New resting-state fMRI related studies at PubMed

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Longitudinal Alterations of Local Spontaneous Brain Activity in Parkinson's Disease.

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Longitudinal Alterations of Local Spontaneous Brain Activity in Parkinson's Disease.

Neurosci Bull. 2017 Aug 21;:

Authors: Zeng Q, Guan X, Law Yan Lun JCF, Shen Z, Guo T, Xuan M, Gu Q, Xu X, Chen M, Zhang M

Abstract
We used resting-state fMRI to evaluate longitudinal alterations in local spontaneous brain activity in Parkinson's disease (PD) over a 2-year period. Data were acquired from 23 PD patients at baseline and follow-up, and 27 age- and sex-matched normal controls. Regional homogeneity (ReHo) and voxel-based-morphometry (VBM) were used to identify differences in local spontaneous brain activity and grey matter volume. With disease progression, we observed a progressive decrease in ReHo in the sensorimotor cortex, default-mode network, and left cerebellum, but increased ReHo in the supplementary motor area, bilateral temporal gyrus, and hippocampus. Moreover, there was a significant positive correlation between the rates of ReHo change in the left cerebellum and the rates of change in the Unified Parkinson's Disease Rating Scale-III scores. VBM revealed no significant differences in the grey matter volume among the three sets of acquisitions. We conclude that ReHo may be a suitable non-invasive marker of progression in PD.

PMID: 28828757 [PubMed - as supplied by publisher]

Altered resting state connectivity in right side frontoparietal network in primary insomnia patients.

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Altered resting state connectivity in right side frontoparietal network in primary insomnia patients.

Eur Radiol. 2017 Aug 21;:

Authors: Li S, Tian J, Li M, Wang T, Lin C, Yin Y, Zeng L, Li C, Jiang G

Abstract
OBJECTIVE: This study investigated alterations of resting-state networks (RSNs) in primary insomnia patients as well as relationships between these changes and clinical features.
METHODS: Fifty-nine primary insomnia patients and 53 healthy control subjects underwent a resting-state fMRI scan (rs-fMRI). Ten RSNs were identified using independent component analysis of rs-fMRI data. To assess significant differences between the two groups, voxel-wise analysis of ten RSNs was conducted using dual regression with FSL randomised non-parametric permutation testing and a threshold-free cluster enhanced technique to control for multiple comparisons. Relationships between abnormal functional connectivity and clinical variables were then investigated with Pearson's correlation analysis.
RESULTS: Primary insomnia patients showed decreased connectivity in regions of the right frontoparietal network (FPN), including the superior parietal lobule and superior frontal gyrus. Moreover, decreased connectivity in the right middle temporal gyrus and right lateral occipital cortex with the FPN showed significant positive correlations with disease duration and self-rated anxiety, respectively.
CONCLUSIONS: Our study suggests that primary insomnia patients are characterised by abnormal organisation of the right FPN, and dysfunction of the FPN is correlated with disease duration and anxiety. The results enhance our understanding of neural substrates underlying symptoms of primary insomnia from the viewpoint of resting-state networks.
KEY POINTS: • Primary insomnia patients showed altered functional connectivity in the right FPN. • Middle temporal gyrus FC with FPN was significantly correlated with disease duration. • Lateral occipital cortex FC with FPN was significantly correlated with SAS scores.

PMID: 28828546 [PubMed - as supplied by publisher]

Dynamic connectivity modulates local activity in the core regions of the default-mode network.

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Dynamic connectivity modulates local activity in the core regions of the default-mode network.

Proc Natl Acad Sci U S A. 2017 Aug 21;:

Authors: Tang W, Liu H, Douw L, Kramer MA, Eden UT, Hämäläinen MS, Stufflebeam SM

Abstract
Segregation and integration are distinctive features of large-scale brain activity. Although neuroimaging studies have been unraveling their neural correlates, how integration takes place over segregated modules remains elusive. Central to this problem is the mechanism by which a brain region adjusts its activity according to the influence it receives from other regions. In this study, we explore how dynamic connectivity between two regions affects the neural activity within a participating region. Combining functional magnetic resonance imaging (fMRI) and magnetoencephalography (MEG) in the same group of subjects, we analyzed resting-state data from the core of the default-mode network. We observed directed influence from the posterior cingulate cortex (PCC) to the anterior cingulate cortex (ACC) in the 10-Hz range. This time-varying influence was associated with the power alteration in the ACC: strong influence corresponded with a decrease of power around 13-16 Hz and an increase of power in the lower (1-7 Hz) and higher (30-55 Hz) ends of the spectrum. We also found that the amplitude of the 30- to 55-Hz activity was coupled to the phase of the 3- to 4-Hz activity in the ACC. These results characterized the local spectral changes associated with network interactions. The specific spectral information both highlights the functional roles of PCC-ACC connectivity in the resting state and provides insights into the dynamic relationship between local activity and coupling dynamics of a network.

