New resting-state fMRI related studies at PubMed

Subscribe to New resting-state fMRI related studies at PubMed feed New resting-state fMRI related studies at PubMed
NCBI: db=pubmed; Term=resting state fMRI
Updated: 3 hours 40 min ago

Abnormal Functional Connectivity of Ventral Anterior Insula in Asthmatic Patients with Depression.

Fri, 07/07/2017 - 11:40
Related Articles

Abnormal Functional Connectivity of Ventral Anterior Insula in Asthmatic Patients with Depression.

Neural Plast. 2017;2017:7838035

Authors: Zhang Y, Yang Y, Bian R, Yin Y, Hou Z, Yue Y, Xu Z, Yuan Y

Abstract
OBJECTIVE: To explore the underlying mechanism of depression in asthmatic patients, the ReHo in the insula and its FC was used to probe the differences between depressed asthmatic (DA) and nondepressed asthmatic (NDA) patients.
METHODS: 18 DA patients, 24 NDA patients, and 60 healthy controls (HCs) received resting-state fMRI scan, severity of depression, and asthma control assessment.
RESULTS: DA patients showed increased FC between the left ventral anterior insula (vAI) and the left middle temporal gyrus compared with both NDA and HC groups. In addition, compared with HCs, the DA and NDA patients both exhibited increased FC between the left vAI and the right anterior cingulate cortex (ACC), decreased FC between the left vAI and the bilateral parietal lobe, and increased FC between the right vAI and the left putamen and the right caudate, respectively. Furthermore, the increased FC between the left vAI and the right ACC could differentiate HCs from both DA and NDA patients, and the increased FC between the right vAI and both the left putamen and the right caudate could separate NDA patients from HCs.
CONCLUSIONS: This study confirmed that abnormal vAI FC may be involved in the neuropathology of depression in asthma. The increased FC between the left vAI and the left MTG could distinguish DA from the NDA and HC groups.

PMID: 28680706 [PubMed - in process]

A Comprehensive Analysis of the Correlations between Resting-State Oscillations in Multiple-Frequency Bands and Big Five Traits.

Fri, 07/07/2017 - 11:40
Related Articles

A Comprehensive Analysis of the Correlations between Resting-State Oscillations in Multiple-Frequency Bands and Big Five Traits.

Front Hum Neurosci. 2017;11:321

Authors: Ikeda S, Takeuchi H, Taki Y, Nouchi R, Yokoyama R, Kotozaki Y, Nakagawa S, Sekiguchi A, Iizuka K, Yamamoto Y, Hanawa S, Araki T, Miyauchi CM, Sakaki K, Nozawa T, Yokota S, Magistro D, Kawashima R

Abstract
Recently, the association between human personality traits and resting-state brain activity has gained interest in neuroimaging studies. However, it remains unclear if Big Five personality traits are represented in frequency bands (~0.25 Hz) of resting-state functional magnetic resonance imaging (fMRI) activity. Based on earlier neurophysiological studies, we investigated the correlation between the five personality traits assessed by the NEO Five-Factor Inventory (NEO-FFI), and the fractional amplitude of low-frequency fluctuation (fALFF) at four distinct frequency bands (slow-5 (0.01-0.027 Hz), slow-4 (0.027-0.073 Hz), slow-3 (0.073-0.198 Hz) and slow-2 (0.198-0.25 Hz)). We enrolled 835 young subjects and calculated the correlations of resting-state fMRI signals using a multiple regression analysis. We found a significant and consistent correlation between fALFF and the personality trait of extraversion at all frequency bands. Furthermore, significant correlations were detected in distinct brain regions for each frequency band. This finding supports the frequency-specific spatial representations of personality traits as previously suggested. In conclusion, our data highlight an association between human personality traits and fALFF at four distinct frequency bands.

PMID: 28680397 [PubMed - in process]

Altered interhemispheric functional connectivity in remitted bipolar disorder: A Resting State fMRI Study.

Fri, 07/07/2017 - 11:40
Related Articles

Altered interhemispheric functional connectivity in remitted bipolar disorder: A Resting State fMRI Study.

Sci Rep. 2017 Jul 05;7(1):4698

Authors: Zhao L, Wang Y, Jia Y, Zhong S, Sun Y, Qi Z, Zhang Z, Huang L

Abstract
Abnormalities in structural and functional brain connectivity have been increasingly reported in patients with bipolar disorder (BD). However, alterations of remitted BD (RBD) in functional connectivity between the cerebral hemispheres are still not well understood. This study was designed to analyze the pattern of the interhemispheric functional connectivity of the whole brain in patients with remitted BD during resting state. Twenty patients with RBD and 38 healthy controls (HC) underwent the resting-state functional magnetic resonance imaging. The functional connectivity between any pair of symmetrical interhemispheric voxels (i.e., functional homotopy) was measured by voxel-mirrored homotopic connectivity (VMHC). The patients with RBD showed lower VMHC than HC in the middle frontal gyrus and precentral gyrus. No regions of increased VMHC were detected in the RBD patients. There were no significant correlations between the VMHC values in these regions and the clinical variables. These findings suggest substantial impairment of interhemispheric coordination in RBD and they may represent trait, rather than state, neurobiological feature of brain function in BD.

