A Single Bout of High-Intensity Cardiovascular Exercise Does Not Enhance Motor Performance and Learning of a Visuomotor Force Modulation Task, but Triggers Ipsilateral Task-Related EEG Activity.

Acute cardiovascular exercise (aCE) seems to be a promising strategy to improve motor performance and learning. However, results are heterogeneous, and the related neurophysiological mechanisms are not well understood. Oscillatory brain activitiy, such as task-related power (TRPow) in the alpha and beta frequencies, are known neural signatures of motor activity. Here, we tested the effects of aCE on motor performance and learning, along with corresponding modulations in EEG TRPow over the sensorimotor cortex. Forty-five right-handed participants (aged 18-34 years) practiced a visuomotor force-matching (FM) task after either high-intensity (HEG), low-intensity (LEG), or no exercise (control group, CG). Motor performance was assessed immediately, 15 min, 30 min, and 24 h after aCE/control. EEG was measured during the FM task. Results of frequentist and Bayesian statistics revealed that high- and low-intensity aCE had no effect at the behavioral level, adding to the previous mixed results. Interestingly, EEG analyses showed an effect of aCE on the ipsilateral sensorimotor cortex, with a stronger decrease in ß-TRPow 15 min after exercise in both groups compared to the CG. Overall, aCE applied before motor practice increased ipsilateral sensorimotor activity, while motor learning was not affected; it remains to be seen whether aCE might affect motor learning in the long run.

Moderate Cardiovascular Exercise Speeds Up Neural Markers of Stimulus Evaluation During Attentional Control Processes.

Moderate intensity cardiovascular exercise appears to provide a low-cost "intervention" on neurocognitive processes such as attentional control, yet the effects vary depending, for example, on cognitive task, time of testing, or exercise intensity. However, while a number of studies show that brief bouts of acute exercise can modulate behavioral indices of cognitive control, relatively few studies have attempted to identify the brain activity associated with these changes immediately following exercise. Here, we tested 11 young adults in a crossover design with a Flanker task at rest and immediately (within 2-3 minutes) following 20 minutes of acute exercise at 60% of the individual VO2max. In order to prevent delayed exercise effects that might confound or dilute immediate effects, a short version of the Flanker task (8 minutes) was chosen and an EEG was recorded simultaneously. The N2 and P3 ERP components were analyzed in addition to accuracy and response time. The N2 reflects conflict resolution, and the P3 has been linked to stimulus evaluation processes. No effect of exercise was found for behavioral data but P3 peak latencies were shorter following exercise as compared to rest. The N2 amplitude data suggest that exercise seems to prevent a decline in resources of attentional control over time. These data indicate that acute exercise, at a moderate intensity level, speeds up neural processing of attentional control by modulating stimulus evaluation processes immediately following exercise and that exercise helps maintain a steady level of neurocognitive resources.

A Non-linear Relationship Between Selective Attention and Associated ERP Markers Across the Lifespan.

The ability to selectively attend to task-relevant information increases throughout childhood and decreases in older age. Here, we intended to investigate these opposing developmental trajectories, to assess whether gains and losses early and late in life are associated with similar or different electrophysiological changes, and to get a better understanding about the development in middle-adulthood. We (re-)analyzed behavioral and electrophysiological data of 211 participants, who performed a colored Flanker task while their Electroencephalography (EEG) was recorded. Participants were subdivided into six groups depending on their age, ranging from 8 to 83 years. We analyzed response speed and accuracy as well as the event replated potential (ERP) components P1 and N1, associated with visual processing and attention, N2 as marker of interference suppression and cognitive control, and P3 as a marker of cognitive updating and stimulus categorization. Response speed and accuracy were low early and later in life, with peak performance in young adults. Similarly, ERP latencies of all components and P1 and N1 amplitudes followed a u-shape pattern with shortest latencies and smallest amplitudes occurring in middle-age. N2 amplitudes were larger in children, and for incongruent stimuli in adults middle-aged and older. P3 amplitudes showed a parietal-to-frontal shift with age. Further, group-wise regression analyses suggested that children's performance depended on cognitive processing speed, while older adults' performance depended on cognitive resources. Together these results imply that different mechanisms restrict performance early and late in life and suggest a non-linear relationship between electrophysiological markers and performance in the Flanker task across the lifespan.