PMID: 28827337 [PubMed - as supplied by publisher]

Conventional and ZOOMit DWI for Evaluation of Testis in Patients With Ipsilateral Varicocele.

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Conventional and ZOOMit DWI for Evaluation of Testis in Patients With Ipsilateral Varicocele.

AJR Am J Roentgenol. 2017 May;208(5):1045-1050

Authors: Yıldırım İO, Sağlık S, Çelik H

Abstract
OBJECTIVE: The current study aimed to investigate the effects of varicocele on testis parenchyma by using ZOOMit DWI and conventional DWI and to compare both diffusion methods.
SUBJECTS AND METHODS: Forty-five patients with unilateral varicocele diagnosed by physical examination and color Doppler ultrasound between July 2015 and December 2015 and 32 healthy volunteers were included in the study. ZOOMit and conventional DWI were performed for all patients with a 3-T MRI scanner.
RESULTS: Apparent diffusion coefficient (ADC) values calculated using both conventional and ZOOMit DWI decreased in the patients with varicocele of the testis, when compared with the healthy volunteer control group. Furthermore, it was determined that conventional and ZOOMit ADC values for the contralateral side without varicocele also decreased when compared with the healthy volunteer control group (p < 0.05). However, there was no statistically significant difference between testes with or without varicocele in terms of conventional ADC values (p = 0.183), whereas ZOOMit ADC values for testes with varicocele were found to be statistically significantly lower than those for testes without varicocele (p < 0.05). A significant negative correlation was found between venous diameter measured both at rest and during the Valsalva maneuver and ZOOMit ADC values in testes with varicocele.
CONCLUSION: For patients with varicocele, conventional and ZOOMit DWI may be predictive of histopathologic changes in the testis, and ZOOMit DWI may be more effective in the diagnosis, treatment, and postoperative response in patients with varicocele when compared with conventional DWI.

PMID: 28225646 [PubMed - indexed for MEDLINE]

Specific Frontostriatal Circuits for Impaired Cognitive Flexibility and Goal-Directed Planning in Obsessive-Compulsive Disorder: Evidence From Resting-State Functional Connectivity.

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Specific Frontostriatal Circuits for Impaired Cognitive Flexibility and Goal-Directed Planning in Obsessive-Compulsive Disorder: Evidence From Resting-State Functional Connectivity.

Biol Psychiatry. 2017 Apr 15;81(8):708-717

Authors: Vaghi MM, Vértes PE, Kitzbichler MG, Apergis-Schoute AM, van der Flier FE, Fineberg NA, Sule A, Zaman R, Voon V, Kundu P, Bullmore ET, Robbins TW

Abstract
BACKGROUND: A recent hypothesis has suggested that core deficits in goal-directed behavior in obsessive-compulsive disorder (OCD) are caused by impaired frontostriatal function. We tested this hypothesis in OCD patients and control subjects by relating measures of goal-directed planning and cognitive flexibility to underlying resting-state functional connectivity.
METHODS: Multiecho resting-state acquisition, combined with micromovement correction by blood oxygen level-dependent sensitive independent component analysis, was used to obtain in vivo measures of functional connectivity in 44 OCD patients and 43 healthy comparison subjects. We measured cognitive flexibility (attentional set-shifting) and goal-directed performance (planning of sequential response sequences) by means of well-validated, standardized behavioral cognitive paradigms. Functional connectivity strength of striatal seed regions was related to cognitive flexibility and goal-directed performance. To gain insights into fundamental network alterations, graph theoretical models of brain networks were derived.
RESULTS: Reduced functional connectivity between the caudate and the ventrolateral prefrontal cortex was selectively associated with reduced cognitive flexibility. In contrast, goal-directed performance was selectively related to reduced functional connectivity between the putamen and the dorsolateral prefrontal cortex in OCD patients, as well as to symptom severity. Whole-brain data-driven graph theoretical analysis disclosed that striatal regions constitute a cohesive module of the community structure of the functional connectome in OCD patients as nodes within the basal ganglia and cerebellum were more strongly connected to one another than in healthy control subjects.
CONCLUSIONS: These data extend major neuropsychological models of OCD by providing a direct link between intrinsically abnormal functional connectivity within dissociable frontostriatal circuits and those cognitive processes underlying OCD symptoms.

