New resting-state fMRI related studies at PubMed

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Altered Spontaneous Regional Brain Activity in the Insula and Visual Areas of Professional Traditional Chinese Pingju Opera Actors.

Thu, 07/19/2018 - 10:20

Altered Spontaneous Regional Brain Activity in the Insula and Visual Areas of Professional Traditional Chinese Pingju Opera Actors.

Front Neurosci. 2018;12:450

Authors: Zhang W, Zhao F, Qin W, Ma L

Abstract
Recent resting-state fMRI studies have revealed neuroplastic alterations after long-term training. However, the neuroplastic changes that occur in professional traditional Chinese Pingju opera actors remain unclear. Twenty professional traditional Chinese Pingju opera actors and 20 age-, sex-, and handedness-matched laymen were recruited. Resting-state fMRI was obtained by using an echo-planar imaging sequence, and two metrics, amplitude of low frequency fluctuation (ALFF) and regional homogeneity (ReHo), were utilized to assess spontaneous neural activity during resting state. Our results demonstrated that compared with laymen, professional traditional Chinese Pingju actors exhibited significantly decreased ALFF in the bilateral calcarine gyrus and cuneus; decreased ReHo in the bilateral superior occipital and calcarine gyri, cuneus, and right middle occipital gyrus; and increased ReHo in the left anterior insula. In addition, no significant association was found between spontaneous neural activity and Pingju opera training duration. Overall, the changes observed in spontaneous brain activity in professional traditional Chinese Pingju opera actors may indicate their superior performance of multidimensional professional skills, such as music and face perception, dancing, and emotional representation.

PMID: 30018534 [PubMed]

Shared endo-phenotypes of default mode dsfunction in attention deficit/hyperactivity disorder and autism spectrum disorder.

Thu, 07/19/2018 - 10:20

Shared endo-phenotypes of default mode dsfunction in attention deficit/hyperactivity disorder and autism spectrum disorder.

Transl Psychiatry. 2018 Jul 17;8(1):133

Authors: Kernbach JM, Satterthwaite TD, Bassett DS, Smallwood J, Margulies D, Krall S, Shaw P, Varoquaux G, Thirion B, Konrad K, Bzdok D

Abstract
Categorical diagnoses from the Diagnostic and Statistical Manual of Mental Disorders (DSM) or International Classification of Diseases (ICD) manuals are increasingly found to be incongruent with emerging neuroscientific evidence that points towards shared neurobiological dysfunction underlying attention deficit/hyperactivity disorder and autism spectrum disorder. Using resting-state functional magnetic resonance imaging data, functional connectivity of the default mode network, the dorsal attention and salience network was studied in 1305 typically developing and diagnosed participants. A transdiagnostic hierarchical Bayesian modeling framework combining Indian Buffet Processes and Latent Dirichlet Allocation was proposed to address the urgent need for objective brain-derived measures that can acknowledge shared brain network dysfunction in both disorders. We identified three main variation factors characterized by distinct coupling patterns of the temporoparietal cortices in the default mode network with the dorsal attention and salience network. The brain-derived factors were demonstrated to effectively capture the underlying neural dysfunction shared in both disorders more accurately, and to enable more reliable diagnoses of neurobiological dysfunction. The brain-derived phenotypes alone allowed for a classification accuracy reflecting an underlying neuropathology of 67.33% (+/-3.07) in new individuals, which significantly outperformed the 46.73% (+/-3.97) accuracy of categorical diagnoses. Our results provide initial evidence that shared neural dysfunction in ADHD and ASD can be derived from conventional brain recordings in a data-led fashion. Our work is encouraging to pursue a translational endeavor to find and further study brain-derived phenotypes, which could potentially be used to improve clinical decision-making and optimize treatment in the future.

PMID: 30018328 [PubMed - in process]

A Pilot Study Investigating a Novel Non-Linear Measure of Eyes Open versus Eyes Closed EEG Synchronization in People with Alzheimer's Disease and Healthy Controls.

Thu, 07/19/2018 - 10:20

A Pilot Study Investigating a Novel Non-Linear Measure of Eyes Open versus Eyes Closed EEG Synchronization in People with Alzheimer's Disease and Healthy Controls.

