New resting-state fMRI related studies at PubMed

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Comparison of fluctuations in global network topology of modeled and empirical brain functional connectivity.

Wed, 09/26/2018 - 18:00

Comparison of fluctuations in global network topology of modeled and empirical brain functional connectivity.

PLoS Comput Biol. 2018 Sep 25;14(9):e1006497

Authors: Fukushima M, Sporns O

Abstract
Dynamic models of large-scale brain activity have been used for reproducing many empirical findings on human brain functional connectivity. Features that have been shown to be reproducible by comparing modeled to empirical data include functional connectivity measured over several minutes of resting-state functional magnetic resonance imaging, as well as its time-resolved fluctuations on a time scale of tens of seconds. However, comparison of modeled and empirical data has not been conducted yet for fluctuations in global network topology of functional connectivity, such as fluctuations between segregated and integrated topology or between high and low modularity topology. Since these global network-level fluctuations have been shown to be related to human cognition and behavior, there is an emerging need for clarifying their reproducibility with computational models. To address this problem, we directly compared fluctuations in global network topology of functional connectivity between modeled and empirical data, and clarified the degree to which a stationary model of spontaneous brain dynamics can reproduce the empirically observed fluctuations. Modeled fluctuations were simulated using a system of coupled phase oscillators wired according to brain structural connectivity. By performing model parameter search, we found that modeled fluctuations in global metrics quantifying network integration and modularity had more than 80% of magnitudes of those observed in the empirical data. Temporal properties of network states determined based on fluctuations in these metrics were also found to be reproducible, although their spatial patterns in functional connectivity did not perfectly marched. These results suggest that stationary models simulating resting-state activity can reproduce the magnitude of empirical fluctuations in segregation and integration, whereas additional factors, such as active mechanisms controlling non-stationary dynamics and/or greater accuracy of mapping brain structural connectivity, would be necessary for fully reproducing the spatial patterning associated with these fluctuations.

PMID: 30252835 [PubMed - as supplied by publisher]

Reward-related regions form a preferentially coupled system at rest.

Wed, 09/26/2018 - 18:00

Reward-related regions form a preferentially coupled system at rest.

Hum Brain Mapp. 2018 Sep 25;:

Authors: Huckins JF, Adeyemo B, Miezin FM, Power JD, Gordon EM, Laumann TO, Heatherton TF, Petersen SE, Kelley WM

Abstract
Neuroimaging studies have implicated a set of striatal and orbitofrontal cortex (OFC) regions that are commonly activated during reward processing tasks. Resting-state functional connectivity (RSFC) studies have demonstrated that the human brain is organized into several functional systems that show strong temporal coherence in the absence of goal-directed tasks. Here we use seed-based and graph-theory RSFC approaches to characterize the systems-level organization of putative reward regions of at rest. Peaks of connectivity from seed-based RSFC patterns for the nucleus accumbens (NAcc) and orbitofrontal cortex (OFC) were used to identify candidate reward regions which were merged with a previously used set of regions (Power et al., 2011). Graph-theory was then used to determine system-level membership for all regions. Several regions previously implicated in reward-processing (NAcc, lateral and medial OFC, and ventromedial prefrontal cortex) comprised a distinct, preferentially coupled system. This RSFC system is stable across a range of connectivity thresholds and shares strong overlap with meta-analyses of task-based reward studies. This reward system shares between-system connectivity with systems implicated in cognitive control and self-regulation, including the fronto-parietal, cingulo-opercular, and default systems. Differences may exist in the pathways through which control systems interact with reward system components. Whereas NAcc is functionally connected to cingulo-opercular and default systems, OFC regions show stronger connectivity with the fronto-parietal system. We propose that future work may be able to interrogate group or individual differences in connectivity profiles using the regions delineated in this work to explore potential relationships to appetitive behaviors, self-regulation failure, and addiction.

PMID: 30251766 [PubMed - as supplied by publisher]

Functional connectivity with cortical depth assessed by resting state fMRI of subregions of S1 in squirrel monkeys.

Wed, 09/26/2018 - 18:00

Functional connectivity with cortical depth assessed by resting state fMRI of subregions of S1 in squirrel monkeys.

