| 51. |
- Nyberg, Lars, 1966-, et al.
(författare)
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Individual differences in brain aging : heterogeneity in cortico-hippocampal but not caudate atrophy rates
- 2023
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Ingår i: Cerebral Cortex. - : Oxford University Press. - 1047-3211 .- 1460-2199. ; 33:9, s. 5075-5081
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Tidskriftsartikel (refereegranskat)abstract
- It is well documented that some brain regions, such as association cortices, caudate, and hippocampus, are particularly prone to age-related atrophy, but it has been hypothesized that there are individual differences in atrophy profiles. Here, we document heterogeneity in regional-atrophy patterns using latent-profile analysis of 1,482 longitudinal magnetic resonance imaging observations. The results supported a 2-group solution reflecting differences in atrophy rates in cortical regions and hippocampus along with comparable caudate atrophy. The higher-atrophy group had the most marked atrophy in hippocampus and also lower episodic memory, and their normal caudate atrophy rate was accompanied by larger baseline volumes. Our findings support and refine models of heterogeneity in brain aging and suggest distinct mechanisms of atrophy in striatal versus hippocampal-cortical systems.
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| 52. |
- Nyberg, Lars, 1966-, et al.
(författare)
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Longitudinal change-change associations of cognition with cortical thickness and surface area
- 2023
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Ingår i: Aging Brain. - : Elsevier. - 2589-9589. ; 3
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Tidskriftsartikel (refereegranskat)abstract
- Age-related changes in cortical volumes are well established but relatively few studies probed its constituents, surface area (SA) and thickness (TH). Here we analyzed 10-year, 3-waves longitudinal data from a large sample of healthy individuals (baseline age = 55–80). The findings showed marked age-related changes of SA in frontal, temporal, and parietal association cortices, and Bivariate Latent Change Score models revealed significant SA-associations with changes in speed of processing in both the 5- and 10-year models. The corresponding results for TH revealed a late onset of thinning and significant associations with reduced cognition in the 10-year model only. Taken together, our findings suggest that cortical surface area shrinks and impacts information-processing capacity gradually in aging, whereas cortical thinning only manifests and impacts fluid cognition in advanced aging.
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| 53. |
- Nyberg, Lars, 1966-, et al.
(författare)
-
Longitudinal stability in working memory and frontal activity in relation to general brain maintenance
- 2022
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Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 12:1
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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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| 54. |
- Nyberg, Lars, et al.
(författare)
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Striatal dopamine D2 binding is related to frontal BOLD response during updating of long-term memory representations
- 2009
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Ingår i: NeuroImage. - : Elsevier. - 1053-8119 .- 1095-9572. ; 46:4, s. 1194-1199
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Tidskriftsartikel (refereegranskat)abstract
- Multi-modal brain imaging was used to examine the relation between individual differences in resting-state striatal dopamine D2 binding and the magnitude of prefrontal BOLD activation during updating of long-term memory (LTM) representations. Increased activity in the left prefrontal cortex was observed when LTM updating was required, and there was a positive correlation between striatal D2 activity and the magnitude of left prefrontal activity during updating. These findings support predictions from neurocomputational models of a relation of dopaminergic neurotransmission to transient cognitive operations and related brain activity.
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| 55. |
- Papenberg, Goran, et al.
(författare)
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Balance between Transmitter Availability and Dopamine D2 Receptors in Prefrontal Cortex Influences Memory Functioning
- 2020
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Ingår i: Cerebral Cortex. - : Oxford University Press (OUP). - 1047-3211 .- 1460-2199. ; 30:3, s. 989-1000
-
Tidskriftsartikel (refereegranskat)abstract
- Insufficient or excessive dopaminergic tone impairs cognitive performance. We examine whether the balance between transmitter availability and dopamine (DA) D2 receptors (D2DRs) is important for successful memory performance in a large sample of adults (n= 175, 64-68 years). The Catechol-O-Methyltransferase polymorphism served as genetic proxy for endogenous prefrontal DA availability, and D2DRs in dorsolateral prefrontal cortex (dlPFC) were measured with [C-11]raclopride-PET. Individuals for whom D2DR status matched DA availability showed higher levels of episodic and working-memory performance than individuals with insufficient or excessive DA availability relative to the number of receptors. A similar pattern restricted to episodic memory was observed for D2DRs in caudate. Functional magnetic resonance imaging data acquired during working-memory performance confirmed the importance of a balanced DA system for load-dependent brain activity in dlPFC. Our data suggest that the inverted-U-shaped function relating DA signaling to cognition is modulated by a dynamic association between DA availability and receptor status.
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| 56. |
- Papenberg, Goran, et al.
