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Voxel-wise functional connectomics using arterial spin labeling fMRI: the role of denoising.

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Voxel-wise functional connectomics using arterial spin labeling fMRI: the role of denoising.

Brain Connect. 2015 May 28;

Authors: Liang X, Connelly A, Calamante F

Abstract
The objective of this study was to investigate voxel-wise functional connectomics using arterial spin labeling (ASL) fMRI. Since ASL signal has intrinsically low signal-to-noise ratio (SNR), the role of denoising is evaluated; in particular, a novel denoising method, dual-tree complex wavelet transform (DT-CWT) combined with the non-local means (NLM) algorithm is implemented and evaluated. Simulations were conducted to evaluate the performance of the proposed method in denoising images, and in detecting functional networks from noisy data (including the accuracy and sensitivity of detection). In addition, denoising was applied to in-vivo ASL datasets, followed by network analysis using graph theoretical approaches. Efficiencies cost was used to evaluate the performance of denoising in detecting functional networks from in-vivo ASL fMRI data. Simulations showed that denoising is effective in detecting voxel-wise functional networks from low SNR data and/or from data with small total number of time points. The capability of denoised voxel-wise functional connectivity analysis was also demonstrated with in-vivo data. We concluded that denoising is important for voxel-wise functional connectivity using ASL fMRI, and that the proposed DT-CWT-NLM method should be a useful ASL pre-processing step. Key words: Arterial spin labeling, voxel-wise functional connectomics, denoising, non-local means, dual-tree complex wavelet, network efficiency.

PMID: 26020288 [PubMed - as supplied by publisher]

Interactions between the Salience and Default-Mode Networks Are Disrupted in Cocaine Addiction.

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Interactions between the Salience and Default-Mode Networks Are Disrupted in Cocaine Addiction.

J Neurosci. 2015 May 27;35(21):8081-90

Authors: Liang X, He Y, Salmeron BJ, Gu H, Stein EA, Yang Y

Abstract
Cocaine dependence is a complex neuropsychiatric disorder manifested as dysregulation of multiple behavioral, emotional, and cognitive constructs. Neuroimaging studies have begun to identify specific neurobiological circuit impairments in cocaine-dependent (CD) individuals that may underlie these symptoms. However, whether, where, and how the interactions within and between these circuits are disrupted remain largely unknown. We used resting-state fMRI and modularity network analysis to identify brain modules of a priori interest (default-mode network [DMN], salience network [SN], executive control network [ECN], medial temporal lobe [MTL], and striatum) in 47 CD and 47 matched healthy control (HC) participants and explored alterations within and between these brain modules as a function of addiction. At the module level, intermodule connectivity decreased between DMN and SN in CD. At the nodal level, several regions showed decreased connections with multiple modules in CD: the rostral anterior cingulate connection strength was reduced with SN and MTL; the posterior cingulate had reduced connections with ECN; and the bilateral insula demonstrated decreased connections with DMN. Furthermore, alexithymia, a personality trait previously associated with addiction, correlated negatively with intramodule connectivity within SN only in cocaine users. Our results indicate that cocaine addiction is associated with disrupted interactions among DMN, MTL, and SN, which have been implicated, respectively, in self-referential functions, emotion and memory, and coordinating between internal and external stimuli, providing novel and important insights into the neurobiological mechanisms of cocaine addiction.

PMID: 26019326 [PubMed - in process]

Resting state fMRI in cluster headache: which role?

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Resting state fMRI in cluster headache: which role?

Neurol Sci. 2015 May;36(Supplement 1):47-50

Authors: Chiapparini L, Ferraro S, Nigri A, Proietti A, Bruzzone MG, Leone M

Abstract
The pathophysiology of cluster headache (CH) is not well-known. For several years, the most widely accepted theory was that CH was triggered by hypothalamus with secondary activation of the trigeminal-autonomic reflex. However, it was recently suggested that the posterior hypothalamus might be an actor of the pain modulating network more involved in terminating rather than triggering attacks. To investigate this hypothesis, resting state fMRI could provide valuable information on functional connectivity between brainstem and hypothalamus, as well as other brain structures that could be involved in CH pathophysiology. In this framework, here we review recent studies investigating functional connectivity by means of resting state fMRI. Despite the important findings of these studies, we suggest that important steps in the comprehension of CH pathophysiology will be done when the scientific community will use the new methodological approaches recently suggested to study functional connectivity in the brainstem.

PMID: 26017511 [PubMed - as supplied by publisher]

Resting-state fMRI functional connectivity: a new perspective to evaluate pain modulation in migraine?

10 min 44 sec ago
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Resting-state fMRI functional connectivity: a new perspective to evaluate pain modulation in migraine?