Brain Sci. 2018 Jul 17;8(7):

Authors: Blackburn DJ, Sarrigiannis PG, De Marco M, Zhao Y, Venneri A, Lawrence S, Unwin ZC, Blyth M, Angel J, Baster K, Wilkinson ID, Bell SM, He F, Wei HL, Billings SA, Farrow TFD

Abstract
BACKGROUND: The incidence of Alzheimer disease (AD) is increasing with the ageing population. The development of low cost non-invasive diagnostic aids for AD is a research priority. This pilot study investigated whether an approach based on a novel dynamic quantitative parametric EEG method could detect abnormalities in people with AD.
METHODS: 20 patients with probable AD, 20 matched healthy controls (HC) and 4 patients with probable fronto temporal dementia (FTD) were included. All had detailed neuropsychology along with structural, resting state fMRI and EEG. EEG data were analyzed using the Error Reduction Ratio-causality (ERR-causality) test that can capture both linear and nonlinear interactions between different EEG recording areas. The 95% confidence intervals of EEG levels of bi-centroparietal synchronization were estimated for eyes open (EO) and eyes closed (EC) states.
RESULTS: In the EC state, AD patients and HC had very similar levels of bi-centro parietal synchronization; but in the EO resting state, patients with AD had significantly higher levels of synchronization (AD = 0.44; interquartile range (IQR) 0.41 vs. HC = 0.15; IQR 0.17, p < 0.0001). The EO/EC synchronization ratio, a measure of the dynamic changes between the two states, also showed significant differences between these two groups (AD ratio 0.78 versus HC ratio 0.37 p < 0.0001). EO synchronization was also significantly different between AD and FTD (FTD = 0.075; IQR 0.03, p < 0.0001). However, the EO/EC ratio was not informative in the FTD group due to very low levels of synchronization in both states (EO and EC).
CONCLUSION: In this pilot work, resting state quantitative EEG shows significant differences between healthy controls and patients with AD. This approach has the potential to develop into a useful non-invasive and economical diagnostic aid in AD.

PMID: 30018264 [PubMed]

Multifocal epilepsy in children is associated with increased long-distance functional connectivity: An explorative EEG-fMRI study.

Thu, 07/19/2018 - 10:20

Multifocal epilepsy in children is associated with increased long-distance functional connectivity: An explorative EEG-fMRI study.

Eur J Paediatr Neurol. 2018 Jul 05;:

Authors: Siniatchkin M, Moehring J, Kroeher B, Galka A, von Ondarza G, Moeller F, Wolff S, Tagliazucchi E, Steinmann E, Boor R, Stephani U

Abstract
OBJECTIVE: Multifocal epileptic activity is an unfavourable feature of a number of epileptic syndromes (Lennox-Gastaut syndrome, West syndrome, severe focal epilepsies) which suggests an overall vulnerability of the brain to pathological synchronization. However, the mechanisms of multifocal activity are insufficiently understood. This explorative study investigates whether pathological connectivity within brain areas of the default mode network as well as thalamus, brainstem and retrosplenial cortex may predispose individuals to multifocal epileptic activity.
METHODS: 33 children suffering from multifocal and monofocal (control group) epilepsies were investigated using EEG-fMRI recordings during sleep. The blood oxygenated level dependent (BOLD) signal of 15 regions of interest was extracted and temporally correlated (resting-state functional connectivity).
RESULTS: Patients with monofocal epilepsies were characterized by strong correlations between the corresponding interhemispheric homotopic regions. This pattern of correlations with pronounced short-distance and weak long-distance functional connectivity resembles the connectivity pattern described for healthy children. Patients with multifocal epileptic activity, however, demonstrated significantly stronger correlations between a large number of regions of the default mode network as well as thalamus and brainstem, with a significant increase in long-distance connectivity compared to children with monofocal epileptic activity. In the group of patients with multifocal epilepsies there were no differences in functional connectivity between patients with or without Lennox-Gastaut syndrome.
CONCLUSION: This explorative study shows that multifocal activity is associated with generally increased long-distance functional connectivity in the brain. It can be suggested that this pronounced connectivity may represent either a risk to pathological over-synchronization or a consequence of the multifocal epileptic activity.

PMID: 30017619 [PubMed - as supplied by publisher]

Does brain functional connectivity contribute to musculoskeletal injury? A preliminary prospective analysis of a neural biomarker of ACL injury risk.

Thu, 07/19/2018 - 10:20

Does brain functional connectivity contribute to musculoskeletal injury? A preliminary prospective analysis of a neural biomarker of ACL injury risk.

J Sci Med Sport. 2018 Jul 10;:

Authors: Diekfuss JA, Grooms DR, Yuan W, Dudley J, Barber Foss KD, Thomas S, Ellis JD, Schneider DK, Leach J, Bonnette S, Myer GD

