New resting-state fMRI related studies at PubMed

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Resting state connectivity between default mode network and insula encodes acute migraine headache.

Wed, 06/14/2017 - 15:45

Resting state connectivity between default mode network and insula encodes acute migraine headache.

Cephalalgia. 2017 Jan 01;:333102417715230

Authors: Coppola G, Di Renzo A, Tinelli E, Di Lorenzo C, Scapeccia M, Parisi V, Serrao M, Evangelista M, Ambrosini A, Colonnese C, Schoenen J, Pierelli F

Abstract
Background Previous functional MRI studies have revealed that ongoing clinical pain in different chronic pain syndromes is directly correlated to the connectivity strength of the resting default mode network (DMN) with the insula. Here, we investigated seed-based resting state DMN-insula connectivity during acute migraine headaches. Methods Thirteen migraine without aura patients (MI) underwent 3 T MRI scans during the initial six hours of a spontaneous migraine attack, and were compared to a group of 19 healthy volunteers (HV). We evaluated headache intensity with a visual analogue scale and collected seed-based MRI resting state data in the four core regions of the DMN: Medial prefrontal cortex (MPFC), posterior cingulate cortex (PCC), and left and right inferior parietal lobules (IPLs), as well as in bilateral insula. Results Compared to HV, MI patients showed stronger functional connectivity between MPFC and PCC, and between MPFC and bilateral insula. During migraine attacks, the strength of MPFC-to-insula connectivity was negatively correlated with pain intensity. Conclusion We show that greater subjective intensity of pain during a migraine attack is associated with proportionally weaker DMN-insula connectivity. This is at variance with other chronic extra-cephalic pain disorders where the opposite was found, and may thus be a hallmark of acute migraine head pain.

PMID: 28605972 [PubMed - as supplied by publisher]

Olanzapine modulates the default-mode network homogeneity in recurrent drug-free schizophrenia at rest.

Wed, 06/14/2017 - 15:45

Olanzapine modulates the default-mode network homogeneity in recurrent drug-free schizophrenia at rest.

Aust N Z J Psychiatry. 2017 Jun 01;:4867417714952

Authors: Guo W, Liu F, Chen J, Wu R, Li L, Zhang Z, Chen H, Zhao J

Abstract
BACKGROUND: Previous studies on brain function alterations associated with antipsychotic treatment for schizophrenia have produced conflicting results because they used short treatment periods and different designs.
METHODS: Resting-state functional magnetic resonance imaging scans were obtained from 17 drug-free patients with recurrent schizophrenia and 24 healthy controls. The patients were treated with olanzapine for 6 months and were scanned at three time points (baseline, 6 weeks of treatment and 6 months of treatment). Network homogeneity was used to analyze the imaging data to examine default-mode network homogeneity alterations associated with antipsychotic treatment.
RESULTS: Compared with the controls, the patients at baseline showed increased network homogeneity in the bilateral precuneus and decreased network homogeneity in the bilateral middle temporal gyrus. Network homogeneity values in the bilateral precuneus decreased, and network homogeneity values in the left superior medial prefrontal cortex and the right middle temporal gyrus increased in patients administered olanzapine as antipsychotic treatment. By contrast, network homogeneity values in the left middle temporal gyrus remained unchanged in patients after treatment.
CONCLUSION: This study provides evidence that antipsychotic treatment with olanzapine modulates the default-mode network homogeneity in schizophrenia. These findings contribute to the understanding of antipsychotic treatment effects on brain functions.

PMID: 28605934 [PubMed - as supplied by publisher]

Computerized cognitive training for children with neurofibromatosis type 1: A pilot resting-state fMRI study.

Tue, 06/13/2017 - 15:20

Computerized cognitive training for children with neurofibromatosis type 1: A pilot resting-state fMRI study.

Psychiatry Res. 2017 Jun 06;266:53-58

Authors: Yoncheva YN, Hardy KK, Lurie DJ, Somandepalli K, Yang L, Vezina G, Kadom N, Packer RJ, Milham MP, Castellanos FX, Acosta MT

Abstract
In this pilot study, we examined training effects of a computerized working memory program on resting state functional magnetic resonance imaging (fMRI) measures in children with neurofibromatosis type 1 (NF1). We contrasted pre- with post-training resting state fMRI and cognitive measures from 16 participants (nine males; 11.1 ± 2.3 years) with NF1 and documented working memory difficulties. Using non-parametric permutation test inference, we found significant regionally specific differences (family-wise error corrected) in two of four voxel-wise resting state measures: fractional amplitude of low frequency fluctuations (indexing peak-to-trough intensity of spontaneous oscillations) and regional homogeneity (indexing local intrinsic synchrony). Some cognitive task improvement was observed as well. These preliminary findings suggest that regionally specific changes in resting state fMRI indices may be associated with treatment-related cognitive amelioration in NF1. Nevertheless, current results must be interpreted with caution pending independent controlled replication.

