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Träfflista för sökning "hsv:(MEDICIN OCH HÄLSOVETENSKAP) hsv:(Medicinska och farmaceutiska grundvetenskaper) hsv:(Neurovetenskaper) ;pers:(Bäckman Lars)"

Sökning: hsv:(MEDICIN OCH HÄLSOVETENSKAP) hsv:(Medicinska och farmaceutiska grundvetenskaper) hsv:(Neurovetenskaper) > Bäckman Lars

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1.
  • Jonasson, Lars S., et al. (författare)
  • Dopamine release in nucleus accumbens during rewarded task switching measured by [C-11]raclopride
  • 2014
  • Ingår i: NeuroImage. - : Elsevier BV. - 1053-8119 .- 1095-9572. ; 99, s. 357-364
  • Tidskriftsartikel (refereegranskat)abstract
    • Reward and motivation have positive influences on cognitive-control processes in numerous settings. Models of reward implicate corticostriatal loops and the dopamine (DA) system, with special emphasis on D-2 receptors in nucleus accumbens (NAcc). In this study, 11 right-handed males (35-40 years) were scanned with positron emission tomography (PET) in a single [C-11]raclopride dynamic scan during rewarded and non-rewarded task switching. Rewarded task switching (relative to baseline task switching) decreased [11C]raclopride binding in NAcc. Decreasing NAcc [C-11]raclopride binding was strongly associated with task reaction time measures that reflect individual differences in effort and control strategies. Voxelwise analyses additionally revealed reward-related DA release in anterodorsal caudate, a region previously associated with task-switching. These PET findings provide evidence for striatal DA release during motivated cognitive control, and further suggest that NAcc DA release predicts the task reaction time benefits of reward incentives.
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2.
  • Karlsson, Sari, et al. (författare)
  • Modulation of striatal dopamine D1 binding by cognitive processing
  • 2009
  • Ingår i: NeuroImage. - : Elsevier. - 1053-8119 .- 1095-9572. ; 48:2, s. 398-404
  • Tidskriftsartikel (refereegranskat)abstract
    • There is strong evidence that dopamine (DA) is implicated in higher-order cognitive functioning, but it remains controversial whether D1 receptor binding can be modified by cognitive activity. We examined striatal D1 binding potential (BP) in 20 younger (22-30 years) and 20 older (65-75 years) persons who underwent two [(11)C] SCH 23390 PET measurements, one while resting and one while performing a cognitive task taxing inhibitory functioning. The younger persons showed significant task-related BP reductions in sensorimotor, limbic, and associative striatum during cognitive activity compared to rest. Older persons showed no reliable BP reductions in any striatal subregion. These findings demonstrate that D1 receptor binding can be modified by cognitive activity in younger persons, but also provide novel evidence for the notion that human aging is associated not only with lower DA receptor density but also with altered modifiability of the DA system.
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3.
  • Becker, Nina, et al. (författare)
  • Structural brain correlates of associative memory in older adults
  • 2015
  • Ingår i: NeuroImage. - : Elsevier BV. - 1053-8119 .- 1095-9572. ; 118, s. 146-153
  • Tidskriftsartikel (refereegranskat)abstract
    • Associative memory involves binding two or more items into a coherent memory episode. Relative to memory for single items, associative memory declines greatly in aging. However, older individuals vary substantially in their ability to memorize associative information. Although functional studies link associative memory to the medial temporal lobe (MTL) and prefrontal cortex (PFC), little is known about how volumetric differences in MTL and PFC might contribute to individual differences in associative memory. We investigated regional gray-matter volumes related to individual differences in associative memory in a sample of healthy older adults (n = 54; age = 60 years). To differentiate item from associative memory, participants intentionally learned face-scene picture pairs before performing a recognition task that included single faces, scenes, and face-scene pairs. Gray-matter volumes were analyzed using voxel-based morphometry region-of-interest (ROI) analyses. To examine volumetric differences specifically for associative memory, item memory was controlled for in the analyses. Behavioral results revealed large variability in associative memory that mainly originated from differences in false-alarm rates. Moreover, associative memory was independent of individuals' ability to remember single items. Older adults with better associative memory showed larger gray-matter volumes primarily in regions of the left and right lateral PFC. These findings provide evidence for the importance of PFC in intentional learning of associations, likely because of its involvement in organizational and strategic processes that distinguish older adults with good from those with poor associative memory.
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4.
