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Träfflista för sökning "WFRF:(Walhovd Kristine B.) srt2:(2015-2019)"

Sökning: WFRF:(Walhovd Kristine B.) > (2015-2019)

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1.
  • Walhovd, Kristine B., et al. (författare)
  • Neurodevelopmental origins of lifespan changes in brain and cognition
  • 2016
  • Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 113:33, s. 9357-9362
  • Tidskriftsartikel (refereegranskat)abstract
    • Neurodevelopmental origins of functional variation in older age are increasingly being acknowledged, but identification of how early factors impact human brain and cognition throughout life has remained challenging. Much focus has been on age-specific mechanisms affecting neural foundations of cognition and their change. In contrast to this approach, we tested whether cerebral correlates of general cognitive ability (GCA) in development could be extended to the rest of the lifespan, and whether early factors traceable to prenatal stages, such as birth weight and parental education, may exert continuous influences. We measured the area of the cerebral cortex in a longitudinal sample of 974 individuals aged 4-88 y (1,633 observations). An extensive cortical region was identified wherein area related positively to GCA in development. By tracking area of the cortical region identified in the child sample throughout the lifespan, we showed that the cortical change trajectories of higher and lower GCA groups were parallel through life, suggesting continued influences of early life factors. Birth weight and parental education obtained from the Norwegian Mother-Child Cohort study were identified as such early factors of possible lifelong influence. Support for a genetic component was obtained in a separate twin sample (Vietnam Era Twin Study of Aging), but birth weight in the child sample had an effect on cortical area also when controlling for possible genetic differences in terms of parental height. Our results provide novel evidence for stability in brain-cognition relationships throughout life, and indicate that early life factors impact brain and cognition for the entire life course.
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2.
  • Glasø de Lange, Ann-Marie, et al. (författare)
  • White matter integrity as a marker for cognitive plasticity in aging
  • 2016
  • Ingår i: Neurobiology of Aging. - : Elsevier BV. - 0197-4580 .- 1558-1497. ; 47, s. 74-82
  • Tidskriftsartikel (refereegranskat)abstract
    • Age-related differences in white matter (WM) integrity are substantial, but it is unknown whether between subject variability in WM integrity influences the capacity for cognitive improvement. We investigated the effects of memory training related to active and passive control conditions in older adults and tested whether WM integrity at baseline was predictive of training benefits. We hypothesized that (1) memory improvement would be restricted to the training group, (2) widespread areas would show greater mean diffusivity (MD) and lower fractional anisotropy in older adults relative to young adults, and (3) within these areas, variability in WM microstructure in the older group would be predictive of training gains. The results showed that only the group receiving training improved their memory. Significant age differences in MD and fractional anisotropy were found in widespread areas. Within these areas, voxelwise analyses showed a negative relationship between MD and memory improvement in 3 clusters, indicating that WM integrity could serve as a marker for the ability to adapt in response to cognitive challenges in aging. 
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3.
  • Persson, Ninni, 1975- (författare)
  • The aging brain and changes in cognitive performance : Findings from morphometry and quantitative susceptibility mapping of iron
  • 2015
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Brain aging is a heterogeneous phenomenon, and this thesis illustrates how the course of aging can vary within individuals over time and between individuals as a function of age, sex, and genetic variability. We used two contrasts from magnetic resonance imaging (MRI), namely spin-lattice T1-weighted imaging, and quantitative susceptibility mapping (QSM) from gradient-echo images, to picture the aging brain, by means of morphometric measures and brain-iron concentrations. Within each study, the same rigorous imaging acquisitioning protocols were used over large samples sizes of 167-183 individuals, which contribute to the uniqueness of the studies. Most of the current knowledge about the aging brain rests on the foundation of cross-sectional age-related differences, and studies I and III contribute to current knowledge with longitudinal designs to investigate individual rates of change. The importance of genetic variation in relation to regional brain changes was addressed with a specific emphasis on functional polymorphisms involved in pro-inflammatory responses. These studies further shed light on the importance of bi-directional relations between structural integrity and maintained cognitive abilities over time. Study II is the largest study to date to have quantitative susceptibility estimates examined in healthy adults, and the first in-vivo report to show a lowering in overall subcortical brain iron estimates in women from midlife to old age. Studies I and III are unique by examining longitudinal differences in anatomical brain regions using high resolution images from a 4 Tesla scanner. Peripheral vascular risk factors were not strong determinants of either brain- or cognitive changes in the studied samples. The results are discussed in the context of cognitive reserve, the brain maintenance hypothesis, and potential influences of hormones, inflammation and oxidative stress.
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4.
  • Sneve, Markus H., et al. (författare)
  • Mechanisms Underlying Encoding of Short-Lived Versus Durable Episodic Memories
  • 2015
  • Ingår i: Journal of Neuroscience. - 0270-6474 .- 1529-2401. ; 35:13, s. 5202-5212
  • Tidskriftsartikel (refereegranskat)abstract
    • We continuously encounter and process novel events in the surrounding world, but only some episodes will leave detailed memory traces that can be recollected after weeks and months. Here, our aim was to monitor brain activity during encoding of events that eventually transforms into long-term stable memories. Previous functional magnetic resonance imaging (fMRI) studies have shown that the degree of activation of different brain regions during encoding is predictive of later recollection success. However, most of these studies tested participants' memories the same day as encoding occurred, whereas several lines of research suggest that extended post-encoding processing is of crucial importance for long-term consolidation. Using fMRI, we tested whether the same encoding mechanisms are predictive of recollection success after hours as after a retention interval of several weeks. Seventy-eight participants were scanned during an associative encoding task and given a source memory test the same day or after similar to 6 weeks. We found a strong link between regional activity levels during encoding and recollection success over short time intervals. However, results further showed that durable source memories, i.e., events recollected after several weeks, were not simply the events associated with the highest activity levels at encoding. Rather, strong levels of connectivity between the right hippocampus and perceptual areas, as well as with parts of the self-referential default-mode network, seemed instrumental in establishing durable source memories. Thus, we argue that an initial intensity-based encoding is necessary for short-term encoding of events, whereas additional processes involving hippocampal-cortical communication aid transformation into stable long-term memories.
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5.
  • Vidal-Pineiro, Didac, et al. (författare)
  • Maintained Frontal Activity Underlies High Memory Function Over 8 Years in Aging
  • 2019
  • Ingår i: Cerebral Cortex. - : OXFORD UNIV PRESS INC. - 1047-3211 .- 1460-2199. ; 29:7, s. 3111-3123
  • Tidskriftsartikel (refereegranskat)abstract
    • Aging is characterized by substantial average decline in memory performance. Yet contradictory explanations have been given for how the brains of high-performing older adults work: either by engagement of compensatory processes such as recruitment of additional networks or by maintaining young adults' patterns of activity. Distinguishing these components requires large experimental samples and longitudinal follow-up. Here, we investigate which features are key to high memory in aging, directly testing these hypotheses by studying a large sample of adult participants (n > 300) with fMRI during an episodic memory experiment where item-context relationships were implicitly encoded. The analyses revealed that low levels of activity in frontal networks-known to be involved in memory encoding-were associated with low memory performance in the older adults only. Importantly, older participants with low memory performance and low frontal activity exhibited a strong longitudinal memory decline in an independent verbal episodic memory task spanning 8 years back (n = 52). These participants were also characterized by lower hippocampal volumes and steeper rates of cortical atrophy. Altogether, maintenance of frontal brain function during encoding seems to be a primary characteristic of preservation of memory function in aging, likely reflecting intact ability to integrate information.
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