Explaining Individual Differences in Fine Motor Performance and Learning in Older Adults: The Contribution of Muscle Strength and Cardiovascular Fitness.

It remains controversial whether aging influences motor learning and whether physiological factors, such as local strength or fitness, are associated with fine motor performance and learning in older adults (OA). OA (n = 51) and young adults (YA, n = 31) performed a short-term motor learning session using a precision grip force modulation task. The rate of improvement of OA compared with YA was steeper with respect to performance variability and temporal precision. Both age groups showed positive transfer during an unpracticed variant of the force modulation task. Local muscle strength (pinch and grip strength) and high cardiovascular fitness positively predicted fine motor performance, whereas initial performance, muscle strength, and motor fitness (heterogeneous motor test battery) negatively predicted rate of improvement. Analyses indicated potentials, but also limits of plasticity for OA.

Older adults reveal enhanced task-related beta power decreases during a force modulation task.

Older adults (OA) compared to young adults (YA) reveal deteriorated fine motor control. However, it remains unknown whether this age difference is reflected on the central level, i.e., in electrophysiological correlates such as EEG task-related power (TRPow) in alpha (8-13 Hz) or beta band (13-30 Hz). Furthermore, we were interested in the association between age and alpha/beta power at rest as a potential determinant for TRPow changes. Twenty-five YA (19-29 years) and 45 OA (67-83 years) performed a force modulation (FM) task requiring to match a sinusoidal target force by exerting an isometric force with thumb and index finger. EEG was measured at rest and during FM task. YA outperformed OA in the FM task. For alpha, OA demonstrated less frontal power at rest than YA. For beta, OA revealed more power than YA in frontal, central, and parietal areas at rest. TRPow results depended on whether analyses were controlled for power at rest. When analyses were controlled, OA showed higher TRPow decreases than YA in beta in parietal and occipital areas during FM performance. TRPow decreases for beta were stronger in the contralateral than in the ipsilateral frontal hemisphere in OA than in YA. Decreases in TRPow indicate increased cortical activity to accomplish the FM task. Our findings suggest higher parietal and occipital processing demands while performing the FM task in OA than in YA. This study further confirmed the importance of controlling for EEG power at rest when investigating TRPow during motor performance to account for interindividual variability.

Acute Exercise as an Intervention to Trigger Motor Performance and EEG Beta Activity in Older Adults.

Acute bouts of exercise have been shown to improve fine motor control performance and to facilitate motor memory consolidation processes in young adults. Exercise effects might be reflected in EEG task-related power (TRPow) decreases in the beta band (13-30 Hz) as an indicator of active motor processing. This study aimed to investigate those effects in healthy older adults. Thirty-eight participants (65-74 years of age) were assigned to an experimental (EG, acute exercise) or a control group (CG, rest). Fine motor control was assessed using a precision grip force modulation (FM) task. FM performance and EEG were measured at (1) baseline (immediately before acute exercise/rest), (2) during practice sessions immediately after, (3) 30 minutes, and (4) 24 hours (FM only) after exercise/rest. A marginal significant effect indicated that EG revealed more improvement in fine motor performance immediately after exercise than CG after resting. EG showed enhanced consolidation of short-term and long-term motor memory, whereas CG revealed only a tendency for short-term motor memory consolidation. Stronger TRPow decreases were revealed immediately after exercise in the contralateral frontal brain area as compared to the control condition. This finding indicates that acute exercise might enhance cortical activation and thus, improves fine motor control by enabling healthy older adults to better utilize existing frontal brain capacities during fine motor control tasks after exercise. Furthermore, acute exercise can act as a possible intervention to enhance motor memory consolidation in older adults.

Does physical activity benefit motor performance and learning of upper extremity tasks in older adults? - A systematic review.