Neurol Sci. 2015 May;36(Supplement 1):41-45

Authors: Colombo B, Rocca MA, Messina R, Guerrieri S, Filippi M

Abstract
Resting-state (RS) functional magnetic resonance imaging (fMRI) is a relatively novel tool which explores connectivity between functionally linked, but anatomically separated, brain regions. The use of this technique has allowed the identification, at rest, of the main brain functional networks without requiring subjects to perform specific active tasks. Methodologically, several approaches can be applied for the analysis of RS fMRI, including seed-based, independent component analysis-based and/or cluster-based methods. The most consistently described RS network is the so-called "default mode network". Using RS fMRI, several studies have identified functional connectivity abnormalities in migraine patients, mainly located at the level of the pain-processing network. RS functional connectivity is generally increased in pain-processing network, whereas is decreased in pain modulatory circuits. Significant abnormalities of RS functional connectivity occur also in affective networks, the default mode network and the executive control network. These results provide a strong characterization of migraine as a brain dysfunction affecting intrinsic connectivity of brain networks, possibly reflecting the impact of long lasting pain on brain function.

PMID: 26017510 [PubMed - as supplied by publisher]

Altered long- and short-range functional connectivity in the patients with end-stage renal disease: a resting-state functional MRI study.

10 min 44 sec ago
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Altered long- and short-range functional connectivity in the patients with end-stage renal disease: a resting-state functional MRI study.

Metab Brain Dis. 2015 May 28;

Authors: Zhang XD, Wen JQ, Xu Q, Qi R, Chen HJ, Kong X, Wei L, Xu M, Zhang LJ, Lu GM

Abstract
To investigate alterations of functional connectivity density (FCD) in patients with end-stage renal disease (ESRD) by using resting-state functional magnetic resonance imaging (rs-fMRI). Medical research ethics committee approval from Jinling hospital and written informed consent from each subject were obtained. Forty six patients with ESRD, consisting of 21 patients minimal nephrotic encephalopathy (MNE) and 25 non-nephro-encephalopathy (non-NE), as well as 23 healthy controls underwent rs-fMRI. Neuropsychological tests were performed in all subjects, while laboratory tests were performed in ESRD patients. A voxel-wise whole brain functional connectivity analysis was used to generate long- and short-range FCD maps. The maps among MNE, non-NE, and healthy controls groups were compared by using one-way analysis of variance tests. A multiple regression analysis was performed to evaluate the correlations between FCD and the variables of neuropsychological or laboratory tests. Compared with healthy controls, non-NE showed decreased long-range FCD mainly in parietal lobe. Moreover, MNE showed further decreased long-range FCD in bilateral middle prefrontal cortex (MPFC), anterior cingulate cortex (ACC) and right superior frontal gyrus. Meanwhile, non-NE showed decreased short-range FCD mainly in frontal cortex, and further reduction in bilateral ACC and right superior parietal gyrus in MNE. In addition, patients with ESRD mainly exhibited increased long-range FCD in left temporal lobe and caudate; and increased short-range FCD in bilateral orbitofrontal cortex and temporal gyri (P < 0.05, AlphaSim corrected). The number connection test type A score, serum creatinine, urea, and dialysis duration showed negative correlation with FCD in some brain regions, while the digital symbol test scores positively correlated with short-range FCD in left inferior parietal lobule (all P < 0.05, AlphaSim corrected). The prominent long- and short-range FCD reduction was found mainly in default mode network (DMN) and bilateral frontal and parietal lobes, while the progressively decreased long- and short-range FCD in ACC/MPFC and the long-range FCD in left superior frontal gyrus from non-NE to MNE was associated with cognition dysfunction in ESRD patients.

PMID: 26016622 [PubMed - as supplied by publisher]

Task-related modulation of functional connectivity variability and its behavioral correlations.

Fri, 05/29/2015 - 13:00

Task-related modulation of functional connectivity variability and its behavioral correlations.

Hum Brain Mapp. 2015 May 26;

Authors: Elton A, Gao W

Abstract
Two new directions of functional connectivity investigation are emerging to advance studies of the brain's functional organization. First, the identification of task-related dynamics of functional connectivity has elicited a growing interest in characterizing the brain's functional reorganization due to task demands. Second, the nonstationarity of functional connectivity [i.e., functional connectivity variability (FCV)] within a single brain state has been increasingly recognized and studied. However, a combined investigation of these two avenues of research to explore the potential task-modulation of FCV is lacking, which, nevertheless, could both improve our understanding of the potential sources of FCV and also reveal new strategies to study the neural correlates of task performance. In this study, 19 human subjects underwent four functional magnetic resonance imaging (fMRI) scans including both resting and task states to study task-related modulation of FCV. Consistent with the hypothesis that FCV is partly underpinned by unconstrained mind wandering, FCV demonstrated significant task-related decreases measured at the regional, network and system levels, which was greater for between-network interactions than within-network connections. Conversely, there remained a significant degree of residual variability during the task scans, suggesting that FCV is not specific to the resting state and likely includes an intrinsic, physiologically driven component. Finally, the degree of task-induced decreases in FCV was significantly correlated with task performance accuracy, supporting its behavior significance. Overall, task modulation of FCV may represent an important direction for future studies, not only to provide insight into normal brain functioning but also to reveal potential biomarkers of various brain disorders. Hum Brain Mapp, 2015. © 2015 Wiley Periodicals, Inc.

PMID: 26015070 [PubMed - as supplied by publisher]

Variation in homotopic areas' activity and inter-hemispheric intrinsic connectivity with type of language lateralization: an FMRI study of covert sentence generation in 297 healthy volunteers.

