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  • 1
    In: The Journals of Gerontology Series B: Psychological Sciences and Social Sciences, 2008, Vol. 63(3), pp.P121-P128
    Description: Effects of cognitive activities on walking variability are poorly understood. We parametrically manipulated working-memory load by using an n -back task in 32 younger adults and 32 older adults walking on a treadmill at self-selected speed. We found no dual-task costs for cognitive performance. Stride-to-stride variability was lower when participants performed an easy working-memory task than when they walked without cognitive tasks. Increasing working-memory load from 1-back to 4-back produced decreasing variability of stride time and stride length in younger but not in older adults. Extending the 2006 dual-process account proposed by Huxhold, Li, Schmiedek, and Lindenberger, we conclude that normal aging alters the trade-off between the effects of focus of attention and resource competition on walking variability.
    Keywords: Dual - Task Cost ; Resource Competition ; Walking Variability
    ISSN: 1079-5014
    E-ISSN: 1758-5368
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  • 2
    Language: English
    In: Gait & Posture, January 2015, Vol.41(1), pp.258-262
    Description: The dual-process account of sensorimotor-cognitive interactions postulates that easy cognitive tasks can lead to performance improvements in the motor domain (e.g., an increased stability while walking or balancing) across the lifespan. However, cross-domain resource competition can lead to performance decrements in motor tasks when the concurrent cognitive task is very difficult, and older adults have shown performance decrements in their motor functioning under such circumstances. Resource limitations are particularly pronounced not only in old adulthood, but also in childhood. The current study investigates the relationship of walking speed and cognitive load on walking regularity in 7- and 9-year olds and young adults, with 18 participants in each group. Participants were walking on a treadmill at their preferred speed, and with speeds that were 30% faster and 30% slower than preferred. Regularity of lower-body coordination was operationalized as the residual variance of principal component analyses performed on the data of a motion analysis system. All age groups showed a more regular gait with increasing walking speed. Young adults’ gait regularity was not influenced by cognitive load, whereas children showed a U-shaped relationship of cognitive load and walking regularity, with the highest regularity when performing an easy cognitive task. It can be concluded that children are also influenced by cross-domain resources competition in challenging cognitive-motor dual-task situations.
    Keywords: Dual-Task ; Walking ; Cognition ; Children ; Young Adults ; Medicine ; Anatomy & Physiology
    ISSN: 0966-6362
    E-ISSN: 1879-2219
    E-ISSN: 14321106
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  • 3
    Language: English
    In: Psychological Bulletin, 2010, Vol.136(4), pp.659-676
    Description: Does plasticity contribute to adult cognitive development, and if so, in what ways? The vague and overused concept of plasticity makes these controversial questions difficult to answer. In this article, we refine the notion of adult cognitive plasticity and sharpen its conceptual distinctiveness. According to our framework, adult cognitive plasticity is driven by a prolonged mismatch between functional organismic supplies and environmental demands and denotes the brain's capacity for anatomically implementing reactive changes in behavioral flexibility (i.e., the possible range of performance and function). We distinguish between 2 interconnected but distinct cognitive outcomes of adult cognitive plasticity: alterations in processing efficiency and alterations in representations. We demonstrate the usefulness of our framework in evaluating and interpreting (a) increments in frontal brain activations in the course of normal aging and (b) the effects of cognitive training in adulthood and old age. Finally, we outline new research questions and predictions generated by the present framework and recommend design features for future cognitive-training studies.
    Keywords: Adult Cognitive Development ; Aging ; Compensation ; Cognitive Intervention ; Transfer
    ISSN: 0033-2909
    E-ISSN: 1939-1455
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  • 4
    Language: English
    In: Developmental Psychology, 2008, Vol.44(3), pp.747-757
    Description: Task prioritization can lead to trade-off patterns in dual-task situations. The authors compared dual-task performances in 9- and 11-year-old children and young adults performing a cognitive task and a motor task concurrently. The motor task required balancing on an ankle-disc board. Two cognitive tasks measured working memory and episodic memory at difficulty levels individually adjusted during the course of extensive training. Adults showed performance decrements in both task domains under dual-task conditions. In contrast, children showed decrements only in the cognitive tasks but actually swayed less under dual-task than under single-task conditions and continued to reduce their body sway even when instructed to focus on the cognitive task. The authors argue that children perform closer to their stability boundaries in the balance task and therefore prioritize protection of their balance under dual-task conditions.