PMID: 27769568 [PubMed - indexed for MEDLINE]

The Rhesus Monkey Connectome Predicts Disrupted Functional Networks Resulting from Pharmacogenetic Inactivation of the Amygdala.

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The Rhesus Monkey Connectome Predicts Disrupted Functional Networks Resulting from Pharmacogenetic Inactivation of the Amygdala.

Neuron. 2016 Jul 20;91(2):453-66

Authors: Grayson DS, Bliss-Moreau E, Machado CJ, Bennett J, Shen K, Grant KA, Fair DA, Amaral DG

Abstract
Contemporary research suggests that the mammalian brain is a complex system, implying that damage to even a single functional area could have widespread consequences across the system. To test this hypothesis, we pharmacogenetically inactivated the rhesus monkey amygdala, a subcortical region with distributed and well-defined cortical connectivity. We then examined the impact of that perturbation on global network organization using resting-state functional connectivity MRI. Amygdala inactivation disrupted amygdalocortical communication and distributed corticocortical coupling across multiple functional brain systems. Altered coupling was explained using a graph-based analysis of experimentally established structural connectivity to simulate disconnection of the amygdala. Communication capacity via monosynaptic and polysynaptic pathways, in aggregate, largely accounted for the correlational structure of endogenous brain activity and many of the non-local changes that resulted from amygdala inactivation. These results highlight the structural basis of distributed neural activity and suggest a strategy for linking focal neuropathology to remote neurophysiological changes.

PMID: 27477019 [PubMed - indexed for MEDLINE]

On the origin of individual functional connectivity variability: The role of white matter architecture.

Tue, 08/22/2017 - 12:00

On the origin of individual functional connectivity variability: The role of white matter architecture.

Brain Connect. 2017 Aug 21;:

Authors: Chamberland M, Girard G, Bernier M, Fortin D, Descoteaux M, Whittingstall K

Abstract
Fingerprint patterns derived from functional connectivity (FC) can be used to identify subjects across groups and sessions, indicating that the topology of the brain substantially differs between individuals. Yet, the source of FC variability inferred from resting-state functional MRI (rs-fMRI) remains unclear. One possibility is that these variations are related to individual differences in white matter structural connectivity (SC). However, directly comparing FC to SC is challenging given the many potential biases associated with quantifying their respective strengths. In an attempt to circumvent this, we employed a recently proposed test-retest approach that better quantifies inter-subject variability by first correcting for intra-subject nuisance variability (i.e. head motion, physiological differences in brain state, etc.) which can artificially influence FC and SC measures. Therefore, rather than directly comparing the strength of FC to SC, we asked whether brain regions with, for example, low inter-subject FC variability also exhibited low SC variability. From this, we report two main findings: First, at the whole-brain level, SC variability was significantly lower than FC variability, indicating that an individual's structural connectome is far more similar to another relative to their functional counterpart even after correcting for noise. Second, while FC and SC variability were mutually low in some brain areas (e.g. primary somatosensory cortex) and high in others (e.g. memory and language areas), the two were not significantly correlated across all cortical and sub-cortical regions. Taken together, these results indicate that even after correcting for factors which may differently affect FC and SC, the two nonetheless remain largely independent of one another. Further work is needed to understand the role direct anatomical pathways play in supporting vascular-based measures of FC and to what extent these measures are dictated by anatomical connectivity.

PMID: 28825322 [PubMed - as supplied by publisher]

Effects of tissue-specific fMRI signal regression on resting-state functional connectivity.

Tue, 08/22/2017 - 12:00

Effects of tissue-specific fMRI signal regression on resting-state functional connectivity.

Brain Connect. 2017 Aug 21;:

Authors: Vos de Wael R, Hyder F, Thompson GJ

Abstract
Neuroimaging studies typically consider white matter as unchanging in different neural and metabolic states. However, a recent study (Brain Connect. 6(6):435-447) demonstrated that white matter signal regression (WMSR) produced a similar loss of neurometabolic information to "global" (whole-brain) signal regression (GSR) in resting state fMRI (R-fMRI) data. This was unexpected, as the loss of information would normally be attributed to neural activity within gray matter correlating with the global R-fMRI signal. Indeed, WMSR has been suggested as an alternative to avoid such pitfalls in GSR. To address these concerns about tissue-specific regression in R-fMRI data analysis, we performed GSR, WMSR and gray matter signal regression (GMSR) on resting state fMRI (R-fMRI) data from the 1000 Functional Connectomes project. While minor differences between GSR and tissue-specific regressions existed with respect to subject motion and intra-network correlation, overall effects were very similar between all regressions. Our results suggest that tissue-specific regression is not an adequate strategy to counter pitfalls of GSR. Conversely, if GSR is desired but the studied disease excludes either gray matter or white matter from analysis, our results indicate that WMSR or GMSR respectively could be used in GSR's stead.

