| 1. |
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
- Flodin, Pär, et al.
(författare)
-
Fibromyalgia is associated with decreased connectivity between pain- and sensorimotor brain areas.
- 2014
-
Ingår i: Brain Connectivity. - : Mary Ann Liebert Inc. - 2158-0014 .- 2158-0022. ; 4:8, s. 587-94
-
Tidskriftsartikel (refereegranskat)abstract
- Fibromyalgia (FM) is a syndrome characterized by chronic pain without known peripheral causes. Previously, we have reported dysfunctional pain inhibitory mechanisms for FM patients during pain administration. In this study we employed a seed correlation analysis, independent component analysis (ICA), and an analysis of fractional amplitude of low frequency fluctuations (fALFF) to study differences between a cohort of female FM patients and an age- and sex-matched healthy control group during a resting-state condition. FM patients showed decreased connectivity between thalamus and premotor areas, between the right insula and primary sensorimotor areas, and between supramarginal and prefrontal areas. Individual sensitivity to painful pressure was associated with increased connectivity between pain-related regions (e.g., insula and thalamus) and midline regions of the default mode network (including posterior cingulate cortex and medial prefrontal cortex) among patients and controls. However, neither ICA nor fALFF revealed any group differences. Our findings suggest that abnormal connectivity patterns between pain-related regions and the remaining brain during rest reflect an impaired central mechanism of pain modulation in FM. Weaker coupling between pain regions and prefrontal- and sensorimotor areas might indicate a less efficient system level control of pain circuits. Moreover, our results show that multiple, complementary analytical approaches are valuable for obtaining a more comprehensive characterization of deviant resting-state activity. In conclusion, our findings show that FM primarily is associated with decreased connectivity, for example, between several pain-related areas and sensorimotor regions, which could reflect a deficiency in pain regulation.
|
|
| 5. |
- Gorbach, Tetiana, 1991-, et al.
(författare)
-
A Hierarchical Bayesian Mixture Model Approach for Analysis of Resting-State Functional Brain Connectivity : An Alternative to Thresholding
- 2020
-
Ingår i: Brain Connectivity. - : Mary Ann Liebert. - 2158-0014 .- 2158-0022. ; 10:5, s. 202-211
-
Tidskriftsartikel (refereegranskat)abstract
- This article proposes a Bayesian hierarchical mixture model to analyze functional brain connectivity where mixture components represent "positively connected" and "non-connected" brain regions. Such an approach provides a data-informed separation of reliable and spurious connections in contrast to arbitrary thresholding of a connectivity matrix. The hierarchical structure of the model allows simultaneous inferences for the entire population as well as for each individual subject. A new connectivity measure, the posterior probability of a given pair of brain regions of a specific subject to be connected given the observed correlation of regions' activity, can be computed from the model fit. The posterior probability reflects the connectivity of a pair of regions relative to the overall connectivity pattern of an individual, which is overlooked in traditional correlation analyses. This article demonstrates that using the posterior probability might diminish the effect of spurious connections on inferences, which is present when a correlation is used as a connectivity measure. In addition, simulation analyses reveal that the sparsification of the connectivity matrix using the posterior probabilities might outperform the absolute thresholding based on correlations. Therefore, we suggest that posterior probability might be a beneficial measure of connectivity compared with the correlation. The applicability of the introduced method is exemplified by a study of functional resting-state brain connectivity in older adults.
|
|
| 6. |
- Ikegawa, M., et al.
(författare)
-
Mass Spectrometry Imaging in Alzheimer's Disease
- 2023
-
Ingår i: Brain Connectivity. - : Mary Ann Liebert Inc. - 2158-0014 .- 2158-0022. ; 13:6, s. 319-33
-
Tidskriftsartikel (refereegranskat)abstract
- Introduction: Amyloid-beta (A beta) pathology is the precipitating histopathological characteristic of Alzheimer's disease (AD). Although the formation of amyloid plaques in human brains is suggested to be a key factor in initiating AD pathogenesis, it is still not fully understood the upstream events that lead to A beta plaque formation and its metabolism inside the brains.Methods: Matrix-assisted laser desorption ionization mass spectrometry imaging (MALDI-MSI) has been successfully introduced to study AD pathology in brain tissue both in AD mouse models and human samples. By using MALDI-MSI, a highly selective deposition of A beta peptides in AD brains with a variety of cerebral amyloid angiopathy (CAA) involvement was observed.Results: MALDI-MSI visualized depositions of shorter peptides in AD brains; A beta 1-36 to A beta 1-39 were quite similarly distributed with A beta 1-40 as a vascular pattern, and deposition of A beta 1-42 and A beta 1-43 was visualized with a distinct senile plaque pattern distributed in parenchyma. Moreover, how MALDI-MSI covered in situ lipidomics of plaque pathology has been reviewed, which is of interest as aberrations in neuronal lipid biochemistry have been implicated in AD pathogenesis.Discussion: In this study, we introduce the methodological concepts and challenges of MALDI-MSI for the studies of AD pathogenesis. Diverse A beta isoforms including various C- and N-terminal truncations in AD and CAA brain tissues will be visualized. Despite the close relationship between vascular and plaque A beta deposition, the current strategy will define cross talk between neurodegenerative and cerebrovascular processes at the level of A beta metabolism. Impact statementMatrix-assisted laser desorption ionization mass spectrometry-based chemical imaging has been successfully applied to comprehensively delineate spatial A beta peptide- and neuronal lipid patterns in brains with Alzheimer's disease. This rather new approach overcomes major limitations inherent to commonly used biochemical methods and opens up for both static and dynamic biochemical interrogations of amyloid aggregation in situ.