PMID: 28605662 [PubMed - as supplied by publisher]

Abnormal Resting-State Connectivity in a Substantia Nigra-Related Striato-Thalamo-Cortical Network in a Large Sample of First-Episode Drug-Naïve Patients With Schizophrenia.

Tue, 06/13/2017 - 15:20

Abnormal Resting-State Connectivity in a Substantia Nigra-Related Striato-Thalamo-Cortical Network in a Large Sample of First-Episode Drug-Naïve Patients With Schizophrenia.

Schizophr Bull. 2017 Jun 10;:

Authors: Martino M, Magioncalda P, Yu H, Li X, Wang Q, Meng Y, Deng W, Li Y, Li M, Ma X, Lane T, Duncan NW, Northoff G, Li T

Abstract
Objective: The dopamine hypothesis is one of the most influential theories of the neurobiological background of schizophrenia (SCZ). However, direct evidence for abnormal dopamine-related subcortical-cortical circuitry disconnectivity is still lacking. The aim of this study was therefore to test dopamine-related substantia nigra (SN)-based striato-thalamo-cortical resting-state functional connectivity (FC) in SCZ.
Method: Based on our a priori hypothesis, we analyzed a large sample resting-state functional magnetic resonance imaging (fMRI) dataset from first-episode drug-naïve SCZ patients (n = 112) and healthy controls (n = 82) using the SN as the seed region for an investigation of striato-thalamo-cortical FC. This was done in the standard band of slow frequency oscillations and then in its subfrequency bands (Slow4 and Slow5). Results: The analysis showed in SCZ: (1) reciprocal functional hypo-connectivity between SN and striatum, with differential patterns for Slow5 and Slow4; (2) functional hypo-connectivity between striatum and thalamus, as well as functional hyper-connectivity between thalamus and sensorimotor cortical areas, specifically in Slow4; (3) correlation of thalamo-sensorimotor functional hyper-connectivity with psychopathological symptoms. Conclusions: We demonstrate abnormal dopamine-related SN-based striato-thalamo-cortical FC in slow frequency oscillations in first-episode drug-naive SCZ. This suggests that altered dopaminergic function in the SN leads to abnormal neuronal synchronization (as indexed by FC) within subcortical-cortical circuitry, complementing the dopamine hypothesis in SCZ on the regional level of resting-state activity.

PMID: 28605528 [PubMed - as supplied by publisher]

Dynamic brain connectivity is a better predictor of PTSD than static connectivity.

Tue, 06/13/2017 - 15:20
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Dynamic brain connectivity is a better predictor of PTSD than static connectivity.

Hum Brain Mapp. 2017 Jun 12;:

Authors: Jin C, Jia H, Lanka P, Rangaprakash D, Li L, Liu T, Hu X, Deshpande G

Abstract
Using resting-state functional magnetic resonance imaging, we test the hypothesis that subjects with post-traumatic stress disorder (PTSD) are characterized by reduced temporal variability of brain connectivity compared to matched healthy controls. Specifically, we test whether PTSD is characterized by elevated static connectivity, coupled with decreased temporal variability of those connections, with the latter providing greater sensitivity toward the pathology than the former. Static functional connectivity (FC; nondirectional zero-lag correlation) and static effective connectivity (EC; directional time-lagged relationships) were obtained over the entire brain using conventional models. Dynamic FC and dynamic EC were estimated by letting the conventional models to vary as a function of time. Statistical separation and discriminability of these metrics between the groups and their ability to accurately predict the diagnostic label of a novel subject were ascertained using separate support vector machine classifiers. Our findings support our hypothesis that PTSD subjects have stronger static connectivity, but reduced temporal variability of connectivity. Further, machine learning classification accuracy obtained with dynamic FC and dynamic EC was significantly higher than that obtained with static FC and static EC, respectively. Furthermore, results also indicate that the ease with which brain regions engage or disengage with other regions may be more sensitive to underlying pathology than the strength with which they are engaged. Future studies must examine whether this is true only in the case of PTSD or is a general organizing principle in the human brain. Hum Brain Mapp, 2017. © 2017 Wiley Periodicals, Inc.

PMID: 28603919 [PubMed - as supplied by publisher]

Automatic Hippocampal Subfield Segmentation from 3T Multi-modality Images.

