New resting-state fMRI related studies at PubMed

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[Research on the characteristics of the dynamic functional connectivity network related to aging].

Fri, 05/11/2018 - 11:00

[Research on the characteristics of the dynamic functional connectivity network related to aging].

Sheng Wu Yi Xue Gong Cheng Xue Za Zhi. 2017 Apr 01;34(2):161-167

Authors: Zhao X, Zhang X, Wang W, Liu Y, Sha M, Chen Y, Ni H, Ming D

Abstract
Brain aging can affect the strength of functional connectivity between brain regions. In recent years, studies have shown that functional connectivity is fluctuant over time, and can reflect more physiological and pathological information. Therefore, in the study resting state functional magnetic resonance imaging (fMRI) data of 32 elderly subjects and 36 younger subjects were selected, and the sliding window technique was used to estimate dynamic functional connectivity network. Then, the dependency of fluctuating energy difference on frequency band was studied using wavelet packet analysis, conducting the linear regression with age at the same time. Results showed that the fluctuating energy in older group was significantly higher than that in the young group in low frequency, and it was significantly lower than that in the young people in high frequency. These results suggested that the dynamic functional connectivity between networks in the elderly exist slow wave phenomenon, which may be related to the decreased reaction rate of the elderly. This article provides new ideas and methods for the research about brain aging, and promotes a theoretical basis for further understanding of the physiological significance of brain dynamic functional connectivity.

PMID: 29745568 [PubMed]

[Research progress about different levels of cognitive recession using resting state functional connectivity network methods].

Fri, 05/11/2018 - 11:00

[Research progress about different levels of cognitive recession using resting state functional connectivity network methods].

Sheng Wu Yi Xue Gong Cheng Xue Za Zhi. 2017 Aug 01;34(4):632-636

Authors: Liu Y, Chen Y, Sha M, Qi H, Ming D, Zhou P

Abstract
Normal brain aging and a serious of neurodegenerative diseases may lead to decline in memory, attention and executive ability and poorer quality of life. The mechanism of the decline is not clear now and is still a hot issue in the fields of neuroscience and medicine. A large number of researches showed that resting state functional brain networks based functional magnetic resonance imaging (fMRI) are sensitive and susceptive to the change of cognitive function. In this paper, the researches of brain functional connectivity based on resting fMRI in recent years were compared, and the results of subjects with different levels of cognitive decline including normal brain aging, mild cognitive impairment (MCI) and Alzheimer's disease (AD) were reviewed. And the changes of brain functional networks under three different levels of cognitive decline are introduced in this paper, which will provide the basis for the detection of normal brain aging and clinical diseases.

PMID: 29745564 [PubMed]

From swing to cane: Sex differences of EEG resting-state temporal patterns during maturation and aging.

Thu, 05/10/2018 - 16:00
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From swing to cane: Sex differences of EEG resting-state temporal patterns during maturation and aging.

Dev Cogn Neurosci. 2018 Apr 30;31:58-66

Authors: Tomescu MI, Rihs TA, Rochas V, Hardmeier M, Britz J, Allali G, Fuhr P, Eliez S, Michel CM

Abstract
While many insights on brain development and aging have been gained by studying resting-state networks with fMRI, relating these changes to cognitive functions is limited by the temporal resolution of fMRI. In order to better grasp short-lasting and dynamically changing mental activities, an increasing number of studies utilize EEG to define resting-state networks, thereby often using the concept of EEG microstates. These are brief (around 100 ms) periods of stable scalp potential fields that are influenced by cognitive states and are sensitive to neuropsychiatric diseases. Despite the rising popularity of the EEG microstate approach, information about age changes is sparse and nothing is known about sex differences. Here we investigated age and sex related changes of the temporal dynamics of EEG microstates in 179 healthy individuals (6-87 years old, 90 females, 204-channel EEG). We show strong sex-specific changes in microstate dynamics during adolescence as well as at older age. In addition, males and females differ in the duration and occurrence of specific microstates. These results are of relevance for the comparison of studies in populations of different age and sex and for the understanding of the changes in neuropsychiatric diseases.

PMID: 29742488 [PubMed - as supplied by publisher]

Visual perceptual training reconfigures post-task resting-state functional connectivity with a feature-representation region.

