New resting-state fMRI related studies at PubMed

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Abnormal fronto-striatal intrinsic connectivity reflects executive dysfunction in alcohol use disorders.

Mon, 02/11/2019 - 13:40
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Abnormal fronto-striatal intrinsic connectivity reflects executive dysfunction in alcohol use disorders.

Cortex. 2019 Jan 23;115:27-42

Authors: Galandra C, Basso G, Manera M, Crespi C, Giorgi I, Vittadini G, Poggi P, Canessa N

Abstract
The neural bases of cognitive impairment(s) in alcohol use disorders (AUDs) have been explained either with the specific involvement of frontal regions mostly affected by alcohol neurotoxic effects, or with a global brain damage underlying different neuro-cognitive alterations. Novel insights into this issue might come from the analysis of resting-state brain activity, representing a baseline level of intrinsic connectivity within and between the networks underlying cognitive performance. We thus addressed the neural bases of cognitive impairment(s) in 22 AUD patients, compared with 18 healthy controls, by coupling resting-state fMRI with an in-depth neuropsychological assessment of the main cognitive domains. We assessed a relationship between AUD patients' cognitive impairment and two complementary facets of intrinsic brain functioning, i.e., intensity of activation and functional network connectivity, related to the strength of connectivity within and between resting-state networks, respectively. Alcoholic patients' decreased cognitive performance involved specifically an executive domain associated with attentional and working-memory tasks. This impairment reflected an abnormal relationship, in patients versus controls, between cognitive performance and the intensity of intrinsic activity in the dorsolateral prefrontal and striatal nodes of the executive control network. Functional connectivity between the same structures was positively correlated with executive performance in the whole sample, but significantly reduced in patients. The present data suggest that AUD patients' executive impairment reflects dysfunctional connectivity between the cortical and subcortical nodes of the networks underlying cognitive control on goal-directed behavior. This evidence provides a baseline for future studies addressing the abnormal neural architecture underlying cognitive impairment in AUDs and the outcome of rehabilitative treatment.

PMID: 30738999 [PubMed - as supplied by publisher]

Genetic contribution of catechol-O-methyltransferase in dorsolateral prefrontal cortex functional changes in the first episode schizophrenia.

Mon, 02/11/2019 - 13:40
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Genetic contribution of catechol-O-methyltransferase in dorsolateral prefrontal cortex functional changes in the first episode schizophrenia.

Behav Brain Res. 2019 Feb 07;:

Authors: Kang Y, Huang K, Lv Y, Zhang W, Cai S, Wang Y, Wang Q, Huang L, Wang J, Tian J

Abstract
Catechol-O-methyltransferase (COMT) gene variants have been reported to be implicated in the pathogenesis of psychotic symptoms in schizophrenia, especially in negative symptoms. These symptoms including apathy, blunted affect, social withdrawal and motor retardation. Neuroimaging studies suggested that negative symptoms appear to be associated with impaired activities of the prefrontal cortex in particular the dorsolateral prefrontal cortex (DLPFC). Given that the COMT gene is highly expressed in the DLPFC, it is poorly understood whether the disease state and COMT val158met polymorphisms have main and interactive effect on the resting state functional connectivity (RSFC) of DLPFC-related pathways. To this end, fifty-five first episode schizophrenia (FES) and fifty-three healthy controls were genotyped using blood samples and underwent magnetic resonance imaging scanning. Seed-based voxel wise functional connectivity analysis was performed by placing bilateral pairs of seeds with DLPFC in area 46 defined by Brodmann's atlas. A two-ways ANCOVA model was performed with val158met genotypes and disease state as the between subjects factors. Significant disease×COMT interactive effect was found mainly in the left DLPFC with the left anterior cingulate cortex, right precuneus, right superior parietal gyrus, which were overlapped with disease main effect. And these RSFC had positive correlations with affective blunting scores in FES patients with val homozygotes, but not with met carriers. Our results showed that the disease and the genotypes in COMT gene have significant interactive effect on RSFC of DLPFC and provided evidence for a disease-dependent pattern of gene action.

PMID: 30738913 [PubMed - as supplied by publisher]

Increased Functional Connectivity Between Ventral Attention and Default Mode Networks in Adolescents With Bulimia Nervosa.

Mon, 02/11/2019 - 13:40
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Increased Functional Connectivity Between Ventral Attention and Default Mode Networks in Adolescents With Bulimia Nervosa.