Tue, 06/13/2017 - 15:20
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Automatic Hippocampal Subfield Segmentation from 3T Multi-modality Images.

Mach Learn Med Imaging. 2016 Oct;10019:229-236

Authors: Wu Z, Gao Y, Shi F, Jewells V, Shen D

Abstract
Hippocampal subfields play important and divergent roles in both memory formation and early diagnosis of many neurological diseases, but automatic subfield segmentation is less explored due to its small size and poor image contrast. In this paper, we propose an automatic learning-based hippocampal subfields segmentation framework using multi-modality 3TMR images, including T1 MRI and resting-state fMRI (rs-fMRI). To do this, we first acquire both 3T and 7T T1 MRIs for each training subject, and then the 7T T1 MRI are linearly registered onto the 3T T1 MRI. Six hippocampal subfields are manually labeled on the aligned 7T T1 MRI, which has the 7T image contrast but sits in the 3T T1 space. Next, corresponding appearance and relationship features from both 3T T1 MRI and rs-fMRI are extracted to train a structured random forest as a multi-label classifier to conduct the segmentation. Finally, the subfield segmentation is further refined iteratively by additional context features and updated relationship features. To our knowledge, this is the first work that addresses the challenging automatic hippocampal subfields segmentation using 3T routine T1 MRI and rs-fMRI. The quantitative comparison between our results and manual ground truth demonstrates the effectiveness of our method. Besides, we also find that (a) multi-modality features significantly improved subfield segmentation performance due to the complementary information among modalities; (b) automatic segmentation results using 3T multimodality images are partially comparable to those on 7T T1 MRI.

PMID: 28603791 [PubMed - in process]

The Energy Landscape Underpinning Module Dynamics in the Human Brain Connectome.

Tue, 06/13/2017 - 15:20
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The Energy Landscape Underpinning Module Dynamics in the Human Brain Connectome.

Neuroimage. 2017 Jun 07;:

Authors: Ashourvan A, Gu S, Mattar MG, Vettel JM, Bassett DS

Abstract
Human brain dynamics can be viewed through the lens of statistical mechanics, where neurophysiological activity evolves around and between local attractors representing mental states. Many physically-inspired models of these dynamics define brain states based on instantaneous measurements of regional activity. Yet, recent work in network neuroscience has provided evidence that the brain might also be well-characterized by time-varying states composed of locally coherent activity or functional modules. We study this network-based notion of brain state to understand how functional modules dynamically interact with one another to perform cognitive functions. We estimate the functional relationships between regions of interest (ROIs) by fitting a pair-wise maximum entropy model to each ROI's pattern of allegiance to functional modules. This process uses an information theoretic notion of energy (as opposed to a metabolic one) to produce an energy landscape in which local minima represent attractor states characterized by specific patterns of modular structure. The clustering of local minima highlights three classes of ROIs with similar patterns of allegiance to community states. Visual, attention, sensorimotor, and subcortical ROIs are well-characterized by a single functional community. The remaining ROIs affiliate with a putative executive control community or a putative default mode and salience community. We simulate the brain's dynamic transitions between these community states using a random walk process. We observe that simulated transition probabilities between basins are statistically consistent with empirically observed transitions in resting state fMRI data. These results offer a view of the brain as a dynamical system that transitions between basins of attraction characterized by coherent activity in groups of brain regions, and that the strength of these attractors depends on the ongoing cognitive computations.

PMID: 28602945 [PubMed - as supplied by publisher]

The Shared Neural Basis of Music and Language.

Tue, 06/13/2017 - 15:20
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The Shared Neural Basis of Music and Language.

Neuroscience. 2017 Jun 07;:

Authors: Yu M, Xu M, Li X, Chen Z, Song Y, Liu J

Abstract
Human musical ability is proposed to play a key phylogenetical role in the evolution of language, and the similarity of hierarchical structure in music and language has led to considerable speculation about their shared mechanisms. While behavioral and electrophysioglocial studies have revealed associations between music and linguistic abilities, results from functional magnetic resonance imaging (fMRI) studies on their relations are contradictory, possibly because these studies usually treat music or language as single entities without breaking down to their components. Here, we examined the relations between different components of music (i.e., melodic and rhythmic analysis) and language (i.e., semantic and phonological processing) using both behavioral tests and resting-state fMRI. Behaviorally, we found that individuals with music training experiences were better at semantic processing, but not at phonological processing, than those without training. Further correlation analyses showed that semantic processing of language was related to melodic, but not rhythmic, analysis of music. Neurally, we found that performances in both semantic processing and melodic analysis were correlated with spontaneous brain activities in the bilateral precentral gyrus (PCG) and superior temporal plane at the regional level, and with the resting-state functional connectivity of the left PCG with the left supramarginal gyrus and left superior temporal gyrus at the network level. Together, our study revealed the shared spontaneous neural basis of music and language based on the behavioral link between melodic analysis and semantic processing, which possibly relied on a common mechanism of automatic auditory-motor integration.