PMID: 28825320 [PubMed - as supplied by publisher]

Alterations in Spontaneous Brain Activity and Functional Network Reorganization following Surgery in Children with Medically Refractory Epilepsy: A Resting-State Functional Magnetic Resonance Imaging Study.

Tue, 08/22/2017 - 12:00

Alterations in Spontaneous Brain Activity and Functional Network Reorganization following Surgery in Children with Medically Refractory Epilepsy: A Resting-State Functional Magnetic Resonance Imaging Study.

Front Neurol. 2017;8:374

Authors: Li Y, Tan Z, Wang J, Wang Y, Gan Y, Wen F, Chen Q, Abbott D, Wong KKL, Huang W

Abstract
For some patients with medically refractory epilepsy (MRE), surgery is a safe and effective treatment for controlling epilepsy. However, the functional consequences of such surgery on brain activity and connectivity in children remain unknown. In the present study, we carried out a longitudinal study using resting-state functional magnetic resonance imaging in 10 children with MRE before and again at a mean of 79 days after surgery, as well as in a group of 28 healthy controls. Compared with the controls, children with epilepsy exhibited abnormalities in intrinsic activity in the thalamus, putamen, pallidum, insula, hippocampus, cerebellum, and cingulate gyrus both before and after surgery. Longitudinal analyses showed that the amplitude of low frequency fluctuations (ALFF) increased in the parietal-frontal cortex and decreased in the deep nuclei from pre- to post-surgery. The percentage changes in ALFF values in the deep nuclei were positively correlated with the age of epilepsy onset. Functional connectivity (FC) analyses demonstrated a reorganization of FC architecture after surgery. These changes in brain activity and FC after surgery might indicate that the previously disrupted functional interactions were reorganized after surgery. All these results provide preliminary evidence that the age of epilepsy onset may have some potential to predict the outcome of brain functional reorganization after surgery in children with MRE.

PMID: 28824531 [PubMed]

Resting-State Connectivity of the Left Frontal Cortex to the Default Mode and Dorsal Attention Network Supports Reserve in Mild Cognitive Impairment.

Tue, 08/22/2017 - 12:00

Resting-State Connectivity of the Left Frontal Cortex to the Default Mode and Dorsal Attention Network Supports Reserve in Mild Cognitive Impairment.

Front Aging Neurosci. 2017;9:264

Authors: Franzmeier N, Göttler J, Grimmer T, Drzezga A, Áraque-Caballero MA, Simon-Vermot L, Taylor ANW, Bürger K, Catak C, Janowitz D, Müller C, Duering M, Sorg C, Ewers M

Abstract
Reserve refers to the phenomenon of relatively preserved cognition in disproportion to the extent of neuropathology, e.g., in Alzheimer's disease. A putative functional neural substrate underlying reserve is global functional connectivity of the left lateral frontal cortex (LFC, Brodmann Area 6/44). Resting-state fMRI-assessed global LFC-connectivity is associated with protective factors (education) and better maintenance of memory in mild cognitive impairment (MCI). Since the LFC is a hub of the fronto-parietal control network that regulates the activity of other networks, the question arises whether LFC-connectivity to specific networks rather than the whole-brain may underlie reserve. We assessed resting-state fMRI in 24 MCI and 16 healthy controls (HC) and in an independent validation sample (23 MCI/32 HC). Seed-based LFC-connectivity to seven major resting-state networks (i.e., fronto-parietal, limbic, dorsal-attention, somatomotor, default-mode, ventral-attention, visual) was computed, reserve was quantified as residualized memory performance after accounting for age and hippocampal atrophy. In both samples of MCI, LFC-activity was anti-correlated with the default-mode network (DMN), but positively correlated with the dorsal-attention network (DAN). Greater education predicted stronger LFC-DMN-connectivity (anti-correlation) and LFC-DAN-connectivity. Stronger LFC-DMN and LFC-DAN-connectivity each predicted higher reserve, consistently in both MCI samples. No associations were detected for LFC-connectivity to other networks. These novel results extend our previous findings on global functional connectivity of the LFC, showing that LFC-connectivity specifically to the DAN and DMN, two core memory networks, enhances reserve in the memory domain in MCI.

