memory task were only seen in 24- to 26-month-olds. This increased susceptibility of immediate working memory processes to the aging process in mice may be related to their need for more rehearsal in the water maze than other species.     

Age-related differences in sensory conditioning in rats.

Four experiments tested rats 8, 12, or 21 days postnatal for sensory conditioning in terms of the association acquired between two odors presented simultaneously or sequentially. The sensory conditioning of 8- and 12-day-old rats exceeded that of rats 21 days of age when the odors were presented simultaneously. When one odor was presented immediately followed by another, however, 21-day-old rats conditioned as effectively as the younger animals, and with a sufficiently long interval between odors (20 min), the sensory conditioning of the 21-day-old rats surpassed that of the rats 12 days of age. Although consistent across a variety of procedures, in previous experiments and within the present study, the age-related differences in sensory conditioning after simultaneous presentation of two odors are difficult to understand. Increasing knowledge of the ontogeny of orienting may lead to an explanation in terms of Thompson's (1972) theory linking sensory conditioning with orienting and sensitization.     

Effects of methylphenidate in ADHD adults on target evaluation processing reflected by event-related potentials

Attention deficit/hyperactivity disorder (ADHD) is a widely examined disease in childhood. There is evidence that the disease responds well to medication with methylphenidate (MPH). The effect of MPH in adults with ADHD is a question that is often raised, because many adults request such therapy today. As yet, there is a lack of studies on event-related potentials (ERPs) and MPH in ADHD adults. In the present study we examined 10 adults diagnosed with ADHD, with and without MPH medication (30 mg daily), by means of ERP in a visual Go/NoGo experiment to gain information about target evaluation processing in these patients and about the effects on these attentional processes during medication with MPH. Visually, there seem to be differences in the frontal electrodes for the N2 and in the parietal electrodes for the P300. But these differences do not achieve statistical significance. There are also no statistically relevant differences for the N1 or the slow wave. MPH does not seem to have an effect on target evaluation processing, when comparing the ERPs of non-medicated and medicated ADHD adults. Especially the P3 does not appear to be modulated by medication with MPH in these ADHD adults, in contrast to findings in ADHD children.     

Sex differences in weight loss among adults with Type II diabetes mellitus

The treatment of choice for Type II or non-insulin-dependent diabetes mellitus is a behavioral program for the management of weight. However, compliance with this lifelong dietary regimen is often poor. In the current investigation male and female adults with diagnosed Type II diabetes were randomly assigned to either a behavior modification, a cognitive modification, a cognitive-behavior modification, or a control group. Patients were evaluated in terms of weight, percentage of body fat, and glycosylated hemoglobin measures. Men lost signficantly more weight than women and subjects in the behavior modification group lost more weight and demonstrated greater decreases in diabetes control than subjects in the cognitive-behavior modification, cognitive, and control groups. A significant interaction indicated that diabetic men may benefit more from behavioral weight reduction programs than diabetic women. Several explanations for these findings are considered.This work was supported by Grants K04 HL 00809 and R01 AM 27901 from the National Institutes of Health to Robert M. Kaplan.