PMID: 28602921 [PubMed - as supplied by publisher]

Correlation between standardized assessment of concussion scores and small-world brain network in mild traumatic brain injury.

Tue, 06/13/2017 - 15:20
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Correlation between standardized assessment of concussion scores and small-world brain network in mild traumatic brain injury.

J Clin Neurosci. 2017 Jun 08;:

Authors: Yan Y, Song J, Xu G, Yao S, Cao C, Li C, Peng G, Du H

Abstract
This study investigated the characteristics of the small-world brain network architecture of patients with mild traumatic brain injury (MTBI), and a correlation between brain functional connectivity network properties in the resting-state fMRI and Standardized Assessment of Concussion (SAC) parameters. The neurological conditions of 22 MTBI patients and 17 normal control individuals were evaluated according to the SAC. Resting-state fMRI was performed in all subjects 3 and 7days after injury respectively. After preprocessing the fMRI data, cortex functional regions were marked using AAL90 and Dosenbach160 templates. The small-world network parameters and areas under the integral curves were computed in the range of sparsity from 0.01 to 0.5. Independent-sample t-tests were used to compare these parameters between the MTBI and control group. Significantly different parameters were investigated for correlations with SAC scores; those that correlated were chosen for further curve fitting. The clustering coefficient, the communication efficiency across in local networks, and the strength of connectivity were all higher in MTBI patients relative to control individuals. Parameters in 160 brain regions of the MTBI group significantly correlated with total SAC score and score for attention; the network parameters may be a quadratic function of attention scores of SAC and a cubic function of SAC scores. MTBI patients were characterized by elevated communication efficiency across global brain regions, and in local networks, and strength of mean connectivity. These features may be associated with brain function compensation. The network parameters significantly correlated with SAC total and attention scores.

PMID: 28602630 [PubMed - as supplied by publisher]

Resting-state BOLD oscillation frequency predicts vigilance task performance at both normal and high environmental temperatures.

Sun, 06/11/2017 - 14:20
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Resting-state BOLD oscillation frequency predicts vigilance task performance at both normal and high environmental temperatures.

Brain Struct Funct. 2017 Jun 09;:

Authors: Song X, Qian S, Liu K, Zhou S, Zhu H, Zou Q, Liu Y, Sun G, Gao JH

Abstract
Hyperthermia may impair vigilance functions and lead to slower reaction times (RTs) in the psychomotor vigilance task (PVT) and possibly disturbing cerebral hemodynamic rhythms. To test these hypotheses, we acquired the resting-state BOLD and cerebral blood flow (CBF) data, as well as PVTRTs from 15 participants in two simulated environmental thermal conditions (50 °C/25 °C). We adopted a data-driven method, frequency component analysis, to quantify the mean frequency of the BOLD series of each voxel. Across-subject correlation analysis was employed to detect the brain areas whose BOLD oscillation frequency was correlated with the RTs. Significant changes of BOLD frequency and CBF within these areas were compared between hyperthermia and normothermia conditions. Spatial correlations between BOLD frequency and CBF were calculated within different brain areas for each subject under both thermal conditions. Results showed that, under both thermal conditions, the RTs correlated with the BOLD frequency positively in the default mode network (DMN) and negatively in the sensorimotor network (SMN). The increase of BOLD frequency in the thalamus and ventral medial prefrontal cortex was correlated with the increase of RTs in hyperthermia compared with normothermia. Hyperthermia decreased BOLD frequency and CBF in the SMN, while it increased CBF in the thalamus and posterior cingulate. In both thermal conditions, the spatial distribution of CBF negatively correlated with the spatial distribution of BOLD oscillation frequency in most cortical areas, especially in cingulate cortices, precuneus, and primary visual cortex. These results suggest that hyperthermia might deteriorate task performance by interfering with the resting-state CBF, and with BOLD rhythms. The overlapping of the thermoregulatory and vigilance functions in the SMN and DMN might underlie the neural mechanisms of the cognitive-behavioral impairments induced by hyperthermia.

PMID: 28600679 [PubMed - as supplied by publisher]

Robust Granger Analysis in Lp Norm Space for Directed EEG Network Analysis.

Sun, 06/11/2017 - 14:20
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Robust Granger Analysis in Lp Norm Space for Directed EEG Network Analysis.