Hum Brain Mapp. 2018 Sep 25;:

Authors: Mishra A, Majumdar S, Wang F, Wilson GH, Gore JC, Chen LM

Abstract
Whereas resting state blood oxygenation-level dependent (BOLD) functional MRI has been widely used to assess functional connectivity between cortical regions, the laminar specificity of such measures is poorly understood. This study aims to determine: (a) whether the resting state functional connectivity (rsFC) between two functionally related cortical regions varies with cortical depth, (b) the relationship between layer-resolved tactile stimulus-evoked activation pattern and interlayer rsFC pattern between two functionally distinct but related somatosensory areas 3b and 1, and (c) the effects of spatial resolution on rsFC measures. We examined the interlayer rsFC between areas 3b and 1 of squirrel monkeys under anesthesia using tactile stimulus-driven and resting state BOLD acquisitions at submillimeter resolution. Consistent with previous observations in the areas 3b and 1, we detected robust stimulus-evoked BOLD activations with foci were confined mainly to the upper layers (centered at 21% of the cortical depth). By carefully placing seeds in upper, middle, and lower layers of areas 3b and 1, we observed strong rsFC between upper and middle layers of these two areas. The layer-resolved activation patterns in areas 3b and 1 agree with their interlayer rsFC patterns, and are consistent with the known anatomical connections between layers. In summary, using BOLD rsFC pattern, we identified an interlayer interareal microcircuit that shows strong intrinsic functional connections between upper and middle layer areas 3b and 1. RsFC can be used as a robust invasive tool to probe interlayer corticocortical microcircuits.

PMID: 30251760 [PubMed - as supplied by publisher]

Resting state functional connectivity of networks associated with reward and habit in anorexia nervosa.

Wed, 09/26/2018 - 18:00

Resting state functional connectivity of networks associated with reward and habit in anorexia nervosa.

Hum Brain Mapp. 2018 Sep 25;:

Authors: Haynos AF, Hall LMJ, Lavender JM, Peterson CB, Crow SJ, Klimes-Dougan B, Cullen KR, Lim KO, Camchong J

Abstract
Neurobiological disturbances associated with reward and/or habit learning are theorized to maintain symptoms of anorexia nervosa (AN). Although research has investigated responses in brain regions associated with reward and habit to disorder-specific cues (e.g., food) and presumed rewards (e.g., money), little is known about the functional organization of the circuits underlying these constructs independent of stimulus. This study aimed to provide initial data on the synchrony of networks associated with reward and habit in AN by comparing resting-state functional connectivity (RSFC) patterns between AN and healthy control (HC) participants in these circuits and delineating how these patterns relate to symptoms. Using theoretically selected seeds in the nucleus accumbens (NAcc), ventral caudate, and dorsal caudate, reflecting a continuum from reward- to habit- oriented regions, RSFC patterns were compared between AN restricting subtype (n = 19) and HC (n = 19) participants (cluster threshold: p < .01). Exploratory correlations between RSFC z-scores and Eating Disorder Examination (EDE) scores, BMI, and illness duration were conducted. The AN group demonstrated lower RSFC between the NAcc and superior frontal gyrus, between the ventral caudate and frontal and posterior regions, and between the dorsal caudate and frontal, temporal, and posterior regions. In the AN group, lower NAcc- superior frontal gyrus RSFC correlated with greater EDE Global scores (r = -.58, CI: -.83, -.13). These resting-state synchrony disruptions of the ventral and dorsal frontostriatal circuits, considered in context of the broader literature, support the utility of further investigating possible reward and habit disturbances supporting symptoms in AN.

PMID: 30251758 [PubMed - as supplied by publisher]

From eyes-closed to eyes-open: Role of cholinergic projections in EC-to-EO alpha reactivity revealed by combining EEG and MRI.

Wed, 09/26/2018 - 18:00

From eyes-closed to eyes-open: Role of cholinergic projections in EC-to-EO alpha reactivity revealed by combining EEG and MRI.

Hum Brain Mapp. 2018 Sep 25;:

Authors: Wan L, Huang H, Schwab N, Tanner J, Rajan A, Lam NB, Zaborszky L, Li CR, Price CC, Ding M

Abstract
Alpha rhythm (8 to 12 Hz) observed in EEG over human posterior cortex is prominent during eyes-closed (EC) resting and attenuates during eyes-open (EO) resting. Research shows that the degree of EC-to-EO alpha blocking or alpha desynchronization, termed alpha reactivity here, is a neural marker of cognitive health. We tested the role of acetylcholine in EC-to-EO alpha reactivity by applying a multimodal neuroimaging approach to a cohort of young adults and a cohort of older adults. In the young cohort, simultaneous EEG-fMRI was recorded from twenty-one young adults during both EO and EC resting. In the older cohort, functional MRI was recorded from forty older adults during EO and EC resting, along with FLAIR and diffusion MRI. For a subset of twenty older adults, EEG was recorded during EO and EC resting in a separate session. In both young and older adults, functional connectivity between the basal nucleus of Meynert (BNM), the major source of cortical acetylcholine, and the visual cortex increased from EC to EO, and this connectivity increase was positively associated with alpha reactivity; namely, the stronger the BNM-visual cortex functional connectivity increase from EC to EO, the larger the EC-to-EO alpha desynchronization. In older adults, lesions of the fiber tracts linking BNM and visual cortex quantified by leukoaraiosis volume, associated with reduced alpha reactivity. These findings support a role of acetylcholine and particularly cholinergic pathways in mediating EC-to-EO alpha reactivity and suggest that impaired alpha reactivity could serve as a marker of the integrity of the cholinergic system.