J Am Acad Child Adolesc Psychiatry. 2019 Feb;58(2):232-241

Authors: Domakonda MJ, He X, Lee S, Cyr M, Marsh R

Abstract
OBJECTIVE: Bulimia nervosa (BN) is characterized by excessive attention to self and specifically to body shape and weight, but the ventral attention (VAN) and default mode (DMN) networks that support attentional and self-referential processes are understudied in BN. This study assessed whether altered functional connectivity within and between these networks contributes to such excessive concerns in adolescents with BN early the course of the disorder.
METHOD: Resting-state functional magnetic resonance images were acquired from 33 adolescents with BN and 37 healthy control adolescents (12-21 years) group matched by age and body mass index. Region-of-interest analyses were performed to examine group differences in functional connectivity within and between the VAN and DMN. In addition associations of VAN-DMN connectivity with BN symptoms, body shape/weight concerns, and sustained attention were explored using the Continuous Performance Test (CPT).
RESULTS: Compared with control adolescents, those with BN showed significantly increased positive connectivity between the right ventral supramarginal gyrus and all DMN regions and between the right ventrolateral prefrontal cortex and the left lateral parietal cortex. Within-network connectivity did not differ between groups. VAN-DMN connectivity was associated with BN severity and body shape/weight concerns in the BN group. No significant group-by-CPT interactions on VAN-DMN connectivity were detected.
CONCLUSION: Increased positive VAN-DMN connectivity in adolescents with BN could reflect abnormal engagement of VAN-mediated attentional processes at rest, perhaps related to their excessive attention to self-referential thoughts about body shape/weight. Future studies should further investigate these circuits as targets for the development of early interventions aimed at decreasing excessive body shape/weight concerns.

PMID: 30738550 [PubMed - in process]

Editorial: To Eat or Not to Eat: Advancing the Neuroscience of Hedonic Versus Controlled Eating Across Weight and Eating Disorders.

Mon, 02/11/2019 - 13:40
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Editorial: To Eat or Not to Eat: Advancing the Neuroscience of Hedonic Versus Controlled Eating Across Weight and Eating Disorders.

J Am Acad Child Adolesc Psychiatry. 2019 Feb;58(2):151-153

Authors: Ehrlich S, King JA, Boehm I

Abstract
Excessive weight and obesity, especially with childhood onset, is associated with long-term morbidity and mortality and places a major burden on the health care system. In the United States, 17% of children and adolescents are obese (32% overweight). By adulthood, the number rises to 34% or even 68% when also considering overweight individuals.1 Conventional nonsurgical treatments are often ineffective, and weight loss achieved with behaviorally oriented therapy programs is usually small (∼5%) and short-lived.2 A better understanding of the associated psychological mechanisms and their neurobiological underpinnings may allow for the development of more efficient, potentially brain-based, therapeutic interventions. A growing number of human functional magnetic resonance imaging (fMRI) studies point to alterations in reward-related corticostriatal circuity and the hypothalamus, a key area in energy homeostasis.3 Recent studies have analyzed resting state functional connectivity (rsFC), a technique sensitive to changes in the interaction between distant brain regions, which is particularly advantageous in clinical samples, as it requires little compliance and as scanning time is relatively short.

PMID: 30738539 [PubMed - in process]

Human caudate nucleus subdivisions in tinnitus modulation.

Sun, 02/10/2019 - 12:20

Human caudate nucleus subdivisions in tinnitus modulation.

J Neurosurg. 2019 Feb 08;:1-7

Authors: Perez PL, Wang SS, Heath S, Henderson-Sabes J, Mizuiri D, Hinkley LB, Nagarajan SS, Larson PS, Cheung SW

Abstract
OBJECTIVEThe object of this study was to define caudate nucleus locations responsive to intraoperative direct electrical stimulation for tinnitus loudness modulation and relate those locations to functional connectivity maps between caudate nucleus subdivisions and auditory cortex.METHODSSix awake study participants who underwent bilateral deep brain stimulation (DBS) electrode placement in the caudate nucleus as part of a phase I clinical trial were analyzed for tinnitus modulation in response to acute stimulation at 20 locations. Resting-state 3-T functional MRI (fMRI) was used to compare connectivity strength between centroids of tinnitus loudness-reducing or loudness-nonreducing caudate locations and the auditory cortex in the 6 DBS phase I trial participants and 14 other neuroimaging participants with a Tinnitus Functional Index > 50.RESULTSAcute tinnitus loudness reduction was observed at 5 caudate locations, 4 positioned at the body and 1 at the head of the caudate nucleus in normalized Montreal Neurological Institute space. The remaining 15 electrical stimulation interrogations of the caudate head failed to reduce tinnitus loudness. Compared to the caudate head, the body subdivision had stronger functional connectivity to the auditory cortex on fMRI (p < 0.05).CONCLUSIONSAcute tinnitus loudness reduction was more readily achieved by electrical stimulation of the caudate nucleus body. Compared to the caudate head, the caudate body has stronger functional connectivity to the auditory cortex. These first-in-human findings provide insight into the functional anatomy of caudate nucleus subdivisions and may inform future target selection in a basal ganglia-centric neuromodulation approach to treat medically refractory tinnitus.Clinical trial registration no.: NCT01988688 (clinicaltrials.gov).

PMID: 30738400 [PubMed - as supplied by publisher]

Multimodal neuroimaging study reveals dissociable processes between structural and functional networks in patients with subacute intracerebral hemorrhage.