Fri, 05/29/2015 - 13:00

Variation in homotopic areas' activity and inter-hemispheric intrinsic connectivity with type of language lateralization: an FMRI study of covert sentence generation in 297 healthy volunteers.

Brain Struct Funct. 2015 May 27;

Authors: Tzourio-Mazoyer N, Joliot M, Marie D, Mazoyer B

Abstract
We investigated the regional correlates of differences in hemispheric lateralization in 297 healthy volunteers [including 153 left-handers (LH)] previously classified into three types of language lateralization according to their hemispheric functional lateralization index measured with fMRI during covert sentence production versus word list production (PRODSENT-LIST): 250 leftward asymmetrical Typicals, 10 rightward asymmetrical Strong-atypicals (only LH), and 37 Ambilaterals with weak lateralization. Using a functionally driven homotopic atlas (AICHA), we compared patterns of regional asymmetry during PRODSENT-LIST in these three groups. Among the 192 homotopic regions of interest (hROIs) of the AICHA atlas, 58 exhibited a significant effect of the type of lateralization on their BOLD signal variation during PRODSENT-LIST. The analyses of patterns of asymmetry of these 58 hROIs showed that (1) hROIs asymmetries in Strong-atypicals were significantly negatively correlated with those observed in Typicals, which indicates that their regional pattern of rightward asymmetries was comparable to the regional pattern of leftward language asymmetries of Typicals; (2) right- and left-handed Typicals had identical profiles, whereas left-handed Ambilaterals exhibited reduced leftward asymmetry as compared either to right-handed Ambilaterals or to Typicals. Moreover, left-handed Ambilaterals pattern of hROIs asymmetries significantly positively correlated with those of both Typicals and Strong-atypicals. In 291 of the participants, we tested the hypothesis that differences in language lateralization were associated with differences in inter-hemispheric connectivity during resting state by measuring their regional homotopic inter-hemispheric intrinsic connectivity coefficient (rHIICC) in 36 of the 58 hROIs known to be connected via the corpus callosum. Mean rHIICCs were negatively correlated with task-induced functional asymmetries, suggesting that enhanced inter-hemispheric cooperation at rest translates into increased inter-hemispheric cooperation during language production. In addition, the left-handed Ambilaterals exhibited a significantly larger rHIICC compared with right-handed Ambilaterals and Typicals, confirming a difference in inter-hemispheric organization in this group.

PMID: 26013303 [PubMed - as supplied by publisher]

Does motion-related brain functional connectivity reflect both artifacts and genuine neural activity?

Fri, 05/29/2015 - 13:00
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Does motion-related brain functional connectivity reflect both artifacts and genuine neural activity?

Neuroimage. 2014 Nov 1;101:87-95

Authors: Pujol J, Macià D, Blanco-Hinojo L, Martínez-Vilavella G, Sunyer J, de la Torre R, Caixàs A, Martín-Santos R, Deus J, Harrison BJ

Abstract
Imaging research on functional connectivity is uniquely contributing to characterize the functional organization of the human brain. Functional connectivity measurements, however, may be significantly influenced by head motion that occurs during image acquisition. The identification of how motion influences such measurements is therefore highly relevant to the interpretation of a study's results. We have mapped the effect of head motion on functional connectivity in six different populations representing a wide range of potential influences of motion on functional connectivity. Group-level voxel-wise maps of the correlation between a summary head motion measurement and functional connectivity degree were estimated in 80 young adults, 71 children, 53 older adults, 20 patients with Down syndrome, 24 with Prader-Willi syndrome and 20 with Williams syndrome. In highly compliant young adults, motion correlated with functional connectivity measurements showing a system-specific anatomy involving the sensorimotor cortex, visual areas and default mode network. Further characterization was strongly indicative of these changes expressing genuine neural activity related to motion, as opposed to pure motion artifact. In the populations with larger head motion, results were more indicative of widespread artifacts, but showing notably distinct spatial distribution patterns. Group-level regression of motion effects was efficient in removing both generalized changes and changes putatively related to neural activity. Overall, this study endorses a relatively simple approach for mapping distinct effects of head motion on functional connectivity. Importantly, our findings support the intriguing hypothesis that a component of motion-related changes may reflect system-specific neural activity.

PMID: 24999036 [PubMed - indexed for MEDLINE]

The neurological underpinnings of cluttering: Some initial findings.

Fri, 05/29/2015 - 13:00
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The neurological underpinnings of cluttering: Some initial findings.