Thu, 05/10/2018 - 16:00
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Visual perceptual training reconfigures post-task resting-state functional connectivity with a feature-representation region.

PLoS One. 2018;13(5):e0196866

Authors: Sarabi MT, Aoki R, Tsumura K, Keerativittayayut R, Jimura K, Nakahara K

Abstract
The neural mechanisms underlying visual perceptual learning (VPL) have typically been studied by examining changes in task-related brain activation after training. However, the relationship between post-task "offline" processes and VPL remains unclear. The present study examined this question by obtaining resting-state functional magnetic resonance imaging (fMRI) scans of human brains before and after a task-fMRI session involving visual perceptual training. During the task-fMRI session, participants performed a motion coherence discrimination task in which they judged the direction of moving dots with a coherence level that varied between trials (20, 40, and 80%). We found that stimulus-induced activation increased with motion coherence in the middle temporal cortex (MT+), a feature-specific region representing visual motion. On the other hand, stimulus-induced activation decreased with motion coherence in the dorsal anterior cingulate cortex (dACC) and bilateral insula, regions involved in decision making under perceptual ambiguity. Moreover, by comparing pre-task and post-task rest periods, we revealed that resting-state functional connectivity (rs-FC) with the MT+ was significantly increased after training in widespread cortical regions including the bilateral sensorimotor and temporal cortices. In contrast, rs-FC with the MT+ was significantly decreased in subcortical regions including the thalamus and putamen. Importantly, the training-induced change in rs-FC was observed only with the MT+, but not with the dACC or insula. Thus, our findings suggest that perceptual training induces plastic changes in offline functional connectivity specifically in brain regions representing the trained visual feature, emphasising the distinct roles of feature-representation regions and decision-related regions in VPL.

PMID: 29742133 [PubMed - in process]

The Comorbidity Between Internet Gaming Disorder and Depression: Interrelationship and Neural Mechanisms.

Thu, 05/10/2018 - 16:00
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The Comorbidity Between Internet Gaming Disorder and Depression: Interrelationship and Neural Mechanisms.

Front Psychiatry. 2018;9:154

Authors: Liu L, Yao YW, Li CR, Zhang JT, Xia CC, Lan J, Ma SS, Zhou N, Fang XY

Abstract
Internet gaming disorder (IGD) is characterized by cognitive and emotional deficits. Previous studies have reported the co-occurrence of IGD and depression. However, extant brain imaging research has largely focused on cognitive deficits in IGD. Few studies have addressed the comorbidity between IGD and depression symptoms and underlying neural mechanisms. Here, we systematically investigated this issue by combining a longitudinal survey study, a cross-sectional resting-state functional connectivity (rsFC) study and an intervention study. Autoregressive cross-lagged modeling on a longitudinal dataset of college students showed that IGD severity and depression are reciprocally predictive. At the neural level, individuals with IGD exhibited enhanced rsFC between the left amygdala and right dorsolateral prefrontal cortex (DLPFC), inferior frontal and precentral gyrus, compared with control participants, and the amygdala-frontoparietal connectivity at the baseline negatively predicted reduction in depression symptoms following a psychotherapy intervention. Further, following the intervention, individuals with IGD showed decreased connectivity between the left amygdala and left middle frontal and precentral gyrus, as compared with the non-intervention group. These findings together suggest that IGD may be closely associated with depression; aberrant rsFC between emotion and executive control networks may underlie depression and represent a therapeutic target in individuals with IGD. Registry name: The behavioral and brain mechanism of IGD; URL: https://www.clinicaltrials.gov/ct2/show/NCT02550405; Registration number: NCT02550405.

PMID: 29740358 [PubMed]

Reduced Dynamic Coupling Between Spontaneous BOLD-CBF Fluctuations in Older Adults: A Dual-Echo pCASL Study.

Thu, 05/10/2018 - 16:00
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Reduced Dynamic Coupling Between Spontaneous BOLD-CBF Fluctuations in Older Adults: A Dual-Echo pCASL Study.