Sun, 02/10/2019 - 12:20
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Multimodal neuroimaging study reveals dissociable processes between structural and functional networks in patients with subacute intracerebral hemorrhage.

Med Biol Eng Comput. 2019 Feb 09;:

Authors: Zhang X, Yu X, Bao Q, Yang L, Sun Y, Qi P

Abstract
Emerging evidence has revealed widespread stroke-induced brain dysconnectivity, which leads to abnormal network organization. However, there are apparent discrepancies in dysconnectivity between structural connectivity and functional connectivity studies. In this work, resting-state fMRI and structural diffusion tensor imaging were obtained from 26 patients with subacute (10-14 days) intracerebral hemorrhage (ICH) and 20 matched healthy participants (patients/controls = 21/18 after head motion rejection). Graph theoretical approaches were applied to multimodal brain networks to quantitatively compare topological properties between both groups. Prominent small-world properties were found in the structural and functional brain networks of both groups. However, a significant deficit in global integration was revealed in the structural brain networks of the patient group and was associated with more severe clinical manifestations of ICH. Regarding ICH-related nodal deficits, reduced nodal interconnectivity was mainly detected in motor-related regions. Moreover, in the functional brain network, topological properties were mostly comparable between patients with ICH and healthy participants. Beyond the prominent small-world architecture in multimodal brain networks, there are dissociable alterations between structural and functional brain networks in patients with ICH. These findings highlight the potential for using aberrant network metrics as neural biomarkers for evaluation of the severity of ICH. Graphical abstract Intracerebral hemorrhage (ICH) also known as cerebral bleed, a major type of stroke, would significantly affect brain structure and function. Using multimodal neuroimaging, Zhang et al. investigate the ICH-related dysconnectivity in structural and functional brain networks and show a significantly disintegrated structural brain network with a preserved functional network topology in subacute phase (10-14 days).

PMID: 30737626 [PubMed - as supplied by publisher]

Dopaminergic mechanisms underlying normal variation in trait anxiety.

Sun, 02/10/2019 - 12:20
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Dopaminergic mechanisms underlying normal variation in trait anxiety.

J Neurosci. 2019 Feb 08;:

Authors: Berry AS, White RL, Furman DJ, Naskolnakorn JR, Shah VD, D'Esposito M, Jagust WJ

Abstract
Trait anxiety has been associated with altered activity within corticolimbic pathways connecting the amygdala and rostral anterior cingulate cortex (rACC), which receive rich dopaminergic input. Though the popular culture uses the term "chemical imbalance" to describe the pathophysiology of psychiatric conditions such as anxiety disorders, we know little about how individual differences in human dopamine neurochemistry are related to variation in anxiety and activity within corticolimbic circuits. We addressed this issue by examining inter-individual variability in dopamine release at rest using [11C]raclopride positron emission tomography (PET), functional connectivity between amygdala and rACC using resting-state functional magnetic resonance imaging (fMRI), and trait anxiety measures in healthy adult male and female humans. To measure endogenous dopamine release, we collected two [11C]raclopride PET scans per participant. We contrasted baseline [11C]raclopride D2/3 receptor binding and D2/3 receptor binding following oral methylphenidate administration. Methylphenidate blocks the dopamine transporter, which increases extracellular dopamine and leads to reduced [11C]raclopride D2/3 receptor binding via competitive displacement. We found that individuals with higher dopamine release in the amygdala and rACC self-reported lower trait anxiety. Lower trait anxiety was also associated with reduced rACC-amygdala functional connectivity at baseline. Further, functional connectivity showed a modest negative relationship with dopamine release such that reduced rACC-amygdala functional connectivity was accompanied by higher levels of dopamine release in these regions. Together, these findings contribute to hypodopaminergic models of anxiety and support the utility of combining fMRI and PET measures of neurochemical function to advance our understanding of basic affective processes in humans.SIGNIFICANCE STATEMENTIt is common wisdom that individuals vary in their baseline levels of anxiety. We all have a friend or colleague we know to be more "tightly wound" than others, or, perhaps, we are the ones marveling at others' ability to "just go with the flow." While such observations about individual differences within non-clinical populations are commonplace, the neural mechanisms underlying normal variation in trait anxiety have not been established. Using multimodal brain imaging in humans, this study takes initial steps in linking intrinsic measures of neuromodulator release and functional connectivity within regions implicated in anxiety disorders. Our findings suggest that in healthy adults, higher levels of trait anxiety may arise, at least in part, from reduced dopamine neurotransmission.

PMID: 30737306 [PubMed - as supplied by publisher]

On the analysis of rapidly sampled fMRI data.

Sat, 02/09/2019 - 11:20

On the analysis of rapidly sampled fMRI data.