PMID: 30251753 [PubMed - as supplied by publisher]

Resting state cerebral blood flow with arterial spin labeling MRI in developing human brains.

Wed, 09/26/2018 - 18:00
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Resting state cerebral blood flow with arterial spin labeling MRI in developing human brains.

Eur J Paediatr Neurol. 2018 Jul;22(4):642-651

Authors: Liu F, Duan Y, Peterson BS, Asllani I, Zelaya F, Lythgoe D, Kangarlu A

Abstract
The development of brain circuits is coupled with changes in neurovascular coupling, which refers to the close relationship between neural activity and cerebral blood flow (CBF). Studying the characteristics of CBF during resting state in developing brain can be a complementary way to understand the functional connectivity of the developing brain. Arterial spin labeling (ASL), as a noninvasive MR technique, is particularly attractive for studying cerebral perfusion in children and even newborns. We have collected pulsed ASL data in resting state for 47 healthy subjects from young children to adolescence (aged from 6 to 20 years old). In addition to studying the developmental change of static CBF maps during resting state, we also analyzed the CBF time series to reveal the dynamic characteristics of CBF in differing age groups. We used the seed-based correlation analysis to examine the temporal relationship of CBF time series between the selected ROIs and other brain regions. We have shown the developmental patterns in both static CBF maps and dynamic characteristics of CBF. While higher CBF of default mode network (DMN) in all age groups supports that DMN is the prominent active network during the resting state, the CBF connectivity patterns of some typical resting state networks show distinct patterns of metabolic activity during the resting state in the developing brains.

PMID: 29656926 [PubMed - indexed for MEDLINE]

Modeling regional dynamics in low-frequency fluctuation and its application to Autism spectrum disorder diagnosis.

Tue, 09/25/2018 - 16:20
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Modeling regional dynamics in low-frequency fluctuation and its application to Autism spectrum disorder diagnosis.

Neuroimage. 2018 Sep 21;:

Authors: Jun E, Kang E, Choi J, Suk HI

Abstract
With the advent of neuroimaging techniques, many studies in the literature have validated the use of resting-state fMRI (rs-fMRI) for understanding functional mechanisms of the brain, as well as for identifying brain disorders or diseases. One of the main streams in recent studies of modeling and analyzing rs-fMRI data is to account for the dynamic characteristics of a brain. In this study, we propose a novel method that directly models the regional temporal BOLD fluctuations in a stochastic manner and estimates the dynamic characteristics in the form of likelihoods. Specifically, we modeled temporal BOLD fluctuation of individual Regions Of Interest (ROIs) by means of Hidden Markov Models (HMMs), and then estimated the 'goodness-of-fit' of each ROI's BOLD signals to the corresponding trained HMM in terms of a likelihood. Using estimated likelihoods of the ROIs over the whole brain as features, we built a classifier that can discriminate subjects with Autism Spectrum Disorder (ASD) from Typically Developing (TD) controls at an individual level. In order to interpret the trained HMMs and a classifier from a neuroscience perspective, we also conducted model analysis. First, we investigated the learned weight coefficients of a classifier by transforming them into activation patterns, from which we could identify the ROIs that are highly associated with ASD and TD groups. Second, we explored the characteristics of temporal BOLD signals in terms of functional networks by clustering them based on sequences of the hidden states decoded with the trained HMMs. We validated the effectiveness of the proposed method by achieving the state-of-the-art performance on the ABIDE dataset and observed insightful patterns related to ASD.

PMID: 30248456 [PubMed - as supplied by publisher]

The impact of motor impairment on the processing of sensory information.

Tue, 09/25/2018 - 16:20
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The impact of motor impairment on the processing of sensory information.

Behav Brain Res. 2018 Sep 21;:

Authors: Klingner CM, Brodoehl S, Witte OW, Guntinas-Lichius O, Volk GF

Abstract
Sensorimotor adaptation is driven by mismatch errors between desired movements and actual movement outcomes. A mismatch error can be minimized by adjusting movements or by altering the interpretation of sensory information. While the effect of mismatch errors on the motor system has received much attention, the contribution of somatosensory feedback, particularly the sensory-motor interplay in the process of adaptation, remains poorly understood. Our study analyzes the impact of peripheral deefferentation on the plasticity of the brain networks responsible for sensory-motor adaptation, focusing particularly on changes in the processing of somatosensory information. For this aim, task-based and resting-state functional MRI was performed on 24 patients in the acute state of a left-sided idiopathic peripheral facial nerve palsy. The functional connectivity of cortical and subcortical networks was analyzed and compared to a healthy control group. We found a strong involvement of the somatosensory system and the thalamus in the adaptation process following an acute peripheral deefferentation. The investigated network shows the principal pattern of a reduced connectivity between cortical areas, while the connectivity to subcortical areas (the basal ganglia and the thalamus) is increased. We suggest that the increased connectivity between the subcortical and cortical structures indicates an active sensory-motor adaptation process. We further hypothesize that the decreased functional connectivity at the cortical level reflects an unsuccessful sensorimotor adaptation process due to the inability to solve the somatosensory-motor mismatch. These results extend our understanding of the somatosensory-motor interaction in response to a mismatch signal and highlight the importance of the thalamus in this process.

PMID: 30248364 [PubMed - as supplied by publisher]

Resting-state Functional Magnetic Resonance Imaging Identifies Cerebrovascular Reactivity Impairment in Patients With Arterial Occlusive Diseases: A Pilot Study.

Tue, 09/25/2018 - 16:20
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Resting-state Functional Magnetic Resonance Imaging Identifies Cerebrovascular Reactivity Impairment in Patients With Arterial Occlusive Diseases: A Pilot Study.

Neurosurgery. 2018 Sep 20;:

Authors: Nishida S, Aso T, Takaya S, Takahashi Y, Kikuchi T, Funaki T, Yoshida K, Okada T, Kunieda T, Togashi K, Fukuyama H, Miyamoto S

Abstract
BACKGROUND: The development of noninvasive approaches for identifying hypoperfused brain tissue at risk is of major interest. Recently, the temporal-shift (TS) maps estimated from resting-state blood oxygenation level-dependent (BOLD) signals have been proposed for determining hemodynamic state.
OBJECTIVE: To examine the equivalency of the TS map and the cerebrovascular reactivity (CVR) map derived from acetazolamide-challenged single-photon emission computed tomography (SPECT) in identifying hemodynamic impairment in patients with arterial occlusive diseases.
METHODS: Twenty-three patients with arterial occlusive diseases who underwent SPECT were studied. With a recursive TS analysis of low-frequency fluctuation of the BOLD signal, a TS map relative to the global signal was created for each patient. The voxel-by-voxel correlation coefficient was calculated to examine the image similarity between TS and SPECT-based cerebral blood flow (CBF) or CVR maps in each patient. Furthermore, simple linear regression analyses were performed to examine the quantitative relationship between the TS of BOLD signals and CVR in each cerebrovascular territory.
RESULTS: The within-patient, voxel-by-voxel comparison revealed that the TS map was more closely correlated with SPECT-CVR map ([Z(r)] = 0.42 ± 0.18) than SPECT-CBF map ([Z(r)] = 0.058 ± 0.11; P < .001, paired t-test). The regression analysis showed a significant linear association between the TS of BOLD signals and CVR in the anterior circulation where the reduction of CVR was evident in the patient group.
CONCLUSION: BOLD TS analysis has potential as a noninvasive alternative to current methods based on CVR for identification of tissue at risk of ischemic stroke.

PMID: 30247676 [PubMed - as supplied by publisher]

Anterior cingulate cortex connectivity is associated with suppression of behaviour in a rat model of chronic pain.

Tue, 09/25/2018 - 16:20
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Anterior cingulate cortex connectivity is associated with suppression of behaviour in a rat model of chronic pain.

Brain Neurosci Adv. 2018;2:2398212818779646

Authors: Morris LS, Sprenger C, Koda K, de la Mora DM, Yamada T, Mano H, Kashiwagi Y, Yoshioka Y, Morioka Y, Seymour B

Abstract
A cardinal feature of persistent pain that follows injury is a general suppression of behaviour, in which motivation is inhibited in a way that promotes energy conservation and recuperation. Across species, the anterior cingulate cortex is associated with the motivational aspects of phasic pain, but whether it mediates motivational functions in persistent pain is less clear. Using burrowing behaviour as an marker of non-specific motivated behaviour in rodents, we studied the suppression of burrowing following painful confirmatory factor analysis or control injection into the right knee joint of 30 rats (14 with pain) and examined associated neural connectivity with ultra-high-field resting state functional magnetic resonance imaging. We found that connectivity between anterior cingulate cortex and subcortical structures including hypothalamic/preoptic nuclei and the bed nucleus of the stria terminalis correlated with the reduction in burrowing behaviour observed following the pain manipulation. In summary, the findings implicate anterior cingulate cortex connectivity as a correlate of the motivational aspect of persistent pain in rodents.

PMID: 30246156 [PubMed]

Group analysis data representing the effects of frontopolar transcranial direct current stimulation on the default mode network.