PMID: 28680123 [PubMed - in process]

Altered brain network centrality in patients with adult comitant exotropia strabismus: A resting-state fMRI study.

Fri, 07/07/2017 - 11:40
Related Articles

Altered brain network centrality in patients with adult comitant exotropia strabismus: A resting-state fMRI study.

J Int Med Res. 2017 Jan 01;:300060517715340

Authors: Tan G, Dan ZR, Zhang Y, Huang X, Zhong YL, Ye LH, Rong R, Ye L, Zhou Q, Shao Y

Abstract
Objective To investigate the underlying functional network brain-activity changes in patients with adult comitant exotropia strabismus (CES) and the relationship with clinical features using the voxel-wise degree centrality (DC) method. Methods A total of 30 patients with CES (17 men, 13 women), and 30 healthy controls (HCs; 17 men, 13 women) matched in age, sex, and education level participated in the study. DC was used to evaluate spontaneous brain activity. Receiver operating characteristic (ROC) curve analysis was conducted to distinguish CESs from HCs. The relationship between mean DC values in various brain regions and behavioral performance was examined with correlation analysis. Results Compared with HCs, CES patients exhibited decreased DC values in the right cerebellum posterior lobe, right inferior frontal gyrus, right middle frontal gyrus and right superior parietal lobule/primary somatosensory cortex (S1), and increased DC values in the right superior temporal gyrus, bilateral anterior cingulate, right superior temporal gyrus, and left inferior parietal lobule. However, there was no correlation between mean DC values and behavioral performance in any brain regions. Conclusions Adult comitant exotropia strabismus is associated with abnormal brain network activity in various brain regions, possibly reflecting the pathological mechanisms of ocular motility disorders in CES.

PMID: 28679330 [PubMed - as supplied by publisher]

Sample heterogeneity in unipolar depression as assessed by functional connectivity analyses is dominated by general disease effects.

Thu, 07/06/2017 - 10:20

Sample heterogeneity in unipolar depression as assessed by functional connectivity analyses is dominated by general disease effects.

J Affect Disord. 2017 Jun 27;222:79-87

Authors: Feder S, Sundermann B, Wersching H, Teuber A, Kugel H, Teismann H, Heindel W, Berger K, Pfleiderer B

Abstract
OBJECTIVES: Combinations of resting-state fMRI and machine-learning techniques are increasingly employed to develop diagnostic models for mental disorders. However, little is known about the neurobiological heterogeneity of depression and diagnostic machine learning has mainly been tested in homogeneous samples. Our main objective was to explore the inherent structure of a diverse unipolar depression sample. The secondary objective was to assess, if such information can improve diagnostic classification.
MATERIALS AND METHODS: We analyzed data from 360 patients with unipolar depression and 360 non-depressed population controls, who were subdivided into two independent subsets. Cluster analyses (unsupervised learning) of functional connectivity were used to generate hypotheses about potential patient subgroups from the first subset. The relationship of clusters with demographical and clinical measures was assessed. Subsequently, diagnostic classifiers (supervised learning), which incorporated information about these putative depression subgroups, were trained.
RESULTS: Exploratory cluster analyses revealed two weakly separable subgroups of depressed patients. These subgroups differed in the average duration of depression and in the proportion of patients with concurrently severe depression and anxiety symptoms. The diagnostic classification models performed at chance level.
LIMITATIONS: It remains unresolved, if subgroups represent distinct biological subtypes, variability of continuous clinical variables or in part an overfitting of sparsely structured data.
CONCLUSIONS: Functional connectivity in unipolar depression is associated with general disease effects. Cluster analyses provide hypotheses about potential depression subtypes. Diagnostic models did not benefit from this additional information regarding heterogeneity.

PMID: 28679115 [PubMed - as supplied by publisher]

Functional brain MRI in patients complaining of electrohypersensitivity after long term exposure to electromagnetic fields.

Thu, 07/06/2017 - 10:20

Functional brain MRI in patients complaining of electrohypersensitivity after long term exposure to electromagnetic fields.