Neuroimage. 2019 Feb 05;:

Authors: Chen JE, Polimeni JR, Bollmann S, Glover GH

Abstract
Recent advances in parallel imaging and simultaneous multi-slice techniques have permitted whole-brain fMRI acquisitions at sub-second sampling intervals, without significantly sacrificing the spatial coverage and resolution. Apart from probing brain function at finer temporal scales, faster sampling rates may potentially lead to enhanced functional sensitivity, owing possibly to both cleaner neural representations (due to less aliased physiological noise) and additional statistical benefits (due to more degrees of freedom for a fixed scan duration). Accompanying these intriguing aspects of fast acquisitions, however, confusion has also arisen regarding (1) how to preprocess/analyze these fast fMRI data, and (2) what exactly is the extent of benefits with fast acquisitions, i.e., how fast is fast enough for a specific research aim? The first question is motivated by the altered spectral distribution and noise characteristics at short sampling intervals, while the second question seeks to reconcile the complicated trade-offs between the functional contrast-to-noise ratio and the effective degrees of freedom. Although there have been recent efforts to empirically approach different aspects of these two questions, in this work we discuss, from a theoretical perspective accompanied by some illustrative, proof-of-concept experimental in vivo human fMRI data, a few considerations that are rarely mentioned, yet are important for both preprocessing and optimizing statistical inferences for studies that employ acquisitions with sub-second sampling intervals. Several summary recommendations include concerns regarding advisability of relying on low-pass filtering to de-noise physiological contributions, employment of statistical models with sufficient complexity to account for the substantially increased serial correlation, and cautions regarding using rapid sampling to enhance functional sensitivity given that different analysis models may associate with distinct trade-offs between contrast-to-noise ratios and the effective degrees of freedom. As an example, we demonstrate that as TR shortens, the intrinsic differences in how noise is accommodated in general linear models and Pearson correlation analyses (assuming Gaussian distributed stochastic signals and noise) can result in quite different outcomes, either gaining or losing statistical power.

PMID: 30735828 [PubMed - as supplied by publisher]

Primary biliary cholangitis patients exhibit MRI changes in structure and function of interoceptive brain regions.

Sat, 02/09/2019 - 11:20

Primary biliary cholangitis patients exhibit MRI changes in structure and function of interoceptive brain regions.

PLoS One. 2019;14(2):e0211906

Authors: Mosher V, Swain M, Pang J, Kaplan G, Sharkey K, MacQueen G, Goodyear BG

Abstract
BACKGROUND: Many patients with primary biliary cholangitis (PBC) experience non-hepatic symptoms that are possibly linked to altered interoception, the sense of the body's internal state. We used magnetic resonance imaging (MRI) to determine if PBC patients exhibit structural and functional changes of the thalamus and insula, brain regions that process signals related to interoception.
METHODS: Fifteen PBC patients with mild disease and 17 controls underwent 3 Tesla T1-weighted MRI, resting-state functional MRI, and quantitative susceptibility mapping (QSM), to measure thalamic and insular volume, neuronal activity and iron deposition, respectively. Group differences were assessed using analysis of covariance, and stepwise linear regression was used to determine the predictive power of clinical indicators of disease.
RESULTS: PBC patients exhibited reduced thalamic volume (p < 0.01), and ursodeoxycholic acid (UDCA) non-responders exhibited lower left thalamus activity (p = 0.05). PBC patients also exhibited reduced anterior insula activity (p = 0.012), and liver stiffness positively correlated with MRI indicators of anterior insula iron deposition (p < 0.02).
CONCLUSIONS: PBC affects structure and function of brain regions critically important to interoception. Moreover, these brain changes occur in patients with early, milder disease and thus may potentially be reversible.

PMID: 30735529 [PubMed - in process]

Graph-based network analysis of resting-state fMRI: test-retest reliability of binarized and weighted networks.

Sat, 02/09/2019 - 11:20

Graph-based network analysis of resting-state fMRI: test-retest reliability of binarized and weighted networks.

Brain Imaging Behav. 2019 Feb 08;:

Authors: Xiang J, Xue J, Guo H, Li D, Cui X, Niu Y, Yan T, Cao R, Ma Y, Yang Y, Wang B

Abstract
In the past decade, resting-state functional magnetic resonance imaging (rs-fMRI) and graph-based measures have been widely used to quantitatively characterize the architectures of brain functional networks in healthy individuals and in patients with abnormalities related to psychopathic and neurological disorders. To accurately evaluate the topological organization of brain functional networks, the definition of the nodes and edges for the construction of functional networks is critical. Furthermore, both types of brain functional networks (binarized networks and weighted networks) are widely used to analyze topological organization. However, how to best select the network type is still debated. Consequently, we investigated the test-retest reliability of brain functional networks with binarized and weighted edges using two independent datasets and four strategies for defining nodes. We revealed fair to good reliability for a majority of network topological attributes and overall higher reliabilities for weighted networks than for binarized networks. For regional nodal efficiency, weighted networks also showed higher reliability across nodes. Thus, our findings imply that weighted networks contain more information, leading to more stable results. In addition, we found that the reliability of brain functional networks was influenced by the node definition strategy and that more precise of nodal definition were associated with higher reliability. The time effect of reliability was restricted, as no differences between long-term and short-term reliability were observed. In conclusion, our results suggest that weighted networks have better reliability because they reflect more topological information, implying broader applications of weighted networks related to normal and disordered function of the human brain.