(författare)
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Mapping the landscape of human dopamine D2/3 receptors with [11C]raclopride
- 2019
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Ingår i: Brain Structure and Function. - : Springer Science and Business Media LLC. - 1863-2653 .- 1863-2661. ; 224:8, s. 2871-2882
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Tidskriftsartikel (refereegranskat)abstract
- The dopamine D2/3 system is fundamental for sensory, motor, emotional, and cognitive aspects of behavior. Small-scale human histopathological and animal studies show high density of D2/3 dopamine receptors (D2/3DR) in striatum, but also demonstrate the existence of such receptors across cortical and limbic regions. Assessment of D2/3DR BPND in the extrastriatal regions with [C-11]raclopride has long been considered unreliable due to the relatively low density of D2/3DR outside the striatum. We describe the distribution and interregional links of D2/3DR availability measured with PET and [C-11]raclopride across the human brain in a large sample (N = 176; age range 64-68 years). Structural equation modeling revealed that D2/3DR availability can be organized according to anatomical (nigrostriatal, mesolimbic, mesocortical) and functional (limbic, associative, sensorimotor) dopamine pathways. D2/3DR availability in corticolimbic functional subdivisions showed differential associations to corresponding striatal subdivisions, extending animal and pharmacological work. Our findings provide evidence on the dimensionality and organization of [C-11]raclopride D2/3DR availability in the living human brain that conforms to known dopaminergic pathways.
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| 57. |
- Papenberg, Goran, et al.
(författare)
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The Influence of Hippocampal Dopamine D2 Receptors on Episodic Memory Is Modulated by BDNF and KIBRA Polymorphisms
- 2019
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Ingår i: Journal of cognitive neuroscience. - : MIT Press - Journals. - 0898-929X .- 1530-8898. ; 31:9, s. 1422-1429
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Tidskriftsartikel (refereegranskat)abstract
- Episodic memory is a polygenic trait influenced by different molecular mechanisms. We used PET and a candidate gene approach to investigate how individual differences at the molecular level translate into between-person differences in episodic memory performance of elderly persons. Specifically, we examined the interactive effects between hippocampal dopamine D2 receptor (D2DR) availability and candidate genes relevant for hippocampus-related memory functioning. We show that the positive effects of high D2DR availability in the hippocampus on episodic memory are confined to carriers of advantageous genotypes of the brain-derived neurotrophic factor (BDNF, rs6265) and the kidney and brain expressed protein (KIBRA, rs17070145) polymorphisms. By contrast, these polymorphisms did not modulate the positive relationship between caudate D2DR availability and episodic memory.
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| 58. |
- Pedersen, Robin, et al.
(författare)
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When functional blurring becomes deleterious : Reduced system segregation is associated with less white matter integrity and cognitive decline in aging
- 2021
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Ingår i: NeuroImage. - : Elsevier BV. - 1053-8119 .- 1095-9572. ; 242
-
Tidskriftsartikel (refereegranskat)abstract
- Healthy aging is accompanied by progressive decline in cognitive performance and concomitant changes in brain structure and functional architecture. Age-accompanied alterations in brain function have been characterized on a network level as weaker functional connections within brain networks along with stronger interactions between networks. This phenomenon has been described as age-related differences in functional network segregation. It has been suggested that functional networks related to associative processes are particularly sensitive to age-related deterioration in segregation, possibly related to cognitive decline in aging. However, there have been only a few longitudinal studies with inconclusive results. Here, we used a large longitudinal sample of 284 participants between 25 to 80 years of age at baseline, with cognitive and neuroimaging data collected at up to three time points over a 10-year period. We investigated age-related changes in functional segregation among two large-scale systems comprising associative and sensorimotor-related resting-state networks. We found that functional segregation of associative systems declines in aging with exacerbated deterioration from the late fifties. Changes in associative segregation were positively associated with changes in global cognitive ability, suggesting that decreased segregation has negative consequences for domain-general cognitive functions. Age-related changes in system segregation were partly accounted for by changes in white matter integrity, but white matter integrity only weakly influenced the association between segregation and cognition. Together, these novel findings suggest a cascade where reduced white-matter integrity leads to less distinctive functional systems which in turn contributes to cognitive decline in aging.
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| 59. |
- Persson, Ninni, et al.
(författare)
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Hippocampal volume, and the anterior-posterior sub regions relates to recall and recognition over five years : Bidirectional brain-behaviour associations
- 2022
-
Ingår i: NeuroImage. - : Elsevier. - 1053-8119 .- 1095-9572. ; 256
-
Tidskriftsartikel (refereegranskat)abstract
- Longitudinal studies of brain-behavior links between episodic memory (EM) and the hippocampus (HC), including anterior-posterior subregions, are few. This study assessed brain-cognition relationships between HC volumes, including the anterior-posterior subregions, item recall, and recognition, in 358 adults (52%♀; 20–80 yrs. at baseline, 221 returned at follow-up). Bivariate latent change score models assessed mean change, variance, and bidirectional associations between the hippocampal regions and the EM tasks. The influence of chronological age, sex, and education were included as covariates. The results showed that: larger baseline HC volume slowed subsequent decline in EM scores; higher associative memory scores at offset mitigated five-year HC volume loss; larger anterior HC volumes slowed decline in recognition memory, while larger posterior volumes mitigated decline in recall scores; the volume of the anterior HC was not associated with change in recall scores; and posterior HC volume did not predict change in recognition memory scores. The covariates examined — age, sex, and education— had some cross-sectional influence, but only limited longitudinal effects. The results explain the bidirectional associations in brain-cognition links, and how the distinct sub-regional HC correlates for recall and recognition, respectively. These results also shed light on potential links between maintained brain volumes and restored cognitive functions during the aging process.
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| 60. |
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