New resting-state fMRI related studies at PubMed

Subscribe to New resting-state fMRI related studies at PubMed feed New resting-state fMRI related studies at PubMed
NCBI: db=pubmed; Term=resting state fMRI
Updated: 6 hours 17 min ago

Effects of spatial smoothing on functional brain networks.

Tue, 09/19/2017 - 15:00
Related Articles

Effects of spatial smoothing on functional brain networks.

Eur J Neurosci. 2017 Sep 18;:

Authors: Alakörkkö T, Saarimäki H, Glerean E, Saramäki J, Korhonen O

Abstract
Graph-theoretical methods have rapidly become a standard tool in studies of the structure and function of the human brain. Whereas the structural connectome can be fairly straightforwardly mapped onto a complex network, there are more degrees of freedom in constructing networks that represent functional connections between brain areas. For fMRI data, such networks are typically built by aggregating the BOLD signal time series of voxels into larger entities (such as Regions of Interest in some brain atlas), and determining their connection strengths from some measure of time-series correlations. Although it is evident that the outcome must be affected by how the voxel-level time series are treated at the preprocessing stage, there is a lack of systematic studies of the effects of preprocessing on network structure. Here, we focus on the effects of spatial smoothing, a standard preprocessing method for fMRI. We apply various levels of spatial smoothing to resting-state fMRI data and measure the changes induced in functional networks. We show that the level of spatial smoothing clearly affects the degrees and other centrality measures of functional network nodes; these changes are non-uniform, systematic, and depend on the geometry of the brain. The composition of the largest connected network component is also affected in a way that artificially increases the similarity of the networks of different subjects. Our conclusion is that wherever possible, spatial smoothing should be avoided when preprocessing fMRI data for network analysis. This article is protected by copyright. All rights reserved.

PMID: 28922510 [PubMed - as supplied by publisher]

Altered Gray Matter Volume, Cerebral Blood Flow and Functional Connectivity in Chronic Stroke Patients.

Tue, 09/19/2017 - 15:00
Related Articles

Altered Gray Matter Volume, Cerebral Blood Flow and Functional Connectivity in Chronic Stroke Patients.

Neurosci Lett. 2017 Sep 14;:

Authors: Miao P, Wang C, Li P, Wei S, Deng C, Zheng D, Cheng J

Abstract
It is entangled connections and intensive functional interactions between cortex and subcortical structures that enable our brain to perform delicate movement, and poses plasticity to recover from stroke. However, it is still unclear how cortical structures and functions change in well-recovered patients from subcortical infarctions in motor pathway. In order to reveal neuroplasticity underlying well-recovered stroke patients, both structural (gray matter volume, GMV) and functional reorganizations (cerebral blood flow, CBF and resting-state functional connectivity, rsFC) were investigated by using multi-modal MRI. Our results showed that well-recovered stroke patients exhibited significantly increased GMV in contralesional supplementary motor area (SMA), increased CBFs in contralesional superior frontal gyrus (SFG) and supramarginal gyrus (SMG) irrespective of GMV correction. Furthermore, our results showed increased rsFC between contralesional middle temporal gyrus (MTG) and SMG. Negative correlations between CBF increases and behavior test scores were also observed, suggesting neural mechanism underlying clinical improvement. Our results suggested that neuroplasticity after chronic stroke showed in both structural and functional levels, and correlation between CBF change and clinical test suggested possible biomarker for stroke recovery.

PMID: 28919535 [PubMed - as supplied by publisher]

Cognitive control networks in OCD: A resting-state connectivity study in unmedicated patients with obsessive-compulsive disorder and their unaffected relatives.

Tue, 09/19/2017 - 15:00
Related Articles

Cognitive control networks in OCD: A resting-state connectivity study in unmedicated patients with obsessive-compulsive disorder and their unaffected relatives.

World J Biol Psychiatry. 2017 Sep 18;:1-13

Authors: de Vries FE, de Wit SJ, van den Heuvel OA, Veltman DJ, Cath DC, van Balkom AJLM, van der Werf YD

Abstract
OBJECTIVES: Executive network deficits are putative neurocognitive endophenotypes for obsessive-compulsive disorder (OCD). Yet, unlike alterations in fronto-striatal and limbic connectivity, connectivity in the fronto-parietal (FPN) and cingulo-opercular (CON) networks involved in cognitive control has received little attention.
METHODS: The coherence of FPN, CON and fronto-limbic networks was investigated in 39 unmedicated OCD patients, 16 of their unaffected siblings and 36 healthy controls using resting-state functional-connectivity MRI and a seed-based analysis approach.
RESULTS: FPN and CON connectivity was similar for patients and controls. Siblings showed higher connectivity than patients within the CON, and between the CON and FPN compared to patients and controls (trend level). In OCD patients, but not in siblings, fronto-limbic hyperconnectivity was present compared to controls. In contrast to our expectations, no group differences in resting-state connectivity of the cognitive control networks were observed between OCD patients and controls.
CONCLUSIONS: The increased within- and between-network connectivity in siblings, but not in patients, could indicate a mechanism of increased cognitive control that may act as a protective mechanism. None of the observed network alterations can be considered an endophenotype for OCD since differences were present in either patients or siblings, but not in both groups.

