| 1. |
- de Boer, Lieke, et al.
(författare)
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Corticostriatal White Matter Integrity and Dopamine D1 Receptor Availability Predict Age Differences in Prefrontal Value Signaling during Reward Learning
- 2020
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Ingår i: Cerebral Cortex. - : Oxford University Press (OUP). - 1047-3211 .- 1460-2199. ; 30:10, s. 5270-5280
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Tidskriftsartikel (refereegranskat)abstract
- Probabilistic reward learning reflects the ability to adapt choices based on probabilistic feedback. The dopaminergically innervated corticostriatal circuit in the brain plays an important role in supporting successful probabilistic reward learning. Several components of the corticostriatal circuit deteriorate with age, as it does probabilistic reward learning. We showed previously that D1 receptor availability in NAcc predicts the strength of anticipatory value signaling in vmPFC, a neural correlate of probabilistic learning that is attenuated in older participants and predicts probabilistic reward learning performance. We investigated how white matter integrity in the pathway between nucleus accumbens (NAcc) and ventromedial prefrontal cortex (vmPFC) relates to the strength of anticipatory value signaling in vmPFC in younger and older participants. We found that in a sample of 22 old and 23 young participants, fractional anisotropy in the pathway between NAcc and vmPFC predicted the strength of value signaling in vmPFC independently from D1 receptor availability in NAcc. These findings provide tentative evidence that integrity in the dopaminergic and white matter pathways of corticostriatal circuitry supports the expression of value signaling in vmPFC which supports reward learning, however, the limited sample size calls for independent replication. These and future findings could add to the improved understanding of how corticostriatal integrity contributes to reward learning ability.
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| 2. |
- Garzón, Benjamín, et al.
(författare)
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Role of dopamine and gray matter density in aging effects and individual differences of functional connectomes
- 2021
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Ingår i: Brain Structure and Function. - : Springer Science and Business Media LLC. - 1863-2653 .- 1863-2661. ; 226, s. 743-758
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Tidskriftsartikel (refereegranskat)abstract
- With increasing age, functional connectomes become dissimilar across normal individuals, reflecting heterogenous aging effects on functional connectivity (FC). We investigated the distribution of these effects across the connectome and their relationship with age-related differences in dopamine (DA) D1 receptor availability and gray matter density (GMD). With this aim, we determined aging effects on mean and interindividual variance of FC using fMRI in 30 younger and 30 older healthy subjects and mapped the contribution of each connection to the patterns of age-related similarity loss. Aging effects on mean FC accounted mainly for the dissimilarity between connectomes of younger and older adults, and were related, across brain regions, to aging effects on DA D1 receptor availability. Aging effects on the variance of FC indicated a global increase in variance with advancing age, explained connectome dissimilarity among older subjects and were related to aging effects on variance of GMD. The relationship between aging and the similarity of connectomes can thus be partly explained by age differences in DA modulation and gray matter structure.
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| 3. |
- Grill, Filip, et al.
(författare)
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Dissecting Motor and Cognitive Component Processes of a Finger-Tapping Task With Hybrid Dopamine Positron Emission Tomography and Functional Magnetic Resonance Imaging
- 2021
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Ingår i: Frontiers in Human Neuroscience. - : Frontiers Media S.A.. - 1662-5161. ; 15
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Tidskriftsartikel (refereegranskat)abstract
- Striatal dopamine is involved in facilitation of motor action as well as various cognitive and emotional functions. Positron emission tomography (PET) is the primary imaging method used to investigate dopamine function in humans. Previous PET studies have shown striatal dopamine release during simple finger tapping in both the putamen and the caudate. It is likely that dopamine release in the putamen is related to motor processes while dopamine release in the caudate could signal sustained cognitive component processes of the task, but the poor temporal resolution of PET has hindered firm conclusions. In this study we simultaneously collected [11C]Raclopride PET and functional Magnetic Resonance Imaging (fMRI) data while participants performed finger tapping, with fMRI being able to isolate activations related to individual tapping events. The results revealed fMRI-PET overlap in the bilateral putamen, which is consistent with a motor component process. Selective PET responses in the caudate, ventral striatum, and right posterior putamen, were also observed but did not overlap with fMRI responses to tapping events, suggesting that these reflect non-motor component processes of finger tapping. Our findings suggest an interplay between motor and non-motor-related dopamine release during simple finger tapping and illustrate the potential of hybrid PET-fMRI in revealing distinct component processes of cognitive functions.