PMID: 28824423 [PubMed]

Frequency-Dependent Altered Functional Connections of Default Mode Network in Alzheimer's Disease.

Tue, 08/22/2017 - 12:00

Frequency-Dependent Altered Functional Connections of Default Mode Network in Alzheimer's Disease.

Front Aging Neurosci. 2017;9:259

Authors: Li Y, Yao H, Lin P, Zheng L, Li C, Zhou B, Wang P, Zhang Z, Wang L, An N, Wang J, Zhang X

Abstract
Alzheimer's disease (AD) is a neurodegenerative disorder associated with the progressive dysfunction of cognitive ability. Previous research has indicated that the default mode network (DMN) is closely related to cognition and is impaired in Alzheimer's disease. Because recent studies have shown that different frequency bands represent specific physiological functions, DMN functional connectivity studies of the different frequency bands based on resting state fMRI (RS-fMRI) data may provide new insight into AD pathophysiology. In this study, we explored the functional connectivity based on well-defined DMN regions of interest (ROIs) from the five frequency bands: slow-5 (0.01-0.027 Hz), slow-4 (0.027-0.073 Hz), slow-3 (0.073-0.198 Hz), slow-2 (0.198-0.25 Hzs) and standard low-frequency oscillations (LFO) (0.01-0.08 Hz). We found that the altered functional connectivity patterns are mainly in the frequency band of slow-5 and slow-4 and that the decreased connections are long distance, but some relatively short connections are increased. In addition, the altered functional connections of the DMN in AD are frequency dependent and differ between the slow-5 and slow-4 bands. Mini-Mental State Examination scores were significantly correlated with the altered functional connectivity patterns in the slow-5 and slow-4 bands. These results indicate that frequency-dependent functional connectivity changes might provide potential biomarkers for AD pathophysiology.

PMID: 28824420 [PubMed]

Disconnectivity between Dorsal Raphe Nucleus and Posterior Cingulate Cortex in Later Life Depression.

Tue, 08/22/2017 - 12:00

Disconnectivity between Dorsal Raphe Nucleus and Posterior Cingulate Cortex in Later Life Depression.

Front Aging Neurosci. 2017;9:236

Authors: Ikuta T, Matsuo K, Harada K, Nakashima M, Hobara T, Higuchi N, Higuchi F, Otsuki K, Shibata T, Watanuki T, Matsubara T, Yamagata H, Watanabe Y

Abstract
The dorsal raphe nucleus (DRN) has been repeatedly implicated as having a significant relationship with depression, along with its serotoninergic innervation. However, functional connectivity of the DRN in depression is not well understood. The current study aimed to isolate functional connectivity of the DRN distinct in later life depression (LLD) compared to a healthy age-matched population. Resting state functional magnetic resonance imaging (rsfMRI) data from 95 participants (33 LLD and 62 healthy) were collected to examine functional connectivity from the DRN to the whole brain in voxel-wise fashion. The posterior cingulate cortex (PCC) bilaterally showed significantly smaller connectivity in the LLD group than the control group. The DRN to PCC connectivity did not show any association with the depressive status. The findings implicate that the LLD involves disruption of serotoninergic input to the PCC, which has been suggested to be a part of the reduced default mode network in depression.

PMID: 28824410 [PubMed]

Individual Differences in the Accuracy of Judgments of Learning Are Related to the Gray Matter Volume and Functional Connectivity of the Left Mid-Insula.

Tue, 08/22/2017 - 12:00

Individual Differences in the Accuracy of Judgments of Learning Are Related to the Gray Matter Volume and Functional Connectivity of the Left Mid-Insula.