PMID: 28918693 [PubMed - as supplied by publisher]

Selective functional dysconnectivity of the dorsal-anterior subregion of the precuneus in drug-naive major depressive disorder.

Sun, 09/17/2017 - 12:40
Related Articles

Selective functional dysconnectivity of the dorsal-anterior subregion of the precuneus in drug-naive major depressive disorder.

J Affect Disord. 2017 Aug 30;225:676-683

Authors: Zhu J, Lin X, Lin C, Zhuo C, Yu Y

Abstract
BACKGROUND: Patients with major depressive disorder (MDD) have shown altered resting-state functional connectivity (rsFC) of the precuneus; however, it is unknown whether rsFC of the precuneus subregions is differentially affected in this disorder.
METHODS: In this study, we aimed to clarify this issue by comparing rsFC of each precuneus subregion between patients with MDD and healthy controls. Forty-seven drug-naive patients with MDD and 47 sex-, age- and education-matched healthy controls underwent resting-state functional magnetic resonance imaging (fMRI). The precuneus was divided into PCun-1 (dorsal-central portion; medial area 7), PCun-2 (dorsal-anterior portion; medial area 5), PCun-3 (dorsal-posterior portion; dorsomedial parietooccipital sulcus) and PCun-4 (ventral portion; area 31). The rsFC of each precuneus subregion was compared between the two groups.
RESULTS: Compared with healthy controls, patients with MDD exhibited increased rsFC between the left PCun-2 and the right fusiform gyrus, lateral prefrontal cortex, sensorimotor cortex and supramarginal gyrus. No significant inter-group difference was observed in the rsFC of other precuneus subregions. In addition, there was no difference in gray matter volume of all the precuneus subregions between patients with MDD and healthy controls.
LIMITATIONS: Some of the patients had chronic MDD and relevant neuropsychological data were not collected.
CONCLUSIONS: These findings suggest a selective functional dysconnectivity of the precuneus subregions in drug-naive MDD, characterized by the hyperconnnectivity between the dorsal-anterior subregion and regions involved in visual, executive control, sensorimotor and bottom-up attention functions.

PMID: 28917194 [PubMed - as supplied by publisher]

Direct modulation of aberrant brain network connectivity through real-time neurofeedback.

Sun, 09/17/2017 - 12:40
Related Articles

Direct modulation of aberrant brain network connectivity through real-time neurofeedback.

Elife. 2017 Sep 16;6:

Authors: Ramot M, Kimmich S, Gonzalez-Castillo J, Roopchansingh V, Popal H, White E, Gotts SJ, Martin A

Abstract
The existence of abnormal connectivity patterns between resting state networks in neuropsychiatric disorders, including Autism Spectrum Disorder (ASD), has been well established. Traditional treatment methods in ASD are limited, and do not address the aberrant network structure. Using real-time fMRI neurofeedback, we directly trained 3 brain nodes in participants with ASD, in which the aberrant connectivity has been shown to correlate with symptom severity. Desired network connectivity patterns were reinforced in real-time, without participants' awareness of the training taking place. This training regimen produced large, significant long-term changes in correlations at the network level, and whole brain analysis revealed that the greatest changes were focused on the areas being trained. These changes were not found in the control group. Moreover, changes in ASD resting state connectivity following the training were correlated to changes in behavior, suggesting that neurofeedback can be used to directly alter complex, clinically relevant network connectivity patterns.

PMID: 28917059 [PubMed - as supplied by publisher]

Early-Life Stress Modulates Neural Networks Associated with Habitual Use of Reappraisal.

Sun, 09/17/2017 - 12:40
Related Articles

Early-Life Stress Modulates Neural Networks Associated with Habitual Use of Reappraisal.