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| 4. |
- Karalija, Nina, 1984-, et al.
(författare)
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Longitudinal Dopamine D2 Receptor Changes and Cerebrovascular Health in Aging
- 2022
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Ingår i: Neurology. - 1526-632X .- 0028-3878. ; 99, s. e1278-e1289
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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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| 5. |
- Karalija, Nina, 1984-, et al.
(författare)
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Sex differences in dopamine integrity and brain structure among healthy older adults : Relationships to episodic memory
- 2021
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Ingår i: Neurobiology of Aging. - : Elsevier. - 0197-4580 .- 1558-1497. ; 105, s. 272-279
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Tidskriftsartikel (refereegranskat)abstract
- Normal brain aging is a multidimensional process that includes deterioration in various brain structures and functions, with large heterogeneity in patterns and rates of decline. Sex differences have been reported for various cognitive and brain parameters, but little is known in relation to neuromodulatory aspects of brain aging. We examined sex differences in dopamine D2-receptor (D2DR) availability in relation to episodic memory, but also, grey-matter volumes, white-matter lesions, and cerebral perfusion in healthy older adults (n = 181, age: 64-68 years) from the Cognition, Brain, and Aging study. Women had higher D2DR availability in midbrain and left caudate and putamen, as well as superior episodic memory performance. Controlling for left caudate D2DR availability attenuated sex differences in memory performance. In men, lower left caudate D2DR levels were associated with lower cortical perfusion and higher burden of white-matter lesions, as well as with episodic memory performance. However, sex was not a significant moderator of the reported links to D2DR levels. Our findings suggest that sex differences in multiple associations among DA receptor availability, vascular factors, and structural connectivity contribute to sex differences in episodic memory. Future longitudinal studies need to corroborate these patterns by lead-lag associations. This manuscript is part of the Special Issue entitled 'Cognitive Neuroscience of Healthy and Pathological Aging' edited by Drs. M. N. Rajah, S. Belleville, and R. Cabeza.
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| 6. |
- 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
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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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| 7. |
- Axelsson, Lars, et al.
(författare)
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Swedish National Multicenter Study on Head and Neck Cancer of Unknown Primary: Prognostic Factors and Impact of Treatment on Survival
- 2021
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Ingår i: International Archives of Otorhinolaryngology. - : Georg Thieme Verlag KG. - 1809-9777 .- 1809-4864. ; 25:3, s. e433-e442
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Tidskriftsartikel (refereegranskat)abstract
- Introduction Head and neck cancer of unknown primary (HNCUP) is a rare condition whose prognostic factors that are significant for survival vary between studies. No randomized treatment study has been performed thus far, and the optimal treatment is not established. Objective The present study aimed to explore various prognostic factors and compare the two main treatments for HNCUP: neck dissection and (chemo) radiation vs primary (chemo) radiation. Methods A national multicenter study was performed with data from the Swedish Head and Neck Cancer Register (SweHNCR) and from the patients' medical records from 2008 to 2012. Results Two-hundred and sixty HNCUP patients were included. The tumors were HPVpositive in 80%. The overall 5-year survival rate of patients treated with curative intent was 71%. Age (p < 0.001), performance status (p = 0.036), and N stage (p = 0.046) were significant factors for overall survival according to the multivariable analysis. Treatment with neck dissection and (chemo) radiation (122 patients) gave an overall 5-year survival of 73%, and treatment with primary (chemo) radiation (87 patients) gave an overall 5-year survival of 71%, with no significant difference in overall or disease-free survival between the 2 groups. Conclusions Age, performance status, and N stage were significant prognostic factors. Treatment with neck dissection and ( chemo) radiation and primary (chemo)
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| 8. |
- Censoni, Luciano, et al.