Abstract
OBJECTIVES: We aimed to present a unique prospective neurological dataset for participants who experienced an ACL injury.
DESIGN: Prospective longitudinal case-control.
METHODS: High school female soccer athletes were evaluated using functional magnetic resonance imaging to capture resting-state brain connectivity prior to their competitive season. Two of these athletes later experienced an ACL injury (ACLI). We matched these ACLI participants with eight teammates who did not go on to sustain an ACL injury (uninjured controls, Con) based on age, grade, sex, height, and weight to examine differences in preseason connectivity. Knee-motor regions of interest (ROIs) were created based on previously published data from which five specific areas were selected as seeds for analysis. Independent-samples t-tests with a false discovery rate correction for multiple comparisons determined differences in connectivity between the ACLI and Con.
RESULTS: There was significantly greater connectivity between the left primary sensory cortex (a brain region responsible for proprioception) and the right posterior lobe of the cerebellum (a brain region responsible for balance and coordination) for the Con relative to ACLI, t (8)=4.53, p=0.03 (false discovery rate corrected).
CONCLUSIONS: These preliminary data indicate that those who do not later sustain an ACL injury exhibit a stronger functional connection between a cortical sensory-motor region and a cerebellar region responsible for balance and coordination. These findings may help to guide development of brain-driven biofeedback training that optimizes and promotes adaptive neuroplasticity to reduce motor coordination errors and injury risk.

PMID: 30017465 [PubMed - as supplied by publisher]

Decreased functional connectivity within the default-mode network in acute brainstem ischemic stroke.

Thu, 07/19/2018 - 10:20

Decreased functional connectivity within the default-mode network in acute brainstem ischemic stroke.

Eur J Radiol. 2018 Aug;105:221-226

Authors: Jiang L, Geng W, Chen H, Zhang H, Bo F, Mao CN, Chen YC, Yin X

Abstract
PURPOSE: Ischemic stroke within the brainstem is associated with an increased risk of cognitive dysfunction. This study aimed to explore the integrity of a default-mode network (DMN) and its relationship with clinical variables in patients with acute ischemic brainstem stroke using an independent component analysis (ICA) approach.
MATERIALS AND METHODS: Twenty-one patients with acute ischemic brainstem stroke and 25 well-matched healthy subjects were enrolled in this study and underwent resting-state functional magnetic resonance imaging. The ICA was adopted to extract the DMN, including its anterior and posterior components. Pearson correlation analyses were performed to investigate the relationship between DMN connectivity and clinical variables.
RESULTS: Compared with healthy controls, patients with acute ischemic stroke showed significantly decreased functional connectivity in the right medial prefrontal cortex (mPFC) and right precuneus within the anterior and posterior DMN, respectively. After correcting for age, sex, and education, hypoconnectivity in the right mPFC and right precuneus was negatively correlated with higher homocysteine in patients with stroke (r = -0.592, p = 0.010 and r = -0.491, p = 0.039, respectively).
CONCLUSION: The finding of decreased functional connectivity within the DMN of patients with acute brainstem stroke provides novel insight into the neural mechanisms that underlie cognitive impairment following ischemic insult to this brain region.

PMID: 30017284 [PubMed - in process]

Impaired topographic organization in cognitively unimpaired drug-naïve patients with rigidity-dominant Parkinson's disease.

Thu, 07/19/2018 - 10:20

Impaired topographic organization in cognitively unimpaired drug-naïve patients with rigidity-dominant Parkinson's disease.

Parkinsonism Relat Disord. 2018 Jun 13;:

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

Abstract
BACKGROUND: Resting-state functional magnetic resonance imaging (fMRI) and graph theory approaches have been combined to investigate the topographic organization in Parkinson's disease (PD).
METHOD: Twenty cognitively unimpaired drug-naïve patients with rigidity-dominant PD (PDAR) and 20 age-, sex-, and education-matched healthy controls were included. Small-world profile and topographic properties (clustering coefficient (Cp), characteristic path length (Lp), local efficiency (Eloc), global efficiency (Eglob), nodal efficiency (Enod), nodal degree (NDeg), and nodal betweenness (NBet)) were measured and compared between two groups, with age, gender and education as covariates. Correlation analyses between topographic features and the unified PD rating scale part-III (UPDRS-III) scores, cognitive scores were performed.
RESULTS: PDAR patients presented the small-world property, and abnormalities at the nodal level (Enod, NDeg, and NBet) but not at the global level (Cp, Lp, Eloc, and Eglob). Our results revealed lower nodal centralities mainly in the occipital lobe and areas of the limbic system (including amygdala nucleus), and higher nodal centralities in distributed frontal and temporal regions. Notably, the decreased nodal efficiency of occipital regions (including the calcarine area, lingual area and superior occipital gyrus (SOG)) was negatively correlated with UPDRS-III scores. And the nodal efficiency of the calcarine area was positively correlated with visuospatial scores.
CONCLUSION: Our results may provide insights into the underlying pathophysiology of PDAR and aid the development of potential biomarkers of the disease progression and cognitive decline in PDAR patients.

PMID: 30017248 [PubMed - as supplied by publisher]

Brain networks of happiness: Dynamic functional connectivity among the default, cognitive and salience networks relates to subjective well-being.