Rev Environ Health. 2017 Jul 05;:

Authors: Heuser G, Heuser SA

Abstract
INTRODUCTION: Ten adult patients with electromagnetic hypersensitivity underwent functional magnetic resonance imaging (fMRI) brain scans. All scans were abnormal with abnormalities which were consistent and similar. It is proposed that fMRI brain scans be used as a diagnostic aid for determining whether or not a patient has electromagnetic hypersensitivity. Over the years we have seen an increasing number of patients who had developed multi system complaints after long term repeated exposure to electromagnetic fields (EMFs). These complaints included headaches, intermittent cognitive and memory problems, intermittent disorientation, and also sensitivity to EMF exposure. Regular laboratory tests were within normal limits in these patients. The patients refused to be exposed to radioactivity. This of course ruled out positron emission tomography (PET) and single-photon emission computed tomography (SPECT) brain scanning. This is why we ordered fMRI brain scans on these patients. We hoped that we could document objective abnormalities in these patients who had often been labeled as psychiatric cases.
MATERIALS AND METHODS: Ten patients first underwent a regular magnetic resonance imaging (MRI) brain scan, using a 3 Tesla Siemens Verio MRI open system. A functional MRI study was then performed in the resting state using the following sequences: A three-dimensional, T1-weighted, gradient-echo (MPRAGE) Resting state network. The echo-planar imaging (EPI) sequences for this resting state blood oxygenation level dependent (BOLD) scan were then post processed on a 3D workstation and the independent component analysis was performed separating out the various networks. Arterial spin labeling. Tractography and fractional anisotropy.
RESULTS: All ten patients had abnormal functional MRI brain scans. The abnormality was often described as hyper connectivity of the anterior component of the default mode in the medial orbitofrontal area. Other abnormalities were usually found. Regular MRI studies of the brain were mostly unremarkable in these patients.
CONCLUSION: We propose that functional MRI studies should become a diagnostic aid when evaluating a patient who claims electrohypersensitivity (EHS) and has otherwise normal studies. Interestingly, the differential diagnosis for the abnormalities seen on the fMRI includes head injury. It turns out that many of our patients indeed had a history of head injury which was then followed sometime later by the development of EHS. Many of our patients also had a history of exposure to potentially neurotoxic chemicals, especially mold. Head injury and neurotoxic chemical exposure may make a patient more vulnerable to develop EHS.

PMID: 28678737 [PubMed - as supplied by publisher]

Brain network dynamics in high-functioning individuals with autism.

Thu, 07/06/2017 - 10:20

Brain network dynamics in high-functioning individuals with autism.

Nat Commun. 2017 Jul 05;8:16048

Authors: Watanabe T, Rees G

Abstract
Theoretically, autism should be underpinned by aberrant brain dynamics. However, how brain activity changes over time in individuals with autism spectrum disorder (ASD) remains unknown. Here we characterize brain dynamics in autism using an energy-landscape analysis applied to resting-state fMRI data. Whereas neurotypical brain activity frequently transits between two major brain states via an intermediate state, high-functioning adults with ASD show fewer neural transitions due to an unstable intermediate state, and these infrequent transitions predict the severity of autism. Moreover, in contrast to the controls whose IQ is correlated with the neural transition frequency, IQ scores of individuals with ASD are instead predicted by the stability of their brain dynamics. Finally, such brain-behaviour associations are related to functional segregation between brain networks. These findings suggest that atypical functional coordination in the brains of adults with ASD underpins overly stable neural dynamics, which supports both their ASD symptoms and cognitive abilities.

PMID: 28677689 [PubMed - in process]

Functional connectivity density mapping: comparing multiband and conventional EPI protocols.

Thu, 07/06/2017 - 10:20

Functional connectivity density mapping: comparing multiband and conventional EPI protocols.

Brain Imaging Behav. 2017 Jul 04;:

Authors: Cohen AD, Tomasi D, Shokri-Kojori E, Nencka AS, Wang Y

Abstract
Functional connectivity density mapping (FCDM) is a newly developed data-driven technique that quantifies the number of local and global functional connections for each voxel in the brain. In this study, we evaluated reproducibility, sensitivity, and specificity of both local functional connectivity density (lFCD) and global functional connectivity density (gFCD). We compared these metrics using the human connectome project (HCP) compatible high-resolution (2 mm isotropic, TR = 0.8 s) multiband (MB), and more typical, lower resolution (3.5 mm isotropic, TR = 2.0 s) single-band (SB) resting state functional MRI (rs-fMRI) acquisitions. Furthermore, in order to be more clinically feasible, only rs-fMRI scans that lasted seven minutes were tested. Subjects were scanned twice within a two-week span. We found sensitivity and specificity increased and reproducibility either increased or did not change for the MB compared to the SB acquisitions. The MB scans also showed improved gray matter/white matter contrast compared to the SB scans. The lFCD and gFCD patterns were similar across MB and SB scans and confined predominantly to gray matter. We also observed a strong spatial correlation of FCD between MB and SB scans indicating the two acquisitions provide similar information. These findings indicate high-resolution MB acquisitions improve the quality of FCD data, and seven minute rs-fMRI scan can provide robust FCD measurements.