PMID: 30734917 [PubMed - as supplied by publisher]

Machine learning identifies "rsfMRI epilepsy networks" in temporal lobe epilepsy.

Sat, 02/09/2019 - 11:20

Machine learning identifies "rsfMRI epilepsy networks" in temporal lobe epilepsy.

Eur Radiol. 2019 Feb 08;:

Authors: Bharath RD, Panda R, Raj J, Bhardwaj S, Sinha S, Chaitanya G, Raghavendra K, Mundlamuri RC, Arimappamagan A, Rao MB, Rajeshwaran J, Thennarasu K, Majumdar KK, Satishchandra P, Gandhi TK

Abstract
OBJECTIVES: Experimental models have provided compelling evidence for the existence of neural networks in temporal lobe epilepsy (TLE). To identify and validate the possible existence of resting-state "epilepsy networks," we used machine learning methods on resting-state functional magnetic resonance imaging (rsfMRI) data from 42 individuals with TLE.
METHODS: Probabilistic independent component analysis (PICA) was applied to rsfMRI data from 132 subjects (42 TLE patients + 90 healthy controls) and 88 independent components (ICs) were obtained following standard procedures. Elastic net-selected features were used as inputs to support vector machine (SVM). The strengths of the top 10 networks were correlated with clinical features to obtain "rsfMRI epilepsy networks."
RESULTS: SVM could classify individuals with epilepsy with 97.5% accuracy (sensitivity = 100%, specificity = 94.4%). Ten networks with the highest ranking were found in the frontal, perisylvian, cingulo-insular, posterior-quadrant, thalamic, cerebello-thalamic, and temporo-thalamic regions. The posterior-quadrant, cerebello-thalamic, thalamic, medial-visual, and perisylvian networks revealed significant correlation (r > 0.40) with age at onset of seizures, the frequency of seizures, duration of illness, and a number of anti-epileptic drugs.
CONCLUSIONS: IC-derived rsfMRI networks contain epilepsy-related networks and machine learning methods are useful in identifying these networks in vivo. Increased network strength with disease progression in these "rsfMRI epilepsy networks" could reflect epileptogenesis in TLE.
KEY POINTS: • ICA of resting-state fMRI carries disease-specific information about epilepsy. • Machine learning can classify these components with 97.5% accuracy. • "Subject-specific epilepsy networks" could quantify "epileptogenesis" in vivo.

PMID: 30734849 [PubMed - as supplied by publisher]

Neuroanatomical and functional alterations of insula in mild traumatic brain injury patients at the acute stage.

Sat, 02/09/2019 - 11:20
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Neuroanatomical and functional alterations of insula in mild traumatic brain injury patients at the acute stage.

Brain Imaging Behav. 2019 Feb 08;:

Authors: Li F, Lu L, Chen H, Wang P, Zhang H, Chen YC, Yin X

Abstract
Cognitive impairment is a major cause of disability and decline in quality of life in mild traumatic brain injury (mTBI) survivors, but the underlying pathophysiology is still poorly understood. The insula has extensive connections to other cortex and is believed to responsible for integrating external and internal processes and controlling cognitive functions. To explore this hypothesis, we investigated early alterations in the gray matter volume (GMV) and brain functional connectivity (FC) of insula in mTBI patients within 7 days after injury and any possible correlations with cognitive function. A total of 58 mTBI patients at the acute stage and 32 matched healthy controls were recruited and underwentT1-weighted magnetic resonance imaging (MRI)andresting-state functional MRI scans within 7 days of injury. FC was characterized using seed-based region of interest analysis method. The patients' cognitive function was evaluated with Montreal Cognitive Assessment (MoCA) score. The resulting of GMV and FC of insula were correlated with cognitive alterations. We found that the GMV was significantly reduced only in the right insula in mTBI patients and no significant GMV increase was observed in either hemisphere. mTBI patients demonstrated decreased FC in the right parahippocampal gyrus and increased FC in the right supramargianl gyrus. In addition, compared to the healthy controls, the mTBI patients in the acute stage presented a decline in the visuospatial/executive (p = 0.013) and attention (p = 0.038) subcategories. In the mTBI group, the changes in GMV in the right insula were positively correlated with poor attention performance (r = 0.316, p = 0.016). Our data demonstrated alterations of the GMV and resting-stateFC of the right insula in mTBI patients at the acute stage. These early changes in GMV and resting-state FC perhaps serve as a potential biomarker for improving the understanding of cognitive decline for mTBI in the acute setting.

PMID: 30734204 [PubMed - as supplied by publisher]

Oxytocin modulates the effective connectivity between the precuneus and the dorsolateral prefrontal cortex.