J Fluency Disord. 2015 Mar;43:1-16

Authors: Ward D, Connally EL, Pliatsikas C, Bretherton-Furness J, Watkins KE

Abstract
BACKGROUND: Cluttering is a fluency disorder characterised by overly rapid or jerky speech patterns that compromise intelligibility. The neural correlates of cluttering are unknown but theoretical accounts implicate the basal ganglia and medial prefrontal cortex. Dysfunction in these brain areas would be consistent with difficulties in selection and control of speech motor programs that are characteristic of speech disfluencies in cluttering. There is a surprising lack of investigation into this disorder using modern imaging techniques. Here, we used functional MRI to investigate the neural correlates of cluttering.
METHOD: We scanned 17 adults who clutter and 17 normally fluent control speakers matched for age and sex. Brain activity was recorded using sparse-sampling functional MRI while participants viewed scenes and either (i) produced overt speech describing the scene or (ii) read out loud a sentence provided that described the scene. Speech was recorded and analysed off line. Differences in brain activity for each condition compared to a silent resting baseline and between conditions were analysed for each group separately (cluster-forming threshold Z>3.1, extent p<0.05, corrected) and then these differences were further compared between the two groups (voxel threshold p<0.01, extent>30 voxels, uncorrected).
RESULTS: In both conditions, the patterns of activation in adults who clutter and control speakers were strikingly similar, particularly at the cortical level. Direct group comparisons revealed greater activity in adults who clutter compared to control speakers in the lateral premotor cortex bilaterally and, as predicted, on the medial surface (pre-supplementary motor area). Subcortically, adults who clutter showed greater activity than control speakers in the basal ganglia. Specifically, the caudate nucleus and putamen were overactive in adults who clutter for the comparison of picture description with sentence reading. In addition, adults who clutter had reduced activity relative to control speakers in the lateral anterior cerebellum bilaterally. Eleven of the 17 adults who clutter also stuttered. This comorbid diagnosis of stuttering was found to contribute to the abnormal overactivity seen in the group of adults who clutter in the right ventral premotor cortex and right anterior cingulate cortex. In the remaining areas of abnormal activity seen in adults who clutter compared to controls, the subgroup who clutter and stutter did not differ from the subgroup who clutter but do not stutter.
CONCLUSIONS: Our findings were in good agreement with theoretical predictions regarding the neural correlates of cluttering. We found evidence for abnormal function in the basal ganglia and their cortical output target, the medial prefrontal cortex. The findings are discussed in relation to models of cluttering that point to problems with motor control of speech.
EDUCATIONAL OBJECTIVES: This paper reports findings on the neural correlates seen in adults who clutter, and offers hypotheses as to how these might map onto the behaviours seen amongst those who clutter. Readers will be able to (a) identify the structures that are implicated in the disorder of cluttering, (b) understand arguments relating these structures to the behavioural expression of the disorder, (c) understand some of the complexities in interpreting data pertaining to recovery from cluttering, (d) understand where future efforts in research into the neurological correlates of cluttering should be focussed.

PMID: 25662409 [PubMed - indexed for MEDLINE]

Default mode network mechanisms of transcranial magnetic stimulation in depression.

Fri, 05/29/2015 - 13:00
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Default mode network mechanisms of transcranial magnetic stimulation in depression.

Biol Psychiatry. 2014 Oct 1;76(7):517-26

Authors: Liston C, Chen AC, Zebley BD, Drysdale AT, Gordon R, Leuchter B, Voss HU, Casey BJ, Etkin A, Dubin MJ

Abstract
BACKGROUND: Repetitive transcranial magnetic stimulation (TMS) of the dorsolateral prefrontal cortex (DLPFC) is an established treatment for depression, but its underlying mechanism of action remains unknown. Abnormalities in two large-scale neuronal networks-the frontoparietal central executive network (CEN) and the medial prefrontal-medial parietal default mode network (DMN)-are consistent findings in depression and potential therapeutic targets for TMS. Here, we assessed the impact of TMS on activity in these networks and their relation to treatment response.
METHODS: We used resting state functional magnetic resonance imaging to measure functional connectivity within and between the DMN and CEN in 17 depressed patients, before and after a 5-week course of TMS. Motivated by prior reports, we focused on connectivity seeded from the DLPFC and the subgenual cingulate, a key region closely aligned with the DMN in depression. Connectivity was also compared with a cohort of 35 healthy control subjects.
RESULTS: Before treatment, functional connectivity in depressed patients was abnormally elevated within the DMN and diminished within the CEN, and connectivity between these two networks was altered. Transcranial magnetic stimulation normalized depression-related subgenual hyperconnectivity in the DMN but did not alter connectivity in the CEN. Transcranial magnetic stimulation also induced anticorrelated connectivity between the DLPFC and medial prefrontal DMN nodes. Baseline subgenual connectivity predicted subsequent clinical improvement.
CONCLUSIONS: Transcranial magnetic stimulation selectively modulates functional connectivity both within and between the CEN and DMN, and modulation of subgenual cingulate connectivity may play an important mechanistic role in alleviating depression. The results also highlight potential neuroimaging biomarkers for predicting treatment response.

PMID: 24629537 [PubMed - indexed for MEDLINE]

The Posterior Medial Cortex in Urologic Chronic Pelvic Pain Syndrome: Detachment from Default Mode Network. A Resting-State Study from the MAPP Research Network.

Thu, 05/28/2015 - 15:30

The Posterior Medial Cortex in Urologic Chronic Pelvic Pain Syndrome: Detachment from Default Mode Network. A Resting-State Study from the MAPP Research Network.

