Exercise-Induced Fitness Changes Correlate with Changes in Neural Specificity in Older Adults

Neural specificity refers to the degree to which neural representations of different stimuli can be distinguished. Evidence suggests that neural specificity, operationally defined as stimulus-related differences in functional magnetic resonance imaging (fMRI) activation patterns, declines with advancing adult age, and that individual differences in neural specificity are associated with individual differences in fluid intelligence. A growing body of literature also suggests that regular physical activity may help preserve cognitive abilities in old age. Based on this literature, we hypothesized that exercise-induced improvements in fitness would be associated with greater neural specificity among older adults. A total of 52 adults aged 59–74 years were randomly assigned to one of two aerobic-fitness training regimens, which differed in intensity. Participants in both groups trained three times a week on stationary bicycles. In the low-intensity (LI) group, the resistance was kept constant at a low level (10 Watts). In the high-intensity (HI) group, the resistance depended on participants’ heart rate and therefore typically increased with increasing fitness. Before and after the 6-month training phase, participants took part in a functional MRI experiment in which they viewed pictures of faces and buildings. We used multivariate pattern analysis (MVPA) to estimate the distinctiveness of neural activation patterns in ventral visual cortex (VVC) evoked by face or building stimuli. Fitness was also assessed before and after training. In line with our hypothesis, traininginduced changes in fitness were positively associated with changes in neural specificity. We conclude that physical activity may protect against age-related declines in neural specificity

Educational attainment does not influence brain aging.

Education has been related to various advantageous lifetime outcomes. Here, using longitudinal structural MRI data (4,422 observations), we tested the influential hypothesis that higher education translates into slower rates of brain aging. Cross-sectionally, education was modestly associated with regional cortical volume. However, despite marked mean atrophy in the cortex and hippocampus, education did not influence rates of change. The results were replicated across two independent samples. Our findings challenge the view that higher education slows brain aging

Exercise - A Cerebral Anti-aging Cure?

Fortschreitendes Alter geht häufig mit Leistungsabnahmen in kognitiven Aufgaben einher. Eine steigende Anzahl Studien zeigt, dass regelmäßige körperliche Aktivität negativen Alterseffekten entgegenwirken kann und somit zur Erhaltung kognitiver und zerebraler Funktionen im Alter beiträgt. Die vorliegende Dissertation untersuchte im Rahmen eines Ausdauertrainings die Zusammenhänge zwischen Veränderungen in der körperlichen Fitness und Veränderungen in Gehirn und Verhalten bei älteren Erwachsenen. Studie I zeigt, dass zuvor gefundene Vergrößerungen des Hippocampus auf Änderungen der Mikrostruktur des zugrundeliegenden Gewebes zurückgeführt werden können. Die Probanden, die ihre Fitness am meisten verbesserten, zeigten auch die stärkste Verdichtung des Hippocampusgewebes. Die Verdichtung des Gewebes stand wiederum in positivem Zusammenhang mit der Veränderung im Hippocampusvolumen. Diese Ergebnisse weisen darauf hin, dass Veränderungen im Volumen aus einer Vermehrung der Zellmembranen resultieren und nicht aus der Ausdehnung bereits vorhandener Zellen. In Studie II hingen Veränderungen in der Fitness zusammen mit Veränderungen in der Mikrostruktur eines präfrontalen Traktes der weißen Substanz, nämlich dem Forceps minor. Gleichermaßen hingen die Veränderungen in der Mikrostruktur des Forceps minor mit Veränderungen in einem zusammengesetzten Maß fluider kognitiver Fähigkeiten zusammen. Dieses Ergebnis zeigt, dass Veränderungen in der Mikrostruktur der weißen Substanz möglicherweise zu den positiven Auswirkungen von körperlicher Aktivität auf kognitive Fähigkeiten beitragen. Studie III zeigt, dass Veränderungen der Fitness positiv mit Veränderungen der neuronalen Spezifität korrelieren, welches als indirektes Maß für dopaminerge Neuromodulation angenommen wird. Zusammenfassend erweitern die Ergebnisse dieser Dissertation die Literatur über positive Effekte von körperlicher Aktivität auf Alterungsprozesse und stärken den Kenntnisstand über zugrundeliegende Mechanismen.Advanced age has been consistently linked to performance deterioration in cognitive tasks targeting the ability to mentally manipulate information. A growing body of literature suggests that regular physical exercise alleviates the adverse effects of age and helps to preserve cognitive and cerebral capacities in old age. The present dissertation investigated associations between changes in fitness and changes in cerebral and cognitive measures within a group of older adults who participated in an exercise intervention. Paper I shows that previously reported increases in hippocampal volume can be linked to exercise-induced changes in the underlying tissue microstructure. The participants who improved most in fitness showed most increments in hippocampal tissue density. Changes in tissue density were in turn positively associated with changes in hippocampal volume. This finding suggests that volumetric changes result from an increase in the bulk of cell membranes, and not from a mere dilation of existing cells. In Paper II, changes in fitness were associated with changes in the microstructure of a prefrontal white matter tract, namely the forceps minor. Likewise, changes in forceps minor microstructure were related to changes in a composite score of fluid cognitive abilities. This result indicates that changes in white matter microstructure may contribute to the beneficial effects of exercise on cognition. Paper III demonstrates that changes in fitness are positively correlated with changes in neural specificity, presumably an indirect marker of dopaminergic neuromodulation. In summary, findings from the present dissertation extend the literature on beneficial effects of exercise on age-related deterioration and add knowledge regarding the underlying mechanisms