Wed, 07/18/2018 - 15:20

Brain networks of happiness: Dynamic functional connectivity among the default, cognitive and salience networks relates to subjective well-being.

Soc Cogn Affect Neurosci. 2018 Jul 17;:

Authors: Shi L, Sun J, Wu X, Wei D, Chen Q, Yang W, Chen H, Qiu J

Abstract
Subjective well-being (SWB) reflects the cognitive and emotional evaluations of an individual's life and plays an important role in individual's success in health, work, and social relationships. Although previous studies have revealed the spontaneous brain activity underlying SWB, little is known about the relationship between brain network interactions and SWB. The present study investigated the static and dynamic functional connectivity among large-scale brain networks during resting state fMRI in relation to SWB in two large independent datasets. The results showed that SWB is negatively correlated with static functional connectivity between the salience network (SN) and the anterior default mode network (DMN). Dynamic functional network connectivity (dFNC) analysis found that SWB is negatively correlated with the fraction of time that participants spent in a brain state characterized by weak cross-network connectivity (between the DMN, SN, and frontal-parietal network [FPN]) and strong within-network connectivity (within the DMN and within the FPN). This connectivity profile may account for the good mental adaptability and flexible information communication of people with high levels of SWB. The dFNC results were well replicated with different analysis parameters and further validated in an independent sample. Taken together, these findings reveal that the dynamic interaction between networks involved in self-reflection, emotional regulation, and cognitive control underlies SWB.

PMID: 30016499 [PubMed - as supplied by publisher]

Structural and functional brain scans from the cross-sectional Southwest University adult lifespan dataset.

Wed, 07/18/2018 - 15:20

Structural and functional brain scans from the cross-sectional Southwest University adult lifespan dataset.

Sci Data. 2018 Jul 17;5:180134

Authors: Wei D, Zhuang K, Ai L, Chen Q, Yang W, Liu W, Wang K, Sun J, Qiu J

Abstract
Recently, the field of developmental neuroscience has aimed to uncover the developmental trajectory of the human brain and to understand the changes that occur as a function of ageing. Here, we present a dataset of functional magnetic resonance imaging (fMRI) data covering the adult lifespan that includes structural MRI and resting-state functional MRI. Four hundred ninety-four healthy adults (age range: 19-80 years; Males=187) were recruited and completed two multi-modal MRI scan sessions at the Brain Imaging Center of Southwest University, Chongqing, China. The goals of the dataset are to give researchers the opportunity to map the developmental trajectories of structural and functional changes in the human brain and to replicate previous findings.

PMID: 30015807 [PubMed - in process]

Brain regional synchronous activity predicts tauopathy in 3×TgAD mice.

Wed, 07/18/2018 - 15:20

Brain regional synchronous activity predicts tauopathy in 3×TgAD mice.

Neurobiol Aging. 2018 Jun 21;70:160-169

Authors: Liu D, Lu H, Stein E, Zhou Z, Yang Y, Mattson MP

Abstract
Alzheimer's disease (AD) is characterized by progressive cognitive impairment and by extensive neuronal loss associated with extracellular amyloid β-peptide (Aβ) plaques and intraneuronal tau pathology in temporal and parietal lobes. AD patients are at increased risk for epileptic seizures, and data from experimental models of AD suggest that aberrant neuronal network activity occurs early in the disease process before cognitive deficits and neuronal degeneration. The contributions of Aβ and/or tau pathologies to dysregulation of neuronal network activity are unclear. Using a transgenic mouse model of AD (3×TgAD mice) in which there occurs differential age-dependent development of tau and Aβ plaque pathologies, we applied analysis of resting state functional magnetic resonance imaging regional homogeneity, a measure of local synchronous activity, to discriminate the effects of Aβ and tau on neuronal network activity throughout the brain. Compared to age-matched wild-type mice, 6- to 8-month-old 3×TgAD mice exhibited increased regional homogeneity in the hippocampus and parietal and temporal cortices, regions with tau pathology but not Aβ pathology at this age. By 18-24 months of age, 3×TgAD mice exhibited extensive tau and Aβ pathologies involving the hippocampus and multiple functionally related brain regions, with a spatial expansion of increased local synchronous activity to include those regions. Our findings demonstrate that age-related brain regional hypersynchronous activity is associated with early tau pathology in a mouse model, consistent with a role for early tau pathology in the neuronal circuit hyperexcitability that is believed to precede and contribute to neuronal degeneration in AD.

PMID: 30015035 [PubMed - as supplied by publisher]

Functional Magnetic Resonance Imaging and Oculomotor Dysfunction in Mild Traumatic Brain Injury.