IEEE Trans Neural Syst Rehabil Eng. 2017 Jun 05;:

Authors: Li P, Huang X, Li F, Wang X, Zhou W, Liu H, Ma T, Zhang T, Guo D, Yao D, Xu P

Abstract
Granger analysis (GA) is widely used to construct directed brain networks based on various physiological recordings, such as functional magnetic resonance imaging (fMRI), electroencephalogram (EEG), etc. However, in real applications, EEGs are inevitably contaminated by unexpected artifacts that may distort the networks because of the L2 norm structure utilized in GAs when estimating directed links. Compared with the L2 norm, the Lp (p ≤ 1) norm can compress outlier effects. In this study, an extended GA is constructed by applying the Lp (p ≤ 1) norm strategy to estimate robust causalities under outlier conditions, and a feasible iteration procedure is utilized to solve the new GA model. A quantitative evaluation using a predefined simulation network demonstrates smaller bias errors and higher linkage consistence for the Lp (p = 1.0, 0.8, 0.6, 0.4, 0.2) -GAs compared to both the Lasso- and L2-GAs under various simulated outlier conditions. Applications in resting-state EEGs that contain ocular artifacts also show that the proposed GA can effectively compress the ocular outlier influence and recover the reliable networks. The proposed Lp-GA may be helpful in capturing the reliable network structure when EEGs are contaminated with artifacts in related studies.

PMID: 28600253 [PubMed - as supplied by publisher]

Resting-state fMRI correlations: from link-wise unreliability to whole brain stability.

Sun, 06/11/2017 - 14:20
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Resting-state fMRI correlations: from link-wise unreliability to whole brain stability.

Neuroimage. 2017 Jun 06;:

Authors: Pannunzi M, Hindriks R, Bettinardi RG, Wenger E, Lisofsky N, Martensson J, Butler O, Filevich E, Becker M, Lochstet M, Kühn S, Deco G

Abstract
The functional architecture of spontaneous BOLD fluctuations has been characterized in detail by numerous studies, demonstrating its potential relevance as a biomarker. However, the systematic investigation of its consistency is still in its infancy. Here, we analyze within- and between-subject variability and test-retest reliability of resting-state functional connectivity (FC) in a unique data set comprising multiple fMRI scans (42) from 5 subjects, and 50 single scans from 50 subjects. We adopt a statistical framework that enables us to identify different sources of variability in FC. We show that the low reliability of single links can be significantly improved by using multiple scans per subject. Moreover, in contrast to earlier studies, we show that spatial heterogeneity in FC reliability is not significant. Finally, we demonstrate that despite the low reliability of individual links, the information carried by the whole-brain FC matrix is robust and can be used as a functional fingerprint to identify individual subjects from the population.

PMID: 28599964 [PubMed - as supplied by publisher]

Functional Disintegration of the Default Mode Network in Prodromal Alzheimer's Disease.

Sat, 06/10/2017 - 14:00
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Functional Disintegration of the Default Mode Network in Prodromal Alzheimer's Disease.

J Alzheimers Dis. 2017 Jun 03;:

Authors: Dillen KNH, Jacobs HIL, Kukolja J, Richter N, von Reutern B, Onur ÖA, Langen KJ, Fink GR

Abstract
Neurodegenerative brain changes can affect the functional connectivity strength between nodes of the default-mode network (DMN), which may underlie changes in cognitive performance. It remains unclear how the functional connectivity strength of DMN nodes differs from healthy to pathological aging and whether these changes are cognitively relevant. We used resting-state functional magnetic resonance imaging to investigate the functional connectivity strength across five DMN nodes in 25 healthy controls (HC), 28 subjective cognitive decline (SCD) participants, and 25 prodromal Alzheimer's disease (AD) patients. After identifying the ventral medial prefrontal cortex (vmPFC), posterior cingulate cortex (PCC), retrosplenial cortex (RSC), inferior parietal lobule, and the hippocampus we investigated the functional strength between DMN nodes using temporal network modeling. Functional coupling of the vmPFC and PCC in prodromal AD patients was disrupted. This vmPFC-PCC coupling correlated positively with memory performance in prodromal AD. Furthermore, the hippocampus de-coupled from posterior DMN nodes in SCD and prodromal AD patients. There was no coupling between the hippocampus and the anterior DMN. Additional mediation analyses indicated that the RSC enables communication between the hippocampus and DMN regions in HC but none of the other two groups. These results suggest an anterior-posterior disconnection and a hippocampal de-coupling from posterior DMN nodes with disease progression. Hippocampal de-coupling already occurring in SCD may provide valuable information for the development of a functional biomarker.