(författare)
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Verification of multi-structure targeting in chronic microelectrode brain recordings from CT scans
- 2022
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Ingår i: Journal of Neuroscience Methods. - : Elsevier. - 0165-0270 .- 1872-678X. ; 382
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Tidskriftsartikel (refereegranskat)abstract
- Background: Large-scale microelectrode recordings offer a unique opportunity to study neurophysiological processes at the network level with single cell resolution. However, in the small brains of many experimental animals, it is often technically challenging to verify the correct targeting of the intended structures, which inherently limits the reproducibility of acquired data.New method: To mitigate this problem, we have developed a method to programmatically segment the trajectory of electrodes arranged in larger arrays from acquired CT-images and thereby determine the position of individual recording tips with high spatial resolution, while also allowing for coregistration with an anatomical atlas, without pre-processing of the animal samples or post-imaging histological analyses.Results: Testing the technical limitations of the developed method, we found that the choice of scanning angle influences the achievable spatial resolution due to shadowing effects caused by the electrodes. However, under optimal acquisition conditions, individual electrode tip locations within arrays with 250 µm inter-electrode spacing were possible to reliably determine.Comparison to existing methods: Comparison to a histological verification method suggested that, under conditions where individual wires are possible to track in slices, a 90% correspondence could be achieved in terms of the number of electrodes groups that could be reliably assigned to the same anatomical structure.Conclusions: The herein reported semi-automated procedure to verify anatomical targeting of brain structures in the rodent brain could help increasing the quality and reproducibility of acquired neurophysiological data by reducing the risk of assigning recorded brain activity to incorrectly identified anatomical locations.
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| 9. |
- Constantinescu, Clara, 1995, et al.
(författare)
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Persons with suspicious onset of multiple sclerosis but with undetermined diagnosis had persistent lower cognition and reduced quality of life
- 2021
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Ingår i: Multiple Sclerosis and Related Disorders. - : Elsevier BV. - 2211-0348. ; 52
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Tidskriftsartikel (refereegranskat)abstract
- Backgound: Differential diagnosis of multiple sclerosis (MS) includes a variety of disorders and misdiagnosis is common. Objective: To follow-up persons with suspected onset of MS but in whom the diagnostic investigation was negative. Methods: In a prospective study including 271 persons with clinical features of suspected MS onset, 136 persons were diagnosed with MS or clinically isolated syndrome (PwMS), 46 had other disorders, and 89 persons had a negative diagnostic work-up, i.e. persons with undetermined diagnosis (PwUD). They underwent diagnostic reassessment, and those who remained without a diagnosis were investigated for signs of pathology including cognitive tests and assessments of quality of life (QoL). Results were compared with those of PwMS and 24 age and sex matched healthy controls (HC). Results: After reassement 55 (20%) persons still had undetermined diagnosis (PwUD). They had similar age and gender distribution as PwMS. In 76% of PwUD, the suspected clinical onset included sensory symptoms. PwUD and PwMS scored similarly in cognitive tests and QoL but significantly lower than HC. At 3 years follow-up, PwMS and PwUD improved in most test parameters, but PwUD scored lower than PwMS in cognition. Conclusion: PwUD constituted the dominating differential diagnosis in persons with suspected clinical onset of MS. QoL and cognition were comparable with those of PwMS but significantly lower than in HC.
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| 10. |
- Giacobbo, B., et al.
(författare)
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The Aged Striatum : Evidence of Molecular and Structural Changes Using a Longitudinal Multimodal Approach in Mice
- 2022
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Ingår i: Frontiers in Aging Neuroscience. - : Frontiers Media S.A.. - 1663-4365 .- 1663-4365. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- To study the aging human brain requires significant resources and time. Thus, mice models of aging can provide insight into changes in brain biological functions at a fraction of the time when compared to humans. This study aims to explore changes in dopamine D1 and D2 receptor availability and of gray matter density in striatum during aging in mice and to evaluate whether longitudinal imaging in mice may serve as a model for normal brain aging to complement cross-sectional research in humans. Mice underwent repeated structural magnetic resonance imaging (sMRI), and [11C]Raclopride and [11C]SCH23390 positron emission tomography (PET) was performed on a subset of aging mice. PET and sMRI data were analyzed by binding potential (BP ND ), voxel- and tensor-based morphometry (VBM and TBM, respectively). Longitudinal PET revealed a significant reduction in striatal BP ND for D2 receptors over time, whereas no significant change was found for D1 receptors. sMRI indicated a significant increase in modulated gray matter density (mGMD) over time in striatum, with limited clusters showing decreased mGMD. Mouse [11C]Raclopride data is compatible with previous reports in human cross-sectional studies, suggesting that a natural loss of dopaminergic D2 receptors in striatum can be assessed in mice, reflecting estimates from humans. No changes in D1 were found, which may be attributed to altered [11C]SCH23390 kinetics in anesthetized mice, suggesting that this tracer is not yet able to replicate human findings. sMRI revealed a significant increase in mGMD. Although contrary to expectations, this increase in modulated GM density may be attributed to an age-related increase in non-neuronal cells.
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