Wed, 07/18/2018 - 15:20

Functional Magnetic Resonance Imaging and Oculomotor Dysfunction in Mild Traumatic Brain Injury.

J Neurotrauma. 2018 Jul 17;:

Authors: Rockswold SB, Burton PC, Chang A, McNally N, Grant A, Rockswold G, Low WC, Eberly L, Yacoub E, Lenglet C

Abstract
Mild traumatic brain injury (mTBI) is a significant cause of disability, especially when symptoms become chronic. This chronicity is often linked to oculomotor dysfunction (OMD).1,2 To our knowledge, this is the first prospective study to localize aberrations in brain function between mTBI cohorts, by comparing mTBI patients with OMD to an mTBI control group without OMD, using task and resting-state functional magnetic resonance imaging (fMRI). Ten mTBI subjects who had OMD (OMD group) were compared to nine mTBI subjects who had no findings of OMD (control group). These groups were determined by a developmental optometrist using objective testing for OMD. The (convergence) task fMRI data demonstrated significantly decreased brain activity, measured as decreases in the blood oxygen level dependent (BOLD) signal, in the OMD group compared to the control group in 3 brain regions: the left posterior lingual gyrus, the bilateral anterior lingual gyrus and cuneus, and the parahippocampal gyrus. When doing a seed-based resting state fMRI analysis in the lingual/parahippocampal region, a large cluster covering the left middle frontal gyrus and the dorsolateral prefrontal cortex (Brodmann's areas (BA) 9 and 10), with decreased functional correlation in the OMD group, was identified. Together these observations provide evidence for neural networks of interactions involving the control of eye movement for visual processing, reading comprehension, spatial localization and navigation, and spatial working memory that appear to be decreased in mTBI patients with OMD compared to mTBI patients without OMD. The clinical symptomatology associated with post-traumatic OMD correlates well with these MRI findings.

PMID: 30014758 [PubMed - as supplied by publisher]

Acute trajectories of neural activation predict remission to pharmacotherapy in late-life depression.

Wed, 07/18/2018 - 15:20
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Acute trajectories of neural activation predict remission to pharmacotherapy in late-life depression.

Neuroimage Clin. 2018;19:831-839

Authors: Karim HT, Wang M, Andreescu C, Tudorascu D, Butters MA, Karp JF, Reynolds CF, Aizenstein HJ

Abstract
Pharmacological treatment of major depressive disorder (MDD) typically involves a lengthy trial and error process to identify an effective intervention. This lengthy period prolongs suffering and worsens all-cause mortality, including from suicide, and is typically longer in late-life depression (LLD). Our group has recently demonstrated that during an open-label venlafaxine (serotonin-norepinephrine reuptake inhibitor) trial, significant changes in functional resting state connectivity occurred following a single dose of treatment, which persisted until the end of the trial. In this work, we propose an analysis framework to translate these perturbations in functional networks into predictors of clinical remission. Participants with LLD (N = 49) completed 12-weeks of treatment with venlafaxine and underwent functional magnetic resonance imaging (fMRI) at baseline and a day following a single dose of venlafaxine. Data was collected at rest as well as during an emotion reactivity task and an emotion regulation task. Remission was defined as a Montgomery-Asberg Depression Rating Scale (MADRS) ≤10 for two weeks. We computed eigenvector centrality (whole brain connectivity) and activation during the emotion regulation and emotion reactivity tasks. We employed principal components analysis, Tikhonov-regularized logistic classification, and least angle regression feature selection to predict remission by the end of the 12-week trial. We utilized ten-fold cross-validation and Receiver Operator Curves (ROC) curve analysis. To determine task-region pairs that significantly contributed to the algorithm's ability to predict remission, we used permutation testing. Using the fMRI data at both baseline and after the first dose of treatment yielded a sensitivity of 72% and a specificity of 68% (AUC = 0.77), a 15% increase in accuracy over baseline MADRS. In general, the accuracy at baseline was further improved by using the change in activation following a single dose. Activation of the frontal cortex, hippocampus, parahippocampus, caudate, thalamus, medial temporal cortex, middle cingulate, and visual cortex predicted treatment remission. Acute, dynamic trajectories of functional imaging metrics in response to a pharmacological intervention are a valuable tool for predicting treatment response in late-life depression and elucidating the mechanism of pharmacological therapies in the context of the brain's functional architecture.

PMID: 30013927 [PubMed - in process]

Identifying first-episode drug naïve patients with schizophrenia with or without auditory verbal hallucinations using whole-brain functional connectivity: A pattern analysis study.

Wed, 07/18/2018 - 15:20
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Identifying first-episode drug naïve patients with schizophrenia with or without auditory verbal hallucinations using whole-brain functional connectivity: A pattern analysis study.