PMID: 28598839 [PubMed - as supplied by publisher]

[Regional Homogeneity Changes in Patients with Social Anxiety Disorders after Cognitive Behavioral Therapy.]

Sat, 06/10/2017 - 14:00
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[Regional Homogeneity Changes in Patients with Social Anxiety Disorders after Cognitive Behavioral Therapy.]

Sichuan Da Xue Xue Bao Yi Xue Ban. 2016 Nov;47(6):898-903

Authors: Yuan ML, Ren ZJ, Zhu HR, Zhang Y, Meng YJ, Zhang W

Abstract
OBJECTIVES: To examine the altered spontaneous brain activity in patients with social anxiety disorders (SAD) before and after cognitive behavior therapy (CBT),and determine the neuromechanism of formation,treatment and recovery of SAD.
METHODS: Fifteen SAD patients were treated with an eight-week group CBT.The patients underwent functional magnetic resonance imaging (fMRI) at resting state before and after the treatments.Eighteen healthy controls (HC) were recruited and underwent a baseline fMRI scan.The regional homogeneity (ReHo) of the patients was compared with the healthy controls.Before the baseline scanning,all participants were assessed with the Liebowitz Social Anxiety Scale(LSAS),the Hamilton Anxiety Rating Scale (HAMA) and the Hamilton Depression Rating Scale (HAMD).
RESULTS: All participants were right-handed.10 males and 4 females were in the patient group,with mean age of (27.07±8.11) years.13 males and 5 females were in the HC group,with mean age of (26.28±2.42) years.There was no difference for gender and age while significant differences were found in LSAS,HAMA,HAMD between patients and controls (P<0.01).After 8 weeks of group CBT,clinical assessments significantly decreased (P<0.05) in patients group.Compared with HC,the pre-treatment SAD patients showed significantly increased ReHo in right cerebellum lobe at baseline [(P<0.05,with Gaussian random field (GRF) correction]; but the difference became insignificant after the group CBT.The post-treatment patients showed increased ReHo in left putamen and right caudate compared with their pre-treatment conditions (P<0.05,with GRF correction).Pre-post ReHo change in right cerebellum posterior in patients was positively correlated with pre-post change of LSAS-fear scores (r=0.62,P=0.015).
CONCLUSIONS: The activity of cerebellum might be one of the potential biomakers to modulate the treatment effect of CBT in SAD,which provides a basis for further investigation into the pathophysiology of SAD.

PMID: 28598121 [PubMed - in process]

Dobutamine stress MRI in pulmonary hypertension: relationships between stress pulmonary artery relative area change, RV performance, and 10-year survival.

Sat, 06/10/2017 - 14:00
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Dobutamine stress MRI in pulmonary hypertension: relationships between stress pulmonary artery relative area change, RV performance, and 10-year survival.

Pulm Circ. 2017 Apr-Jun;7(2):465-475

Authors: Blyth KG, Bellofiore A, Jayasekera G, Foster JE, Steedman T, Chesler NC, Peacock AJ

Abstract
In pulmonary hypertension (PH), right ventricular (RV) performance determines survival. Pulmonary artery (PA) stiffening is an important biomechanical event in PH and also predicts survival based on the PA relative area change (RAC) measured at rest using magnetic resonance imaging (MRI). In this exploratory study, we sought to generate novel hypotheses regarding the influence of stress RAC on PH prognosis and the interaction between PA stiffening, RV performance and survival. Fifteen PH patients underwent dobutamine stress-MRI (ds-MRI) and right heart catheterization. RACREST, RACSTRESS, and ΔRAC (RAC STRESS - RAC REST) were correlated against resting invasive hemodynamics and ds-MRI data regarding RV performance and RV-PA coupling efficiency (n'vv [RV stroke volume/RV end-systolic volume]). The impact of RAC, RV data, and n'vv on ten-year survival were determined using Kaplan-Meier analysis. PH patients with a low ΔRAC (<-2.6%) had a worse long-term survival (log-rank P = 0.045, HR for death = 4.46 [95% CI = 1.08-24.5]) than those with ΔRAC ≥ -2.6%. Given the small sample, these data should be interpreted with caution; however, low ΔRAC was associated with an increase in stress diastolic PA area indicating proximal PA stiffening. Associations of borderline significance were observed between low RACSTRESS and low n'vvSTRESS, Δη'VV, and ΔRVEF. Further studies are required to validate the potential prognostic impact of ΔRAC and the biomechanics potentially connecting low ΔRAC to shorter survival. Such studies may facilitate development of novel PH therapies targeted to the proximal PA.

PMID: 28597775 [PubMed - in process]

l-Dopa responsiveness is associated with distinctive connectivity patterns in advanced Parkinson's disease.

