Brain-thyroid crosstalk: 18F-FDG-PET/MRI evidence in patients with follicular thyroid adenomas.

BackgroundIndividuals with Mild Cognitive Impairment (MCI) are at greater risk of developing Alzheimer's disease (AD). Previous studies have shown that physical exercise is a protective factor against the clinical evolution of dementia in MCI. Lower muscle strength levels are associated with a greater risk of AD incidence. Physical exercises can also promote improvements in brain networks' functional connectivity (FC). However, the influence of resistance exercise, which significantly impacts the development of muscular strength and cognition, remains unknown concerning FC in MCI. We aimed to investigate the FC of brain networks after 24 weeks of resistance training.Method37 older adults with MCI were investigated. Nineteen performed the resistance training protocol, and 18 constituted the control group, not performing the exercises. Participants were evaluated before and after the intervention using a magnetic resonance imaging device (3 Tesla) for functional magnetic resonance imaging. FC was assessed in Matlab software using the uf2c program to investigate intra‐network connectivity, considering a p‐value of 0.05 with an FDR‐corrected comparison. We evaluated 12 networks: AnteSalience, PostSalience, Auditory, BasalGanglia, Dorsal Default Mode Network, Ventral Default Mode Network, Language, Left executive control network, Right executive control network, Sensorimotor, Visual and Visuospatial networks.ResultAnteSalience connectivity decreased in the control group (T‐score > 3.1473) and increased in the exercise group in the PostSalience (T‐score > 3.7114). The results suggest that the training intervention also increased the FC of the visuospatial network (uncorrected results T‐score > 2.7195), while the control group showed no changes. None of the other networks shows differences between the pre‐and post‐intervention moments. The intervention time may have influenced the results, as changes in FC tend to occur over extended periods; even so, resistance exercise proved influential.ConclusionFC increased or tended to increase in some networks in the exercise intervention group, while in the control group, it decreased or remained stable, suggesting that exercise may be a beneficial modulator of brain connectivity in specific networks such as AnteSalience, PostSalience, and the Visuospatial network. More studies are suggested, especially those that monitor FC changes over extended periods.

Diffusion tensor imaging (DTI) is a powerful MRI technique that can be used to estimate both the microstructural integrity and the trajectories of white matter pathways throughout the central nervous system. This fiber tracking (aka, “tractography”) approach is often carried out using anatomically-defined seed points to identify white matter tracts that pass through one or more structures, but can also be performed using functionally-defined regions of interest (ROIs) that have been determined using functional MRI (fMRI) or other methods. In this study, we performed fMRI-guided DTI tractography between all of the previously defined nodes within each of six common resting-state brain networks, including the: dorsal Default Mode Network (dDMN), ventral Default Mode Network (vDMN), left Executive Control Network (lECN), right Executive Control Network (rECN), anterior Salience Network (aSN), and posterior Salience Network (pSN). By normalizing the data from 32 healthy control subjects to a standard template—using high-dimensional, non-linear warping methods—we were able to create probabilistic white matter atlases for each tract in stereotaxic coordinates. By investigating all 198 ROI-to-ROI combinations within the aforementioned resting-state networks (for a total of 6336 independent DTI tractography analyses), the resulting probabilistic atlases represent a comprehensive cohort of functionally-defined white matter regions that can be used in future brain imaging studies to: (1) ascribe DTI or other white matter changes to particular functional brain networks, and (2) compliment resting state fMRI or other functional connectivity analyses.

Functional connectivity changes in males with nicotine addiction: A triple network model study

Alterations in sympathetic and parasympathetic brain networks in obstructive sleep apnea