Neuroimage Clin. 2018;19:351-359

Authors: Huang P, Cui LB, Li X, Lu ZL, Zhu X, Xi Y, Wang H, Li B, Hou F, Miao D, Yin H

Abstract
Many studies have focused on patients with schizophrenia with or without auditory verbal hallucinations (AVHs), but due to the complexity of schizophrenia, biologically based diagnosis of patients with schizophrenia remains unsolved. The objectives of this study are to classify between first-episode drug-naïve patients with schizophrenia and healthy controls, and to classify between patients with and without AVHs. Resting state fMRI data from 41 patients with schizophrenia (22 with and 19 without AVHs) and 23 normal controls (NC) were included to compute functional connectivity between brain regions. Classifiers based on support vector machine (SVM) were developed to classify patients with schizophrenia from NC, as well as between the two subgroups of patients. The classification accuracy was evaluated with a leave-one-out cross-validation (LOOCV) strategy. The accuracy in discriminating both subgroups of patients from NC was 81.3%, with 92.0% (sensitivity) and 65.2% (specificity) for the patients and NC, respectively. The classification accuracy in discriminating patients with and without AVHs was 75.6%, with 77.3% (sensitivity) and 73.9% (specificity) for patients with and without AVHs, respectively. The results suggest that functional connectivity provided good discriminative power not only for identifying patients with schizophrenia among NC, but also in discriminating patients with schizophrenia with and without AVHs.

PMID: 30013918 [PubMed - in process]

Aberrant hemodynamic responses in autism: Implications for resting state fMRI functional connectivity studies.

Wed, 07/18/2018 - 15:20
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Aberrant hemodynamic responses in autism: Implications for resting state fMRI functional connectivity studies.

Neuroimage Clin. 2018;19:320-330

Authors: Yan W, Rangaprakash D, Deshpande G

Abstract
Functional MRI (fMRI) is modeled as a convolution of the hemodynamic response function (HRF) and an unmeasured latent neural signal. However, HRF itself is variable across brain regions and subjects. This variability is induced by both neural and non-neural factors. Aberrations in underlying neurochemical mechanisms, which control HRF shape, have been reported in autism spectrum disorders (ASD). Therefore, we hypothesized that this will lead to voxel-specific, yet systematic differences in HRF shape between ASD and healthy controls. As a corollary, we also hypothesized that such alterations will lead to differences in estimated functional connectivity in fMRI space compared to latent neural space. To test these hypotheses, we performed blind deconvolution of resting-state fMRI time series acquired from large number of ASD and control subjects obtained from the Autism Brain Imaging Data Exchange (ABIDE) database (N = 1102). Many brain regions previously implicated in autism showed systematic differences in HRF shape in ASD. Specifically, we found that precuneus had aberrations in all HRF parameters. Consequently, we obtained precuneus-seed-based functional connectivity differences between ASD and controls using fMRI as well as using latent neural signals. We found that non-deconvolved fMRI data failed to detect group differences in connectivity between precuneus and certain brain regions that were instead observed in deconvolved data. Our results are relevant for the understanding of hemodynamic and neurochemical aberrations in ASD, as well as have methodological implications for resting-state functional connectivity studies in Autism, and more generally in disorders that are accompanied by neurochemical alterations that may impact HRF shape.

PMID: 30013915 [PubMed - in process]

Frequency-Resolved Dynamic Functional Connectivity Reveals Scale-Stable Features of Connectivity-States.

Wed, 07/18/2018 - 15:20
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Frequency-Resolved Dynamic Functional Connectivity Reveals Scale-Stable Features of Connectivity-States.

Front Hum Neurosci. 2018;12:253

Authors: Goldhacker M, Tomé AM, Greenlee MW, Lang EW

Abstract
Investigating temporal variability of functional connectivity is an emerging field in connectomics. Entering dynamic functional connectivity by applying sliding window techniques on resting-state fMRI (rs-fMRI) time courses emerged from this topic. We introduce frequency-resolved dynamic functional connectivity (frdFC) by means of multivariate empirical mode decomposition (MEMD) followed up by filter-bank investigations. In general, we find that MEMD is capable of generating time courses to perform frdFC and we discover that the structure of connectivity-states is robust over frequency scales and even becomes more evident with decreasing frequency. This scale-stability varies with the number of extracted clusters when applying k-means. We find a scale-stability drop-off from k = 4 to k = 5 extracted connectivity-states, which is corroborated by null-models, simulations, theoretical considerations, filter-banks, and scale-adjusted windows. Our filter-bank studies show that filter design is more delicate in the rs-fMRI than in the simulated case. Besides offering a baseline for further frdFC research, we suggest and demonstrate the use of scale-stability as a possible quality criterion for connectivity-state and model selection. We present first evidence showing that connectivity-states are both a multivariate, and a multiscale phenomenon. A data repository of our frequency-resolved time-series is provided.