Tue, 09/25/2018 - 16:20
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Group analysis data representing the effects of frontopolar transcranial direct current stimulation on the default mode network.

Data Brief. 2018 Oct;20:1309-1313

Authors: Ahn J, Lee J, Han JH, Kang MS, Han S

Abstract
The current data provide information about altered activities of the default mode network (DMN) after applying transcranial direct current stimulation (tDCS) over the frontopolar prefrontal cortex. To explore whether frontopolar tDCS with a small current intensity and small electrodes can induce changes in the DMN, resting-state functional magnetic resonance imaging (fMRI) data were collected before and after the application of tDCS. The results of independent component analysis using the resting-state fMRI data are reported in this article.

PMID: 30246109 [PubMed]

Predicting conversion from MCI to AD by integrating rs-fMRI and structural MRI.

Tue, 09/25/2018 - 16:20
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Predicting conversion from MCI to AD by integrating rs-fMRI and structural MRI.

Comput Biol Med. 2018 Sep 15;102:30-39

Authors: Hojjati SH, Ebrahimzadeh A, Khazaee A, Babajani-Feremi A, Alzheimer's Disease Neuroimaging Initiative

Abstract
Structural MRI (sMRI) and resting-state functional MRI (rs-fMRI) have provided promising results in the diagnosis of Alzheimer's disease (AD), though the utility of integrating sMRI with rs-fMRI has not been explored thoroughly. We investigated the performances of rs-fMRI and sMRI in single modality and multi-modality approaches for classifying patients with mild cognitive impairment (MCI) who progress to probable AD-MCI converter (MCI-C) from those with MCI who do not progress to probable AD-MCI non-converter (MCI-NC). The cortical and subcortical measurements, e.g. cortical thickness, extracted from sMRI and graph measures extracted from rs-fMRI functional connectivity were used as features in our algorithm. We trained and tested a support vector machine to classify MCI-C from MCI-NC using rs-fMRI and sMRI features. Our algorithm for classifying MCI-C and MCI-NC utilized a small number of optimal features and achieved accuracies of 89% for sMRI, 93% for rs-fMRI, and 97% for the combination of sMRI with rs-fMRI. To our knowledge, this is the first study that investigated integration of rs-fMRI and sMRI for identification of the early stage of AD. Our findings shed light on integration of sMRI with rs-fMRI for identification of the early stages of AD.

PMID: 30245275 [PubMed - as supplied by publisher]

Patterns of striatal and cerebellar functional connectivity in early-stage drug-naïve patients with Parkinson's disease subtypes.

Mon, 09/24/2018 - 15:20
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Patterns of striatal and cerebellar functional connectivity in early-stage drug-naïve patients with Parkinson's disease subtypes.

Neuroradiology. 2018 Sep 22;:

Authors: Hou Y, Ou R, Yang J, Song W, Gong Q, Shang H

Abstract
PURPOSE: Both the striatal-thalamo-cortical (STC) circuit and cerebello-thalamo-cortical (CTC) circuit play a critical role in Parkinson's disease (PD).
METHODS: Resting-state functional MRI was used to assess functional connectivity (FC) focusing on the basal ganglia (BG) and cerebellum among early-stage drug-naïve PD patients with tremor-dominant (TD) PD patients with postural instability and gait dysfunction (PIGD) and healthy controls (HCs).
RESULTS: Compared to HCs, both PD subgroups had higher FC between the cerebellum and paracentral lobule, sensorimotor areas; lower FC between the BG and superior frontal gyrus, and within the BG circuit; PD-TD patients showed higher FC between the BG and fusiform, paracentral lobule, cerebellum Lobule VI, and between the cerebellum and supplementary motor areas (SMA), insula; lower FC between the BG and rectus, sensorimotor areas, and within the cerebellum circuit; PD-PIGD patients showed higher FC between the cerebellum and middle frontal gyrus, precuneus; lower FC between the BG and cerebellum Crus II. Besides, compared to PD-PIGD patients and HCs, PD-TD patients had higher FC between the BG and calcarine region. In all PD patients, FC in paracentral lobule, SMA, and cerebellum Lobule VI positively correlated with tremor scores, and FC in calcarine area positively correlated with tremor scores, but negatively correlated with PIGD scores.
CONCLUSION: Our findings mainly suggested that the BG and cerebellum had hyper-connectivity with the cortical motor cortex, and the BG had prominent hyper-connectivity with the visual cortex in early-stage PD-TD patients. These findings may be helpful for facilitating the further understanding of potential mechanisms in the early-stage PD-TD. However, our results are preliminary, and further investigations are needed.

PMID: 30244415 [PubMed - as supplied by publisher]

Altered temporal variance and functional connectivity of BOLD signal is associated with state anxiety during acute systemic inflammation.