PMID: 28676985 [PubMed - as supplied by publisher]

Joint prediction of multiple scores captures better individual traits from brain images.

Thu, 07/06/2017 - 10:20

Joint prediction of multiple scores captures better individual traits from brain images.

Neuroimage. 2017 Jul 01;:

Authors: Rahim M, Thirion B, Bzdok D, Buvat I, Varoquaux G

Abstract
To probe individual variations in brain organization, population imaging relates features of brain images to rich descriptions of the subjects such as genetic information or behavioral and clinical assessments. Capturing common trends across these measurements is important: they jointly characterize the disease status of patient groups. In particular, mapping imaging features to behavioral scores with predictive models opens the way toward more precise diagnosis. Here we propose to jointly predict all the dimensions (behavioral scores) that make up the individual profiles, using so-called multi-output models. This approach often boosts prediction accuracy by capturing latent shared information across scores. We demonstrate the efficiency of multi-output models on two independent resting-state fMRI datasets targeting different brain disorders (Alzheimer's Disease and schizophrenia). Furthermore, the model with joint prediction generalizes much better to a new cohort: a model learned on one study is more accurately transferred to an independent one. Finally, we show how multi-output models can easily be extended to multi-modal settings, combining heterogeneous data sources for a better overall accuracy.

PMID: 28676298 [PubMed - as supplied by publisher]

Electrographic patterns in patients with posterior reversible encephalopathy syndrome and seizures.

Thu, 07/06/2017 - 10:20
Related Articles

Electrographic patterns in patients with posterior reversible encephalopathy syndrome and seizures.

J Neurol Sci. 2017 Apr 15;375:294-298

Authors: Kamiya-Matsuoka C, Tummala S

Abstract
INTRODUCTION: Posterior reversible encephalopathy syndrome (PRES) is a neurotoxic encephalopathic state associated with reversible cerebral vasogenic edema. Seizures are a common clinical presentation in PRES, however its electroencephalographic and radiologic pattern correlation is limited in this subset of patients. The aim of this study is to analyze the origin of electrographic dysfunction according to the radiologic pattern in patients with PRES and seizures.
METHODS: We retrospectively identified 46 cancer patients who developed PRES and seizures at The University of Texas MD Anderson Cancer Center between January 2006 and June 2012. Clinical, radiographic and electroencephalographic data were abstracted from their records and reviewed for our analysis.
RESULTS: The average age at presentation was 49.9±19.7years. Thirty-four (73.9%) patients were women. Twenty-two (47.8%) patients had a primary hematological malignancy whereas the rest had a solid tumor. Thirty-three (71.7%) patients had received some form of chemotherapy. The mean systolic blood pressure (SBP) variation was 23.7±16.4mmHg at onset of symptoms. On brain MRI, 32 (69.6%) patients had typical pattern while 14 (30.4%) had an atypical pattern. Thirty-seven (80.4%) patients had scalp electroencephalogram (EEG) evaluation. Thirty-three (89.2%) had abnormal EEG findings: diffuse theta/delta slowing (N=12, 36.4%), followed by diffuse slowing with focal dysfunction (N=8, 24.2%), focal dysfunction with epileptiform discharges (N=4, 12.1%), non-convulsive status epilepticus (N=4, 12.1%), focal seizure activity and burst suppression (N=2, 6.1% each). Lateralized Periodic Discharges (LPDs) were recorded in 1 case. Four patients had focal dysfunction localized to areas without conventional MRI signal changes. Four patients had recurrent seizures, of which 3 had an atypical PRES pattern.
CONCLUSION: PRES appears to be a diffuse neurotoxic encephalopathic state. Origin of seizures seen on scalp EEG may not correlate with the location of vasogenic edema/MRI signal changes raising the possibility of greater degree of dysfunction which may exist beyond those areas.

PMID: 28320152 [PubMed - indexed for MEDLINE]

Grey matter abnormalities in methcathinone abusers with a Parkinsonian syndrome.

Thu, 07/06/2017 - 10:20
Related Articles

Grey matter abnormalities in methcathinone abusers with a Parkinsonian syndrome.