PMID: 30013468 [PubMed]

Spontaneous brain oscillations as neural fingerprints of working memory capacities: A resting-state MEG study.

Wed, 07/18/2018 - 15:20
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Spontaneous brain oscillations as neural fingerprints of working memory capacities: A resting-state MEG study.

Cortex. 2017 Dec;97:109-124

Authors: Oswald V, Zerouali Y, Boulet-Craig A, Krajinovic M, Laverdière C, Sinnett D, Jolicoeur P, Lippé S, Jerbi K, Robaey P

Abstract
Short-term storage and mental information manipulation capacities in the human brain are key to healthy cognition. These brain processes collectively known as working memory (WM) are associated with modulations of rhythmic brain activity across multiple brain areas and frequencies. Yet, it is not clear whether - and, if so, how-intrinsic resting-state neuronal oscillations are related to individual WM capacities, as measured by standard neuropsychological tests. We addressed this question by probing the correlation between resting-state brain activity, recorded with magnetoencephalography (MEG), and verbal and visuo-spatial WM indices obtained from the standardized Wechsler Adult Intelligence Scale (WAIS-IV) and the Wechsler Memory Scale (WMS-IV). To this end, 5-min eyes-open resting-state MEG data were acquired in 28 healthy participants. Source-reconstructed spectral power estimates were then computed in standard frequency bands and their correlation with neuropsychological indices across individuals was assessed using Pearson correlation and cluster-level statistics. We found statistically significant positive correlations between spectral amplitudes measured at rest and standardized scores on both verbal and visuo-spatial WM performance. The correlation clusters primarily involved key medial and dorsolateral components within the parietal and prefrontal regions. In addition, while the correlation in some clusters was frequency selective (e.g., alpha-band oscillations), other areas showed correlations with WM across a wide range of frequencies reflecting a broadband effect. These results provide the first evidence for a positive correlation between neuromagnetic signals measured at rest and WM performance separately assessed by standardized neuropsychological tests. Our results advance our understanding of the link between WM capacities and intrinsic oscillatory dynamics networks. They also suggest that individual differences in baseline spectral power might need to be taken into account when probing differences in brain responses during the execution of WM tasks.

PMID: 29102813 [PubMed - indexed for MEDLINE]

Age, disease and their interaction effects on intrinsic connectivity of children and adolescents in Autism Spectrum Disorder using functional connectomics.

Tue, 07/17/2018 - 14:40

Age, disease and their interaction effects on intrinsic connectivity of children and adolescents in Autism Spectrum Disorder using functional connectomics.

Brain Connect. 2018 Jul 16;:

Authors: Harlalka V, Raju BS, Vinod PK, Roy D

Abstract
Brain connectivity analysis has provided crucial insights to pinpoint the differences between autistic and typically developing (TD) children during development. The aim of this study is to investigate the functional connectomics of Autism Spectrum Disorder (ASD) versus TD and underpin the effects of development, disease, and their interactions on the observed atypical brain connectivity patterns. Resting-state functional magnetic resonance imaging (rs-fMRI) from the Autism Brain Imaging Data Exchange (ABIDE) dataset, which is stratified into two cohorts: children (9-12 years) and adolescents (13-16 years), is used for the analysis. Differences in various graph-theoretical network measures are calculated between ASD and TD in each group. Further, two-factor ANOVA test is used, to study the effect of age, disease and their interaction on the network measures and the network edges. Further, the differences in connection strength between TD and ASD subjects are assessed using Network Based Statistics. The results showed that ASD exhibits increased functional integration at the expense of decreased functional segregation. In ASD adolescents, there is significant decrease in modularity suggesting a less robust modular organization and an increase in participation coefficient suggesting more random integration and widely distributed connection edges. Further, there is significant hypoconnectivity observed in the adolescent group especially in the Default Mode Network while the children group shows both hyper and hypoconnectivity. This study lends support to a model of global atypical connections and further identifies functional networks and areas that are independently affected by age, disease and their interaction.

PMID: 30009617 [PubMed - as supplied by publisher]

Functional connectivity in category-selective brain networks after encoding predicts subsequent memory.

Tue, 07/17/2018 - 14:40
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Functional connectivity in category-selective brain networks after encoding predicts subsequent memory.