Sat, 06/10/2017 - 14:00
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l-Dopa responsiveness is associated with distinctive connectivity patterns in advanced Parkinson's disease.

Mov Disord. 2017 Jun;32(6):874-883

Authors: Akram H, Wu C, Hyam J, Foltynie T, Limousin P, De Vita E, Yousry T, Jahanshahi M, Hariz M, Behrens T, Ashburner J, Zrinzo L

Abstract
BACKGROUND: Neuronal loss and dopamine depletion alter motor signal processing between cortical motor areas, basal ganglia, and the thalamus, resulting in the motor manifestations of Parkinson's disease. Dopamine replacement therapy can reverse these manifestations with varying degrees of improvement.
METHODS: To evaluate functional connectivity in patients with advanced Parkinson's disease and changes in functional connectivity in relation to the degree of response to l-dopa, 19 patients with advanced Parkinson's disease underwent resting-state functional magnetic resonance imaging in the on-medication state. Scans were obtained on a 3-Tesla scanner in 3 × 3 × 2.5 mm(3) voxels. Seed-based bivariate regression analyses were carried out with atlas-defined basal ganglia regions as seeds, to explore relationships between functional connectivity and improvement in the motor section of the UPDRS-III following an l-dopa challenge. False discovery rate-corrected P was set at < 0.05 for a 2-tailed t test.
RESULTS: A greater improvement in UPDRS-III scores following l-dopa administration was characterized by higher resting-state functional connectivity between the prefrontal cortex and the striatum (P = 0.001) and lower resting-state functional connectivity between the pallidum (P = 0.001), subthalamic nucleus (P = 0.003), and the paracentral lobule (supplementary motor area, mesial primary motor, and primary sensory areas).
CONCLUSIONS: Our findings show characteristic basal ganglia resting-state functional connectivity patterns associated with different degrees of l-dopa responsiveness in patients with advanced Parkinson's disease. l-Dopa exerts a graduated influence on remapping connectivity in distinct motor control networks, potentially explaining some of the variance in treatment response. © 2017 International Parkinson and Movement Disorder Society.

PMID: 28597560 [PubMed - in process]

Recent Advances in Translational Magnetic Resonance Imaging in Animal Models of Stress and Depression.

Sat, 06/10/2017 - 14:00
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Recent Advances in Translational Magnetic Resonance Imaging in Animal Models of Stress and Depression.

Front Cell Neurosci. 2017;11:150

Authors: McIntosh AL, Gormley S, Tozzi L, Frodl T, Harkin A

Abstract
Magnetic resonance imaging (MRI) is a valuable translational tool that can be used to investigate alterations in brain structure and function in both patients and animal models of disease. Regional changes in brain structure, functional connectivity, and metabolite concentrations have been reported in depressed patients, giving insight into the networks and brain regions involved, however preclinical models are less well characterized. The development of more effective treatments depends upon animal models that best translate to the human condition and animal models may be exploited to assess the molecular and cellular alterations that accompany neuroimaging changes. Recent advances in preclinical imaging have facilitated significant developments within the field, particularly relating to high resolution structural imaging and resting-state functional imaging which are emerging techniques in clinical research. This review aims to bring together the current literature on preclinical neuroimaging in animal models of stress and depression, highlighting promising avenues of research toward understanding the pathological basis of this hugely prevalent disorder.

PMID: 28596724 [PubMed - in process]

Chemotherapy-induced changes of cerebral activity in resting-state functional magnetic resonance imaging and cerebral white matter in diffusion tensor imaging.

Sat, 06/10/2017 - 14:00
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Chemotherapy-induced changes of cerebral activity in resting-state functional magnetic resonance imaging and cerebral white matter in diffusion tensor imaging.

Oncotarget. 2017 May 23;:

Authors: Mo C, Lin H, Fu F, Lin L, Zhang J, Huang M, Wang C, Xue Y, Duan Q, Lin W, Chen X

Abstract
While chemotherapy related cognitive disorder has been described in many studies, but we still lack relatively reliable and objective diagnostic tools, and there are few similar studies in Asian patients. We recruited Asian breast cancer patients to perform a cohort study to uncover chemotherapy related cognitive disorder by using resting-state functioning magnetic resonance imaging (RS-fMRI) and magnetic resonance diffusion tensor imaging (DTI) combined with neuropsychologic assessments. This is the first prospective study which combines RS-fMRI and DTI to detect chemotherapy related cognitive disorder. The neuropsychologic tests and MRI were performed before and after the chemotherapy. The healthy controls were tested at matched times. The chemotherapy-treated group performed worse on memory and we found significant changes in the cerebellum, right orbitofrontal area, right middle and superior temporal gyrus, right subcentral area, left dorsolateral prefrontal cortex, and precentral gyrus in RS-fMRI after chemotherapy. We found changes in the fornix and superior fronto-occipital fasciculus with DTI. There was a correlation between some cognitive function and MRI measurements in the correlation analysis, but it was not significant after false discovery rate (FDR) multiple testing corrections. The results indicate that RS-fMRI and DTI may be a prospective application for assessing chemotherapy related cognitive disorder.