Brain Behav. 2016 Nov;6(11):e00539

Authors: Juurmaa J, Menke RA, Vila P, Müürsepp A, Tomberg T, Ilves P, Nigul M, Johansen-Berg H, Donaghy M, Stagg CJ, Stepens A, Taba P

Abstract
BACKGROUND: A permanent Parkinsonian syndrome occurs in intravenous abusers of the designer psychostimulant methcathinone (ephedrone). It is attributed to deposition of contaminant manganese, as reflected by characteristic globus pallidus hyperintensity on T1-weighted MRI.
METHODS: We have investigated brain structure and function in methcathinone abusers (n = 12) compared to matched control subjects (n = 12) using T1-weighted structural and resting-state functional MRI.
RESULTS: Segmentation analysis revealed significant (p < .05) subcortical grey matter atrophy in methcathinone abusers within putamen and thalamus bilaterally, and the left caudate nucleus. The volume of the caudate nuclei correlated inversely with duration of methcathinone abuse. Voxel-based morphometry showed patients to have significant grey matter loss (p < .05) bilaterally in the putamina and caudate nucleus. Surface-based analysis demonstrated nine clusters of cerebral cortical thinning in methcathinone abusers, with relative sparing of prefrontal, parieto-occipital, and temporal regions. Resting-state functional MRI analysis showed increased functional connectivity within the motor network of patients (p < .05), particularly within the right primary motor cortex.
CONCLUSION: Taken together, these results suggest that the manganese exposure associated with prolonged methcathinone abuse results in widespread structural and functional changes affecting both subcortical and cortical grey matter and their connections. Underlying the distinctive movement disorder caused by methcathinone abuse, there is a more widespread pattern of brain involvement than is evident from the hyperintensity restricted to the basal ganglia as shown by T1-weighted structural MRI.

PMID: 27843694 [PubMed - indexed for MEDLINE]

Effects of levodopa on corticostriatal circuits supporting working memory in Parkinson's disease.

Wed, 07/05/2017 - 15:20

Effects of levodopa on corticostriatal circuits supporting working memory in Parkinson's disease.

Cortex. 2017 Jun 07;93:193-205

Authors: Simioni AC, Dagher A, Fellows LK

Abstract
Working memory dysfunction is common in Parkinson's disease, even in its early stages, but its neural basis is debated. Working memory performance likely reflects a balance between corticostriatal dysfunction and compensatory mechanisms. We tested this hypothesis by examining working memory performance with a letter n-back task in 19 patients with mild-moderate Parkinson's disease and 20 demographically matched healthy controls. Parkinson's disease patients were tested after an overnight washout of their usual dopamine replacement therapy, and again after a standard dose of levodopa. FMRI was used to assess task-related activation and resting state functional connectivity; changes in BOLD signal were related to performance to disentangle pathological and compensatory processes. Parkinson's disease patients off dopamine replacement therapy displayed significantly reduced spatial extent of task-related activation in left prefrontal and bilateral parietal cortex, and poorer working memory performance, compared to controls. Amongst the Parkinson's disease patients off dopamine replacement therapy, relatively better performance was associated with greater activation of right dorsolateral prefrontal cortex compared to controls, consistent with compensatory right hemisphere recruitment. Administration of levodopa remediated the working memory deficit in the Parkinson's disease group, and resulted in a different pattern of performance-correlated activity, with a shift to greater left ventrolateral prefrontal cortex activation in patients on, compared to off dopamine replacement therapy. Levodopa also significantly increased resting-state functional connectivity between caudate and right parietal cortex (within the right fronto-parietal attentional network). The strength of this connectivity contributed to better performance in patients and controls, suggesting a general compensatory mechanism. These findings argue that Parkinson's disease patients can recruit additional neural resources, here, the right fronto-parietal network, to optimize working memory performance despite impaired corticostriatal function. Levodopa seems to both boost engagement of a task-specific prefrontal region, and strengthen a putative compensatory caudate-cortical network to support this executive function.

PMID: 28675834 [PubMed - as supplied by publisher]

The Significance of Negative Correlations in Brain Connectivity.

Wed, 07/05/2017 - 15:20

The Significance of Negative Correlations in Brain Connectivity.

J Comp Neurol. 2017 Jul 04;:

Authors: Zhan L, Jenkins LM, Wolfson O, GadElkarim JJ, Nocito K, Thompson PM, Ajilore O, Chung MK, Leow A

Abstract
Understanding the modularity of fMRI-derived brain networks or 'connectomes' can inform the study of brain function organization. However, fMRI connectomes additionally involve negative edges, which may not be optimally accounted for by existing approaches to modularity that variably threshold, binarize, or arbitrarily weight these connections. Consequently, many existing Q maximization-based modularity algorithms yield variable modular structures. Here we present an alternative complementary approach that exploits how frequent the BOLD-signal correlation between two nodes is negative. We validated this novel probability-based modularity approach on two independent publicly-available resting-state connectome datasets (the Human Connectome Project and the 1000 Functional Connectomes) and demonstrated that negative correlations alone are sufficient in understanding resting-state modularity. In fact, this approach a) permits a dual formulation, leading to equivalent solutions regardless of whether one considers positive or negative edges; b) is theoretically linked to the Ising model defined on the connectome, thus yielding modularity result that maximizes data likelihood. Additionally, we were able to detect novel and consistent sex differences in modularity in both datasets. As datasets like HCP become widely available for analysis by the neuroscience community at large, alternative and perhaps more advantageous computational tools to understand the neurobiological information of negative edges in fMRI connectomes are increasingly important. This article is protected by copyright. All rights reserved.

