New resting-state fMRI related studies at PubMed

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Estimating Dynamic Connectivity States in fMRI Using Regime-Switching Factor Models.

Wed, 04/04/2018 - 14:00
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Estimating Dynamic Connectivity States in fMRI Using Regime-Switching Factor Models.

IEEE Trans Med Imaging. 2018 Apr;37(4):1011-1023

Authors: Ting CM, Ombao H, Samdin SB, Salleh SH

Abstract
We consider the challenges in estimating the state-related changes in brain connectivity networks with a large number of nodes. Existing studies use the sliding-window analysis or time-varying coefficient models, which are unable to capture both smooth and abrupt changes simultaneously, and rely on ad-hoc approaches to the high-dimensional estimation. To overcome these limitations, we propose a Markov-switching dynamic factor model, which allows the dynamic connectivity states in functional magnetic resonance imaging (fMRI) data to be driven by lower-dimensional latent factors. We specify a regime-switching vector autoregressive (SVAR) factor process to quantity the time-varying directed connectivity. The model enables a reliable, data-adaptive estimation of change-points of connectivity regimes and the massive dependencies associated with each regime. We develop a three-step estimation procedure: 1) extracting the factors using principal component analysis, 2) identifying connectivity regimes in a low-dimensional subspace based on the factor-based SVAR model, and 3) constructing high-dimensional state connectivity metrics based on the subspace estimates. Simulation results show that our estimator outperforms -means clustering of time-windowed coefficients, providing more accurate estimate of time-evolving connectivity. It achieves percentage of reduction in mean squared error by 60% when the network dimension is comparable to the sample size. When applied to the resting-state fMRI data, our method successfully identifies modular organization in the resting-statenetworksin consistencywith other studies. It further reveals changes in brain states with variations across subjects and distinct large-scale directed connectivity patterns across states.

PMID: 29610078 [PubMed - in process]

Regular cannabis and alcohol use is associated with resting-state time course power spectra in incarcerated adolescents.

Wed, 04/04/2018 - 14:00
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Regular cannabis and alcohol use is associated with resting-state time course power spectra in incarcerated adolescents.

Drug Alcohol Depend. 2017 Sep 01;178:492-500

Authors: Thijssen S, Rashid B, Gopal S, Nyalakanti P, Calhoun VD, Kiehl KA

Abstract
Cannabis and alcohol are believed to have widespread effects on the brain. Although adolescents are at increased risk for substance use, the adolescent brain may also be particularly vulnerable to the effects of drug exposure due to its rapid maturation. Here, we examined the association between cannabis and alcohol use duration and resting-state functional connectivity in a large sample of male juvenile delinquents. The present sample was drawn from the Southwest Advanced Neuroimaging Cohort, Youth sample, and from a youth detention facility in Wisconsin. All participants were scanned at the maximum-security facilities using The Mind Research Network's 1.5T Avanto SQ Mobile MRI scanner. Information on cannabis and alcohol regular use duration was collected using self-report. Resting-state networks were computed using group independent component analysis in 201 participants. Associations with cannabis and alcohol use were assessed using Mancova analyses controlling for age, IQ, smoking and psychopathy scores in the complete case sample of 180 male juvenile delinquents. No associations between alcohol or cannabis use and network spatial maps were found. Longer cannabis use was associated with decreased low frequency power of the default mode network, the executive control networks (ECNs), and several sensory networks, and with decreased functional network connectivity. Duration of alcohol use was associated with decreased low frequency power of the right frontoparietal network, salience network, dorsal attention network, and several sensory networks. Our findings suggest that adolescent cannabis and alcohol use are associated with widespread differences in resting-state time course power spectra, which may persist even after abstinence.

PMID: 28715777 [PubMed - indexed for MEDLINE]

Increased temporal variability of striatum region facilitating the early antidepressant response in patients with major depressive disorder.

Tue, 04/03/2018 - 13:00
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Increased temporal variability of striatum region facilitating the early antidepressant response in patients with major depressive disorder.

