| 121. |
- Thibault, Simon, et al.
(författare)
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Tool use and language share syntactic processes and neural patterns in the basal ganglia
- 2021
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 374:6569
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Tidskriftsartikel (refereegranskat)abstract
- Does tool use share syntactic processes with language? Acting with a tool is thought to add a hierarchical level into the motor plan. In the linguistic domain, syntax is the cognitive function handling interdependent elements. Using functional magnetic resonance imaging, we detected common neurofunctional substrates in the basal ganglia subserving both tool use and syntax in language. The two abilities elicited similar patterns of neural activity, indicating the existence of shared functional resources. Manual actions and verbal working memory did not contribute to this common network. Consistent with the existence of shared neural resources, we observed bidirectional behavioral enhancement of tool use and syntactic skills in language so that training one function improves performance in the other. This reveals supramodal syntactic processes for tool use and language.
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| 122. |
- Verrel, Julius, et al.
(författare)
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Interacting Effects of Cognitive Load and Adult Age on the Regularity of Whole-Body Motion During Treadmill Walking
- 2009
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Ingår i: Psychology and Aging. - : American Psychological Association (APA). - 0882-7974 .- 1939-1498. ; 24:1, s. 75-81
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 123. |
- Verrel, Julius, et al.
(författare)
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Motor-equivalent covariation stabilizes step parameters and center of mass position during treadmill walking
- 2010
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Ingår i: Experimental Brain Research. - : Springer Science and Business Media LLC. - 0014-4819 .- 1432-1106. ; 207:1-2, s. 13-26
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Tidskriftsartikel (refereegranskat)abstract
- We investigated motor-equivalent stabilization of task-related variables (TRV) at times of heel strike in eight healthy young men (23-30 years) who walked on a motorized treadmill at self-selected and prescribed speeds within the normal walking speed range. The TRV consisted of step parameters (step length and width) and the center of mass (CoM) position relative to the support (back and front feet). Motor-equivalent stabilization of the TRV was assessed using a decorrelation technique, comparing empirical to decorrelated (covariation-free) variability. Analysis indicated reliable covariation for all TRV. In both the fore-aft and lateral directions, stabilization by covariation was highest for CoM position relative to the front foot, indicating a prioritization of equilibrium-related variables. Correlations among TRV revealed that the relation between CoM and step parameter control differed between the fore-aft and lateral directions. While stabilization of lateral foot position appears to be due to control of CoM relative to each foot, step length showed small, but reliable, stabilization beyond CoM stabilization, which may be related to spatiotemporal regularity of the step pattern.
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| 124. |
- Verrel, Julius, et al.
(författare)
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Normal aging reduces motor synergies in manual pointing
- 2012
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Ingår i: Neurobiology of Aging. - : Elsevier BV. - 1558-1497 .- 0197-4580. ; 33:1
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Tidskriftsartikel (refereegranskat)abstract
- Depending upon its organization, movement variability may reflect poor or flexible control of a motor task. We studied adult age-related differences in the structure of postural variability in manual pointing using the uncontrolled manifold (UCM) method. Participants from 2 age groups (younger: 20-30 years; older: 70-80 years; 12 subjects per group) completed a total of 120 pointing trials to 2 different targets presented according to 3 schedules: blocked, alternating, and random. The age groups were similar with respect to basic kinematic variables, end point precision, as well as the accuracy of the biomechanical forward model of the arm. Following the uncontrolled manifold approach, goal-equivalent and nongoal-equivalent components of postural variability (goal-equivalent variability [GEV] and nongoal-equivalent variability [NGEV]) were determined for 5 time points of the movements (start, 10%, 50%, 90%, and end) and used to define a synergy index reflecting the flexibility/stability aspect of motor synergies. Toward the end of the movement, younger adults showed higher synergy indexes than older adults. Effects of target schedule were not reliable. We conclude that normal aging alters the organization of common multidegree-of-freedom movements, with older adults making less flexible use of motor abundance than younger adults. (C) 2012 Elsevier Inc. All rights reserved.
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| 125. |
- Verrel, Julius, et al.