PMID: 28675490 [PubMed - as supplied by publisher]

Topologically convergent and divergent functional connectivity patterns in unmedicated unipolar depression and bipolar disorder.

Wed, 07/05/2017 - 15:20

Topologically convergent and divergent functional connectivity patterns in unmedicated unipolar depression and bipolar disorder.

Transl Psychiatry. 2017 Jul 04;7(7):e1165

Authors: Wang Y, Wang J, Jia Y, Zhong S, Zhong M, Sun Y, Niu M, Zhao L, Zhao L, Pan J, Huang L, Huang R

Abstract
Bipolar disorder (BD), particularly BD II, is frequently misdiagnosed as unipolar depression (UD), leading to inappropriate treatment and poor clinical outcomes. Although depressive symptoms may be expressed similarly in UD and BD, the similarities and differences in the architecture of brain functional networks between the two disorders are still unknown. In this study, we hypothesized that UD and BD II patients would show convergent and divergent patterns of disrupted topological organization of the functional connectome, especially in the default mode network (DMN) and the limbic network. Brain resting-state functional magnetic resonance imaging (fMRI) data were acquired from 32 UD-unmedicated patients, 31 unmedicated BD II patients (current episode depressed) and 43 healthy subjects. Using graph theory, we systematically studied the topological organization of their whole-brain functional networks at the following three levels: whole brain, modularity and node. First, both the UD and BD II patients showed increased characteristic path length and decreased global efficiency compared with the controls. Second, both the UD and BD II patients showed disrupted intramodular connectivity within the DMN and limbic system network. Third, decreased nodal characteristics (nodal strength and nodal efficiency) were found predominantly in brain regions in the DMN, limbic network and cerebellum of both the UD and BD II patients, whereas differences between the UD and BD II patients in the nodal characteristics were also observed in the precuneus and temporal pole. Convergent deficits in the topological organization of the whole brain, DMN and limbic networks may reflect overlapping pathophysiological processes in unipolar and bipolar depression. Our discovery of divergent regional connectivity that supports emotion processing could help to identify biomarkers that will aid in differentiating these disorders.

PMID: 28675389 [PubMed - in process]

Investigating the Blood Oxygenation Level-Dependent Functional MRI Response to a Verbal Fluency Task in Early Stroke before and after Hemodynamic Scaling.

Wed, 07/05/2017 - 15:20

Investigating the Blood Oxygenation Level-Dependent Functional MRI Response to a Verbal Fluency Task in Early Stroke before and after Hemodynamic Scaling.

Front Neurol. 2017;8:283

Authors: Nair VA, Raut RV, Prabhakaran V

Abstract
BACKGROUND AND OBJECTIVE: Blood oxygenation level-dependent (BOLD) functional MRI (fMRI) has been extensively used as a marker of brain dysfunction and subsequent recovery following stroke. However, growing evidence suggests that straightforward interpretation of BOLD fMRI changes with aging and disease is challenging. In this study, we investigated the effect of calibrating task fMRI data by applying a hemodynamic calibration method using the resting-state fluctuation amplitude (RSFA). Task fMRI responses were obtained during a covert verbal fluency task in a group of early stage stroke patients and matched healthy normal controls.
METHODS: Fifteen acute left hemisphere stroke patients (less than 7 days from stroke; aged 44-84 years, average ~64 years) and 21 healthy controls (aged 55-77 years, average ~61 years) were prospectively studied. All subjects completed a 3-min covert verbal fluency task, and a 10-min eyes-closed resting-state fMRI scan, from which the calibration factor (RSFA) was computed. A behavioral measure on the verbal fluency task was also collected outside the scanner. Whole brain activation volumes and region-of-interest (ROI)-wise percent signal change and activation volumes before and after calibration were computed.
RESULTS: Between-group differences in whole brain activation volumes, although statistically significant before calibration failed to be significant after calibration. There were significant within-group differences before and after calibration with RSFA. Statistically significant between-group differences on ROI-wise measures before calibration also significantly reduced after calibration. Exploratory brain-behavior correlations revealed a similar pattern: significant correlations before calibration failed to survive after calibration.
DISCUSSION AND CONCLUSION: BOLD fMRI changes with aging and disease is confounded by changes in neurofunctional coupling leading to challenges in the straightforward interpretation of task fMRI results. Application of the hemodynamic calibration using the RSFA technique in the current study appeared to mitigate any differences between stroke and age-matched healthy controls. Our study indicates that estimating neural activity after applying hemodynamic scaling is important for studies of aging and for studies tracking post-stroke changes. We recommend that further investigation of hemodynamic calibration with RSFA in healthy subjects and in stroke in larger samples is necessary.