Prog Neuropsychopharmacol Biol Psychiatry. 2018 Mar 30;:

Authors: Hou Z, Kong Y, He X, Yin Y, Zhang Y, Yuan Y

Abstract
The aim of this study is to identify the difference of temporal variability among major depressive disorder (MDD) patients (with different early antidepressant responses) and healthy controls (HC), and further explore the relationship between pre-treatment temporal variability and early antidepressant response. At baseline, 77 treatment-naïve inpatients with MDD and 42 matched HC received clinical assessments and 3.0 Tesla resting-state functional magnetic resonance imaging scans. After 2 weeks' antidepressant treatment, the patients were subgrouped into responsive depression (RD, n = 40) and non-responding depression (NRD, n = 37) based on the reduction of Hamilton depression rating scale (HAMD). The temporal variability of 90 brain nodes was calculated for further analysis. Compared with the HC group, both the RD and NRD subjects showed greater baseline temporal variability (i.e., greater dynamic) in the left inferior occipital gyrus. Significantly greater temporal variability in the left pallidum was found in the RD group than the NRD and the HC groups, and the higher variability of left pallidum correlated positively with the HAMD reduction. Moreover, the pooled MDD (i.e., RD and NRD) group showed greater baseline temporal variability in the right inferior frontal gyrus, the left inferior occipital gyrus, the bilateral fusiform gyri and the left Heschl gyrus than the HC group. The distinctive pattern of dynamically reorganized networks may provide a crucial scaffold to facilitate early antidepressant response, and the temporal variability may serve as a promising indicator for the personalized therapy of MDD.

PMID: 29608926 [PubMed - as supplied by publisher]

Principal States of Dynamic Functional Connectivity Reveal the Link Between Resting-State and Task-State Brain: An fMRI Study.

Tue, 04/03/2018 - 13:00
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Principal States of Dynamic Functional Connectivity Reveal the Link Between Resting-State and Task-State Brain: An fMRI Study.

Int J Neural Syst. 2018 Jan 25;:1850002

Authors: Cheng L, Zhu Y, Sun J, Deng L, He N, Yang Y, Ling H, Ayaz H, Fu Y, Tong S

Abstract
Task-related reorganization of functional connectivity (FC) has been widely investigated. Under classic static FC analysis, brain networks under task and rest have been demonstrated a general similarity. However, brain activity and cognitive process are believed to be dynamic and adaptive. Since static FC inherently ignores the distinct temporal patterns between rest and task, dynamic FC may be more a suitable technique to characterize the brain's dynamic and adaptive activities. In this study, we adopted [Formula: see text]-means clustering to investigate task-related spatiotemporal reorganization of dynamic brain networks and hypothesized that dynamic FC would be able to reveal the link between resting-state and task-state brain organization, including broadly similar spatial patterns but distinct temporal patterns. In order to test this hypothesis, this study examined the dynamic FC in default-mode network (DMN) and motor-related network (MN) using Blood-Oxygenation-Level-Dependent (BOLD)-fMRI data from 26 healthy subjects during rest (REST) and a hand closing-and-opening (HCO) task. Two principal FC states in REST and one principal FC state in HCO were identified. The first principal FC state in REST was found similar to that in HCO, which appeared to represent intrinsic network architecture and validated the broadly similar spatial patterns between REST and HCO. However, the second FC principal state in REST with much shorter "dwell time" implied the transient functional relationship between DMN and MN during REST. In addition, a more frequent shifting between two principal FC states indicated that brain network dynamically maintained a "default mode" in the motor system during REST, whereas the presence of a single principal FC state and reduced FC variability implied a more temporally stable connectivity during HCO, validating the distinct temporal patterns between REST and HCO. Our results further demonstrated that dynamic FC analysis could offer unique insights in understanding how the brain reorganizes itself during rest and task states, and the ways in which the brain adaptively responds to the cognitive requirements of tasks.

PMID: 29607681 [PubMed - as supplied by publisher]

Gender-specific effect of uric acid on resting-state functional networks in de novo Parkinson's disease.

Tue, 04/03/2018 - 13:00
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Gender-specific effect of uric acid on resting-state functional networks in de novo Parkinson's disease.