Behav Brain Res. 2017 Sep 12;:

Authors: Khawli EE, Fan Y, Aust S, Wirth K, Bönke L, Stevense A, Herrera A, Metz S, Loayza A, Bajbouj M, Grimm S

Abstract
Recent evidence shows that early life stress (ELS) is associated with altered resting-state functional connectivity (RSFC) between amygdala and the prefrontal cortex, as well as with maladaptive emotion regulation strategies and negative mood. However, the relation between ELS and maladaptive emotion regulation is not deterministic. Adaptive emotion regulation strategies such as reappraisal can also ensue from experience and learning in adulthood and can prevent negative mood. The present study aims to investigate the joint influence of ELS, in particular early-life emotional abuse (EA), and habitual use of reappraisal on amygdala-centered RSFC and mood. We examined amygdala-centered RSFC using functional magnetic resonance imaging (fMRI) in 28 healthy adults with varied exposure to early-life emotional abuse. We found that in subjects with high early-life emotional abuse, reappraisal was predominantly associated with RSFC between left centromedial amygdala (CMA) and the ventrolateral prefrontal cortex (VLPFC), whereas in subjects with low early-life EA reappraisal predominantly involved RSFC between right CMA, premotor and supplementary motor regions. For subjects with high EA, reappraisal use was associated with a decrease in negative mood whereas it was associated with an increase in positive mood for subjects with low EA. The general findings of the study suggest that reappraisal use might act as a protective factor, notably for individuals who were exposed to ELS, and that this is mediated by alteration of amygdala-centered RSFC.

PMID: 28916500 [PubMed - as supplied by publisher]

Replicability of time-varying connectivity patterns in large resting state fMRI samples.

Sun, 09/17/2017 - 12:40
Related Articles

Replicability of time-varying connectivity patterns in large resting state fMRI samples.

Neuroimage. 2017 Sep 12;:

Authors: Abrol A, Damaraju E, Miller RL, Stephen JM, Claus ED, Mayer AR, Calhoun VD

Abstract
The past few years have seen an emergence of approaches that leverage temporal changes in whole-brain patterns of functional connectivity (the chronnectome). In this chronnectome study, we investigate the replicability of the human brain's inter-regional coupling dynamics during rest by evaluating two different dynamic functional network connectivity (dFNC) analysis frameworks using 7 500 functional magnetic resonance imaging (fMRI) datasets. To quantify the extent to which the emergent functional connectivity (FC) patterns are reproducible, we characterize the temporal dynamics by deriving several summary measures across multiple large, independent age-matched samples. Reproducibility was demonstrated through the existence of basic connectivity patterns (FC states) amidst an ensemble of inter-regional connections. Furthermore, application of the methods to conservatively configured (statistically stationary, linear and Gaussian) surrogate datasets revealed that some of the studied state summary measures were indeed statistically significant and also suggested that this class of null model did not explain the fMRI data fully. This extensive testing of reproducibility of similarity statistics also suggests that the estimated FC states are robust against variation in data quality, analysis, grouping, and decomposition methods. We conclude that future investigations probing the functional and neurophysiological relevance of time-varying connectivity assume critical importance.

PMID: 28916181 [PubMed - as supplied by publisher]

Interpreting temporal fluctuations in resting-state functional connectivity MRI.

Sun, 09/17/2017 - 12:40
Related Articles

Interpreting temporal fluctuations in resting-state functional connectivity MRI.

Neuroimage. 2017 Sep 12;:

Authors: Liégeois R, Laumann TO, Snyder AZ, Zhou J, Yeo BTT

Abstract
Resting-state functional connectivity is a powerful tool for studying human functional brain networks. Temporal fluctuations in functional connectivity, i.e., dynamic functional connectivity (dFC), are thought to reflect dynamic changes in brain organization and non-stationary switching of discrete brain states. However, recent studies have suggested that dFC might be attributed to sampling variability of static FC. Despite this controversy, a detailed exposition of stationarity and statistical testing of dFC is lacking in the literature. This article seeks an in-depth exploration of these statistical issues at a level appealing to both neuroscientists and statisticians. We first review the statistical notion of stationarity, emphasizing its reliance on ensemble statistics. In contrast, all FC measures depend on sample statistics. An important consequence is that the space of stationary signals is much broader than expected, e.g., encompassing hidden markov models (HMM) widely used to extract discrete brain states. In other words, stationarity does not imply the absence of brain states. We then expound the assumptions underlying the statistical testing of dFC. It turns out that the two popular frameworks - phase randomization (PR) and autoregressive randomization (ARR) - generate stationary, linear, Gaussian null data. Therefore, statistical rejection can be due to non-stationarity, nonlinearity and/or non-Gaussianity. For example, the null hypothesis can be rejected for the stationary HMM due to nonlinearity and non-Gaussianity. Finally, we show that a common form of ARR (bivariate ARR) is susceptible to false positives compared with PR and an adapted version of ARR (multivariate ARR). Application of PR and multivariate ARR to Human Connectome Project data suggests that the stationary, linear, Gaussian null hypothesis cannot be rejected for most participants. However, failure to reject the null hypothesis does not imply that static FC can fully explain dFC. We find that first order AR models explain temporal FC fluctuations significantly better than static FC models. Since first order AR models encode both static FC and one-lag FC, this suggests the presence of dynamical information beyond static FC. Furthermore, even in subjects where the null hypothesis was rejected, AR models explain temporal FC fluctuations significantly better than a popular HMM, suggesting the lack of discrete states (as measured by resting-state fMRI). Overall, our results suggest that AR models are not only useful as a means for generating null data, but may be a powerful tool for exploring the dynamical properties of resting-state fMRI. Finally, we discuss how apparent contradictions in the growing dFC literature might be reconciled.