Front Hum Neurosci. 2017;11:399

Authors: Hu X, Liu Z, Chen W, Zheng J, Su N, Wang W, Lin C, Luo L

Abstract
The judgment of learning (JOL) is an important form of prospective metamemory judgment, and the biological basis of the JOL process is an important topic in metamemory research. Although previous task-related functional magnetic resonance imaging (MRI) studies have examined the brain regions underlying the JOL process, the neural correlates of individual differences in JOL accuracy require further investigation. This study used structural and resting-state functional MRI to investigate whether individual differences in JOL accuracy are related to the gray matter (GM) volume and functional connectivity of the bilateral insula and medial Brodmann area (BA) 11, which are assumed to be related to JOL accuracy. We found that individual differences in JOL accuracy were related to the GM volume of the left mid-insula and to the functional connectivity between the left mid-insula and various other regions, including the left superior parietal lobule/precuneus, bilateral inferior parietal lobule/intraparietal sulcus, right frontal pole and left parahippocampal gyrus/fusiform gyrus/cerebellum. Further analyses indicated that the functional connectivity related to individual differences in JOL accuracy could be divided into two factors and might support information integration and selective attention processes underlying accurate JOLs. In addition, individual differences in JOL accuracy were not related to the GM volume or functional connectivity of the medial BA 11. Our findings provide novel evidence for the role of the left mid-insula and its functional connectivity in the JOL process.

PMID: 28824403 [PubMed]

Test-Retest Reliability of "High-Order" Functional Connectivity in Young Healthy Adults.

Tue, 08/22/2017 - 12:00

Test-Retest Reliability of "High-Order" Functional Connectivity in Young Healthy Adults.

Front Neurosci. 2017;11:439

Authors: Zhang H, Chen X, Zhang Y, Shen D

Abstract
Functional connectivity (FC) has become a leading method for resting-state functional magnetic resonance imaging (rs-fMRI) analysis. However, the majority of the previous studies utilized pairwise, temporal synchronization-based FC. Recently, high-order FC (HOFC) methods were proposed with the idea of computing "correlation of correlations" to capture high-level, more complex associations among the brain regions. There are two types of HOFC. The first type is topographical profile similarity-based HOFC (tHOFC) and its variant, associated HOFC (aHOFC), for capturing different levels of HOFC. Instead of measuring the similarity of the original rs-fMRI signals with the traditional FC (low-order FC, or LOFC), tHOFC measures the similarity of LOFC profiles (i.e., a set of LOFC values between a region and all other regions) between each pair of brain regions. The second type is dynamics-based HOFC (dHOFC) which defines the quadruple relationship among every four brain regions by first calculating two pairwise dynamic LOFC "time series" and then measuring their temporal synchronization (i.e., temporal correlation of the LOFC fluctuations, not the BOLD fluctuations). Applications have shown the superiority of HOFC in both disease biomarker detection and individualized diagnosis than LOFC. However, no study has been carried out for the assessment of test-retest reliability of different HOFC metrics. In this paper, we systematically evaluate the reliability of the two types of HOFC methods using test-retest rs-fMRI data from 25 (12 females, age 24.48 ± 2.55 years) young healthy adults with seven repeated scans (with interval = 3-8 days). We found that all HOFC metrics have satisfactory reliability, specifically (1) fair-to-good for tHOFC and aHOFC, and (2) fair-to-moderate for dHOFC with relatively strong connectivity strength. We further give an in-depth analysis of the biological meanings of each HOFC metric and highlight their differences compared to the LOFC from the aspects of cross-level information exchanges, within-/between-network connectivity, and modulatory connectivity. In addition, how the dynamic analysis parameter (i.e., sliding window length) affects dHOFC reliability is also investigated. Our study reveals unique functional associations characterized by the HOFC metrics. Guidance and recommendations for future applications and clinical research using HOFC are provided. This study has made a further step toward unveiling more complex human brain connectome.

PMID: 28824362 [PubMed]

Abnormal long- and short-range functional connectivity in adolescent-onset schizophrenia patients: A resting-state fMRI study.

Tue, 08/22/2017 - 12:00

Abnormal long- and short-range functional connectivity in adolescent-onset schizophrenia patients: A resting-state fMRI study.

Prog Neuropsychopharmacol Biol Psychiatry. 2017 Aug 17;:

Authors: Wang S, Zhan Y, Zhang Y, Lyu L, Lyu H, Wang G, Wu R, Zhao J, Guo W

Abstract
BACKGROUND: Human brain is a topologically complex network embedded in anatomical space, and anatomical distance may affect functional connectivity (FC) in schizophrenia. However, little is known if and how this effect occurs in adolescent-onset schizophrenia (AOS).
METHODS: We explored long- and short-range FC through resting-state functional magnetic resonance imaging in 48 first-episode, drug-naive AOS patients and 31 healthy controls, and we examined if these abnormalities could be utilized to separate patients from controls using receiver operating characteristic curves and support vector machines (SVM).
RESULTS: Patients had increased long-range positive FC (lpFC) and short-range positive FC (spFC) in the right middle frontal gyrus and right superior medial prefrontal cortex within the anterior default mode network (DMN), decreased lpFC and spFC in several regions of the posterior DMN, and decreased lpFC within the important hubs of salience network (SN). The decreased lpFC in the left superior temporal gyrus was positively correlated with cognitive impairment. We found that SVM has high accuracy (up to 92.4%) in classifying patients and control.
CONCLUSION: Disrupted anatomical distance would underlie network-level dysconnectivity, highlighting the importance of the DMN and SN in the neurodevelopment of schizophrenia. Abnormalities of long- and short-range FC in brain regions could discriminate patients from controls with high accuracy.