Pain. 2015 May 20;

Authors: Martucci KT, Shirer WR, Bagarinao E, Johnson KA, Farmer MA, Labus JS, Apkarian AV, Deutsch G, Harris RE, Mayer EA, Clauw DJ, Greicius MD, Mackey SC

Abstract
Altered resting-state brain activity, as a measure of functional connectivity, is commonly observed in chronic pain. Identifying a reliable signature pattern of altered resting-state activity for chronic pain could provide strong mechanistic insights and serve as a highly beneficial neuroimaging-based diagnostic tool. We collected and analyzed resting-state fMRI data from female patients with urologic chronic pelvic pain syndrome (UCPPS, N = 45) and matched healthy participants (N = 45) as part of a NIDDK funded multicenter project (www.mappnetwork.org). Using dual regression and seed-based analyses, we observed significantly decreased functional connectivity of the default mode network (DMN) to two regions in the posterior medial cortex (PMC): the posterior cingulate cortex (PCC) and left precuneus (TFCE, FWE corrected p<0.05). Further investigation revealed that patients demonstrated increased functional connectivity between the PCC and several brain regions implicated in pain, sensory, motor, and emotion regulation processes (e.g., insular cortex, dorsolateral prefrontal cortex, thalamus, globus pallidus, putamen, amygdala, hippocampus). The left precuneus demonstrated decreased functional connectivity to several regions of pain processing, reward, and higher executive functioning within the prefrontal (orbitofrontal, anterior cingulate, ventromedial prefrontal) and parietal cortices (angular gyrus, superior and inferior parietal lobules). The altered PMC connectivity was associated with several phenotype measures, including pain and urologic symptom intensity, depression, anxiety, quality of relationships and self-esteem levels in patients. Collectively, these findings indicate that in UCPPS patients, regions of the PMC are detached from the DMN, while neurological processes of self-referential thought and introspection may be joined to pain and emotion regulatory processes.

PMID: 26010458 [PubMed - as supplied by publisher]

Individual Topographic Variability Is Inherent to Cortical Physiology but Task-Related Differences May Be Noise.

Thu, 05/28/2015 - 15:30

Individual Topographic Variability Is Inherent to Cortical Physiology but Task-Related Differences May Be Noise.

PLoS One. 2015;10(5):e0128343

Authors: Basile LF, Sato JR, Pasquini HA, Lozano MD, Nucci MP, Velasques B, Ribeiro P, Ramos RT, Anghina R

Abstract
The observation of highly variable sets of association neocortical areas across individuals, containing the estimated generators of Slow Potentials (SPs) and beta oscillations, lead to the persistence in individual analyses. This brought to notice an unexpected within individual topographic similarity between task conditions, despite our original interest in task-related differences. A recent related work explored the quantification of the similarity in beta topography between largely differing tasks. In this article, we used Independent Component Analysis (ICA) for the decomposition of beta activity from a visual attention task, and compared it with quiet resting, recorded by 128-channel EEG in 62 subjects. We statistically tested whether each ICA component obtained in one condition could be explained by a linear regression model based on the topographic patterns from the other condition, in each individual. Results were coherent with the previous report, showing a high topographic similarity between conditions. From an average of 12 beta component maps obtained for each task, over 80% were satisfactorily explained by the complementary task. Once more, the component maps including those considered unexplained, putatively "task-specific", had their scalp distribution and estimated cortical sources highly variable across subjects. These findings are discussed along with other studies based on individual data and the present fMRI results, reinforcing the increasingly accepted view that individual variability in sets of active neocortical association areas is not noise, but intrinsic to cortical physiology. Actual 'noise', mainly stemming from group "brain averaging" and the emphasis on statistical differences as opposed to similarities, may explain the overall hardship in replication of the vast literature on supposed task-specific forms of activity, and the ever inconclusive status of a universal functional mapping of cortical association areas. A new hypothesis, that individuals may use the same idiosyncratic sets of areas, at least by their fraction of activity in the sub-delta and beta range, in various non-sensory-motor forms of conscious activities, is a corollary of the discussed variability.

PMID: 26010428 [PubMed - as supplied by publisher]

Dimensionality of ICA in resting-state fMRI investigated by feature optimized classification of independent components with SVM.

Wed, 05/27/2015 - 16:30

Dimensionality of ICA in resting-state fMRI investigated by feature optimized classification of independent components with SVM.

Front Hum Neurosci. 2015;9:259

Authors: Wang Y, Li TQ

Abstract
Different machine learning algorithms have recently been used for assisting automated classification of independent component analysis (ICA) results from resting-state fMRI data. The success of this approach relies on identification of artifact components and meaningful functional networks. A limiting factor of ICA is the uncertainty of the number of independent components (NIC). We aim to develop a framework based on support vector machines (SVM) and optimized feature-selection for automated classification of independent components (ICs) and use the framework to investigate the effects of input NIC on the ICA results. Seven different resting-state fMRI datasets were studied. 18 features were devised by mimicking the empirical criteria for manual evaluation. The five most significant (p < 0.01) features were identified by general linear modeling and used to generate a classification model for the framework. This feature-optimized classification of ICs with SVM (FOCIS) framework was used to classify both group and single subject ICA results. The classification results obtained using FOCIS and previously published FSL-FIX were compared against manually evaluated results. On average the false negative rate in identifying artifact contaminated ICs for FOCIS and FSL-FIX were 98.27 and 92.34%, respectively. The number of artifact and functional network components increased almost linearly with the input NIC. Through tracking, we demonstrate that incrementing NIC affects most ICs when NIC < 33, whereas only a few limited ICs are affected by direct splitting when NIC is incremented beyond NIC > 40. For a given IC, its changes with increasing NIC are individually specific irrespective whether the component is a potential resting-state functional network or an artifact component. Using FOCIS, we investigated experimentally the ICA dimensionality of resting-state fMRI datasets and found that the input NIC can critically affect the ICA results of resting-state fMRI data.