PMID: 28916180 [PubMed - as supplied by publisher]

A Combined Study of SLC6A15 Gene Polymorphism and the Resting-State Functional Magnetic Resonance Imaging in First-Episode Drug-Naive Major Depressive Disorder.

Sat, 09/16/2017 - 12:00
Related Articles

A Combined Study of SLC6A15 Gene Polymorphism and the Resting-State Functional Magnetic Resonance Imaging in First-Episode Drug-Naive Major Depressive Disorder.

Genet Test Mol Biomarkers. 2017 Sep;21(9):523-530

Authors: Wang L, Liu Z, Cao X, Li J, Zhang A, Sun N, Yang C, Zhang K

Abstract
AIMS: The SLC6A15 gene has been identified as a novel candidate gene for major depressive disorder (MDD). However, the mechanism underlying the effects of how the SLC6A15 gene affects functional brain activity of patients with MDD remains unknown.
METHODS: In the present study, we investigated the effect of the SLC6A15 gene polymorphism, rs1545843, on resting-state brain function in MDD with the imaging genomic technology and the regional homogeneity (ReHo) method. Sixty-seven MDD patients and 44 healthy controls underwent functional magnetic resonance imaging scans and genotyping. The differences in ReHo between genotypes were initially tested using the student's t test. We then performed a 2 × 2 (genotypes × disease status) analysis of variance to identify the main effects of genotypes, disease status, and their interactions in MDD.
RESULTS: MDD patients with A+ genotypes showed decreased ReHo in the medial cingulum compared with MDD patients with the GG genotype. This was in contrast to normal controls with A+ genotypes who showed increased ReHo in the posterior cingulum and the frontal, temporal, and parietal lobes and decreased ReHo in the left corpus callosum, compared with controls with the GG genotypes. The main effect of disease was found in the frontal, parietal, and temporal lobes. The main effect of genotypes was found in the left corpus callosum and the frontal lobe. There was no interaction between rs1545843 genotypes and disease status. We found that the left corpus callosum ReHo was positively correlated with total scores of the Hamilton Depression Scale (HAMD) (p = 0.021), so as was the left inferior parietal gyrus ReHo with cognitive disorder (p = 0.02). In addition, the right middle temporal gyrus had a negative correlation with retardation (p = 0.049).
CONCLUSION: We observed an association between the SLC6A15 rs1545843 and resting-state brain function of the corpus callosum, cingulum and the frontal, parietal, and temporal lobes in MDD patients, which may be involved in the pathogenesis of MDD.

PMID: 28915082 [PubMed - in process]

Age-related resting-state functional connectivity in the olfactory and trigeminal networks.

Sat, 09/16/2017 - 12:00
Related Articles

Age-related resting-state functional connectivity in the olfactory and trigeminal networks.

Neuroreport. 2017 Oct 18;28(15):943-948

Authors: Karunanayaka P, Tobia MJ, Yang QX

Abstract
Brain networks for intranasal chemosensation have been shown to be intrinsically organized in humans . However, little is known about how changes in the intrinsic functional connectivity (FC) in chemosensory networks are related to aging. We, therefore, investigated the impact of age on resting-state FC in the olfactory and trigeminal networks (ON and TN) by combining two freely available resting-state fMRI data sets (obtained from the NITRC.org; Atlanta and New York) with data collected in our lab to generate a large sample size (N=103; 51 women) spanning the age range of 20-61 years. Seed regions were defined using Montreal Neurological Institute's coordinates that anchor ON and TN in activation studies and meta-analyses. The ON included the piriform cortex and the oribtofrontal cortex. The TN included the anterior insula and the cingulate cortex. Scanner site, sex, and age were used as covariates in group-level analyses. The FC between the ON and the parahippocampal gyrus was correlated negatively with age. The FC between the TN and the parahippocampal gyrus, however, was positively correlated. Similarly, age was correlated positively with the ON FC to the ventral striatum and the TN FC to the default mode network. These results reflect divergent age-related alterations in the intrinsic FC of the human chemosensory system.

PMID: 28914738 [PubMed - in process]

Identify a shared neural circuit linking multiple neuropsychiatric symptoms with Alzheimer's pathology.

Sat, 09/16/2017 - 12:00
Related Articles

Identify a shared neural circuit linking multiple neuropsychiatric symptoms with Alzheimer's pathology.