    Keywords: Dual Task ; Children ; Young Adults ; Postural Stability ; Task Prioritization
    ISSN: 0012-1649
    E-ISSN: 1939-0599
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  • 5
    Language: English
    In: Psychology and Aging, 2014, Vol.29(3), pp.503-520
    Description: This study examined how children (9 years), adolescents (13 to 15 years), younger adults (21 to 26 years), and older adults (70 to 76 years) chart age gradients of cognitive and social functioning from childhood to old age. Participants ( N = 156) rated typical performance levels in different life phases for 10 aspects of cognitive and social functioning. Compared with older participants, children expected lower performance levels and higher temporal stability, particularly during adulthood and into old age, and showed lower interindividual consensus in their ratings. Individuals in all 4 age groups recognized that fluid cognitive abilities reach their developmental peak earlier in life and decline more steeply thereafter than crystallized cognitive abilities. Older adults and, to a lesser extent, children evaluated their own current functioning as being better than that of their typical age peers. Furthermore, older adults charted typical cognitive development in middle and earlier late adulthood more positively than the participants in the other 3 age groups, which possibly reflects a partial externalization of their own positive self-views and a self-enhancing bias. Comparisons with life span gradients of cognitive performance ( McArdle, Ferrer-Caja, Hamagami, & Woodcock, 2002 ) suggest that the ratings of adolescents and younger adults were in better agreement with empirically observed average performance trajectories than the ratings of children and older adults. We conclude that beliefs about normative cognitive and social aspects of life span development emerge in late middle childhood, solidify into culturally shared scripts by mid-adolescence, and remain subject to further change into old age.
    Keywords: Beliefs About Aging ; Cognitive Development ; Social Development ; Biexponential Latent Growth Curve Modeling ; Age Differences
    ISSN: 0882-7974
    E-ISSN: 1939-1498
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  • 6
    Language: English
    In: Gait & Posture, 2011, Vol.33(3), pp.401-405
    Description: We investigated dual-task performance of cognitive (semantic fluency) and sensorimotor tasks (walking) in 120 children and adults from four age groups (9-year olds, = 9.52 years; 11-year olds, = 11.51 years; young adults, = 25.34 years; older adults, = 64.28 years; = 30 per group). Distances walked during 90 s and numbers of category exemplars generated in the semantic fluency task showed an inverted U-shape function with age. In line with general resource models proportional dual-task costs in walking also showed a U-shaped relation as a function of age with pronounced decrements in the youngest and oldest groups. Only 9-year olds showed significant costs in the cognitive task. Individual differences in single-task performance accounted for more than half of the variance in dual-task performance. Reliable age-related residual variance implicated additional factors particularly in children's developing multi-tasking performances.
    Keywords: Dual-Task ; Lifespan ; Semantic Fluency ; Cognitive Resources ; Medicine ; Anatomy & Physiology
    ISSN: 0966-6362
    E-ISSN: 1879-2219
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  • 7
    Language: English
    In: NeuroImage, 15 February 2012, Vol.59(4), pp.3389-3397
    Description: A widespread network involving cortical and subcortical brain structures forms the neural substrate of human spatial navigation. Most studies investigating plasticity of this network have focused on the hippocampus. Here, we investigate age differences in cortical thickness changes evoked by four months of spatial navigation training in 91 men aged 20–30 or 60–70 years. Cortical thickness was automatically measured before, immediately after, and four months after termination of training. Younger as well as older navigators evidenced large improvements in navigation performance that were partly maintained after termination of training. Importantly, training-related cortical thickening in left precuneus and paracentral lobule were observed in young navigators only. Thus, spatial navigation training appears to affect cortical brain structure of young adults, but there is reduced potential for experience-dependent cortical alterations in old age.