Front Aging Neurosci. 2018;10:115

Authors: Chiacchiaretta P, Cerritelli F, Bubbico G, Perrucci MG, Ferretti A

Abstract
Measurement of the dynamic coupling between spontaneous Blood Oxygenation Level Dependent (BOLD) and cerebral blood flow (CBF) fluctuations has been recently proposed as a method to probe resting-state brain physiology. Here we investigated how the dynamic BOLD-CBF coupling during resting-state is affected by aging. Fifteen young subjects and 17 healthy elderlies were studied using a dual-echo pCASL sequence. We found that the dynamic BOLD-CBF coupling was markedly reduced in elderlies, in particular in the left supramarginal gyrus, an area known to be involved in verbal working memory and episodic memory. Moreover, correcting for temporal shift between BOLD and CBF timecourses resulted in an increased correlation of the two signals for both groups, but with a larger increase for elderlies. However, even after temporal shift correction, a significantly decreased correlation was still observed for elderlies in the left supramarginal gyrus, indicating that the age-related dynamic BOLD-CBF uncoupling in this region is more pronounced and can be only partially explained with a simple time-shift between the two signals. Interestingly, these results were observed in a group of elderlies with normal cognitive functions, suggesting that the study of dynamic BOLD-CBF coupling during resting-state is a promising technique, potentially able to provide early biomarkers of functional changes in the aging brain.

PMID: 29740310 [PubMed]

Study of Resting-State Functional Connectivity Networks Using EEG Electrodes Position As Seed.

Thu, 05/10/2018 - 16:00
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Study of Resting-State Functional Connectivity Networks Using EEG Electrodes Position As Seed.

Front Neurosci. 2018;12:235

Authors: Rojas GM, Alvarez C, Montoya CE, de la Iglesia-Vayá M, Cisternas JE, Gálvez M

Abstract
Electroencephalography (EEG) is the standard diagnosis method for a wide variety of diseases such as epilepsy, sleep disorders, encephalopathies, and coma, among others. Resting-state functional magnetic resonance (rs-fMRI) is currently a technique used in research in both healthy individuals as well as patients. EEG and fMRI are procedures used to obtain direct and indirect measurements of brain neural activity: EEG measures the electrical activity of the brain using electrodes placed on the scalp, and fMRI detects the changes in blood oxygenation that occur in response to neural activity. EEG has a high temporal resolution and low spatial resolution, while fMRI has high spatial resolution and low temporal resolution. Thus, the combination of EEG with rs-fMRI using different methods could be very useful for research and clinical applications. In this article, we describe and show the results of a new methodology for processing rs-fMRI using seeds positioned according to the 10-10 EEG standard. We analyze the functional connectivity and adjacency matrices obtained using 65 seeds based on 10-10 EEG scheme and 21 seeds based on 10-20 EEG. Connectivity networks are created using each 10-20 EEG seeds and are analyzed by comparisons to the seven networks that have been found in recent studies. The proposed method captures high correlation between contralateral seeds, ipsilateral and contralateral occipital seeds, and some in the frontal lobe.

PMID: 29740268 [PubMed]

Altered functional connectivity density in patients with herpes zoster and postherpetic neuralgia.

Thu, 05/10/2018 - 16:00
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Altered functional connectivity density in patients with herpes zoster and postherpetic neuralgia.

J Pain Res. 2018;11:881-888

Authors: Hong S, Gu L, Zhou F, Liu J, Huang M, Jiang J, He L, Gong H, Zeng X

Abstract
Purpose: The aim of this study was to explore intrinsic functional connectivity patterns in patients with herpes zoster (HZ) and postherpetic neuralgia (PHN).
Patients and methods: Thirty-three right-handed HZ patients (13 males; mean age 57.15±9.30 years), 22 right-handed PHN patients (9 males; mean age 66.13±6.77 years), and 28 well-matched healthy controls (HC) (9 males; mean age 54.21±7.72 years) underwent resting-state functional magnetic resonance imaging for intrinsic functional connectivity analyses. Functional connectivity density (FCD) was calculated and compared among the PHN, HZ, and HC groups. In addition, the Pearson correlation coefficient was calculated to compare various clinical indices in the regions with abnormal FCD values.
Results: Compared with the HC, both HZ and PHN patients showed significantly decreased FCD in the precuneus, and patients with HZ displayed significantly increased FCD in the brainstem/limbic lobe/parahippocampalgyrus, whereas patients with PHN displayed significantly increased FCD in the hippocampus (correlation thresholds r=0.25, voxel level of P<0.01 and Gaussian random field theory at a cluster level of P<0.05). However, the FCD was not significantly different between the PHN and HZ patients. Furthermore, the decreased FCD in the precuneus was positively correlated with the visual analog scale score in the PHN group (r=0.672; P=0.001).
Conclusion: Decreased connectivity of the precuneus occurred in both HZ and PHN patients, indicating a disrupted default-mode network. Furthermore, in the HZ group (initial stage of the virus infection), hyperconnectivity was observed in systems involved in pain transmission and interpretation, but hyperconnectivity only occurred in the hippocampus in the PHN group (neuropathic pain stage).