PMID: 26005413 [PubMed]

Altered Functional Connectivity Strength in Abstinent Chronic Cocaine Smokers Compared to Healthy Controls.

Wed, 05/27/2015 - 16:30

Altered Functional Connectivity Strength in Abstinent Chronic Cocaine Smokers Compared to Healthy Controls.

Brain Connect. 2015 May 25;

Authors: Ray S, Gohel SR, Biswal BB

Abstract
Past research involving cocaine and resting state functional connectivity (RSFC) has shown altered functional connectivity within frontal and between frontal and other cortical and subcortical brain regions in chronic users of cocaine. However, there have been discrepancies in literature regarding the relationship between RSFC between brain regions and cocaine use behavior. This study explored the RSFC between brain regions in cocaine smokers abstinent from cocaine use for 72 hours and healthy controls. Also, the relationship between RSFC between brain regions and various cocaine use measures (cocaine use duration; frequency and money spent on cocaine/week) was examined. Twenty chronic cocaine users and 17 controls completed a resting state scan and an anatomical MPRAGE scan. Group independent component analysis (ICA) performed on fMRI data identified 13 ICs pertaining to distinct resting state networks, and group level differences were examined. To examine inter-network functional connectivity between brain regions, these 13 ICs were divided into 61 distinct regions of interest (ROIs). Correlations were calculated between 61 ROI time series. For the ROI pairs that significantly differed from controls in connectivity strength, correlations were computed between connectivity strength and cocaine use measures. Results showed an enhanced RSFC within the sensory motor cortex and the left frontal-parietal network in cocaine users than controls. An increased inter-network RSFC between frontal-temporal and frontal-parietal brain regions, and a decreased RSFC between parietal-parietal, occipital-limbic, occipital-occipital, and occipital-parietal brain regions was found in cocaine users. This study demonstrated that intra-network connectivity strength of sensory motor cortex was negatively correlated with years of cocaine use. Inter-network connectivity strength between occipital-limbic brain regions was positively correlated with years of cocaine use, while connectivity strength within occipital brain regions was negatively related to cocaine use frequency and money spent on cocaine per week in abstinent cocaine users.

PMID: 26005203 [PubMed - as supplied by publisher]

Spontaneous Regional Brain Activity Links Restrained Eating to Later Weight Gain Among Young Women.

Wed, 05/27/2015 - 16:30

Spontaneous Regional Brain Activity Links Restrained Eating to Later Weight Gain Among Young Women.

Biol Psychol. 2015 May 21;

Authors: Dong D, Jackson T, Wang Y, Chen H

Abstract
Theory and prospective studies have linked restrained eating (RE) to risk for future weight gain and the onset of obesity, but little is known about resting state neural activity may underlie this association. To address this gap, resting fMRI was used to test the extent to which spontaneous neural activity in regions associated with inhibitory control and food reward account for potential relations between baseline RE levels and changes in body weight among dieters over a one-year interval. Spontaneous regional activity patterns corresponding to RE were assessed among 50 young women using regional homogeneity (ReHo) analysis, which measured temporal synchronization of spontaneous fluctuations within a food deprivation condition. Analyses indicated higher baseline RE scores predicted more weight gain at a one-year follow-up. Furthermore, food-deprived dieting women with high dietary restraint scores exhibited more spontaneous local activity in brain regions associated with the expectation and valuation for food reward [i.e., orbitofrontal cortex (OFC)/ventromedial prefrontal cortex (VMPFC)] and reduced spontaneous local activity in inhibitory control regions [i.e., bilateral dorsal-lateral prefrontal cortex (DLPFC)] at baseline. Notably, the association between baseline RE and follow-up weight gain was mediated by decreased local synchronization of the right DLPFC in particular and, to a lesser degree, increased local synchronization of the right VMPFC. In conjunction with previous research, these findings highlight possible neural mechanisms underlying the relation between RE and risk for weight gain.

PMID: 26004091 [PubMed - as supplied by publisher]

Altered brain rhythms and functional network disruptions involved in patients with generalized fixation-off epilepsy.

Tue, 05/26/2015 - 11:00
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Altered brain rhythms and functional network disruptions involved in patients with generalized fixation-off epilepsy.