  • Burzynska, Agnieszka Z., et al. (författare)
  • Cortical thickness is linked to executive functioning in adulthood and aging
  • 2012
  • Ingår i: Human Brain Mapping. - : Wiley. - 1065-9471 .- 1097-0193. ; 33:7, s. 1607-20
  • Tidskriftsartikel (refereegranskat)abstract
    • Executive functions that are dependent upon the frontal-parietal network decline considerably during the course of normal aging. To delineate neuroanatomical correlates of age-related executive impairment, we investigated the relation between cortical thickness and executive functioning in 73 younger (20-32 years) and 56 older (60-71 years) healthy adults. Executive functioning was assessed using the Wisconsin Card Sorting Test (WCST). Cortical thickness was measured at each location of the cortical mantle using surface-based segmentation procedures on high-resolution T1-weighted magnetic resonance images. For regions involved in WCST performance, such as the lateral prefrontal and parietal cortices, we found that thicker cortex was related to higher accuracy. Follow-up ROI-based analyses revealed that these associations were stronger in older than in younger adults. Moreover, among older adults, high and low performers differed in cortical thickness within regions generally linked to WCST performance. Our results indicate that the structural cortical correlates of executive functioning largely overlap with previously identified functional patterns. We conclude that structural preservation of relevant brain regions is associated with higher levels of executive performance in old age, and underscore the need to consider the heterogeneity of brain aging in relation to cognitive functioning.
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5.
  • Karalija, Nina, 1984-, et al. (författare)
  • Longitudinal Dopamine D2 Receptor Changes and Cerebrovascular Health in Aging
  • 2022
  • Ingår i: Neurology. - 1526-632X .- 0028-3878. ; 99, s. e1278-e1289
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND AND OBJECTIVES: Cross-sectional studies suggest marked dopamine (DA) decline in aging, but longitudinal evidence is lacking. The aim of this study was to estimate within-person decline rates for DA D2-like receptors (DRD2) in aging and examine factors that may contribute to individual differences in DRD2 decline rates. METHODS: We investigated 5-year within-person changes in DRD2 availability in a sample of older adults. At both occasions, PET with 11C-raclopride and MRI were used to measure DRD2 availability in conjunction with structural and vascular brain integrity. RESULTS: Longitudinal analyses of the sample (baseline: n = 181, ages: 64-68 years, 100 men and 81 women; 5-year follow-up: n = 129, 69 men and 60 women) revealed aging-related striatal and extrastriatal DRD2 decline, along with marked individual differences in rates of change. Notably, the magnitude of striatal DRD2 decline was ∼50% of past cross-sectional estimates, suggesting that the DRD2 decline rate has been overestimated in past cross-sectional studies. Significant DRD2 reductions were also observed in select extrastriatal regions, including hippocampus, orbitofrontal cortex (OFC), and anterior cingulate cortex (ACC). Distinct profiles of correlated DRD2 changes were found across several associative regions (ACC, dorsal striatum, and hippocampus) and in the reward circuit (nucleus accumbens and OFC). DRD2 losses in associative regions were associated with white matter lesion progression, whereas DRD2 losses in limbic regions were related to reduced cortical perfusion. DISCUSSION: These findings provide the first longitudinal evidence for individual and region-specific differences of DRD2 decline in older age and support the hypothesis that cerebrovascular factors are linked to age-related dopaminergic decline.
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6.
  • Köhncke, Ylva, et al. (författare)
  • Self-rated intensity of habitual physical activities is positively associated with dopamine D-2/3 receptor availability and cognition
  • 2018
  • Ingår i: NeuroImage. - : Elsevier BV. - 1053-8119 .- 1095-9572. ; 181, s. 605-616
  • Tidskriftsartikel (refereegranskat)abstract
    • Between-person differences in cognitive performance in older age are associated with variations in physical activity. The neurotransmitter dopamine (DA) contributes to cognitive performance, and the DA system deteriorates with advancing age. Animal data and a patient study suggest that physical activity modulates DA receptor availability, but data from healthy humans are lacking. In a cross-sectional study with 178 adults aged 64-68 years, we investigated links among self-reported physical activity, D(2/3)DA receptor (D2/3DR) availability, and cognitive performance. D2/3DR availability was measured with [C-11]raclopride positron emission tomography at rest. We used structural equation modeling to obtain latent factors for processing speed, episodic memory, working memory, physical activity, and D2/3DR availability in caudate, putamen, and hippocampus. Physical activity intensity was positively associated with D2/3DR availability in caudate, but not putamen and hippocampus. Frequency of physical activity was not related to D2/3DR availability. Physical activity intensity was positively related to episodic memory and working memory. D2/3DR availability in caudate and hippocampus was positively related to episodic memory. Taken together, our results suggest that striatal DA availability might be a neurochemical correlate of episodic memory that is also associated with physical activity.
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7.
  • Larsson, Maria, et al. (författare)
  • Olfactory memory in the old and very old : relations to episodic and semantic memory and APOE genotype
  • 2016
  • Ingår i: Neurobiology of Aging. - : Elsevier BV. - 0197-4580 .- 1558-1497. ; 38, s. 118-126
  • Tidskriftsartikel (refereegranskat)abstract
    • The neuroanatomical organization that underlies olfactory memory is different from that of other memory types. The present work examines olfactory memory in an elderly population-based sample (Swedish National Study on Aging and Care in Kungsholmen) aged 60-100 years (n = 2280). We used structural equation modeling to investigate whether olfactory memory in old age is best conceptualized as a distinct category, differentiated from episodic and semantic memory. Further, potential olfactory dedifferentiation and genetic associations (APOE) to olfactory function in late senescence were investigated. Results are in support of a 3-factor solution where olfactory memory, as indexed by episodic odor recognition and odor identification, is modeled separately from episodic and semantic memory for visual and verbal information. Increasing age was associated with poorer olfactory memory performance, and observed age-related deficits were further exacerbated for carriers of the APOE epsilon 4 allele; these effects tended to be larger for olfactory memory compared to episodic and semantic memory pertaining to other sensory systems (vision, auditory). Finally, stronger correlations between olfactory and episodic memory, indicating dedifferentiation, were observed in the older age groups.