PMID: 29740216 [PubMed]

Experience-Driven Differences in Childhood Cortisol Predict Affect-Relevant Brain Function and Coping in Adolescent Monozygotic Twins.

Thu, 05/10/2018 - 16:00
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Experience-Driven Differences in Childhood Cortisol Predict Affect-Relevant Brain Function and Coping in Adolescent Monozygotic Twins.

Sci Rep. 2016 11 22;6:37081

Authors: Burghy CA, Fox ME, Cornejo MD, Stodola DE, Sommerfeldt SL, Westbrook CA, Van Hulle C, Schmidt NL, Goldsmith HH, Davidson RJ, Birn RM

Abstract
Stress and emotion involve diverse developmental and individual differences. Partially attributed to the development of the prefrontal cortex (PFC), the amygdala, and hypothalamic-pituitary-adrenal axis, the precise genetic and experiential contributions remain unknown. In previous work, childhood basal cortisol function predicted adolescent resting-state functional connectivity (rs-FC) and psychopathology. To parse experience-driven (non-genetic) contributions, we investigated these relations with a monozygotic (MZ) twin design. Specifically, we examined whether intrapair differences in childhood afternoon cortisol levels predicted cotwin differences in adolescent brain function and coping. As expected, intrapair differences in childhood cortisol forecast amygdala-perigenual PFC rs-FC (R2 = 0.84, FWE-corrected p = 0.01), and amygdala recovery following unpleasant images (R2 = 0.40, FWE-corrected p < 0.05), such that the cotwin with higher childhood cortisol evinced relatively lower rs-FC and poorer amygdala recovery in adolescence. Cotwin differences in amygdala recovery also predicted coping styles. These data highlight experience-dependent change in childhood and adolescence.

PMID: 27872489 [PubMed - indexed for MEDLINE]

A comprehensive evaluation of increasing temporal resolution with multiband-accelerated protocols and effects on statistical outcome measures in fMRI.

Wed, 05/09/2018 - 15:00
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A comprehensive evaluation of increasing temporal resolution with multiband-accelerated protocols and effects on statistical outcome measures in fMRI.

Neuroimage. 2018 May 05;:

Authors: Demetriou L, Kowalczyk OS, Tyson G, Bello T, Newbould RD, Wall MB

Abstract
Accelerated functional Magnetic Resonance Imaging (fMRI) with 'multiband' protocols is now relatively widespread. These protocols can be used to dramatically reduce the repetition time (TR) and produce a time-series sampled at a higher temporal resolution, which may produce benefits in the statistical methods typically used to analyse fMRI data. We tested the effects of higher temporal resolutions for fMRI on statistical outcome measures in a comprehensive manner on two different MRI scanner platforms. Spatial resolution was maintained at a constant of 3 mm isotropic voxels, and an in-plane acceleration factor of 2 was used for all experiments. Experiment 1 tested a range of acceleration factors (1-6) against a standard EPI protocol on a single composite task that mapped a number of basic sensory, motor, and cognitive networks. Experiment 2 compared the standard protocol with acceleration factors of 2 and 3 on both resting-state and two task paradigms (an N-back task, and faces/places task), with a number of different analysis approaches. Results from experiment 1 showed modest but relatively inconsistent effects of the higher sampling rate on statistical outcome measures. Experiment 2 showed strong benefits of the multiband protocols on results derived from resting-state data, but more varied effects on results from the task paradigms. Notably, the multiband protocols were superior when Multi-Voxel Pattern Analysis was used to interrogate the faces/places data, but showed less benefit in conventional General Linear Model analyses of the same data. In general, ROI-derived measures of statistical effects benefitted only modestly from higher sampling resolution, with greater effects seen when using a measure of the top range of statistical values. Across both experiments, results from the two scanner platforms were broadly comparable. The statistical benefits of high temporal resolution fMRI with multiband protocols may therefore depend on a number of factors, including the nature of the investigation (resting-state vs. task-based), the experimental design, the particular statistical outcome measure, and the type of analysis used.