Brain Imaging Behav. 2015 May 23;

Authors: Solana AB, Martínez K, Hernández-Tamames JA, San Antonio-Arce V, Toledano R, García-Morales I, Alvárez-Linera J, Gil-Nágel A, Del Pozo F

Abstract
Generalized Fixation-off Sensitivity (CGE-FoS) patients present abnormal EEG patterns when losing fixation. In the present work, we studied two CGE-FoS epileptic patients with simultaneous EEG-fMRI. We aim to identify brain areas that are specifically related to the pathology by identifying the brain networks that are related to the EEG brain altered rhythms. Three main analyses were performed: EEG standalone, where the voltage fluctuations in delta, alpha, and beta EEG bands were obtained; fMRI standalone, where resting-state fMRI ICA analyses for opened and closed eyes conditions were computed per subject; and, EEG-informed fMRI, where EEG delta, alpha and beta oscillations were used to analyze fMRI. Patient 1 showed EEG abnormalities for lower beta band EEG brain rhythm. Fluctuations of this rhythm were correlated with a brain network mainly composed by temporo-frontal areas only found in the closed eyes condition. Patient 2 presented alterations in all the EEG brain rhythms (delta, alpha, beta) under study when closing eyes. Several biologically relevant brain networks highly correlated (r > 0.7) to each other in the closed eyes condition were found. EEG-informed fMRI results in patient 2 showed hypersynchronized patterns in the fMRI correlation spatial maps. The obtained findings allow a differential diagnosis for each patient and different profiles with respect to healthy volunteers. The results suggest a different disruption in the functional brain networks of these patients that depends on their altered brain rhythms. This knowledge could be used to treat these patients by novel brain stimulation approaches targeting specific altered brain networks in each patient.

PMID: 26001771 [PubMed - as supplied by publisher]

The effect of body-mind relaxation meditation induction on major depressive disorder: A resting-state fMRI study.

Tue, 05/26/2015 - 11:00
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The effect of body-mind relaxation meditation induction on major depressive disorder: A resting-state fMRI study.

J Affect Disord. 2015 Apr 28;183:75-82

Authors: Chen F, Lv X, Fang J, Yu S, Sui J, Fan L, Li T, Hong Y, Wang X, Wang W, Jiang T

Abstract
BACKGROUND: Meditation has been increasingly evaluated as an important complementary therapeutic tool for the treatment of depression. The present study employed resting-state functional magnetic resonance imaging (rs-fMRI) to examine the effect of body-mind relaxation meditation induction (BMRMI) on the brain activity of depressed patients and to investigate possible mechanisms of action for this complex intervention.
METHOD: 21 major depressive disorder patients (MDDs) and 24 age and gender-matched healthy controls (HCs) received rs-fMRI scans at baseline and after listening to a selection of audio designed to induce body-mind relaxation meditation. The rs-fMRI data were analyzed using Matlab toolbox to obtain the amplitude of low-frequency fluctuations (ALFF) of the BOLD signal for the whole brain. A mixed-design repeated measures analysis of variance (ANOVA) was performed on the whole brain to find which brain regions were affected by the BMRMI. An additional functional connectivity analysis was used to identify any atypical connection patterns after the BMRMI.
RESULTS: After the BMRMI experience, both the MDDs and HCs showed decreased ALFF values in the bilateral frontal pole (BA10). Additionally, increased functional connectivity from the right dorsal medial prefrontal cortex (dmPFC) to the left dorsal lateral prefrontal cortex (dlPFC) and the left lateral orbitofrontal cortex (OFC) was identified only in the MDDs after the BMRMI.
LIMITATION: In order to exclude the impact of other events on the participants׳ brain activity, the Hamilton Rating Scales for Depression (HDRS) was not measured after the body-mind relaxation induction.
CONCLUSION: Our findings support the hypothesis that body-mind relaxation meditation induction may regulate the activities of the prefrontal cortex and thus may have the potential to help patients construct reappraisal strategies that can modulate the brain activity in multiple emotion-processing systems.

PMID: 26001666 [PubMed - as supplied by publisher]

Aberrant connectivity within the default mode network in first-episode, treatment-naïve major depressive disorder.

Tue, 05/26/2015 - 11:00
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Aberrant connectivity within the default mode network in first-episode, treatment-naïve major depressive disorder.

J Affect Disord. 2015 May 8;183:49-56

Authors: Chen Y, Wang C, Zhu X, Tan Y, Zhong Y

Abstract
BACKGROUND: Convergent studies have highlighted the dysfunction of default mode network (DMN) in major depressive disorder (MDD). The altered connectivity in posterior cingulate cortex (PCC) and medial prefrontal cortex (mPFC) was especially found to be of interest in the resting state functional connectivity analysis. Recently, more attention has turned to the internal functional connectivity within the DMN. However, the internal connection patterns within the DMN remain unclear at the initial onset of MDD.
METHODS: Resting-state fMRI was performed on 38 first-episode, treatment-naïve MDD patients along with 38 matched healthy controls. Seed-based analysis was used to define the DMN and then a region-to-region connectivity analysis was performed to inspect the functional connectivity within the DMN. Spearman׳s rank correlation analysis was performed between significantly abnormal connectivities in MDD patients and clinical measurements.
RESULTS: Decreased region-to-region connectivities within DMN were found between the PCC and dorsal medial prefrontal cortex (dmPFC), between PCC and the right inferior parietal gyrus/angular, as well as between the left thalamus and cerebellar tonsil. No significant increase in connectivity was found. Moreover, functional connectivity between the left thalamus and cerebellar tonsil revealed a marginal significant negative correlation with clinical Hamilton Depression Rating Scale (HDRS) scores.
LIMITATIONS: Noteworthiness in morbidity, a high risk of mortality, and a high rate of medical service utilization of MDD make the current results uncertain to apply to the more complicated situations.
CONCLUSIONS: Each region within DMN may have a specific, individual functional role. The reason to identify the pathological mechanism of MDD may not lie in the abnormal DMN functional connectivity, but rather in the abnormal functional connectivity within DMN.