Diabetic retinopathy (DR) patients are at an increased risk of cognitive decline and dementia. There is accumulating evidence that specific functional and structural architecture changes in the brain are related to cognitive impairment in DR patients. However, little is known regarding whether the functional architecture of resting-state networks (RSNs) changes in DR patients. The purpose of this study was to investigate the intranetwork functional connectivity (FC) and functional network connectivity (FNC) of RSN changes in DR patients using independent component analysis (ICA). Thirty-four DR patients (18 men and 16 women; mean age, 53.53 ± 8.67 years) and 38 nondiabetic healthy controls (HCs) (15 men and 23 women; mean age, 48.63 ± 11.83 years), closely matched for age, sex, and education, underwent resting-state magnetic resonance imaging scans. ICA was applied to extract the nine RSNs. Then, two-sample t-tests were conducted to investigate different intranetwork FCs within nine RSNs between the two groups. The FNC toolbox was used to assess interactions among RSNs. Pearson correlation analysis was conducted to explore the relationship between intranetwork FCs and clinical variables in the DR group. A receiver operating characteristic (ROC) curve was conducted to assess the ability of the intranetwork FCs of RSNs in discriminating between the two groups. Compared to the HC group, DR patients showed significant decreased intranetwork FCs within the basal ganglia network (BGN), visual network (VN), ventral default mode network (vDMN), right executive control network (rECN), salience network (SN), left executive control network (lECN), auditory network (AN), and dorsal default mode network (dDMN). In addition, FNC analysis showed increased VN-BGN, VN-vDMN, VN-dDMN, vDMN-lECN, SN-BGN, lECN-dDMN, and AN-BGN FNCs in the DR group, relative to the HC group. Furthermore, altered intranetwork FCs of RSNs were significantly correlated with the glycosylated hemoglobin (HbA1c) level in DR patients. A ROC curve showed that these specific intranetwork FCs of RSNs discriminated between the two groups with a high degree of sensitivity and specificity. Our study highlighted that DR patients had widespread deficits in both low-level perceptual and higher-order cognitive networks. Our results offer important insights into the neural mechanisms of visual loss and cognitive decline in DR patients.

Resting-state activity in the left executive control network is associated with behavioral approach and is increased in substance dependence

Purpose: This study aimed to explore alterations in functional connectivity (FC) within and between default mode network (DMN), central executive network, and salience network in autism spectrum disorder (ASD) with co-occurring attention deficit hyperactivity disorder (ADHD).Method: A total of 135 individuals' date of the Autism Brain Imaging Data Exchange II was used to compare the ASD+ADHD group with the ASD group in relation to the abnormal within-network and between-network connectivity of the ASD group relative to the TD group; consequently, the correlation analysis between abnormal FC and behavior was performed.Results: The ASD+ADHD group exhibited decreased within-network connectivity in the precuneus of the ventral DMN compared with the ASD group. Among the three groups, the ASD+ADHD group showed lower connectivity, whereas the ASD group had higher connectivity than the TD group, although the effect of the separate post hoc test was not significant. Meanwhile, the ASD+ADHD group showed increased between-network connectivity between the ventral DMN and dorsal DMN and between the ventral DMN and left executive control network, compared with the ASD and TD groups.Conclusion: Dysfunction of DMN in the “triple-network model” is the core evidence for ASD with co-occurring ADHD.

Major Depressive Disorder (MDD) is one of the most prevalent psychological disorders all over the world. Suicide ideation is the most dangerous and crucial consequence of this mental disturbance that can lead to suicide attempting. In this study, we compared both functional and effective brain connectivity of female MDD patients having suicide thoughts with female healthy controls. We used COMBI algorithm for identifying independent components in resting state fMRI data (rsfMRI) of 32 female subjects (16 MDDs with suicide ideation and 16 healthy controls). We performed Group Information Guided Independent Component Analysis (GIG-ICA) as a back-reconstruction step and finally, extracted the static and Dynamic Functional Connectivity (DFC) for all participants. Besides that, Dynamic Effective Connectivity (DEC) was characterized using Dynamic Granger Causality (DGC). Significant connectivity differences were detected between some network pairs including: Auditory Network with right Executive Control Network (ECN), ventral Default Mode Network (DMN) with Visuospatial, right ECN with anterior Salience Network (SN), ventral DMN with Precuneus, dorsal DMN with Precuneus, Language with dorsal DMN, Language with posterior SN and Primary Visual with dorsal DMN. Except the connectivity difference between right ECN and anterior Salience network, other connectivity changes were consistent with previous studies. As far as we know, this is the first study to investigate the effective connectivity by the information extracted from ICA in this specific study group.