    Keywords: Cortical Thickness ; Plasticity ; Spatial Navigation ; Aging ; Medicine
    ISSN: 1053-8119
    E-ISSN: 1095-9572
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  • 8
    Language: English
    In: CEREBRAL CORTEX, 2011
    Description: Recent evidence indicates experience-dependent brain volume changes in humans, but the functional and histological nature of such changes is unknown. Here, we report that adult men performing a cognitively demanding spatial navigation task every other day over 4 months display increases in hippocampal N-acetylaspartate (NAA) as measured with magnetic resonance spectroscopy. Unlike measures of brain volume, changes in NAA are sensitive to metabolic and functional aspects of neural and glia tissue and unlikely to reflect changes in microvasculature. Training-induced changes in NAA were, however, absent in carriers of the Met substitution in the brain-derived neurotrophic factor (BDNF) gene, which is known to reduce activity-dependent secretion of BDNF. Among BDNF Val homozygotes, increases in NAA were strongly related to the degree of practice-related improvement in navigation performance and normalized to pretraining levels 4 months after the last training session. We conclude that changes in demands on spatial navigation can alter hippocampal NAA concentrations, confirming epidemiological studies suggesting that mental experience may have direct effects on neural integrity and cognitive performance. BDNF genotype moderates these plastic changes, in line with the contention that gene-context interactions shape the ontogeny of complex phenotypes.
    Keywords: Social Sciences ; Val66met Polymorphism ; Activity-Dependent Secretion ; Neurotrophic Factor ; Taxi Drivers ; Human-Memory ; Brain ; Plasticity ; Experience ; Strategies ; Neurons ; Brain-Derived Neurotrophic Factor (Bdnf) ; Cognitive Training ; Hippocampus ; N-Acetylaspartate (Naa) ; Spatial Navigation
    ISSN: 1047-3211
    E-ISSN: 14602199
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  • 9
    Language: English
    In: Psychology and Aging, 2009, Vol.24(1), pp.75-81
    Description: We investigated effects of concurrent cognitive task difficulty ( n -back) on the regularity of whole-body movements during treadmill walking in women and men from 3 age groups (20–30, 60–70, and 70–80 years old). Using principal component analysis of individual gait patterns, we separated main (regular) from residual (irregular) components of whole-body motion. Proportion of residual variance (RV) was used as an index of gait irregularity. The gait in all age groups became more regular (reduced RV) upon introduction of a simple cognitive task (1-back), relative to walking without a concurrent cognitive task. In contrast, parametrically increasing working memory load from 1-back to 4-back led to age-differential effects, with gait patterns becoming more regular in those 20–30 years old, becoming less regular in those 70–80 years old, and showing no significant effects in those 60–70 years old. Our results support the dual-process account of sensorimotor–cognitive interactions ( O. Huxhold, S.-C. Li, F. Schmiedek, and U. Lindenberger, 2006 ), with age-general effects of internal versus external attentional focus and age-specific effects of resource competition with increasing cognitive task difficulty.
    Keywords: Gait ; Principal Component Analysis ; Dual-Tasking ; Aging ; Working Memory
    ISSN: 0882-7974
    E-ISSN: 1939-1498
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  • 10
    In: Human Brain Mapping, August 2014, Vol.35(8), pp.4236-4248
    Description: We compared hippocampal volume measures obtained by manual tracing to automatic segmentation with FreeSurfer in 44 younger (20–30 years) and 47 older (60–70 years) adults, each measured with magnetic resonance imaging (MRI) over three successive time points, separated by four months. Retest correlations over time were very high for both manual and FreeSurfer segmentations. With FreeSurfer, correlations over time were significantly lower in the older than in the younger age group, which was not the case with manual segmentation. Pearson correlations between manual and FreeSurfer estimates were sufficiently high, numerically even higher in the younger group, whereas intra‐class correlation coefficient (ICC) estimates were lower in the younger than in the older group. FreeSurfer yielded higher volume estimates than manual segmentation, particularly in the younger age group. Importantly, FreeSurfer consistently overestimated hippocampal volumes independently of manually assessed volume in the younger age group, but overestimated larger volumes in the older age group to a less extent, introducing a systematic age bias in the data. Age differences in hippocampal volumes were significant with FreeSurfer, but not with manual tracing. Manual tracing resulted in a significant difference between left and right hippocampus (right 〉 left), whereas this asymmetry effect was considerably smaller with FreeSurfer estimates. We conclude that FreeSurfer constitutes a feasible method to assess differences in hippocampal volume in young adults. FreeSurfer estimates in older age groups should, however, be interpreted with care until the automatic segmentation pipeline has been further optimized to increase validity and reliability in this age group. . © .
    Keywords: Hippocampus ; Freesurfer ; Manual Segmentation ; Left Right Asymmetry ; Aging
    ISSN: 1065-9471
    E-ISSN: 1097-0193
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