PMID: 26001663 [PubMed - as supplied by publisher]

Diagnostic approaches to predict persistent posttraumatic symptoms after mild traumatic brain injury - a literature review.

Sun, 05/24/2015 - 15:30

Diagnostic approaches to predict persistent posttraumatic symptoms after mild traumatic brain injury - a literature review.

Int J Neurosci. 2015 May 22;:1-30

Authors: Studerus-Germann AM, Thiran JP, Daducci A, Gautschi OP

Abstract
Mild traumatic brain injury (mTBI) is one of the most frequently diagnosed neurological disorder in emergency departments. Although there are established recommendations for the diagnosis and treatment in the acute stage, there is an ongoing debate which diagnostic methods and risk factors predict unfavourable long-term outcome after mTBI. This literature review addresses the question, which diagnostic approaches may best predict persistent posttraumatic symptoms (pPTS). A literature search for experimental studies from January 2000 to September 2014 evaluating the following diagnostic approaches (1) susceptibility-weighted imaging (SWI), (2) diffusion tensor imaging (DTI), (3) magnetic resonance spectroscopy (MRS), (4) functional magnetic resonance imaging (fMRI), as predictive factors of pPTS or unfavourable cognitive outcome in adult populations with mTBI was performed. DTI has been proved to be a valuable tool to identify diffuse axonal injury (DAI) after mTBI. Additionally, some studies showed associations between DAI and unfavorable cognitive outcome. SWI has shown to be a highly sensitive imaging method to identify microbleeds. The presence and quantity of microbleeds in this imaging technique can further provide etiological evidence for pPTS. MRS provides information about local neurons metabolism and preliminary data show that creatine-phosphocreatine levels measured after mTBI are predictive of cognitive outcome and emotional distress. The results of one study have shown fMRI as a useful tool to differentiate mTBI patients with pPTS from controls and mTBI patients without pPTS in a resting-state condition. From the evaluated diagnostic approaches to predict pPTS after mTBI, DTI, SWI, MRS, and fMRI seem to have adequate sensitivity and specificity as predictive diagnostic tools for pPTS. Large longitudinal clinical trials are warranted to validate the prognostic applicability and practicability in daily clinical practice.

PMID: 26000929 [PubMed - as supplied by publisher]

The BDNF Val66Met polymorphism, resting-state hippocampal functional connectivity and cognitive deficits in acute late-onset depression.

Sun, 05/24/2015 - 15:30

The BDNF Val66Met polymorphism, resting-state hippocampal functional connectivity and cognitive deficits in acute late-onset depression.

J Affect Disord. 2015 May 8;183:22-30

Authors: Yin Y, Hou Z, Wang X, Sui Y, Yuan Y

Abstract
OBJECTIVE: To investigate the relationship between hippocampal functional connectivity (HFC), cognitive deficits, and the influence of BDNF Val66Met polymorphism on the HFC in acute late-onset depression (LOD).
METHODS: 26 LOD patients and 33 and normal controls (NCs) completed clinical assessments, neuropsychological testing, blood samples collecting for genotyping, and resting-state functional MRI (R-fMRI) scans. The LOD and NCs groups were further divided into four groups according to BDNF Met allele carrier or not (LOD Met-(n=8); LOD Met+(n=18); NCs Met-(n=9); NCs Met+(n=24)). Then, seed-based correlation analyses and two-way analysis of covariance (ANCOVA) were performed to explore the main effects and interactive effects of LOD and BDNF Val66Met polymorphism on the HFC. Spearman correlation was applied to examine the cognitive and emotional significance of these altered HFC networks.
RESULTS: Compared with NCs, bilateral positive HFC with the right insula, left positive HFC with bilateral orbit-frontal cortex (OFC) and left precuneus, right positive HFC with right dorsolateral prefrontal cortex (dlPFC) were decreased, and bilateral negative HFC with right postcentral gyrus were reversed in LOD patients. BDNF Met allele mainly decreased bilateral positive HFC with the cerebellum. The interaction of LOD and BDNF Met allele primarily influenced the bilateral HFC with the temporal cortex and dorsal nexus. The changed HFC with the OFC, postcentral gyrus, cerebellum and temporal cortex significantly correlated to the cognitive deterioration. There was no significant association between the depressive severity and any altered HFC networks.
CONCLUSION: The cognitive deterioration in LOD patients, BDNF Met allele carriers, and LOD patients carring Met allele were associated with the changed HFC networks in the OFC/postcentral gyrus, cerebellum and temporal cortex respectively.

PMID: 26000753 [PubMed - as supplied by publisher]