PMID: 28674515 [PubMed - in process]

Abnormal cortical-basal ganglia network in amyotrophic lateral sclerosis: a voxel-wise network efficiency analysis.

Wed, 07/05/2017 - 15:20

Abnormal cortical-basal ganglia network in amyotrophic lateral sclerosis: a voxel-wise network efficiency analysis.

Behav Brain Res. 2017 Jun 30;:

Authors: Xu J, Li H, Li C, Yao JC, Hu J, Wang J, Hu Q, Zhang Y, Zhang J

Abstract
Evidence suggests that dysfunctional cortical-basal ganglia (CBG) network plays important roles in the motor symptoms in amyotrophic lateral sclerosis (ALS). However, little effort has been made to investigate the functional abnormalities of CBG network in ALS. Here, we constructed voxel-wise CBG networks using the resting-state fMRI data of 20 patients with ALS and 21 normal controls, and characterized the differences of their efficiency parameters between the two groups. Compared to normal controls, patients with ALS exhibited decreased nodal efficiency in the right thalamus (THA), the left caudate (CAU) and the right precentral gyrus (preCG), and increased nodal efficiency in the left preCG. In the patient group, we observed a significant negative correlation between the nodal efficiency of the right preCG and disease progression rate. These results demonstrate that both ineffective information transfer and compensatory mechanisms are involved in the pathophysiological mechanism underlying the motor dysfunctions in patients with ALS. In summary, the present study provides a novel perspective on pathophysiological explanation for the motor symptoms in patients with ALS.

PMID: 28673766 [PubMed - as supplied by publisher]

Brain Functional Connectivity Is Modified by a Hypocaloric Mediterranean Diet and Physical Activity in Obese Women.

Tue, 07/04/2017 - 14:00

Brain Functional Connectivity Is Modified by a Hypocaloric Mediterranean Diet and Physical Activity in Obese Women.

Nutrients. 2017 Jul 01;9(7):

Authors: García-Casares N, Bernal-López MR, Roé-Vellvé N, Gutiérrez-Bedmar M, Fernández-García JC, García-Arnés JA, Ramos-Rodriguez JR, Alfaro F, Santamaria-Fernández S, Steward T, Jiménez-Murcia S, Garcia-Garcia I, Valdivielso P, Fernández-Aranda F, Tinahones FJ, Gómez-Huelgas R

Abstract
Functional magnetic resonance imaging (fMRI) in the resting state has shown altered brain connectivity networks in obese individuals. However, the impact of a Mediterranean diet on cerebral connectivity in obese patients when losing weight has not been previously explored. The aim of this study was to examine the connectivity between brain structures before and six months after following a hypocaloric Mediterranean diet and physical activity program in a group of sixteen obese women aged 46.31 ± 4.07 years. Before and after the intervention program, the body mass index (BMI) (kg/m²) was 38.15 ± 4.7 vs. 34.18 ± 4.5 (p < 0.02), and body weight (kg) was 98.5 ± 13.1 vs. 88.28 ± 12.2 (p < 0.03). All subjects underwent a pre- and post-intervention fMRI under fasting conditions. Functional connectivity was assessed using seed-based correlations. After the intervention, we found decreased connectivity between the left inferior parietal cortex and the right temporal cortex (p < 0.001), left posterior cingulate (p < 0.001), and right posterior cingulate (p < 0.03); decreased connectivity between the left superior frontal gyrus and the right temporal cortex (p < 0.01); decreased connectivity between the prefrontal cortex and the somatosensory cortex (p < 0.025); and decreased connectivity between the left and right posterior cingulate (p < 0.04). Results were considered significant at a voxel-wise threshold of p ≤ 0.05, and a cluster-level family-wise error correction for multiple comparisons of p ≤ 0.05. In conclusion, functional connectivity between brain structures involved in the pathophysiology of obesity (the inferior parietal lobe, posterior cingulate, temporo-insular cortex, prefrontal cortex) may be modified by a weight loss program including a Mediterranean diet and physical exercise.

PMID: 28671558 [PubMed - in process]

Modulation of cognitive cerebello-cerebral functional connectivity by lateral cerebellar continuous theta burst stimulation.

Tue, 07/04/2017 - 14:00

Modulation of cognitive cerebello-cerebral functional connectivity by lateral cerebellar continuous theta burst stimulation.