PMID: 28823850 [PubMed - as supplied by publisher]

Fluctuations between high- and low-modularity topology in time-resolved functional connectivity.

Tue, 08/22/2017 - 12:00

Fluctuations between high- and low-modularity topology in time-resolved functional connectivity.

Neuroimage. 2017 Aug 17;:

Authors: Fukushima M, Betzel RF, He Y, de Reus MA, van den Heuvel MP, Zuo XN, Sporns O

Abstract
Modularity is an important topological attribute for functional brain networks. Recent human fMRI studies have reported that modularity of functional networks varies not only across individuals being related to demographics and cognitive performance, but also within individuals co-occurring with fluctuations in network properties of functional connectivity, estimated over short time intervals. However, characteristics of these time-resolved functional networks during periods of high and low modularity have remained largely unexplored. In this study we investigate basic spatiotemporal properties of time-resolved networks in the high and low modularity periods during rest, with a particular focus on their spatial connectivity patterns, temporal homogeneity and test-retest reliability. We show that spatial connectivity patterns of time-resolved networks in the high and low modularity periods are represented by increased and decreased dissociation of the default mode network module from task-positive network modules, respectively. We also find that the instances of time-resolved functional connectivity sampled from within the high (respectively, low) modularity period are relatively homogeneous (respectively, heterogeneous) over time, indicating that during the low modularity period the default mode network interacts with other networks in a variable manner. We confirmed that the occurrence of the high and low modularity periods varies across individuals with moderate inter-session test-retest reliability and that it is correlated with previously-reported individual differences in the modularity of functional connectivity estimated over longer timescales. Our findings illustrate how time-resolved functional networks are spatiotemporally organized during periods of high and low modularity, allowing one to trace individual differences in long-timescale modularity to the variable occurrence of network configurations at shorter timescales.

PMID: 28823827 [PubMed - as supplied by publisher]

Instantaneous brain dynamics mapped to a continuous state space.

Tue, 08/22/2017 - 12:00

Instantaneous brain dynamics mapped to a continuous state space.

Neuroimage. 2017 Aug 17;:

Authors: Billings J, Medda A, Shakil S, Shen X, Kashyap A, Chen S, Abbas A, Zhang X, Nezafati M, Pan WJ, Berman G, Keilholz S

Abstract
Measures of whole-brain activity, from techniques such as functional Magnetic Resonance Imaging, provide a means to observe the brain's dynamical operations. However, interpretation of whole-brain dynamics has been stymied by the inherently high-dimensional structure of brain activity. The present research addresses this challenge through a series of scale transformations in the spectral, spatial, and relational domains. Instantaneous multispectral dynamics are first developed from input data via a wavelet filter bank. Voxel-level signals are then projected onto a representative set of spatially independent components. The correlation distance over the instantaneous wavelet-ICA state vectors is a graph that may be embedded onto a lower-dimensional space to assist the interpretation of state-space dynamics. Applying this procedure to a large sample of resting and task data (acquired through the Human Connectome Project), we segment the empirical state space into a continuum of stimulus-dependent brain states. We also demonstrate that resting brain activity includes brain states that are very similar to those adopted during some tasks, as well as brain states that are distinct from experimentally-defined tasks. Back-projection of segmented brain states onto the brain's surface reveals the patterns of brain activity that support each experimental state.

PMID: 28823826 [PubMed - as supplied by publisher]

Understanding marijuana's effects on functional connectivity of the default mode network in patients with schizophrenia and co-occurring cannabis use disorder: A pilot investigation.

Tue, 08/22/2017 - 12:00

Understanding marijuana's effects on functional connectivity of the default mode network in patients with schizophrenia and co-occurring cannabis use disorder: A pilot investigation.