Sat, 02/09/2019 - 11:20
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Oxytocin modulates the effective connectivity between the precuneus and the dorsolateral prefrontal cortex.

Eur Arch Psychiatry Clin Neurosci. 2019 Feb 07;:

Authors: Kumar J, J Iwabuchi S, A Völlm B, Palaniyappan L

Abstract
Our social activity is heavily influenced by the process of introspection, with emerging research suggesting a role for the Default Mode Network (DMN) in social cognition. We hypothesize that oxytocin, a neuropeptide with an important role in social behaviour, can effectively alter the connectivity of the DMN. We test this hypothesis using a randomized, double-blind, crossover, placebo-controlled trial where 15 healthy male participants received 24 IU oxytocin or placebo prior to a resting-state functional MRI scan. We used Granger Causality Analysis for the first time to probe the role of oxytocin on brain networks and found that oxytocin reverses the pattern of effective connectivity between the bilateral precuneus and the left dorsolateral prefrontal cortex (dlPFC), a key central executive network (CEN) region. Under placebo, the bilateral precuneus exerted a significant negative causal influence on the left dlPFC and the left dlPFC exerted a significant positive causal influence on the bilateral precuneus. However, under oxytocin, these patterns were reversed, i.e. positive causal influence from the bilateral precuneus to the left dlPFC and negative causal influence from the left dlPFC to the bilateral precuneus (with statistically significant effects for the right precuneus). We propose that these oxytocin-induced effects could be a mechanistic process by which it modulates social cognition. These results provide a measurable target for the physiological effects of oxytocin in the brain and offer oxytocin as a potential agent to enhance the cooperative role of the predominantly 'task-inactive' 'default mode' brain regions in both healthy and patient populations.

PMID: 30734090 [PubMed - as supplied by publisher]

Disease Definition for Schizophrenia by Functional Connectivity Using Radiomics Strategy.

Sat, 02/09/2019 - 11:20
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Disease Definition for Schizophrenia by Functional Connectivity Using Radiomics Strategy.

Schizophr Bull. 2018 08 20;44(5):1053-1059

Authors: Cui LB, Liu L, Wang HN, Wang LX, Guo F, Xi YB, Liu TT, Li C, Tian P, Liu K, Wu WJ, Chen YH, Qin W, Yin H

Abstract
Specific biomarker reflecting neurobiological substrates of schizophrenia (SZ) is required for its diagnosis and treatment selection of SZ. Evidence from neuroimaging has implicated disrupted functional connectivity in the pathophysiology. We aimed to develop and validate a method of disease definition for SZ by resting-state functional connectivity using radiomics strategy. This study included 2 data sets collected with different scanners. A total of 108 first-episode SZ patients and 121 healthy controls (HCs) participated in the current study, among which 80% patients and HCs (n = 183) and 20% (n = 46) were selected for training and testing in intra-data set validation and 1 of the 2 data sets was selected for training and the other for testing in inter-data set validation, respectively. Functional connectivity was calculated for both groups, features were selected by Least Absolute Shrinkage and Selection Operator (LASSO) method, and the clinical utility of its features and the generalizability of effects across samples were assessed using machine learning by training and validating multivariate classifiers in the independent samples. We found that the accuracy of intra-data set training was 87.09% for diagnosing SZ patients by applying functional connectivity features, with a validation in the independent replication data set (accuracy = 82.61%). The inter-data set validation further confirmed the disease definition by functional connectivity features (accuracy = 83.15% for training and 80.07% for testing). Our findings demonstrate a valid radiomics approach by functional connectivity to diagnose SZ, which is helpful to facilitate objective SZ individualized diagnosis using quantitative and specific functional connectivity biomarker.

PMID: 29471434 [PubMed - indexed for MEDLINE]

Coupling and segregation of large-scale brain networks predict individual differences in delay discounting.

Sat, 02/09/2019 - 11:20
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Coupling and segregation of large-scale brain networks predict individual differences in delay discounting.

Biol Psychol. 2018 03;133:63-71

Authors: Chen Z, Guo Y, Suo T, Feng T

Abstract
Decision-making about rewards, which requires us to choose between different time points, generally refers to intertemporal choice. Converging evidence suggests that some of the brain networks recruited in the delay discounting task have been well characterized for intertemporal choice. However, little is known about how the connectivity patterns of these large-scale brain networks are associated with delay discounting. Here, we use a resting-state functional connectivity MRI (rs-fcMRI) and a graph theoretical analysis to address this question. We found that the delay discounting rates showed a positive correlation with the functional network connectivity (FNC) between the cingulo-opercular network (CON) and the default mode network (DMN), while they showed a negative correlation with the FNC of both the CON-SAN (salience network) and the SAN-FPN (fronto-parietal network). Our results showed the association of both coupling and segregating processes with large-scale brain networks in delay discounting. Thus, the present study highlights the pivotal role of the functional connectivity patterns of intrinsic large-scale brain networks in delay discounting and extends our perspective on the neural mechanism of delay discounting.