It is always challenging to correctly differentiate between minimally conscious state (MCS) and vegetative state/unresponsive wakefulness syndrome (VS/UWS) among disorders of consciousness (DOC) patients. However, the underlying neural mechanisms of awareness identification remain incompletely understood. Using regional homogeneity (ReHo) analysis, we evaluated how regional connectivity of brain regions is disrupted in MCS and VS/UWS patients. Resting-state functional magnetic resonance imaging was conducted in 14 MCS patients, 25 VS/UWS patients, and 30 age-matched healthy individuals. We found that MCS and VS/UWS patients demonstrated DOC-dependent reduced ReHo within widespread brain regions including posterior cingulate cortices (PCC), medial prefrontal cortices (mPFC), and bilateral fronto-parieto-temporal cortices and showed increased ReHo in limbic structures. Moreover, a positive correlation between Coma Recovery Scale-Revised (CRS-R) total scores and reduced ReHo in the left precuneus was observed in VS/UWS patients, despite the linear trend was not found in MCS patients. In addition, ReHo were also observed reduced in three mainly intrinsic connectivity networks (ICNs), including default mode network (DMN), executive control network (ECN), and salience network (SN). Notably, as the clinical symptoms of consciousness disorders worsen from MCS to VS/UWS, ReHo in dorsal DMN, left ECN, and posterior SN became significantly reduced. These findings make a further understanding of the underlying neural mechanism of regional connectivity among DOC patients and provide additional neuroimaging-based biomarkers for the clinical diagnosis of MCS and VS/UWS patients.

Altered static and dynamic functional network connectivity in post-stroke cognitive impairment

Substantial evidence indicates that cognitive training can be efficacious for older adults, but findings regarding training-related brain plasticity have been mixed and vary depending on the imaging modality. Recent years have seen a growth in recognition of the importance of large-scale brain networks on cognition. In particular, task-induced deactivation within the default mode network (DMN) is thought to facilitate externally directed cognition, while aging-related decrements in this neural process are related to reduced cognitive performance. It is not yet clear whether task-induced deactivation within the DMN can be enhanced by cognitive training in the elderly. We previously reported durable cognitive improvements in a sample of healthy older adults (age range = 60–75) who completed 6 weeks of process-based object-location memory training (N = 36) compared to an active control training group (N = 31). The primary aim of the current study is to evaluate whether these cognitive gains are accompanied by training-related changes in task-related DMN deactivation. Given the evidence for heterogeneity of the DMN, we examine task-related activation/deactivation within two separate DMN branches, a ventral branch related to episodic memory and a dorsal branch more closely resembling the canonical DMN. Participants underwent functional magnetic resonance imaging (fMRI) while performing an untrained object-location memory task at four time points before, during, and after the training period. Task-induced (de)activation values were extracted for the ventral and dorsal DMN branches at each time point. Relative to visual fixation baseline: (i) the dorsal DMN was deactivated during the scanner task, while the ventral DMN was activated; (ii) the object-location memory training group exhibited an increase in dorsal DMN deactivation relative to the active control group over the course of training and follow-up; (iii) changes in dorsal DMN deactivation did not correlate with task improvement. These results indicate a training-related enhancement of task-induced deactivation of the dorsal DMN, although the specificity of this improvement to the cognitive task performed in the scanner is not clear.

Background:Non-linear alterations in brain network connectivity may represent early neural signatures of Alzheimer’s disease (AD) pathology in cognitively normal older adults. Understanding these changes and their cognitive relevance could provide sensitive biomarkers for early detection. Most prior studies recruited participants from memory clinics, often with subjective memory concerns, limiting generalizability.Methods:We examined 14 large-scale functional brain networks in 968 cognitively normal older adults recruited from the community using resting-state functional MRI, cerebrospinal fluid (CSF) biomarkers (amyloid-β 1–42 [Aβ], total tau, phosphorylated tau 181), and neuropsychological assessments. Functional networks were identified using group independent component analysis.Results:Inverted U-shaped associations between CSF Aβ and functional connectivity were observed in the precuneus network and ventral default mode network (DMN), but not in the dorsal DMN, indicating network-specific vulnerability to early amyloid pathology. Higher connectivity in Aβ-related networks, including dorsal and ventral DMN, precuneus, and posterior salience networks, was associated with better visual memory, visuospatial, and executive performance. No significant relationships were observed between CSF tau and functional connectivity.Conclusions:Using a large, community-based cohort, we demonstrate that non-linear alterations in functional connectivity occur in specific networks even during the asymptomatic phase of AD. Moreover, Aβ-related network connectivity is cognitively relevant, highlighting functional brain networks as promising imaging markers for early detection and prognosis of AD.