Brain Imaging Behav. 2017 Sep 15;:

Authors: Wang X, Ren P, Mapstone M, Conwell Y, Porsteinsson AP, Foxe JJ, Raizada RDS, Lin F, and the Alzheimer’s Disease Neuroimaging Initiative

Abstract
Neuropsychiatric symptoms (NPS) are common in Alzheimer's disease (AD)-associated neurodegeneration. However, NPS lack a consistent relationship with AD pathology. It is unknown whether any common neural circuits can link these clinically disparate while mechanistically similar features with AD pathology. Here, we explored the neural circuits of NPS in AD-associated neurodegeneration using multivariate pattern analysis (MVPA) of resting-state functional MRI data. Data from 98 subjects (70 amnestic mild cognitive impairment and 28 AD subjects) were obtained. The top 10 regions differentiating symptom presence across NPS were identified, which were mostly the fronto-limbic regions (medial prefrontal cortex, caudate, etc.). These 10 regions' functional connectivity classified symptomatic subjects across individual NPS at 69.46-81.27%, and predicted multiple NPS (indexed by Neuropsychiatric Symptom Questionnaire-Inventory) and AD pathology (indexed by baseline and change of beta-amyloid/pTau ratio) all above 70%. Our findings suggest a fronto-limbic dominated neural circuit that links multiple NPS and AD pathology. With further examination of the structural and pathological changes within the circuit, the circuit may shed light on linking behavioral disturbances with AD-associated neurodegeneration.

PMID: 28913718 [PubMed - as supplied by publisher]

General and selective brain connectivity alterations in essential tremor: A resting state fMRI study.

Sat, 09/16/2017 - 12:00
Related Articles

General and selective brain connectivity alterations in essential tremor: A resting state fMRI study.

Neuroimage Clin. 2017;16:468-476

Authors: Mueller K, Jech R, Hoskovcová M, Ulmanová O, Urgošík D, Vymazal J, Růžička E

Abstract
Although essential tremor is the most common movement disorder, there is little knowledge about the pathophysiological mechanisms of this disease. Therefore, we explored brain connectivity based on slow spontaneous fluctuations of blood oxygenation level dependent (BOLD) signal in patients with essential tremor (ET). A cohort of 19 ET patients and 23 healthy individuals were scanned in resting condition using functional magnetic resonance imaging (fMRI). General connectivity was assessed by eigenvector centrality (EC) mapping. Selective connectivity was analyzed by correlations of the BOLD signal between the preselected seed regions and all the other brain areas. These measures were then correlated with the tremor severity evaluated by the Fahn-Tolosa-Marin Tremor Rating Scale (FTMTS). Compared to healthy subjects, ET patients were found to have lower EC in the cerebellar hemispheres and higher EC in the anterior cingulate and in the primary motor cortices bilaterally. In patients, the FTMTS score correlated positively with the EC in the putamen. In addition, the FTMTS score correlated positively with selective connectivity between the thalamus and other structures (putamen, pre-supplementary motor area (pre-SMA), parietal cortex), and between the pre-SMA and the putamen. We observed a selective coupling between a number of areas in the sensorimotor network including the basal ganglia and the ventral intermediate nucleus of thalamus, which is widely used as neurosurgical target for tremor treatment. Finally, ET was marked by suppression of general connectivity in the cerebellum, which is in agreement with the concept of ET as a disorder with cerebellar damage.

PMID: 28913163 [PubMed - in process]

Functional Connectivity of the Corpus Callosum in Epilepsy Patients with Secondarily Generalized Seizures.

Sat, 09/16/2017 - 12:00
Related Articles

Functional Connectivity of the Corpus Callosum in Epilepsy Patients with Secondarily Generalized Seizures.

Front Neurol. 2017;8:446

Authors: Peng SJ, Hsin YL

Abstract
The corpus callosum (CC) plays an important role in generalization of seizure activity. We used resting-state function magnetic resonance imaging (rs-fMRI) to investigate the regional and interregional functional connectivity of CC in patients with magnetic resonance imaging (MRI)-negative and secondarily generalized seizures. We measured the multi-regional coherences of blood oxygen level-dependent (BOLD) signals via rs-fMRI, cortical thickness via high-resolution T1-weighted MRI, and white matter (WM) integrity via diffusion-tensor imaging in 16 epilepsy patients as well as in 16 age- and gender-matched healthy subjects. All patients had non-lesional MRI, medically well-controlled focal epilepsy and history of secondarily generalized convulsions. Individuals with epilepsy had significant differences in regional and interregional hypersynchronization of BOLD signals intrahemispherically and interhemispherically, but no difference in cortical thickness and WM integrity. The only area with increased regional hypersynchrony in WM was over the anterior CC, which also exhibited lower activation of neighboring resting-state networks. The present study revealed abnormal local and distant synchronization of spontaneous neural activities in epileptic patients with secondarily generalized seizures.