PMID: 28596484 [PubMed - as supplied by publisher]

Functional Connectivity in Virally Suppressed Patients with HIV-Associated Neurocognitive Disorder: A Resting-State Analysis.

Sat, 06/10/2017 - 14:00
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Functional Connectivity in Virally Suppressed Patients with HIV-Associated Neurocognitive Disorder: A Resting-State Analysis.

AJNR Am J Neuroradiol. 2017 Jun 08;:

Authors: Chaganti JR, Heinecke A, Gates TM, Moffat KJ, Brew BJ

Abstract
BACKGROUND AND PURPOSE: HIV-associated neurocognitive disorder still occurs despite virally suppressive combination antiretroviral therapy. In the pre-combination antiretroviral era and in patients without HIV suppression, HIV-associated neurocognitive disorder was caused by synaptodendritic injury resulting in impairment of neural networks, characterized by decreased attention, psychomotor slowing, and working memory deficits. Whether similar pathogenesis is true for HIV-associated neurocognitive disorder in the context of viral suppression is not clear. Resting-state fMRI has been shown to be efficient in detecting impaired neural networks in various neurologic illnesses. This pilot study aimed to assess resting-state functional connectivity of the brain in patients with active HIV-associated neurocognitive disorder in the context of HIV viral suppression in both blood and CSF.
MATERIALS AND METHODS: Eighteen patients with active HIV-associated neurocognitive disorder (recent diagnosis with progressing symptoms) on combination antiretroviral therapy with viral suppression in both blood and CSF and 9 demographically matched control subjects underwent resting-state functional MR imaging. The connectivity in the 6 known neural networks was assessed. To localize significant ROIs within the HIV and control group, we performed a seed-based correlation for each known resting-state network.
RESULTS: There were significant group differences between the control and HIV-associated neurocognitive disorder groups in the salience (0.26 versus 0.14, t = 2.6978, df = 25, P = .0123) and executive networks (0.52 versus 0.32, t = 2.2372, df = 25, P = .034). The covariate analysis with neuropsychological scores yielded statistically significant correlations in all 6 studied functional networks, with the most conspicuous correlation in salience networks.
CONCLUSIONS: Active HIV-associated neurocognitive disorder in virally suppressed patients is associated with significantly decreased connectivity in the salience and executive networks, thereby making it potentially useful as a biomarker.

PMID: 28596187 [PubMed - as supplied by publisher]

No changes in functional connectivity during motor recovery beyond 5 weeks after stroke; A longitudinal resting-state fMRI study.

Fri, 06/09/2017 - 13:35
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No changes in functional connectivity during motor recovery beyond 5 weeks after stroke; A longitudinal resting-state fMRI study.

PLoS One. 2017;12(6):e0178017

Authors: Nijboer TCW, Buma FE, Winters C, Vansteensel MJ, Kwakkel G, Ramsey NF, Raemaekers M

Abstract
Spontaneous motor recovery after stroke appears to be associated with structural and functional changes in the motor network. The aim of the current study was to explore time-dependent changes in resting-state (rs) functional connectivity in motor-impaired stroke patients, using rs-functional MRI at 5 weeks and 26 weeks post-stroke onset. For this aim, 13 stroke patients from the EXPLICIT-stroke Trial and age and gender-matched healthy control subjects were included. Patients' synergistic motor control of the paretic upper-limb was assessed with the upper extremity section of the Fugl-Meyer Assessment (FMA-UE) within 2 weeks, and at 5 and 26 weeks post-stroke onset. Results showed that the ipsilesional rs-functional connectivity between motor areas was lower compared to the contralesional rs-functional connectivity, but this difference did not change significantly over time. No relations were observed between changes in rs-functional connectivity and upper-limb motor recovery, despite changes in upper-limb function as measured with the FMA-UE. Last, overall rs-functional connectivity was comparable for patients and healthy control subjects. To conclude, the current findings did not provide evidence that in moderately impaired stroke patients the lower rs-functional connectivity of the ipsilesional hemisphere changed over time.

PMID: 28594850 [PubMed - in process]

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