Mon, 09/24/2018 - 15:20
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Altered temporal variance and functional connectivity of BOLD signal is associated with state anxiety during acute systemic inflammation.

Neuroimage. 2018 Sep 20;:

Authors: Labrenz F, Ferri F, Wrede K, Forsting M, Schedlowski M, Engler H, Elsenbruch S, Benson S, Costantini M

Abstract
Systemic inflammation is accompanied by complex behavioral changes and disturbed emotion regulation that have been related to the pathophysiology of mood disorders including depression and anxiety. However, the causal role of systemic inflammation on mood disorders is still unclear. We herein investigated neural resting state patterns of temporal variance of the amygdala and functional connectivity within the salience network underlying changes in state anxiety during experimentally-induced systemic inflammation. In this randomized, double-blind study, N = 43 healthy men received an intravenous injection of either low-dose lipopolysaccharide (LPS, 0.4 ng/kg body weight) or saline. Resting state functional magnetic resonance imaging was assessed before and 3.5 h after injection. State anxiety, assessed with a standardized questionnaire, and plasma cytokine concentrations were repeatedly measured. LPS administration induced a transient systemic inflammatory response reflected in increases in plasma Interleukin (IL)-6 and Tumor Necrosis Factor (TNF)-α concentration. Compared to placebo, state anxiety and temporal variance in the amygdala significantly increased while functional connectivity in the salience network decreased during LPS-induced systemic inflammation. Together, these data indicate that acute systemic inflammation alters temporal variance of the BOLD signal as well as functional connectivity in brain regions and networks implicated in emotion processing and regulation. These results are of translational importance to encourage further research on the role of inflammatory pathways in the pathophysiology of neuropsychiatric conditions including anxiety disorders.

PMID: 30243957 [PubMed - as supplied by publisher]

Intranasal Oxytocin and OXTR Genotype Effects on Resting State Functional Connectivity: A Systematic Review.

Mon, 09/24/2018 - 15:20
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Intranasal Oxytocin and OXTR Genotype Effects on Resting State Functional Connectivity: A Systematic Review.

Neurosci Biobehav Rev. 2018 Sep 19;:

Authors: Seeley SH, Chou YH, O'Connor MF

Abstract
OBJECTIVE: Evaluate effects of intranasal oxytocin (IN-OT) and OXTR genotype on resting state functional connectivity in the human brain.
METHODS: We searched research databases for peer-reviewed empirical studies. Of 71 unique citations, 18 articles (13 IN-OT, five OXTR) met full inclusion criteria.
RESULTS: Two studies examined effects on large-scale networks; most examined acute effects on amygdala connectivity with other social and affective regions. OXTR studies identified three polymorphisms (rs2254298, rs2268498, rs53576) having allele- and sex-dependent effects on prefrontal functional connectivity, and additive effects of OXTR risk alleles on reward circuitry. Age, sex, early life stress, and psychopathology emerged as potential moderators of both IN-OT and OXTR effects.
DISCUSSION: IN-OT appears to modulate resting state functional connectivity in a manner similar to its effects on task fMRI, consistent with hypothesized models of IN-OT. However, conclusions are limited by the narrow range of neuroanatomical seed regions, and methodological and experimental design heterogeneity. Future studies should take into account individual differences. Findings may provide insight into mechanisms through which IN-OT impacts human behavior.

PMID: 30243577 [PubMed - as supplied by publisher]

Altered attention networks and DMN in refractory epilepsy: A resting-state functional and causal connectivity study.

Sun, 09/23/2018 - 14:00
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Altered attention networks and DMN in refractory epilepsy: A resting-state functional and causal connectivity study.