PMID: 28912749 [PubMed]

Intrinsic neural network dysfunction in quiescent Crohn's Disease.

Sat, 09/16/2017 - 12:00
Related Articles

Intrinsic neural network dysfunction in quiescent Crohn's Disease.

Sci Rep. 2017 Sep 14;7(1):11579

Authors: Thomann AK, Griebe M, Thomann PA, Hirjak D, Ebert MP, Szabo K, Reindl W, Wolf RC

Abstract
Psychological factors and comorbidities play an important role in inflammatory bowel diseases. Such comorbidity could be associated with a specific neural phenotype. Brain regions associated with emotion regulation and self-referential processing, including areas assigned to the "default mode network" (DMN), could be promising candidates in this regard. We investigated the functional integrity of multiple intrinsic neural networks in remitted patients with Crohn's disease (CD) and sought to establish relationships between neural network connectivity and psychiatric symptoms. Fifteen CD patients in remission and 14 controls were investigated. We employed resting-state functional magnetic resonance imaging (fMRI) at 3 Tesla followed by a spatial Independent Component Analysis for fMRI data. Abnormal connectivity in CD patients was observed in DMN subsystems only (p < 0.05, cluster-corrected). Increased connectivity was found in the anterior cingulate and left superior medial frontal gyrus (aDMN) and the middle cingulate cortex (pDMN). Middle cingulate activity showed a significant association with anxiety scores in patients (p = 0.029). This study provides first evidence of selectively disrupted intrinsic neural network connectivity in CD and suggests abnormalities of self-referential neural networks. An increased sensitivity to self-related affective and somatic states in CD patients could account for these findings and explain a higher risk for anxiety symptoms.

PMID: 28912568 [PubMed - in process]

Predictive models of minimal hepatic encephalopathy for cirrhotic patients based on large-scale brain intrinsic connectivity networks.

Sat, 09/16/2017 - 12:00
Related Articles

Predictive models of minimal hepatic encephalopathy for cirrhotic patients based on large-scale brain intrinsic connectivity networks.

Sci Rep. 2017 Sep 14;7(1):11512

Authors: Jiao Y, Wang XH, Chen R, Tang TY, Zhu XQ, Teng GJ

Abstract
We aimed to find the most representative connectivity patterns for minimal hepatic encephalopathy (MHE) using large-scale intrinsic connectivity networks (ICNs) and machine learning methods. Resting-state fMRI was administered to 33 cirrhotic patients with MHE and 43 cirrhotic patients without MHE (NMHE). The connectivity maps of 20 ICNs for each participant were obtained by dual regression. A Bayesian machine learning technique, called Graphical Model-based Multivariate Analysis, was applied to determine ICN regions that characterized group differences. The most representative ICNs were evaluated by the performance of three machine learning methods (support vector machines (SVMs), multilayer perceptrons (MLP), and C4.5). The clinical significance of these potential biomarkers was further tested. The temporal lobe network (TLN), and subcortical network (SCN), and sensorimotor network (SMN) were selected as representative ICNs. The distinct functional integration patterns of the representative ICNs were significantly correlated with behavior criteria and Child-Pugh scores. Our findings suggest the representative ICNs based on GAMMA can distinguish MHE from NMHE and provide supplementary information to current MHE diagnostic criteria.

PMID: 28912425 [PubMed - in process]

Sensory overload and imbalance: Resting-state vestibular connectivity in PTSD and its dissociative subtype.

Sat, 09/16/2017 - 12:00
Related Articles

Sensory overload and imbalance: Resting-state vestibular connectivity in PTSD and its dissociative subtype.

Neuropsychologia. 2017 Sep 11;:

Authors: Harricharan S, Nicholson AA, Densmore M, Théberge J, McKinnon MC, Neufeld RWJ, Lanius RA