Maike Kleemeyer's Quick Files

The Quick Files feature was discontinued and it’s files were migrated into this Project on March 11, 2022. The file URL’s will still resolve properly, and the Quick Files logs are available in the Project’s Recent Activity

ICED MPMs

Investigating reliability of estimates of multiparameter mappin

Tools to support data handling

<p>Given the increasing amount of (digital) research data as well as the strive towards openness and transparency, professional research data management (RDM) has become an essential factor for excellent and sustainable research. In addition, research institutions particularly in the humanities are confronted with strict guidelines regarding the processing of personal data since the European General Data Protection Regulation (GDPR) became effective. Dedicated positions are created as, e.g., data stewards to support researchers when it comes to managing their data effectively, but also to ensure legally compliant data handling. However, the complexity of the task often coupled with the unavailability of critical information challenges RDM staff in providing adequate support. We present two tools that we developed in the recent past to help RDM staff on the one hand to keep track of studies acquiring data, thus potentially needing support and, on the other hand to ensure GDPR compliant data handling</p&gt

Exercise-Induced Fitness Changes Correlate with Changes in Neural Specificity in Older Adults

Neural specificity refers to the degree to which neural representations of different stimuli can be distinguished. Evidence suggests that neural specificity, operationally defined as stimulus-related differences in functional magnetic resonance imaging (fMRI) activation patterns, declines with advancing adult age, and that individual differences in neural specificity are associated with individual differences in fluid intelligence. A growing body of literature also suggests that regular physical activity may help preserve cognitive abilities in old age. Based on this literature, we hypothesized that exercise-induced improvements in fitness would be associated with greater neural specificity among older adults. A total of 52 adults aged 59–74 years were randomly assigned to one of two aerobic-fitness training regimens, which differed in intensity. Participants in both groups trained three times a week on stationary bicycles. In the low-intensity (LI) group, the resistance was kept constant at a low level (10 Watts). In the high-intensity (HI) group, the resistance depended on participants’ heart rate and therefore typically increased with increasing fitness. Before and after the 6-month training phase, participants took part in a functional MRI experiment in which they viewed pictures of faces and buildings. We used multivariate pattern analysis (MVPA) to estimate the distinctiveness of neural activation patterns in ventral visual cortex (VVC) evoked by face or building stimuli. Fitness was also assessed before and after training. In line with our hypothesis, traininginduced changes in fitness were positively associated with changes in neural specificity. We conclude that physical activity may protect against age-related declines in neural specificity

Changes in fitness are associated with changes in hippocampal microstructure and hippocampal volume among older adults

This study investigates the effects of fitness changes on hippocampal microstructure and hippocampal volume. Fifty-two healthy participants aged 59-74 years with a sedentary lifestyle were randomly assigned to either of two levels of exercise intensity. Training lasted for six months. Physical fitness, hippocampal volumes, and hippocampal microstructure were measured before and after training. Hippocampal microstructure was assessed by mean diffusivity, which inversely reflects tissue densityhence, mean diffusivity is lower for more densely packed tissue. Mean changes in fitness did not differ reliably across intensity levels of training, so data were collapsed across groups. Multivariate modeling of pretest-posttest differences using structural equation modeling (SEM) revealed that individual differences in latent change were reliable for all three constructs. More positive changes in fitness were associated with more positive changes in tissue density (i.e., more negative changes in mean diffusivity), andmore positive changes in tissue density were associated with more positive changes in volume. We conclude that fitness-related changes in hippocampal volume may be brought about by changes in tissue density. The relative contributions of angiogenesis, gliogenesis, and/or neurogenesis to changes in tissue density remain to be identified. (C) 2015 Elsevier Inc. All rights reserved

Aerobic exercise is associated with region-specific changes in volumetric, tensor-based, and fixel-based measures of white matter integrity in healthy older adults

White matter integrity and cognition have been found to decline with advancing adult age. Aerobic exercise may be effective in counteracting these declines. Generally, white matter integrity has been quantified using a volumetric measure (WMV) and with tensor-based parameters, such as fractional anisotropy (FA) and mean diffusivity (MD), the validity of which appears to be compromised in the presence of crossing fibers. Fixel-based analysis techniques claim to overcome this problem by yielding estimates of fiber density (FD), cross-section (FC), and their product (FDC) in multiple directions per voxel. In a sample of 61 healthy older adults (63–76 years old), we quantified changes in white matter integrity following an aerobic exercise intervention with the commonly used volumetric and tensor-based metrics (WMV, FA, MD) and with fixel-based metrics (FD, FC, FDC). We investigated the associations of changes in these white matter parameters with changes in cardiovascular fitness and Digit Symbol Substitution task (DSST) performance, a marker of perceptual speed. In line with previous findings, we observed maintained WMV in the corpus callosum of exercisers, and positive change-change correlations between WMV and fitness, and between WMV and perceptual speed. For FA and MD, group differences in change opposite to those hypothesized were found in the corpus callosum, posterior corona radiata, and superior longitudinal fasciculus at an uncorrected significance threshold. Likewise, regions in superficial WM in the prefrontal cortex showed group differences in FD and FDC change, uncorrected, with more positive change in controls and more negative change in exercisers. Finally, changes in FD and FDC were found to be inversely correlated to changes in fitness and DSST performance. The present results corroborate previous findings of WMV changes, but cast doubt on current physiological interpretations of both tensor-based and fixel-based indicators of white matter properties in the context of exercise intervention studies