(författare)
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Older Adults Show Preserved Equilibrium but Impaired Step Length Control in Motor-Equivalent Stabilization of Gait
- 2012
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 7:12
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Tidskriftsartikel (refereegranskat)abstract
- Stable walking depends on the coordination of multiple biomechanical degrees of freedom to ensure the dynamic maintenance of whole-body equilibrium as well as continuous forward progression. We investigated adult age-related differences in whole-body coordination underlying stabilization of center of mass (CoM) position and step pattern during locomotion. Sixteen younger (20-30 years) and 16 healthy older men (65-80 years) walked on a motorized treadmill at 80%, 100% and 120% of their self-selected preferred speed. Preferred speeds did not differ between the age groups. Motor-equivalent stabilization of step parameters (step length and width) and CoM position relative to the support (back and front foot) was examined using a generalized covariation analysis. Across age groups, covariation indices were highest for CoM position relative to the front foot, the measure most directly related to body equilibrium. Compared to younger adults, older adults showed lower covariation indices with respect to step length, extending previous findings of age-related differences in motor-equivalent coordination. In contrast, no reliable age differences were found regarding stabilization of step width or any of the CoM parameters. The observed pattern of results may reflect robust prioritization of balance over step pattern regularity, which may be adaptive in the face of age-associated sensorimotor losses and decline of coordinative capacities.
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| 126. |
- Walhovd, Kristine B., et al.
(författare)
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Timing of lifespan influences on brain and cognition
- 2023
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Ingår i: Trends in Cognitive Sciences. - 1364-6613 .- 1879-307X. ; 27:10, s. 901-915
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Forskningsöversikt (refereegranskat)abstract
- Modifiable risk and protective factors for boosting brain and cognitive development and preventing neurodegeneration and cognitive decline are embraced in neuroimaging studies. We call for sobriety regarding the timing and quantity of such influences on brain and cognition. Individual differences in the level of brain and cognition, many of which present already at birth and early in development, appear stable, larger, and more pervasive than differences in change across the lifespan. Incorporating early-life factors, including genetics, and investigating both level and change will reduce the risk of ascribing undue importance and causality to proximate factors in adulthood and older age. This has implications for both mechanistic understanding and prevention.
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| 127. |
- Wang, Rui, et al.
(författare)
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Mixed brain lesions mediate the association between cardiovascular risk burden and cognitive decline in old age : A population-based study
- 2017
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Ingår i: Alzheimer's & Dementia. - : Wiley. - 1552-5260 .- 1552-5279. ; 13:3, s. 247-256
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: The underlying pathological mechanisms linking cardiovascular burden to cognitive decline remain unclear. Methods: We investigated the associations of the Framingham general cardiovascular risk score (FGCRS), apolipoprotein E (APOE) 64, and brain structure with the Mini-Mental State Examination (MMSE) decline using the 9-year follow-up data from Swedish National Study on Aging and Care in Kungsholmen (n = 2189, age >= 60) and the embedded magnetic resonance imaging (MRI) (n = 448) studies. Volumes of white matter hyperintensities (WMHs), total gray matter, ventricles, and hippo campus were assessed in the MRI sample. Results: A higher FGCRS was associated with faster MMSE decline in young-old people (60-72 years) but not in old-old (>= 78 years). Larger volumes of cerebral WMHs and ventricles and smaller volumes of total gray matter and hippocampus were all associated with accelerated MMSE decline (P <.01); these associations were stronger among APOE epsilon 4 carriers than noncarriers. Simultaneously entering multiple brain lesion markers as mediators in the model substantially attenuated the association between FGCRS and MMSE decline. Discussion: The effect of cardiovascular risk burden on cognitive deterioration in old age is largely mediated by mixed brain lesions.
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| 128. |
- Wenger, Elisabeth, et al.
(författare)
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Comparing Manual and Automatic Segmentation of Hippocampal Volumes : Reliability and Validity Issues in Younger and Older Brains
- 2014
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Ingår i: Human Brain Mapping. - : Wiley. - 1065-9471 .- 1097-0193. ; 35:8, s. 4236-4248
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 129. |
- Wenger, Elisabeth, et al.
(författare)
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Cortical thickness changes following spatial navigation training in adulthood and aging
- 2012
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Ingår i: NeuroImage. - : Elsevier BV. - 1053-8119 .- 1095-9572. ; 59:4, s. 3389-3397
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 130. |
- Wenger, Elisabeth, et al.
(författare)
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Expansion and Renormalization of Human Brain Structure During Skill Acquisition
- 2017
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Ingår i: Trends in cognitive sciences. - : Elsevier BV. - 1364-6613 .- 1879-307X. ; 21:12, s. 930-939
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Forskningsöversikt (refereegranskat)abstract
- Research on human brain changes during skill acquisition has revealed brain volume expansion in task-relevant areas. However, the large number of skills that humans acquire during ontogeny militates against plasticity as a perpetual process of volume growth. Building on animal models and available theories, we promote the expansion-renormalization model for plastic changes in humans. The model predicts an initial increase of gray matter structure, potentially reflecting growth of neural resources like neurons, synapses, and glial cells, which is followed by a selection process operating on this new tissue leading to a complete or partial return to baseline of the overall volume after selection has ended. The model sheds new light on available evidence and current debates and fosters the search for mechanistic explanations.
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