Epilepsy Behav. 2018 Sep 19;88:81-86

Authors: Jiang LW, Qian RB, Fu XM, Zhang D, Peng N, Niu CS, Wang YH

Abstract
PURPOSE: Epilepsy is considered a disorder of neural networks. Patients diagnosed with refractory epilepsy frequently experience attention impairments. Seizure activity in epilepsy may disturb brain networks and damage the brain function of attention. The aims of this study were to assess functional and causal connectivities of the attention networks and default mode network using resting-state functional magnetic resonance imaging (fMRI).
METHOD: Resting-state fMRI data were gathered from 19 patients with refractory epilepsy (mixed localization and aetiologies) and 21 healthy people. The fMRI data were analyzed by group independent component analysis (ICA) fMRI toolbox to extract dorsal attention network (DAN), ventral attention network (VAN), and default mode network (DMN). The components of the selected networks were compared between patients and healthy controls to explore the change in functional connectivity (FC). Granger causality analysis was performed by taking the aforementioned significant brain areas as regions of interest (ROIs) to calculate autoregression coefficients of each pair of ROIs. Comparisons were done to find the significantly different causal connectivity when FC was changed between patients and healthy controls.
RESULTS: In DAN, the FC values of the bilateral frontal eye field (FEF) and left intraparietal sulcus (IPS) were decreased. In VAN, the FC values of the double-side ventral prefrontal cortex (vPFC) and the temporoparietal junction (TPJ) were reduced. As for DMN, the FC values of the bilateral medial prefrontal cortices (mPFC) were decreased whereas those for the bilateral precuneus (PCUN) were increased. Granger causal connectivity values were correlated: causal influence was decreased significantly from the left IPS (in DAN) to the double side of the vPFC but remained the same for the right FEF (in DAN) to the right TPJ. The value was decreased from the left PCUN (in DMN) to the right TPJ and FEF, and the causal flow from the right PCUN to the right TPJ and bilateral vPFC was also significantly inhibited (p < 0.05).
CONCLUSION: Frequent seizures in patients with refractory epilepsy may damage the cortex and disturb DAN, VAN, and DMN, leading to functional and causal connectivity alteration. In addition, epileptic activity may disrupt network interactions and further influence information communication.

PMID: 30243110 [PubMed - as supplied by publisher]

Abnormal changes in functional connectivity between the amygdala and frontal regions are associated with depression in Alzheimer's disease.

Sun, 09/23/2018 - 14:00
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Abnormal changes in functional connectivity between the amygdala and frontal regions are associated with depression in Alzheimer's disease.

Neuroradiology. 2018 Sep 21;:

Authors: Guo Z, Liu X, Xu S, Hou H, Chen X, Zhang Z, Chen W

Abstract
PURPOSE: The aim of the present study was to investigate the functional connectivity (FC) of Alzheimer's disease patients with depression (D-AD) based on an amygdalar seed using resting-state functional magnetic resonance imaging (rs-fMRI).
METHODS: Twenty-one non-depressed AD (nD-AD) patients and 21 D-AD patients underwent rs-fMRI. The Hamilton Depression Rating Scale and Neuropsychiatric Inventory were used to evaluate the severity of depression. The amygdala was used as the seed for FC analysis. The FC differences between the two groups were evaluated by two-sample t tests, and the correlation of FC changes with depressive severity was analyzed by Pearson correlational analysis.
RESULTS: Compared with the nD-AD patients, D-AD patients had increased FC values between the amygdala and orbitofrontal cortex and decreased FC values among the amygdala, medial prefrontal cortex, and inferior frontal gyrus.
CONCLUSION: These data suggest that abnormal amygdala-prefrontal FC may be an important characteristic of AD patients with depression.

PMID: 30242429 [PubMed - as supplied by publisher]

Disrupted asymmetry of inter- and intra-hemispheric functional connectivity in patients with drug-naive, first-episode schizophrenia and their unaffected siblings.

Sun, 09/23/2018 - 14:00
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Disrupted asymmetry of inter- and intra-hemispheric functional connectivity in patients with drug-naive, first-episode schizophrenia and their unaffected siblings.

EBioMedicine. 2018 Sep 18;:

Authors: Zhu F, Liu F, Guo W, Chen J, Su Q, Zhang Z, Li H, Fan X, Zhao J

Abstract
BACKGROUND: Lack of normal asymmetry in the brain has been reported in patients with schizophrenia. However, it remains unclear whether disrupted asymmetry originates from inter-hemispheric functional connectivity (FC) and/or intra-hemispheric FC in this patient population.
METHODS: Forty-four patients with drug-naive, first-episode schizophrenia, 42 unaffected siblings, and 44 healthy controls underwent resting-state functional magnetic resonance imaging (fMRI) scan. The parameter of asymmetry (PAS) and support vector machine (SVM) were used to analyze the data. Patients were treated with olanzapine for 8 weeks.
FINDINGS: Compared with healthy controls, patients showed lower PAS scores in the left middle temporal gyrus (MTG)/inferior temporal gyrus (ITG), left posterior cingulate cortex (PCC)/precuneus and left angular gyrus, and higher PAS scores in the left precentral gyrus/postcentral gyrus. Unaffected siblings also showed lower PAS scores in the left MTG/ITG and left PCC/precuneus relative to healthy controls. Further, SVM analysis showed that a combination of the PAS scores in these two clusters in patients at baseline was able to predict clinical response after 8 weeks of olanzapine treatment with 77.27% sensitivity, 72.73% specificity, and 75.00% accuracy.
INTERPRETATION: The present study suggests disrupted asymmetry of inter- and intra-hemispheric FC in drug-naive, first-episode schizophrenia; in addition, a reduced asymmetry of inter-hemispheric FC in the left MTG/ITG and left PCC/precuneus may serve as an endophenotype for schizophrenia, and may have clinical utility to predict response to olanzapine treatment. FUND: The National Key R&D Program of China and the National Natural Science Foundation of China.