Abstract
BACKGROUND: The vestibular system integrates multisensory information to monitor one's bodily orientation in space, and is influenced by interoceptive awareness. Post-traumatic stress disorder (PTSD) involves typically alterations in interoceptive and bodily self-awareness evidenced by symptoms of hyperarousal, as well as of emotional detachment, including emotional numbing, depersonalization, and derealization. These alterations may disrupt vestibular multisensory integration between the brainstem (vestibular nuclei) and key vestibular cortical regions (parieto-insular vestibular cortex, prefrontal cortex). Accordingly, this study examined functional connectivity of the vestibular system in PTSD and its dissociative subtype.
METHODS: Using resting-state fMRI data in SPM12 and PickAtlas, a seed-based analysis was employed to examine vestibular nuclei functional connectivity differences among PTSD (PTSD, n=60), PTSD dissociative subtype (PTSD+DS, n=41) and healthy controls (n=40).
RESULTS: Increased vestibular nuclei functional connectivity with the parieto-insular vestibular cortex and the dorsolateral prefrontal cortex (dlPFC) was observed in PTSD and in controls as compared to PTSD+DS, and greater connectivity with the posterior insula was observed in controls as compared to PTSD. Interestingly, whereas PTSD symptom severity correlated negatively with dlPFC connectivity, clinical measures of depersonalization/derealization correlated negatively with right supramarginal gyrus connectivity.
DISCUSSION: Taken together, decreased vestibular nuclei functional connectivity with key cortical vestibular regions in the PTSD+DS as compared to PTSD group, and its negative correlations with PTSD and dissociative symptoms, suggest that dysregulation of vestibular multisensory integration may contribute to the unique symptom profiles of each group. Further research examining disruption of vestibular system neural circuitry in PTSD and its dissociative subtype will be critical in capturing the neurophenomenology of PTSD symptoms and in identifying psychotherapeutic techniques that target dysfunction related to the vestibular system.

PMID: 28911803 [PubMed - as supplied by publisher]

Fatigue in multiple sclerosis: The contribution of resting-state functional connectivity reorganization.

Sat, 09/16/2017 - 12:00
Related Articles

Fatigue in multiple sclerosis: The contribution of resting-state functional connectivity reorganization.

Mult Scler. 2017 Sep 01;:1352458517730932

Authors: Bisecco A, Nardo FD, Docimo R, Caiazzo G, d'Ambrosio A, Bonavita S, Capuano R, Sinisi L, Cirillo M, Esposito F, Tedeschi G, Gallo A

Abstract
OBJECTIVES: To investigate resting-state functional connectivity (RS-FC) of the default-mode network (DMN) and of sensorimotor network (SMN) network in relapsing remitting (RR) multiple sclerosis (MS) patients with fatigue (F) and without fatigue(NF).
METHODS: In all, 59 RRMS patients and 29 healthy controls (HC) underwent magnetic resonance imaging (MRI) protocol including resting-state fMRI (RS-fMRI). Functional connectivity of the DMN and SMN was evaluated by independent component analysis (ICA). A linear regression analysis was performed to explore whether fatigue was mainly driven by changes observed in the DMN or in the SMN. Regional gray matter atrophy was assessed by voxel-based morphometry (VBM).
RESULTS: Compared to HC, F-MS patients showed a stronger RS-FC in the posterior cingulate cortex (PCC) and a reduced RS-FC in the anterior cingulated cortex (ACC) of the DMN. F-MS patients, compared to NF-MS patients, revealed (1) an increased RS-FC in the PCC and a reduced RS-FC in the ACC of the DMN and (2) an increased RS-FC in the primary motor cortex and in the supplementary motor cortex of the SMN. The regression analysis suggested that fatigue is mainly driven by RS-FC changes of the DMN.
CONCLUSIONS: Fatigue in RRMS is mainly associated to a functional rearrangement of non-motor RS networks.

PMID: 28911257 [PubMed - as supplied by publisher]

Aberrant Hyperconnectivity in the Motor System at Rest Is Linked to Motor Abnormalities in Schizophrenia Spectrum Disorders.

Sat, 09/16/2017 - 12:00
Related Articles

Aberrant Hyperconnectivity in the Motor System at Rest Is Linked to Motor Abnormalities in Schizophrenia Spectrum Disorders.

Schizophr Bull. 2017 Sep 01;43(5):982-992

Authors: Walther S, Stegmayer K, Federspiel A, Bohlhalter S, Wiest R, Viher PV

Abstract
Motor abnormalities are frequently observed in schizophrenia and structural alterations of the motor system have been reported. The association of aberrant motor network function, however, has not been tested. We hypothesized that abnormal functional connectivity would be related to the degree of motor abnormalities in schizophrenia. In 90 subjects (46 patients) we obtained resting stated functional magnetic resonance imaging (fMRI) for 8 minutes 40 seconds at 3T. Participants further completed a motor battery on the scanning day. Regions of interest (ROI) were cortical motor areas, basal ganglia, thalamus and motor cerebellum. We computed ROI-to-ROI functional connectivity. Principal component analyses of motor behavioral data produced 4 factors (primary motor, catatonia and dyskinesia, coordination, and spontaneous motor activity). Motor factors were correlated with connectivity values. Schizophrenia was characterized by hyperconnectivity in 3 main areas: motor cortices to thalamus, motor cortices to cerebellum, and prefrontal cortex to the subthalamic nucleus. In patients, thalamocortical hyperconnectivity was linked to catatonia and dyskinesia, whereas aberrant connectivity between rostral anterior cingulate and caudate was linked to the primary motor factor. Likewise, connectivity between motor cortex and cerebellum correlated with spontaneous motor activity. Therefore, altered functional connectivity suggests a specific intrinsic and tonic neural abnormality in the motor system in schizophrenia. Furthermore, altered neural activity at rest was linked to motor abnormalities on the behavioral level. Thus, aberrant resting state connectivity may indicate a system out of balance, which produces characteristic behavioral alterations.