PMID: 29382543 [PubMed - indexed for MEDLINE]

Sensorimotor network hypersynchrony as an endophenotype in families with genetic generalized epilepsy: A resting-state functional magnetic resonance imaging study.

Fri, 02/08/2019 - 23:00
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Sensorimotor network hypersynchrony as an endophenotype in families with genetic generalized epilepsy: A resting-state functional magnetic resonance imaging study.

Epilepsia. 2019 Feb 07;:

Authors: Tangwiriyasakul C, Perani S, Abela E, Carmichael DW, Richardson MP

Abstract
Recent evidence suggests that three specific brain networks show state-dependent levels of synchronization before, during, and after episodes of generalized spike-wave discharges (GSW) in patients with genetic generalized epilepsy (GGE). Here, we investigate whether synchronization in these networks differs between patients with GGE (n = 13), their unaffected first-degree relatives (n = 17), and healthy controls (n = 18). All subjects underwent two 10-minute simultaneous electroencephalographic-functional magnetic resonance imaging (fMRI) recordings without GSW. Whole-brain data were divided into 90 regions, and blood oxygen level-dependent (BOLD) phase synchrony in a 0.04-0.07-Hz band was estimated between all pairs of regions. Three networks were defined: (1) the network with highest synchrony during GSW events, (2) a sensorimotor network, and (3) an occipital network. Average synchrony (mean node degree) was inferred across each network over time. Notably, synchrony was significantly higher in the sensorimotor network in patients and in unaffected relatives, compared to controls. There was a trend toward higher synchrony in the GSW network in patients and in unaffected relatives. There was no difference between groups for the occipital network. Our findings provide evidence that elevated fMRI BOLD synchrony in a sensorimotor network is a state-independent endophenotype of GGE, present in patients in the absence of GSW, and present in unaffected relatives.

PMID: 30730052 [PubMed - as supplied by publisher]

A study of within-subject reliability of the brain's default-mode network.

Fri, 02/08/2019 - 23:00
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A study of within-subject reliability of the brain's default-mode network.

MAGMA. 2019 Feb 07;:

Authors: Postema MC, De Marco M, Colato E, Venneri A

Abstract
OBJECTIVE: Resting-state functional magnetic resonance imaging (fMRI) is promising for Alzheimer's disease (AD). This study aimed to examine short-term reliability of the default-mode network (DMN), one of the main haemodynamic patterns of the brain.
MATERIALS AND METHODS: Using a 1.5 T Philips Achieva scanner, two consecutive resting-state fMRI runs were acquired on 69 healthy adults, 62 patients with mild cognitive impairment (MCI) due to AD, and 28 patients with AD dementia. The anterior and posterior DMN and, as control, the visual-processing network (VPN) were computed using two different methodologies: connectivity of predetermined seeds (theory-driven) and dual regression (data-driven). Divergence and convergence in network strength and topography were calculated with paired t tests, global correlation coefficients, voxel-based correlation maps, and indices of reliability.
RESULTS: No topographical differences were found in any of the networks. High correlations and reliability were found in the posterior DMN of healthy adults and MCI patients. Lower reliability was found in the anterior DMN and in the VPN, and in the posterior DMN of dementia patients.
DISCUSSION: Strength and topography of the posterior DMN appear relatively stable and reliable over a short-term period of acquisition but with some degree of variability across clinical samples.

PMID: 30730023 [PubMed - as supplied by publisher]

Sex-related differences in resting-state brain activity and connectivity in the orbital frontal cortex and insula in patients with functional constipation.

Fri, 02/08/2019 - 23:00
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Sex-related differences in resting-state brain activity and connectivity in the orbital frontal cortex and insula in patients with functional constipation.

Neurogastroenterol Motil. 2019 Feb 06;:e13566

Authors: Jin Q, Duan S, Li G, Sun L, Hu Y, Hu C, Zhao J, von Deneen KM, Qian L, Wang H, Ji G, Wu K, Fan D, Cui G, Nie Y, Zhang Y

Abstract
Functional magnetic resonance imaging (fMRI) has been used to investigate sex-related differences in brain abnormalities in patients with irritable bowel syndrome (IBS). Like IBS, women with functional constipation (FC) are 2.1 times as many as men. No study has been performed yet to examine sex-related differences in brain activity and connectivity in patients with FC. Here, we employed resting-state fMRI with amplitude of low-frequency fluctuation (ALFF) to investigate brain functional differences in 51 patients with FC (34 females) and 52 healthy controls (34 females). Results showed abdominal pain and abdominal distension correlated with trait (TAI) and state (SAI) anxiety ratings in the female FC group, and abdominal distension correlated with sensation of incomplete evacuation in the male FC group. Two-way ANOVA revealed sex effects on ALFF in precentral gyrus, thalamus, insula (INS), and orbital frontal cortex (OFC, PFWE  < 0.05). Post hoc test showed that the female FC group had lower ALFF than males in these brain regions (P < 0.01), and ALFF in INS and OFC was correlated with abdominal pain and difficulty of defecation, respectively. Seed voxel correlation analysis showed that the female FC group had weaker connectivity than males between INS and lateral OFC (lOFC). INS-lOFC connectivity was negatively correlated with the anxiety score in the female FC group and was negatively correlated with abdominal distension in the male FC group. These findings provide the first insight into sex-related differences in patients with FC and highlight that INS and OFC play an important role in modulating the intrinsic functional connectivity of the resting brain network showing that this role is influenced by sex.