PMID: 30241918 [PubMed - as supplied by publisher]

Improved Detection of Pelvic Organ Prolapse: Comparative Utility of Defecography Phase Sequence to Nondefecography Valsalva Maneuvers in Dynamic Pelvic Floor Magnetic Resonance Imaging.

Sun, 09/23/2018 - 14:00
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Improved Detection of Pelvic Organ Prolapse: Comparative Utility of Defecography Phase Sequence to Nondefecography Valsalva Maneuvers in Dynamic Pelvic Floor Magnetic Resonance Imaging.

Curr Probl Diagn Radiol. 2018 Aug 23;:

Authors: Arif-Tiwari H, Twiss CO, Lin FC, Funk JT, Vedantham S, Martin DR, Kalb BT

Abstract
PURPOSE: To evaluate the utility of a defecography phase (DP) sequence in dynamic pelvic floor MRI (DPMRI), in comparison to DPMRI utilizing only non-defecography Valsalva maneuvers (VM).
MATERIALS AND METHODS: Inclusion criteria identified 237 female patients with symptoms and/or physical exam findings of pelvic floor prolapse. All DPMRI exams were obtained following insertion of ultrasound gel into the rectum and vagina. Steady-state free-precession sequences in sagittal plane were acquired in the resting state, followed by dynamic cine acquisitions during VM and DP. In all phases, two experienced radiologists performed blinded review using the H-line, M-line, Organ prolapse (HMO) system. The presence of a rectocele, enterocele and inferior descent of the anorectal junction, bladder base, and vaginal vault were recorded in all patients using the pubococcygeal line as a fixed landmark.
RESULTS: DPMRI with DP detected significantly more number of patients than VM (p<0.0001) with vaginal prolapse (231/237, 97.5% vs. 177/237, 74.7%), anorectal prolapse (227/237, 95.8% vs. 197/237, 83.1%), cystocele (197/237, 83.1% vs. 108/237, 45.6%), and rectocele (154/237, 65% vs. 93/237, 39.2%). The median cycstocele (3.2cm vs. 1cm), vaginal prolapse (3cm vs. 1.5cm), anorectal prolapse (5.4cm vs. 4.2cm), H-line (8cm vs. 7.2cm) and M-line (5.3cm vs. 3.9cm) were significantly higher with DP than VM (p<0.0001).
CONCLUSIONS: Addition of DP to DPMRI demonstrates a greater degree of pelvic floor instability as compared to imaging performed during VM alone. Pelvic floor structures may show mild descent or appear normal during VM, with marked prolapse on subsequent DP images.

PMID: 30241870 [PubMed - as supplied by publisher]

Education, and the balance between dynamic and stationary functional connectivity jointly support executive functions in relapsing-remitting multiple sclerosis.

Sat, 09/22/2018 - 19:20
Related Articles

Education, and the balance between dynamic and stationary functional connectivity jointly support executive functions in relapsing-remitting multiple sclerosis.

Hum Brain Mapp. 2018 Sep 21;:

Authors: Lin SJ, Vavasour I, Kosaka B, Li DKB, Traboulsee A, MacKay A, McKeown MJ

Abstract
Graphical network characteristics and nonstationary functional connectivity features, both derived from resting-state functional magnetic resonance imaging (rsfMRI) data, have been associated with cognitive performance in healthy subjects. How these features jointly relate to cognition in diseased states has not been investigated. In this study, 46 relapsing-remitting multiple sclerosis subjects underwent rsfMRI scans and a focused cognitive battery. With a sliding window approach, we examined six dynamic network features that indicated how connectivity changed over time as well as six measures derived from graph theory to reflect static network characteristics. Multiset canonical correlation analysis (MCCA) was then carried out to investigate the relations between dynamic network features, stationary network characteristics, cognitive testing, demographic, disease severity, and mood. Multiple sclerosis (MS) subjects demonstrated weaker connectivity strength, decreased network density, reduced global changes, but increased changes in interhemispheric connectivity compared to controls. The MCCA model determined that executive functions and processing speed ability measured by Wechsler Adult Intelligence Scale IV (WAIS-IV) Working Memory Index, WAIS-IV Processing Speed Index, and the Verbal Fluency Test were positively correlated with education, dynamic connectivity, and static connectivity strength; while poor task switching was correlated with disease severity, psychiatric comorbidities such as depression, anxiety, and fatigue, and static network density. Taken together, our results suggest that better executive functioning in MS requires maintenance of a continued coordination between stationary and dynamic functional connectivity as well as the support of education, and dynamic functional connectivity may provide an additional cognitive biomarker of disease severity in the MS population.

PMID: 30240533 [PubMed - as supplied by publisher]

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