PMID: 28911049 [PubMed - in process]

Identify changes of brain regional homogeneity in early and later adult onset patients with first-episode depression using resting-state fMRI.

Fri, 09/15/2017 - 15:00
Related Articles

Identify changes of brain regional homogeneity in early and later adult onset patients with first-episode depression using resting-state fMRI.

PLoS One. 2017;12(9):e0184712

Authors: Shen Z, Jiang L, Yang S, Ye J, Dai N, Liu X, Li N, Lu J, Liu F, Lu Y, Sun X, Cheng Y, Xu X

Abstract
OBJECTIVE: Previous work exhibited different brain grey matter volume (GMV) changes between patients with early adult onset depression (EOD, age 18-29) and later adult onset depression (LOD, age 30-44) by using 30-year-old as the cut-off age. To identify whether regional homogeneity (ReHo) changes are also different between EOD and LOD by using same cut-off age, we used resting-state functional magnetic resonance imaging (fMRI) to detect the abnormal ReHo between patients with EOD and LOD in the present study.
METHODS: Resting-state fMRI scans of 58 patients with EOD, 62 patients with LOD, 60 young healthy controls (HC), and 52 old HC were obtained. The ReHo approach was used to analyze the images.
RESULTS: The ANOVA analysis revealed that the ReHo values in the frontoparietal, occipital, and cerebellar regions were significantly different among the four groups. Relative to patients with LOD, patients with EOD displayed significantly increased ReHo in the left precuneus, and decreased ReHo in the right fusiform. The ReHo values in the left precuneus and the right fusiform had no significant correlation with the score of the depression rating scale or illness duration in both patient subgroups. Compared to young HC, patients with EOD showed significantly increased ReHo in the right frontoparietal regions and the right calcarine. Furthermore, the increased ReHo in the right frontoparietal regions, right insula and left hippocampus, and decreased ReHo in the left inferior occipital gyrus, right middle occipital gyrus, left calcarine, and left supplementary motor area were observed in patients with LOD when compared to old HC.
CONCLUSIONS: The ReHo of brain areas that were related to mood regulation was changed in the first-episode, drug-naive adult patients with MDD. Adult patients with EOD and LOD exhibited different ReHo abnormalities relative to each age-matched comparison group, suggesting that depressed adult patients with different age-onset might have different pathological mechanism.

PMID: 28910390 [PubMed - in process]

Altered default mode network configuration in posttraumatic stress disorder after earthquake: A resting-stage functional magnetic resonance imaging study.

Fri, 09/15/2017 - 15:00
Related Articles

Altered default mode network configuration in posttraumatic stress disorder after earthquake: A resting-stage functional magnetic resonance imaging study.

Medicine (Baltimore). 2017 Sep;96(37):e7826

Authors: Zhang XD, Yin Y, Hu XL, Duan L, Qi R, Xu Q, Lu GM, Li LJ

Abstract
The neural substrates of posttraumatic stress disorder (PTSD) are still not fully elucidated. Hence, this study is to explore topological alterations of the default mode network (DMN) in victims with PTSD after a magnitude of 8.0 earthquake using resting-state functional magnetic resonance imaging (rs-fMRI).This study was approved by the local ethical review board, and all participants signed written informed consent. Sixty-two PTSD victims from the 2008 Sichuan earthquake and 62 matched exposed controls underwent rs-fMRI. PTSD was diagnosed by Clinician-Administered PTSD Scale, and underwent PTSD Checklist-Civilian Version for symptom scoring. The DMN was analyzed by using graph theoretical approaches. Further, Pearson correlation analysis was performed to correlate neuroimaging metrics to neuropsychological scores in victims with PTSD.Victims with PTSD showed decreased DMN functional connectivity strength between the right superior frontal gyrus and left inferior parietal lobule (IPL), and showed increased functional connectivity between the right IPL and precuneus or left posterior cingulate cortex. It was also found that victims with PTSD exhibited decreased nodal efficiency in right superior frontal gyrus and precuneus, and increased nodal efficiency in right hippocampus/parahippocampus. Apart from that, PTSD showed higher nodal degree in bilateral hippocampus/parahippocampus. In addition, the functional connectivity strength between the right IPL and precuneus correlated negatively to the avoid scores (r = -0.26, P = .04).This study implicates alteration of topological features on the DMN in PTSD victims after major earthquake, and provides new insights into DMN malfunction in PTSD based on graph theory.

PMID: 28906364 [PubMed - in process]

Pages