|
|
| 7. |
|
|
| 8. |
- Koutarapu, Srinivas, et al.
(författare)
-
Correlative Chemical Imaging Identifies Amyloid Peptide Signatures of Neuritic Plaques and Dystrophy in Human Sporadic Alzheimer's Disease.
- 2023
-
Ingår i: Brain connectivity. - : Mary Ann Liebert Inc. - 2158-0014 .- 2158-0022. ; 15:5, s. 297-306
-
Tidskriftsartikel (refereegranskat)abstract
- Objective: Alzheimer's disease (AD) is the most common neurodegenerative disease. The predominantly sporadic form of AD is age-related, but the underlying pathogenic mechanisms remain not fully understood. Current efforts to combat the disease focus on the main pathological hallmarks, in particular beta-amyloid (Aβ) plaque pathology. According to the amyloid cascade hypothesis, Aβ is the critical early initiator of AD pathogenesis. Plaque pathology is very heterogeneous, where a subset of plaques, neuritic plaques (NPs), are considered most neurotoxic rendering their in-depth characterization essential to understand Aβ pathogenicity. Methods: To delineate the chemical traits specific to NP types, we investigated senile Aβ pathology in the postmortem, human sporadic AD brain using advanced correlative biochemical imaging based on immunofluorescence (IF) microscopy and mass spectrometry imaging (MSI). Results: Immunostaining-guided MSI identified distinct Aβ signatures of NPs characterized by increased Aβ1-42(ox) and Aβ2-42. Moreover, correlation with a marker of dystrophy (reticulon 3 [RTN3]) identified key Aβ species that both delineate NPs and display association with neuritic dystrophy. Conclusion: Together, these correlative imaging data shed light on the complex biochemical architecture of NPs and associated dystrophic neurites. These in turn are obvious targets for disease-modifying treatment strategies, as well as novel biomarkers of Aβ pathogenicity.
|
|
| 9. |
|
|
| 10. |
- Nystedt, Jessika, et al.
(författare)
-
Functional Connectivity Changes in Systemic Lupus Erythematosus : A Resting-State Study
- 2018
-
Ingår i: Brain Connectivity. - : Mary Ann Liebert Inc. - 2158-0014 .- 2158-0022. ; 8:4, s. 220-234
-
Tidskriftsartikel (refereegranskat)abstract
- To investigate resting-state functional connectivity of lupus patients and associated subgroups according to the ACR NPSLE case definitions (ACR ad hoc). In addition, we investigated whether or not the observed alterations correlated with disease duration, the systemic lupus erythematosus (SLE)-Disease Activity Index-2000 (SLEDAI-2k), and Systemic Lupus International Collaborating Clinical/ACR organ damage index (SDI)-scores. Anatomical 3T magnetic resonance imaging (MRI) and resting-state functional MRI were performed in 61 female lupus patients (mean age = 37.0 years, range = 18.2-52.0 years) and 20 gender- and age-matched controls (mean age = 36.2 years, range = 23.3-52.2 years) in conjunction with clinical examination and laboratory testing. Whole-brain voxelwise functional connectivity analysis with permutation testing was performed to extract network components that differed in lupus patients relative to healthy controls (HCs). Lupus patients exhibited both inter- and intranetwork hypo- and hyperconnectivity involving several crucial networks. We found reduced connectivity within the default mode network (DMN), the central executive network (CEN), and in-between the DMN and CEN in lupus patients. Increased connectivity was primarily observed within and between the sensory motor network in lupus patients when compared to HCs. Comparing lupus patients with and without neuropsychiatric symptoms, hypoconnectivity was more pronounced in the group with neuropsychiatric complaints. The functional connectivity of SLE patients was both positively and negatively correlated to duration of disease. We conclude that SLE patients in general and neuropsychiatric SLE patients in particular experience altered brain connectivity. These patterns may be due both to direct neuronal damage and compensatory mechanisms through neuronal rewiring and recruitment and may partly explain neuropsychiatric symptoms in SLE patients.
|
|