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8.
  • Laukka, Erika J., et al. (författare)
  • Combined Genetic Influences on Episodic Memory Decline in Older Adults Without Dementia
  • 2020
  • Ingår i: Neuropsychology. - : American Psychological Association (APA). - 0894-4105 .- 1931-1559. ; 34:6, s. 654-666
  • Tidskriftsartikel (refereegranskat)abstract
    • Objective: Although heritability explains a large proportion of the variance in old-age cognition, studies on the influence of specific genes have been inconclusive. We investigated the individual and combined effects of four single polymorphisms, previously associated with episodic memory, on cognitive or performance and rate of change. Method: Participants were 2490 individuals without dementia (mean age = 72 years) from the population-based Swedish National Study on Aging and Care in Kungsholmen (SNAC-K). Genotyping was performed for APOE (rs429358, rs7412), BDNF (rs6265), KIBRA (rs17070145), and CLSTN2 (rs6439886). We used latent difference score models to estimate the effects of age and genetic variation on level and change in five latent cognitive factors: episodic and semantic memory, letter and category fluency, and perceptual speed. Results: Of the individual genes, only APOE was associated with cognitive performance; epsilon 4 carriers showed lower perceptual speed performance and faster category fluency decline. A cumulative score, combining APOE, BDNF, KIBRA and CLSTN2, was associated with faster cognitive decline that was specific to the episodic memory domain (regression coefficient -0.064, p < .01). Similar results were obtained for a score not including APOE. Conclusions: Results suggest a benefit of investigating the combined influence of polymorphisms related to specific mechanistic factors.
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9.
  • Nordin, Kristin, et al. (författare)
  • DyNAMiC: A prospective longitudinal study of dopamine and brain connectomes : A new window into cognitive aging
  • 2022
  • Ingår i: Journal of Neuroscience Research. - : Wiley. - 0360-4012 .- 1097-4547. ; 100:6, s. 1296-1320
  • Tidskriftsartikel (refereegranskat)abstract
    • Concomitant exploration of structural, functional, and neurochemical brain mechanisms underlying age-related cognitive decline is crucial in promoting healthy aging. Here, we present the DopamiNe, Age, connectoMe, and Cognition (DyNAMiC) project, a multimodal, prospective 5-year longitudinal study spanning the adult human lifespan. DyNAMiC examines age-related changes in the brain’s structural and functional connectome in relation to changes in dopamine D1 receptor availability (D1DR), and their associations to cognitive decline. Critically, due to the complete lack of longitudinal D1DR data, the true trajectory of one of the most age-sensitive dopamine systems remains unknown. The first DyNAMiC wave included 180 healthy participants (20–80 years). Brain imaging included magnetic resonance imaging assessing brain structure (white matter, gray matter, iron), perfusion, and function (during rest and task), and positron emission tomography (PET) with the [11C]SCH23390 radioligand. A subsample (n = 20, >65 years) was additionally scanned with [11C]raclopride PET measuring D2DR. Age-related variation was evident for multiple modalities, such as D1DR; D2DR, and performance across the domains of episodic memory, working memory, and perceptual speed. Initial analyses demonstrated an inverted u-shaped association between D1DR and resting-state functional connectivity across cortical network nodes, such that regions with intermediate D1DR levels showed the highest levels of nodal strength. Evident within each age group, this is the first observation of such an association across the adult lifespan, suggesting that emergent functional architecture depends on underlying D1DR systems. Taken together, DyNAMiC is the largest D1DR study worldwide, and will enable a comprehensive examination of brain mechanisms underlying age-related cognitive decline. 
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10.
  • Nyberg, Lars, 1966-, et al. (författare)
  • Longitudinal stability in working memory and frontal activity in relation to general brain maintenance
  • 2022
  • Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 12:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Cognitive functions are well-preserved for some older individuals, but the underlying brain mechanisms remain disputed. Here, 5-year longitudinal 3-back in-scanner and offline data classified individuals in a healthy older sample (baseline age = 64–68 years) into having stable or declining working-memory (WM). Consistent with a vital role of the prefrontal cortex (PFC), WM stability or decline was related to maintained or reduced longitudinal PFC functional responses. Subsequent analyses of imaging markers of general brain maintenance revealed higher levels in the stable WM group on measures of neurotransmission and vascular health. Also, categorical and continuous analyses showed that rate of WM decline was related to global (ventricles) and local (hippocampus) measures of neuronal integrity. Thus, our findings support a role of the PFC as well as general brain maintenance in explaining heterogeneity in longitudinal WM trajectories in aging.
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