Parkinsonism Relat Disord. 2018 Mar 26;:

Authors: Lee Y, Park YH, Lee JJ, Sohn YH, Lee JM, Lee PH

Abstract
INTRODUCTION: The pattern of resting-state networks is influenced by several factors besides the underlying pathological changes of Parkinson's disease (PD). Uric acid (UA), as an antioxidant, has a neuroprotective property against PD-related microenvironment; however, this effect would be gender-specific. We aimed to evaluate a gender-sensitive resting-state networks (RSN) according to the UA level in drug naïve de novo patients with PD to elucidate the role of antioxidant in cortical functional networks of PD.
METHODS: This study enrolled 135 de novo patients with PD underwent functional magnetic resonance imaging (MRI). Based on the distribution, the serum UA level was stratified into tertiles in the PD patients by gender. With a seed-based approach, we investigated the pattern of RSN within the dorsal attention network (DAN), executive control network (ECN), and default mode network (DMN).
RESULTS: Interaction analysis showed a significant interaction between the lowest (PD-L-UA) and the highest UA level (PD-H-UA) groups according to gender within the DAN, ECN, and DMN. Compared to the control subjects, male patients with PD-H-UA had higher cortical functional connectivity (FC), while female patients had lower cortical FC regardless of UA level within all seeds. In a direct comparison, male patients with PD-H-UA had increased FC than did those with PD-L-UA. However, there was no significant difference in FC between PD-L-UA and PD-H-UA in female PD patients.
CONCLUSIONS: These data suggest that RSN might be closely and gender-specifically associated with the status of serum UA in de novo PD patients.

PMID: 29606606 [PubMed - as supplied by publisher]

Spontaneous Infra-slow Brain Activity Has Unique Spatiotemporal Dynamics and Laminar Structure.

Tue, 04/03/2018 - 13:00
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Spontaneous Infra-slow Brain Activity Has Unique Spatiotemporal Dynamics and Laminar Structure.

Neuron. 2018 Mar 24;:

Authors: Mitra A, Kraft A, Wright P, Acland B, Snyder AZ, Rosenthal Z, Czerniewski L, Bauer A, Snyder L, Culver J, Lee JM, Raichle ME

Abstract
Systems-level organization in spontaneous infra-slow (<0.1Hz) brain activity, measured using blood oxygen signals in fMRI and optical imaging, has become a major theme in the study of neural function in both humans and animal models. Yet the neurophysiological basis of infra-slow activity (ISA) remains unresolved. In particular, is ISA a distinct physiological process, or is it a low-frequency analog of faster neural activity? Here, using whole-cortex calcium/hemoglobin imaging in mice, we show that ISA in each of these modalities travels through the cortex along stereotypical spatiotemporal trajectories that are state dependent (wake versus anesthesia) and distinct from trajectories in delta (1-4 Hz) activity. Moreover, mouse laminar electrophysiology reveals that ISA travels through specific cortical layers and is organized into unique cross-laminar temporal dynamics that are different from higher frequency local field potential activity. These findings suggest that ISA is a distinct neurophysiological process that is reflected in fMRI blood oxygen signals.

PMID: 29606579 [PubMed - as supplied by publisher]

Regional Brain Activity During Rest and Gastric Water Load in Subtypes of Functional Dyspepsia: A Preliminary Brain Functional Magnetic Resonance Imaging Study.

Tue, 04/03/2018 - 13:00
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Regional Brain Activity During Rest and Gastric Water Load in Subtypes of Functional Dyspepsia: A Preliminary Brain Functional Magnetic Resonance Imaging Study.