Schizophr Res. 2017 Aug 17;:

Authors: Whitfield-Gabrieli S, Fischer AS, Henricks AM, Khokhar JY, Roth RM, Brunette MF, Green AI

Abstract
Nearly half of patients with schizophrenia (SCZ) have co-occurring cannabis use disorder (CUD), which has been associated with decreased treatment efficacy, increased risk of psychotic relapse, and poor global functioning. While reports on the effects of cannabis on cognitive performance in patients with SCZ have been mixed, study of brain networks related to executive function may clarify the relationship between cannabis use and cognition in these dual-diagnosis patients. In the present pilot study, patients with SCZ and CUD (n=12) and healthy controls (n=12) completed two functional magnetic resonance imaging (fMRI) resting scans. Prior to the second scan, patients smoked a 3.6% tetrahydrocannabinol (THC) cannabis cigarette or ingested a 15mg delta-9-tetrahydrocannabinol (THC) pill. We used resting-state functional connectivity to examine the default mode network (DMN) during both scans, as connectivity/activity within this network is negatively correlated with connectivity of the network involved in executive control and shows reduced activity during task performance in normal individuals. At baseline, relative to controls, patients exhibited DMN hyperconnectivity that correlated with positive symptom severity, and reduced anticorrelation between the DMN and the executive control network (ECN). Cannabinoid administration reduced DMN hyperconnectivity and increased DMN-ECN anticorrelation. Moreover, the magnitude of anticorrelation in the controls, and in the patients after cannabinoid administration, positively correlated with WM performance. The finding that DMN brain connectivity is plastic may have implications for future pharmacotherapeutic development, as treatment efficacy could be assessed through the ability of therapies to normalize underlying circuit-level dysfunction.

PMID: 28823723 [PubMed - as supplied by publisher]

Altered language network in benign childhood epilepsy patients with spikes from non-dominant side: A resting-state fMRI study.

Tue, 08/22/2017 - 12:00

Altered language network in benign childhood epilepsy patients with spikes from non-dominant side: A resting-state fMRI study.

Epilepsy Res. 2017 Aug 01;136:109-114

Authors: Fang J, Chen S, Luo C, Gong Q, An D, Zhou D

Abstract
Benign childhood epilepsy with centrotemporal spikes (BECTS) is one of the most common childhood epilepsy syndromes, and language deficits associated with BECTS have become a hot topic. This study investigated alterations of the language network in BECTS children with spikes from the non-dominant side in comparison with healthy controls. Twenty-three children with BECTS and 20 age-matched healthy controls were enrolled. Region of interest -based whole brain functional connectivity analysis was used to identify the potential differences in the functional connectivity of the Broca's area between the two groups. Increased positive functional connectivity within the Broca's region was detected mainly at the left superior frontal gyrus (Brodmann area 8), bilateral insula, and anterior and posterior cingulate in the BECTS group. No regions showed significantly decreased connection in the BECTS patients compared to the controls. This study suggested alterations in the language network that was related with the Broca's area in children with BECTS from the non-dominant side. Further studies with longitudinal assessments from the perceptive of functional neuroimaging are needed to illustrate the dynamic course of language development and corresponding neuroimaging evidence.

PMID: 28822871 [PubMed - as supplied by publisher]

Religious and spiritual importance moderate relation between default mode network connectivity and familial risk for depression.

Tue, 08/22/2017 - 12:00
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Religious and spiritual importance moderate relation between default mode network connectivity and familial risk for depression.

Neurosci Lett. 2016 Nov 10;634:94-97

Authors: Svob C, Wang Z, Weissman MM, Wickramaratne P, Posner J

Abstract
Individuals at high risk for depression have increased default mode network (DMN) connectivity, as well as reduced inverse connectivity between the DMN and the central executive network (CEN) [8]. Other studies have indicated that the belief in the importance of religion/spirituality (R/S) is protective against depression in high risk individuals [5]. Given these findings, we hypothesized that R/S importance would moderate DMN connectivity, potentially reducing DMN connectivity or increasing DMN-CEN inverse connectivity in individuals at high risk for depression. Using resting-state functional connectivity MRI (rs-fcMRI) in a sample of 104 individuals (aged 11-60) at high and low risk for familial depression, we previously reported increased DMN connectivity and reduced DMN-CEN inverse connectivity in high risk individuals. Here, we found that this effect was moderated by self-report measures of R/S importance. Greater R/S importance in the high risk group was associated with decreased DMN connectivity. These results may represent a protective neural adaptation in the DMN of individuals at high risk for depression, and may have implications for other meditation-based therapies for depression.

PMID: 27717831 [PubMed - indexed for MEDLINE]

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