Brain Major depressive disorder (MDD) is a major psychological disorder worldwide. Suicide ideation is one of the most serious side effects of MDD. Suicide attempt in normal people is about 15 individuals in 100,000 but in people with MDD, this reaches 15,000 persons in 100,000. In this study, we investigated the effects of the transcranial magnetic stimulation (TMS) on network-based whole-brain connectivity in an MDD patient with suicide ideation. We implemented a combination of weight-adjusted second order blind identification (WASOBI) and efficient fast independent component analysis (EFICA) algorithms, called COMBI, as a promising method for identifying independent components in the resting-state fMRI data (rsfMRI) of a female subject. We performed group information guided independent component analysis (GIG-ICA) as a back-reconstruction step and then extracted the functional connectivity (FC). The results showed significant changes in specific brain networks. Functional connectivity increased between the following networks after TMS: sensorimotor and language; left executive control network (ECN) and language; dorsal DMN and auditory; and dorsal default mode network (DMN) and basal ganglia. Besides, ventral DMN and language networks illustrated decrement in connectivity. To the best of our knowledge, this is the first study that has investigated the network-based functional connectivity in an MDD patient with Suicide Ideation (SI) throughout long-term treatment.

In this study, we investigated changes in resting state networks (RSNs) in patients with gliomas located in the left hemisphere and its relation to cognitive function. We hypothesized that long distance connection, especially between hemispheres, would be affected by the presence of the tumor. We further hypothesized that these changes would correlate with, or reflect cognitive changes observed in patients with gliomas. Resting state functional MRI datasets from 12 patients and 12 healthy controls were used in the analysis. The tumor’s effect on three well-known RSNs including the default mode network (DMN), executive control network (ECN), and salience network (SN) identified using independent component analysis were investigated using dual regression analysis. Scores of neuropsychometric testing (WAIS-III and WMS-R) were also compared. Compared to the healthy control group, the patient group showed significant decrease in functional connectivity in the right angular gyrus/inferior parietal lobe of the ventral DMN and in the dorsolateral prefrontal cortex of the left ECN, whereas a significant increase in connectivity in the right ECN was observed in the right parietal lobe. Changes in connectivity in the right ECN correlated with spatial memory, while that on the left ECN correlated with attention. Connectivity changes in the ventral DMN correlated with attention, working memory, full IQ, and verbal IQ measures. Although the tumors were localized in the left side of the brain, changes in connectivity were observed in the contralateral side. Moreover, these changes correlated with some aspects of cognitive function indicating that patients with gliomas may undergo cognitive changes even in the absence of or before the onset of major symptoms. Evaluation of resting state networks could be helpful in advancing our hodological understanding of brain function in glioma cases.

Understanding the patterns of brain glucose metabolism and connectivity in hypoxic-ischemic encephalopathy (HIE) patients with prolonged disorders of consciousness (DOC) may be of positive significance to the accurate assessment of consciousness and the optimization of neuromodulation strategy. We retrospectively analyzed the brain glucose metabolism pattern and its correlation with clinical Coma Recovery Scale-Revised (CRS-R) score in six HIE patients with prolonged DOC who had undergone 18F-deoxyglucose brain positron emission tomography scanning (FDG-PET). We also compared the differences in global metabolic connectivity patterns and the characteristics of several brain networks between HIE patients and healthy controls (HC). The metabolism of multiple brain regions decreased significantly in HIE patients, and the degree of local metabolic preservation was correlated with CRS-R score. The internal metabolic connectivity of occipital lobe and limbic system in HIE patients decreased, and their metabolic connectivity with frontal lobe, parietal lobe and temporal lobe also decreased. The metabolic connectivity patterns of default mode network, dorsal attention network, salience network, executive control network and subcortex network of HIE also changed compared with HC. The present study suggested that pattern of cerebral glucose metabolism and network connectivity of HIE patients with prolonged DOC were significantly different from those of healthy people.