J Neurogastroenterol Motil. 2018 Apr 30;24(2):268-279

Authors: Chen Y, Wang R, Hou B, Feng F, Fang X, Zhu L, Sun X, Wang Z, Ke M

Abstract
Background/Aims: Functional dyspepsia (FD) remains a great clinical challenge since the FD subtypes, defined by Rome III classification, still have heterogeneous pathogenesis. Previous studies have shown notable differences in visceral sensation processing in the CNS in FD compared to healthy subjects (HS). However, the role of CNS in the pathogenesis of each FD subtype has not been recognized.
Methods: Twenty-eight FD patients, including 10 epigastric pain syndrome (EPS), 9 postprandial distress syndrome (PDS), and 9 mixed-type, and 10 HS, were enrolled. All subjects underwent a proximal gastric perfusion water load test and the regional brain activities during resting state and water load test were investigated by functional magnetic resonance imaging.
Results: For regional brain activities during the resting state and water load test, each FD subtype was significantly different from HS (P < 0.05). Focusing on EPS and PDS, the regional brain activities of EPS were stronger than PDS in the left paracentral lobule, right inferior frontal gyrus pars opercularis, postcentral gyrus, precuneus, insula, parahippocampal gyrus, caudate nucleus, and bilateral cingulate cortices at the resting state (P < 0.05), and stronger than PDS in the left inferior temporal and fusiform gyri during the water load test (P < 0.05).
Conclusions: Compared to HS, FD subtypes had different regional brain activities at rest and during water load test, whereby the differences displayed distinct manifestations for each subtype. Compared to PDS, EPS presented more significant differences from HS at rest, suggesting that the abnormality of central visceral pain processing could be one of the main pathogenesis mechanisms for EPS.

PMID: 29605982 [PubMed]

Functional hypergraph uncovers novel covariant structures over neurodevelopment.

Tue, 04/03/2018 - 13:00
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Functional hypergraph uncovers novel covariant structures over neurodevelopment.

Hum Brain Mapp. 2017 Aug;38(8):3823-3835

Authors: Gu S, Yang M, Medaglia JD, Gur RC, Gur RE, Satterthwaite TD, Bassett DS

Abstract
Brain development during adolescence is marked by substantial changes in brain structure and function, leading to a stable network topology in adulthood. However, most prior work has examined the data through the lens of brain areas connected to one another in large-scale functional networks. Here, we apply a recently developed hypergraph approach that treats network connections (edges) rather than brain regions as the unit of interest, allowing us to describe functional network topology from a fundamentally different perspective. Capitalizing on a sample of 780 youth imaged as part of the Philadelphia Neurodevelopmental Cohort, this hypergraph representation of resting-state functional MRI data reveals three distinct classes of subnetworks (hyperedges): clusters, bridges, and stars, which respectively represent homogeneously connected, bipartite, and focal architectures. Cluster hyperedges show a strong resemblance to previously-described functional modules of the brain including somatomotor, visual, default mode, and salience systems. In contrast, star hyperedges represent highly localized subnetworks centered on a small set of regions, and are distributed across the entire cortex. Finally, bridge hyperedges link clusters and stars in a core-periphery organization. Notably, developmental changes within hyperedges are ordered in a similar core-periphery fashion, with the greatest developmental effects occurring in networked hyperedges within the functional core. Taken together, these results reveal a novel decomposition of the network organization of human brain, and further provide a new perspective on the role of local structures that emerge across neurodevelopment. Hum Brain Mapp 38:3823-3835, 2017. © 2017 Wiley Periodicals, Inc.

PMID: 28493536 [PubMed - indexed for MEDLINE]

A Novel Approach to Identifying a Neuroimaging Biomarker for Patients With Serious Mental Illness.

Tue, 04/03/2018 - 13:00
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A Novel Approach to Identifying a Neuroimaging Biomarker for Patients With Serious Mental Illness.

J Neuropsychiatry Clin Neurosci. 2017;29(3):275-283

Authors: Madan A, Fowler JC, Patriquin MA, Salas R, Baldwin PR, Velasquez KM, Viswanath H, Molfese DL, Sharp C, Allen JG, Hardesty S, Oldham JM, Frueh BC

Abstract
Serious mental illness (SMI) is disabling, and current interventions are ineffective for many. This exploratory study sought to demonstrate the feasibility of applying topological data analysis (TDA) to resting-state functional connectivity data obtained from a heterogeneous sample of 235 adult inpatients to identify a biomarker of treatment response. TDA identified two groups based on connectivity between the prefrontal cortex and striatal regions: patients admitted with greater functional connectivity between these regions evidenced less improvement from admission to discharge than patients with lesser connectivity between them. TDA identified a potential biomarker of an attenuated treatment response among inpatients with SMI. Insofar as the observed pattern of resting-state functional connectivity collected early during treatment is replicable, this potential biomarker may indicate the need to modify standard of care for a small, albeit meaningful, percentage of patients.

PMID: 28238273 [PubMed - indexed for MEDLINE]

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