PMID: 29738911 [PubMed - as supplied by publisher]

Diminished neural network dynamics in amnestic mild cognitive impairment.

Wed, 05/09/2018 - 15:00
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Diminished neural network dynamics in amnestic mild cognitive impairment.

Int J Psychophysiol. 2018 May 05;:

Authors: Brenner EK, Hillary FG, Grossner EC, Bernier RA, Gilbert N, Sathian K, Hampstead BM

Abstract
Mild cognitive impairment (MCI) is widely regarded as an intermediate stage between typical aging and dementia, with nearly 50% of patients with amnestic MCI (aMCI) converting to Alzheimer's dementia (AD) within 30 months of follow-up (Fischer et al., 2007). The growing literature using resting-state functional magnetic resonance imaging reveals both increased and decreased connectivity in individuals with MCI and connectivity loss between the anterior and posterior components of the default mode network (DMN) throughout the course of the disease progression (Hillary et al., 2015; Sheline & Raichle, 2013; Tijms et al., 2013). In this paper, we use dynamic connectivity modeling and graph theory to identify unique brain "states," or temporal patterns of connectivity across distributed networks, that distinguish individuals with aMCI from healthy older adults (HOAs). We enrolled 44 individuals diagnosed with aMCI and 33 HOAs of comparable age and education. Our results indicated that individuals with aMCI spent significantly more time in one state in particular, whereas neural network analysis in the HOA sample revealed approximately equivalent representation across four distinct states. Among individuals with aMCI, spending a higher proportion of time in the dominant state relative to a state where participants exhibited high cost (a measure combining connectivity and distance), predicted better language performance and perseveration. This is the first report to examine neural network dynamics in individuals with aMCI.

PMID: 29738855 [PubMed - as supplied by publisher]

Regional entropy of functional imaging signals varies differently in sensory and cognitive systems during propofol-modulated loss and return of behavioral responsiveness.

Wed, 05/09/2018 - 15:00
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Regional entropy of functional imaging signals varies differently in sensory and cognitive systems during propofol-modulated loss and return of behavioral responsiveness.

Brain Imaging Behav. 2018 May 08;:

Authors: Liu X, Lauer KK, Ward BD, Roberts CJ, Liu S, Gollapudy S, Rohloff R, Gross W, Xu Z, Chen S, Wang L, Yang Z, Li SJ, Binder JR, Hudetz AG

Abstract
The level and richness of consciousness depend on information integration in the brain. Altered interregional functional interactions may indicate disrupted information integration during anesthetic-induced unconsciousness. How anesthetics modulate the amount of information in various brain regions has received less attention. Here, we propose a novel approach to quantify regional information content in the brain by the entropy of the principal components of regional blood oxygen-dependent imaging signals during graded propofol sedation. Fifteen healthy individuals underwent resting-state scans in wakeful baseline, light sedation (conscious), deep sedation (unconscious), and recovery (conscious). Light sedation characterized by lethargic behavioral responses was associated with global reduction of entropy in the brain. Deep sedation with completely suppressed overt responsiveness was associated with further reductions of entropy in sensory (primary and higher sensory plus orbital prefrontal cortices) but not high-order cognitive (dorsal and medial prefrontal, cingulate, parietotemporal cortices and hippocampal areas) systems. Upon recovery of responsiveness, entropy was restored in the sensory but not in high-order cognitive systems. These findings provide novel evidence for a reduction of information content of the brain as a potential systems-level mechanism of reduced consciousness during propofol anesthesia. The differential changes of entropy in the sensory and high-order cognitive systems associated with losing and regaining overt responsiveness are consistent with the notion of "disconnected consciousness", in which a complete sensory-motor disconnection from the environment occurs with preserved internal mentation.

PMID: 29737490 [PubMed - as supplied by publisher]

Asymptomatic HIV vertical transmitted adolescents' brain functional changes: based on resting state functional MRI.

Wed, 05/09/2018 - 15:00
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Asymptomatic HIV vertical transmitted adolescents' brain functional changes: based on resting state functional MRI.