Neuroimage. 2017 Jun 29;:

Authors: Rastogi A, Cash R, Dunlop K, Vesia M, Kucyi A, Ghahremani A, Downar J, Chen J, Chen R

Abstract
Network connectivity measured with resting state functional magnetic resonance imaging (rsfMRI) has revealed the contribution of distinct cerebellar lobules to an array of brain wide networks sub-serving motor and cognitive processes. As distinct cerebellar lobules form relatively accessible nodes of different brain networks, this raises the possibility for site-specific modulation of network connectivity using non-invasive brain stimulation techniques such as transcranial magnetic stimulation (TMS). Continuous theta burst transcranial magnetic stimulation (cTBS) induces long-lasting inhibition of cortical areas. Although previous studies have shown that cTBS of the lateral cerebellum modulates motor cortical excitability and improves symptoms in several movement disorders, the effect on cognitive domains has not been examined. We explored the immediate effects of cTBS in a sham-controlled study on the strength of intrinsic functional connectivity between cerebellar and cortical motor and cognitive regions in 12 participants. Lateral cerebellar cTBS significantly decreased functional connectivity with frontal and parietal cognitive regions, while connectivity with motor regions remained unaltered. Sham stimulation had no effect on either motor or cognitive connectivity. These results show that inhibitory cerebellar stimulation reduces intrinsic functional connectivity between different cortical areas, in keeping with the known connectivity pattern of the cerebellum. The results highlight the plasticity of cerebello-cerebral networks and indicate for the first time that this functional connectivity can be downregulated using an inhibitory neurostimulation paradigm. This may shed light on the pathophysiology of network dysfunction and is a potential treatment for cognitive and movement disorders.

PMID: 28669908 [PubMed - as supplied by publisher]

Characterizing Variability of Modular Brain Connectivity with Constrained Principal Component Analysis.

Tue, 07/04/2017 - 14:00
Related Articles

Characterizing Variability of Modular Brain Connectivity with Constrained Principal Component Analysis.

PLoS One. 2016;11(12):e0168180

Authors: Hirayama JI, Hyvärinen A, Kiviniemi V, Kawanabe M, Yamashita O

Abstract
Characterizing the variability of resting-state functional brain connectivity across subjects and/or over time has recently attracted much attention. Principal component analysis (PCA) serves as a fundamental statistical technique for such analyses. However, performing PCA on high-dimensional connectivity matrices yields complicated "eigenconnectivity" patterns, for which systematic interpretation is a challenging issue. Here, we overcome this issue with a novel constrained PCA method for connectivity matrices by extending the idea of the previously proposed orthogonal connectivity factorization method. Our new method, modular connectivity factorization (MCF), explicitly introduces the modularity of brain networks as a parametric constraint on eigenconnectivity matrices. In particular, MCF analyzes the variability in both intra- and inter-module connectivities, simultaneously finding network modules in a principled, data-driven manner. The parametric constraint provides a compact module-based visualization scheme with which the result can be intuitively interpreted. We develop an optimization algorithm to solve the constrained PCA problem and validate our method in simulation studies and with a resting-state functional connectivity MRI dataset of 986 subjects. The results show that the proposed MCF method successfully reveals the underlying modular eigenconnectivity patterns in more general situations and is a promising alternative to existing methods.

PMID: 28002474 [PubMed - indexed for MEDLINE]

Alteration of cortico-limbic-striatal neural system in major depressive disorder and bipolar disorder.

Mon, 07/03/2017 - 13:00

Alteration of cortico-limbic-striatal neural system in major depressive disorder and bipolar disorder.

J Affect Disord. 2017 May 10;221:297-303

Authors: Jiang X, Dai X, Kale Edmiston E, Zhou Q, Xu K, Zhou Y, Wu F, Kong L, Wei S, Zhou Y, Chang M, Geng H, Wang D, Wang Y, Cui W, Wang F, Tang Y

Abstract
BACKGROUND: It is often difficult to differentiate major depressive disorder (MDD) and bipolar disorder (BD) merely according to clinical symptoms. Similarities and differences in neural activity between the two disorders remain unclear. In current study, we use amplitude of low-frequency fluctuations (ALFF) to compare neural activation changes between MDD and BD patients.
METHODS: One hundred and eighty-three adolescents and young adults (57 MDD, 46 BD and 80 healthy controls, HC) were scanned during resting state. The ALFF for each participant was calculated, and were then compared among all groups using voxel-based analysis.
RESULTS: There was a significant effect of diagnosis in the core regions of cortico-limbic-striatal neural system. Furthermore, MDD showed left-sided abnormal neural activity while BD showed a bilateral abnormality in this neural system.
LIMITATIONS: This study was underpowered to consider medications, mood states and neural developmental effects on the neural activation.
CONCLUSIONS: Differences in lateralization of ALFF alterations were found. Alterations predominated in the left hemisphere for MDD, whereas alterations were bilateral for BD.

PMID: 28668591 [PubMed - as supplied by publisher]

Pages