Upper extremity motor performance declines with increasing age. However, older adults need to maintain, learn new and relearn known motor tasks. Research with young adults indicated that regular and acute physical activity might facilitate motor performance and motor learning processes. Therefore, this review aimed to examine the association between chronic physical activity and acute bouts of exercise on motor performance and motor learning in upper extremity motor tasks in older adults. Literature was searched via Cochrane library, PubMED, PsycINFO and Scopus and 27 studies met all inclusion criteria. All studies dealt with the influence of chronic physical activity on motor performance or motor learning, no appropriate study examining the influence of an acute bout of exercise in older adults was found. Results concerning the association of chronic physical activity and motor performance are mixed and seem to be influenced by the study design, kind of exercise, motor task, and exercise intensity. Regarding motor learning, a high physical activity or cardiovascular fitness level seems to boost the initial phase of motor learning; results differ with respect to motor retention. Overall, (motor-coordinative) intervention studies seem to be more promising than cross-sectional studies.

Altered NK cell function in obese healthy humans.

BACKGROUND: Obesity is associated with an elevated risk for several types of cancer and thus a major health hazard. However, the mechanism between overweight and cancer susceptibility is still elusive. Leptin, mainly produced by adipocytes links food intake and energy expenditure. In addition, recent studies have shown an immunomodulatory impact of leptin on NK cells. The purpose of the present study was to investigate whether leptin stimulation of NK cells from obese humans leads to altered functions as compared to NK cells from lean subjects. On the basis of body mass index 20 healthy individuals were classified in two groups: normal weight (<25 kg/m(2)) and obese (>30 kg/m(2)). Peripheral blood mononuclear cells (PBMC) were isolated from blood samples. We used flow cytometry to assess differences in phenotype and activity markers (CD107a, CD178 and TRAIL) of PBMCs between both groups. Furthermore, we determined after short-term in vitro leptin stimulation the phosphorylation of JAK2, downstream target of the intracellular signaling cascade of the leptin receptor, by Western Blotting and numbers of NK-cell-tumor-cell-conjugates as well as Granzyme(+) and IFN-γ(+) NK cells by flow cytometry. Finally, the proliferative capacity of control and long-term (7 days) leptin-stimulated NK cells was examined. RESULTS: As opposed to similar NK cell counts, the number of CD3(+)CD56(+) cells was significantly lower in obese compared to lean subjects. Human NK cells express the leptin receptor (Ob-R). For further determination of Ob-R, intracellular target proteins of PBMCs were investigated by Western Blotting. Phosphorylation of JAK2 was lower in obese as compared to normal weight subjects. Furthermore, significantly lower levels of TNF-related apoptosis-inducing ligand (TRAIL) as an NK cell functional marker in obese subjects were found. In vitro leptin stimulation resulted in a higher production of interferon-γ in NK cells of normal weight subjects. Interestingly, long-term leptin stimulation had no significant influence on numbers of proliferating NK cells. CONCLUSIONS: NK cells from obese healthy humans show functional deficits and altered responses after in vitro leptin challenge.

Sex- and habitat-specific movement of an omnivorous semi-terrestrial crab controls habitat connectivity and subsidies: a multi-parameter approach.