PMID: 30729624 [PubMed - as supplied by publisher]

Disrupted Regional Spontaneous Neural Activity in Mild Cognitive Impairment Patients with Depressive Symptoms: A Resting-State fMRI Study.

Fri, 02/08/2019 - 23:00
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Disrupted Regional Spontaneous Neural Activity in Mild Cognitive Impairment Patients with Depressive Symptoms: A Resting-State fMRI Study.

Neural Plast. 2019;2019:2981764

Authors: Liu X, Tu Y, Zang Y, Wu A, Guo Z, He J

Abstract
Depressive symptoms are common in individuals with mild cognitive impairment (MCI) who have an increased risk of dementia. It is currently unclear whether the pattern of spontaneous brain activity in patients with MCI differs between subjects with and without depressive symptoms. The current study sought to investigate the features of spontaneous brain activity in MCI patients with depressive symptoms (D-MCI) using coherence regional homogeneity (CReHo) analysis with resting-state functional magnetic resonance imaging (rsfMRI). We obtained rsfMRI data in 16 MCI patients with depressive symptoms and 18 nondepressed MCI patients (nD-MCI) using a 3 T scanner. Statistical analyses were performed to determine the regions in which ReHo differed between the two groups in specific frequency bands, slow-4 (0.027-0.073 Hz) and slow-5 (0.010-0.027 Hz), and typical bands (0.01-0.08 Hz). Correlation analyses were performed between the CReHo index of these regions and clinical variables to evaluate the relationship between CReHo and pathophysiological measures in the two groups. Our results showed that D-MCI patients exhibited significantly higher CReHo in the left Heschl's gyrus and left thalamus and lower CReHo in the left postcentral gyrus in the typical frequency band. In the slow-4 frequency band, D-MCI patients showed significantly higher CReHo in the left Heschl's gyrus and left thalamus. In the slow-5 frequency band, D-MCI patients exhibited significantly lower CReHo in the superior medial prefrontal gyrus. In addition, the results revealed that CReHo values in the left thalamus were positively correlated with Hamilton Depression Rating Scale (HAMD) scores in D-MCI patients. These results suggest that the sensorimotor network may be one of the main pathophysiological factors in D-MCI.

PMID: 30728833 [PubMed - in process]

Examining Neural Plasticity for Slip-Perturbation Training: An fMRI Study.

Fri, 02/08/2019 - 23:00
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Examining Neural Plasticity for Slip-Perturbation Training: An fMRI Study.

Front Neurol. 2018;9:1181

Authors: Patel PJ, Bhatt T, DelDonno SR, Langenecker SA, Dusane S

Abstract
Perturbation-based balance training has shown to induce adaptation of reactive balance responses that can significantly reduce longer-term fall risk in older adults. While specific cortical and subcortical areas in control of posture and locomotion have been identified, little is known about the training-induced plasticity occurring in neural substrates for challenging tasks involving reactive balance control. The purpose of this study was to use functional neuroimaging to examine and determine the neural substrates, if any, involved in inducing adaptation to slip-like perturbations experienced during walking over 3 consecutive training days. We used a mental imagery task to examine the neural changes accompanied by treadmill-slip perturbation training. Ten healthy young adults were exposed to increasing magnitude of displacements during slip-like perturbations while walking, with an acceleration of 6 m/s2 on a motorized treadmill for 3 consecutive days. Brain activity was recorded through MRI while performing imagined slipping and imagined walking tasks before and after the perturbation training. The number of compensatory steps and center of mass state stability at compensatory step touchdown were recorded. As compared with day 1 (first trial), on day 3 (last trial) there was a significant reduction in number of compensatory steps and increase in stability at compensatory step touchdown on the mid and highest perturbation intensities. Before perturbation training, imagined slipping showed increased activity in the SMA, parietal regions, parahippocampal gyrus, and cingulate gyrus compared with rest. After perturbation training, imagined slipping showed increased activation in DLPFC, superior parietal lobule, inferior occipital gyrus, and lingual gyrus. Perturbation training was not associated with decline in activity in any of the brain regions. This study provides evidence for learning-related changes in cortical structures while adapting to slip-like perturbations while walking. The findings reflect that higher-level processing is required for timing and sequencing of movements to execute an effective balance response to perturbations. Specifically, the CNS relies on DLPFC along with motor, parietal, and occipital cortices for adapting to postural tasks posing a significant threat to balance.

PMID: 30728803 [PubMed]

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