AIDS Res Hum Retroviruses. 2018 May 08;:

Authors: Wang P, Li J, Wang X, Wu GY, Thapa D

Abstract
OBJECTIVE: Perinatal HIV-infected (PHIV+) adolescents survive longer with the use of readily found combination antiretroviral therapy(cART), however, they still have the risk of developing cognitive deficits. The paper aims to explore the brain functional changes in asymptomatic PHIV+ adolescents with cART based on the resting-state functional MRI (rs-fMRI).
MATERIALS AND METHODS: rs-fMRI was performed on 20 PHIV+ adolescents and 28 PHIV- controls to evaluate the regional homogeneity (ReHo) in different brain regions by calculating the Kendall harmonious coefficient(KCC). Montreal cognitive assessment(MoCA)and laboratory studies (nadir CD4+ T-cell counts) were also performed on all the subjects to evaluate their cognitive and immune status.
RESULTS: 13 PHIV+ adolescents and 22 PHIV- controls were enrolled. There was a significant difference of ReHo values in PHIV+ adolescents compared to PHIV- controls, the areas with increased ReHo values include bilateral precentral/postcentral gyrus and right middle temporal pole. And the areas with decreased ReHo values locate in right putamen/pallidum/insula, left caudate/putamen/insula, right superior temporal pole/insula, right caudate/putamen, bilateral anterior cingulate cortex and left inferior temporal pole. Furthermore, age, cognitive scores and laboratory studies (nadir CD4+ T-cell counts) did not show any significant correlation with altered ReHo values of brain regions neither in PHIV+ groups nor in PHIV- control groups.
CONCLUSION: Among PHIV+ adolescents, brain areas with increased ReHo values were mainly located in the central somatic motor-sensory cortex, that might be related to the compensatory mechanism. Whereas, brain areas with decreased ReHo values were mainly focused on cortico-striatal pathway, that might be associated with abnormal dopamine consumption. Thus, rs-fMRI could demonstrate the brain functional changes in resting-state of the asymptomatic PHIV+ adolescents.

PMID: 29737186 [PubMed - as supplied by publisher]

Resting-State Functional Connectivity in the Human Connectome Project: Current Status and Relevance to Understanding Psychopathology.

Wed, 05/09/2018 - 15:00
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Resting-State Functional Connectivity in the Human Connectome Project: Current Status and Relevance to Understanding Psychopathology.

Harv Rev Psychiatry. 2017 Sep/Oct;25(5):209-217

Authors: Barch DM

Abstract
A key tenet of modern psychiatry is that psychiatric disorders arise from abnormalities in brain circuits that support human behavior. Our ability to examine hypotheses around circuit-level abnormalities in psychiatric disorders has been made possible by advances in human neuroimaging technologies. These advances have provided the basis for recent efforts to develop a more complex understanding of the function of brain circuits in health and of their relationship to behavior-providing, in turn, a foundation for our understanding of how disruptions in such circuits contribute to the development of psychiatric disorders. This review focuses on the use of resting-state functional connectivity MRI to assess brain circuits, on the advances generated by the Human Connectome Project, and on how these advances potentially contribute to understanding neural circuit dysfunction in psychopathology. The review gives particular attention to the methods developed by the Human Connectome Project that may be especially relevant to studies of psychopathology; it outlines some of the key findings about what constitutes a brain region; and it highlights new information about the nature and stability of brain circuits. Some of the Human Connectome Project's new findings particularly relevant to psychopathology-about neural circuits and their relationships to behavior-are also presented. The review ends by discussing the extension of Human Connectome Project methods across the lifespan and into manifest illness. Potential treatment implications are also considered.

PMID: 28816791 [PubMed - indexed for MEDLINE]

resting state fMRI; +22 new citations

Tue, 05/08/2018 - 19:10

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Estimation of Dynamic Sparse Connectivity Patterns From Resting State fMRI.

Mon, 05/07/2018 - 19:20
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Estimation of Dynamic Sparse Connectivity Patterns From Resting State fMRI.