Distinct habitats are often linked through fluxes of matter and migration of organisms. In particular, intertidal ecotones are prone to being influenced from both the marine and the terrestrial realms, but whether or not small-scale migration for feeding, sheltering or reproducing is detectable may depend on the parameter studied. Within the ecotone of an upper saltmarsh in the United States, we investigated the sex-specific movement of the semi-terrestrial crab Armases cinereum using an approach of determining multiple measures of across-ecotone migration. To this end, we determined food preference, digestive abilities (enzyme activities), bacterial hindgut communities (genetic fingerprint), and the trophic position of Armases and potential food sources (stable isotopes) of males versus females of different sub-habitats, namely high saltmarsh and coastal forest. Daily observations showed that Armases moved frequently between high-intertidal (saltmarsh) and terrestrial (forest) habitats. Males were encountered more often in the forest habitat, whilst gravid females tended to be more abundant in the marsh habitat but moved more frequently. Food preference was driven by both sex and habitat. The needlerush Juncus was preferred over three other high-marsh detrital food sources, and the periwinkle Littoraria was the preferred prey of male (but not female) crabs from the forest habitats; both male and female crabs from marsh habitat preferred the fiddler crab Uca over three other prey items. In the field, the major food sources were clearly vegetal, but males have a higher trophic position than females. In contrast to food preference, isotope data excluded Uca and Littoraria as major food sources, except for males from the forest, and suggested that Armases consumes a mix of C4 and C3 plants along with animal prey. Digestive enzyme activities differed significantly between sexes and habitats and were higher in females and in marsh crabs. The bacterial hindgut community differed significantly between sexes, but habitat effects were greater than sex effects. By combining multiple measures of feeding ecology, we demonstrate that Armases exhibits sex-specific habitat choice and food preference. By using both coastal forest and saltmarsh habitats, but feeding predominantly in the latter, they possibly act as a key biotic vector of spatial subsidies across habitat borders. The degree of contributing to fluxes of matter, nutrients and energy, however, depends on their sex, indicating that changes in population structure would likely have profound effects on ecosystem connectivity and functioning.

Changes in the relationship between volume of consumption and alcohol-related problems in Sweden during 1979-2003.

AIMS: The aim of the study was to investigate (i) whether the strength of the relationship between self-reported volume of consumption and alcohol-related problems has become weaker in Sweden, and (ii) whether such a change can be related to temporal changes in drinking patterns or to changes in the distribution of consumption and related problems in the population. METHODS: Three cross-sectional general population surveys conducted in Sweden in 1979, 1995 and 2003 yielded data on 5650 Swedish adults aged 18-69 years. The relationship between self-reported volume of consumption and self-reported alcohol-related problems was estimated using Poisson regression models. Analyses of drinking patterns focused on changes in frequency of drinking, volume per occasion and frequency of drinking to intoxication. Lorenz curves were used to analyse the distributions of consumption and alcohol-related problems. RESULTS: Poisson regression estimates revealed that the relationship between volume of consumption and alcohol-related problems became weaker over time; a 10% per cent change in self-reported volume of consumption was associated with a smaller per cent change in the number of experienced problems in 2003 (5%) compared with 1995 (6%) and 1979 (7%). This change was not related to a hypothesized general shift towards a more southern European style of drinking, as no such tendency was found. CONCLUSION: The changed relationship appears to be a reflection of a redistribution of consumption and alcohol-related problems in the population, such that a larger share of all consumption and related problems occurs among light or moderate drinkers in 2003 compared with 1979.

Short-term and long-term leptin exposure differentially affect human natural killer cell immune functions.

Epidemiological studies have indicated that obesity is associated with a higher risk for certain cancers caused by elevated levels of adipocyte-derived hormones. Leptin, one such hormone produced by adipocytes, is a major regulator of metabolism and has also been shown to modulate immunity. However, its role in regulating human natural killer (NK) cell functions is largely unknown. Here, we show that the leptin receptor (Ob-R) is expressed on 5% of NK cells isolated from blood donors, as measured with flow cytometry, and expression of the signal-transducing long form of the leptin receptor Ob-Rb was confirmed with quantitative PCR. The Ob-R+ subpopulation displayed a lower expression of CD16, a cell surface receptor mediating antibody-dependent activation. Short-term stimulation with leptin increased IFNγ secretion, CD69 activation marker expression, and cytotoxic lysis of tumor cells; this was mediated by an improved conjugate forming between NK cells and tumor cells as well as higher expression of tumor necrosis factor-related apoptosis-inducing ligand. On the contrary, long-term incubation with leptin significantly impaired these NK cell immune functions and decreased cell proliferation. In addition, phosphorylation of Jak-2 after leptin stimulation was reduced in peripheral mononuclear blood cells from obese humans compared with normal-weight controls. NK cells represent an immune cell population that is crucial for an effective antitumor response. Here, we show that long-term exposure to leptin, similarly to the situation in obese individuals with elevated serum leptin levels, significantly impairs integral parts of NK cell immune functions, possibly linking leptin to increased cancer susceptibility in obesity.