Hippocampus. 2018 Jul 15;:

Authors: Collins JA, Dickerson BC

Abstract
Activity in category selective regions of the temporal and parietal lobes during encoding has been associated with subsequent memory for face and scene stimuli. Reactivation theories of memory consolidation predict that after encoding connectivity between these category-selective regions and the hippocampus should be modulated and predict recognition memory. However, support for this proposal has been limited in humans. Here, participants completed a resting-state functional MRI (fMRI) scan, followed by face- and place-encoding tasks, followed by another resting-state fMRI scan during which they were asked to think about the stimuli they had previously encountered. Individual differences in face recognition memory were predicted by the degree to which connectivity between face-responsive regions of the fusiform gyrus and perirhinal cortex increased following the face-encoding task. In contrast, individual differences in scene recognition were predicted by connectivity between the hippocampus and a scene-selective region of the retrosplenial cortex before and after the place-encoding task. Our results provide novel evidence for category specificity in the neural mechanisms supporting memory consolidation. This article is protected by copyright. All rights reserved.

PMID: 30009477 [PubMed - as supplied by publisher]

Could Prolonged Usage of GPS Navigation Implemented in Augmented Reality Smart Glasses Affect Hippocampal Functional Connectivity?

Tue, 07/17/2018 - 14:40
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Could Prolonged Usage of GPS Navigation Implemented in Augmented Reality Smart Glasses Affect Hippocampal Functional Connectivity?

Biomed Res Int. 2018;2018:2716134

Authors: Fajnerová I, Greguš D, Hlinka J, Nekovářová T, Škoch A, Zítka T, Romportl J, Žáčková E, Horáček J

Abstract
Background: Augmented reality (AR) glasses with GPS navigation represent the rapidly evolving technology which spares (and externalizes) navigational capacities. Regarding the expected everyday usage of this device, its impact on neuroplastic brain changes and navigation abilities should be evaluated.
Aims: This study aimed to assess possible changes in functional connectivity (FC) of hippocampus and other brain regions involved in spatial navigation.
Methods: Thirty-three healthy participants completed two resting state functional magnetic resonance imaging (rsfMRI) measurements at the baseline and after 3 months. For this period, the experimental group (n = 17) has had used AR device (Vuzix M100) with incorporated GPS guidance system during navigation in real world. Participants from the control group (n = 16) have not used any GPS device while navigating during walking. The rsfMRI FC of right and left hippocampi was analyzed using a seed-driven approach. Virtual city task was used to test navigational abilities both before and after the usage of AR device.
Results: We identified strong functional coupling of right and left hippocampi at the baseline (p < 0.05, FDR corrected). Mild changes in bilateral hippocampal FC (p < 0.05, FDR uncorrected) were observed in both assessed groups mainly between the bilateral hippocampi and between each hippocampus and temporal regions and cerebellum. However, the experimental group showed FC decrease after three months of using GPS navigation implemented in AR glasses in contrast to FC increase in the control group without such intervention. Importantly, no effect of intervention on navigational abilities was observed.
Discussion: Our observation supports the assumption that externalization of spatial navigation to technological device (GPS in AR glasses) can decrease the functional coupling between hippocampus and associated brain regions. Considering some limitations of the present study, further studies should elucidate the mechanism of the observed changes and their impact on cognitive abilities.

PMID: 30009166 [PubMed - in process]

The effect of tDCS on functional connectivity in primary progressive aphasia.

Tue, 07/17/2018 - 14:40
Related Articles

The effect of tDCS on functional connectivity in primary progressive aphasia.

Neuroimage Clin. 2018;19:703-715

Authors: Ficek BN, Wang Z, Zhao Y, Webster KT, Desmond JE, Hillis AE, Frangakis C, Vasconcellos Faria A, Caffo B, Tsapkini K

Abstract
Transcranial direct current stimulation (tDCS) is an innovative technique recently shown to improve language outcomes even in neurodegenerative conditions such as primary progressive aphasia (PPA), but the underlying brain mechanisms are not known. The present study tested whether the additional language gains with repetitive tDCS (over sham) in PPA are caused by changes in functional connectivity between the stimulated area (the left inferior frontal gyrus (IFG)) and the rest of the language network. We scanned 24 PPA participants (11 female) before and after language intervention (written naming/spelling) with a resting-state fMRI sequence and compared changes before and after three weeks of tDCS or sham coupled with language therapy. We correlated changes in the language network as well as in the default mode network (DMN) with language therapy outcome measures (letter accuracy in written naming). Significant tDCS effects in functional connectivity were observed between the stimulated area and other language network areas and between the language network and the DMN. TDCS over the left IFG lowered the connectivity between the above pairs. Changes in functional connectivity correlated with improvement in language scores (letter accuracy as a proxy for written naming) evaluated before and after therapy. These results suggest that one mechanism for anodal tDCS over the left IFG in PPA is a decrease in functional connectivity (compared to sham) between the stimulated site and other posterior areas of the language network. These results are in line with similar decreases in connectivity observed after tDCS over the left IFG in aging and other neurodegenerative conditions.

PMID: 30009127 [PubMed - in process]

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