IEEE Trans Med Imaging. 2018 May;37(5):1224-1234

Authors: Cai B, Zille P, Stephen JM, Wilson TW, Calhoun VD, Wang YP

Abstract
Functional connectivity (FC) estimated from functional magnetic resonance imaging (fMRI) time series, especially during resting state periods, provides a powerful tool to assess human brain functional architecture in health, disease, and developmental states. Recently, the focus of connectivity analysis has shifted toward the subnetworks of the brain, which reveals co-activating patterns over time. Most prior works produced a dense set of high-dimensional vectors, which are hard to interpret. In addition, their estimations to a large extent were based on an implicit assumption of spatial and temporal stationarity throughout the fMRI scanning session. In this paper, we propose an approach called dynamic sparse connectivity patterns (dSCPs), which takes advantage of both matrix factorization and time-varying fMRI time series to improve the estimation power of FC. The feasibility of analyzing dynamic FC with our model is first validated through simulated experiments. Then, we use our framework to measure the difference between young adults and children with real fMRI data set from the Philadelphia Neurodevelopmental Cohort (PNC). The results from the PNC data set showed significant FC differences between young adults and children in four different states. For instance, young adults had reduced connectivity between the default mode network and other subnetworks, as well as hyperconnectivity within the visual system in states 1 and 3, and hypoconnectivity in state 2. Meanwhile, they exhibited temporal correlation patterns that changed over time within functional subnetworks. In addition, the dSCPs model indicated that older people tend to spend more time within a relatively connected FC pattern. Overall, the proposed method provides a valid means to assess dynamic FC, which could facilitate the study of brain networks.

PMID: 29727285 [PubMed - in process]

Theta Burst Stimulation Enhances Connectivity of the Dorsal Attention Network in Young Healthy Subjects: An Exploratory Study.

Mon, 05/07/2018 - 19:20
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Theta Burst Stimulation Enhances Connectivity of the Dorsal Attention Network in Young Healthy Subjects: An Exploratory Study.

Neural Plast. 2018;2018:3106918

Authors: Anderkova L, Pizem D, Klobusiakova P, Gajdos M, Koritakova E, Rektorova I

Abstract
We examined effects of theta burst stimulation (TBS) applied over two distinct cortical areas (the right inferior frontal gyrus and the left superior parietal lobule) on the Stroop task performance in 20 young healthy subjects. Neural underpinnings of the behavioral effect were tested using fMRI. A single session of intermittent TBS of the left superior parietal lobule induced certain cognitive speed enhancement and significantly increased resting-state connectivity of the dorsal attention network. This is an exploratory study that prompts further research with multiple-session TBS in subjects with cognitive impairment.

PMID: 29725346 [PubMed - in process]

Effects of Gradient Coil Noise and Gradient Coil Replacement on the Reproducibility of Resting State Networks.

Mon, 05/07/2018 - 19:20
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Effects of Gradient Coil Noise and Gradient Coil Replacement on the Reproducibility of Resting State Networks.

Front Hum Neurosci. 2018;12:148

Authors: Bagarinao E, Tsuzuki E, Yoshida Y, Ozawa Y, Kuzuya M, Otani T, Koyama S, Isoda H, Watanabe H, Maesawa S, Naganawa S, Sobue G

Abstract
The stability of the MRI scanner throughout a given study is critical in minimizing hardware-induced variability in the acquired imaging data set. However, MRI scanners do malfunction at times, which could generate image artifacts and would require the replacement of a major component such as its gradient coil. In this article, we examined the effect of low intensity, randomly occurring hardware-related noise due to a faulty gradient coil on brain morphometric measures derived from T1-weighted images and resting state networks (RSNs) constructed from resting state functional MRI. We also introduced a method to detect and minimize the effect of the noise associated with a faulty gradient coil. Finally, we assessed the reproducibility of these morphometric measures and RSNs before and after gradient coil replacement. Our results showed that gradient coil noise, even at relatively low intensities, could introduce a large number of voxels exhibiting spurious significant connectivity changes in several RSNs. However, censoring the affected volumes during the analysis could minimize, if not completely eliminate, these spurious connectivity changes and could lead to reproducible RSNs even after gradient coil replacement.

PMID: 29725294 [PubMed]

GAD65 promoter polymorphism rs2236418 modulates harm avoidance in women via inhibition/excitation balance in the rostral ACC.

Mon, 05/07/2018 - 19:20
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GAD65 promoter polymorphism rs2236418 modulates harm avoidance in women via inhibition/excitation balance in the rostral ACC.

J Neurosci. 2018 May 03;:

Authors: Colic L, Li M, Ramona Demenescu L, Li S, Müller I, Richter A, Seidenbecher CI, Speck O, Schott BH, Stork O, Walter M

Abstract
Anxiety disorders are common and debilitating conditions with higher prevalence in women. However, factors that predispose women to anxiety phenotypes are not clarified. Here we investigated potential contribution of the single nucleotide polymorphism rs2236418 in GAD2 gene to changes in regional inhibition/excitation balance, anxiety-like traits and related neural activity in both sexes. 105 healthy individuals were examined with high-field (7T) multimodal magnetic resonance imaging (MRI), including resting state fMRI in combination with assessment of GABA and Glutamate (Glu) levels via MR spectroscopy (MRS). Regional GABA/Glu levels in ACC subregions were assessed as mediators of gene-personality interaction for the trait harm avoidance and moderation by sex was tested. In AA homozygotes, with putatively lower GAD2 promoter activity, we observed increased intrinsic neuronal activity and higher inhibition/excitation balance in pregenual ACC (pgACC), as compared to G carriers. The pgACC drove a significant interaction of genotype, region and sex, where inhibition/excitation balance was significantly reduced only in female AA carriers. This finding was specific for rs2236418 as other investigated SNPs of the GABA synthesis related enzymes (GAD1, GAD2 and GLS) were not significant. Furthermore, only in women there was a negative association of pgACC GABA/Glu ratios with harm avoidance. A moderated-mediation model revealed that pgACC GABA/Glu also mediated the association between the genotype variant and level of harm avoidance, dependent on sex. Our data thus provide new insights into the neurochemical mechanisms that control emotional endophenotypes in humans and constitute predisposing factors for the development of anxiety disorders in women.SIGNIFICANCE STATEMENTAnxiety disorders are among the most common and burdensome psychiatric disorders, with higher prevalence rates in women. The causal mechanisms are, however, poorly understood. In this study we propose a neurobiological basis that could help to explain female bias of anxiety endophenotypes. Using magnetic resonance brain imaging and personality questionnaires we show an interaction of the genetic variation rs2236418 in the GAD2 gene and sex on GABA/Glutamate (Glu) balance in the pregenual anterior cingulate cortex (pgACC), a region previously connected to affect regulation and anxiety disorders. The GAD2 gene polymorphism further influenced baseline neuronal activity in the pgACC. Importantly, GABA/Glu was shown to mediate the relationship between the genetic variant and harm avoidance, however only in women.

PMID: 29724796 [PubMed - as supplied by publisher]

Influences of hunger, satiety and oral glucose on functional brain connectivity: A multimethod resting state fMRI study.

Fri, 05/04/2018 - 16:00

Influences of hunger, satiety and oral glucose on functional brain connectivity: A multimethod resting state fMRI study.

Neuroscience. 2018 Apr 30;:

Authors: Al-Zubaidi A, Heldmann M, Mertins A, Jauch-Chara K, Münte TF

Abstract
A major regulatory task of the organism is to keep brain functions relatively constant in spite of metabolic changes (e.g., hunger vs. satiety) or availability of energy (e.g., glucose administration). Resting-state functional magnetic resonance imaging (rs-fMRI) can reveal resulting changes in brain function but previous studies have focused mostly on the hypothalamus. Therefore, we took a whole brain approach and examined 24 healthy normal-weight men once after 36 hours of fasting and once in a satiated state (six meals over the course of 36 hours). At the end of each treatment, rs-fMRI was recorded before and after the oral administration of 75 g of glucose. We calculated local connectivity (regional homogeneity [ReHo]), global connectivity (degree of centrality [DC]), and amplitude (fractional amplitude of low-frequency fluctuation [fALFF]) maps from the rs-fMRI data. We found that glucose administration reduced all measures selectively in the left supplementary motor area and increased ReHo and fALFF in the right middle and superior frontal gyri. For fALFF, we observed a significant interaction between metabolic states and glucose in the left thalamus. This interaction was driven by a fALFF increase after glucose treatment in the hunger relative to the satiety condition. Our results indicate that fALFF analysis is the most sensitive measure to detect effects of metabolic states on resting state brain activity. Moreover, we show that multimethod rs-fMRI provides an unbiased approach to identify spontaneous brain activity associated with changes in homeostasis and caloric intake.

PMID: 29723574 [PubMed - as supplied by publisher]

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