New resting-state fMRI related studies at PubMed

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Non-Invasive Brain Stimulation in Dementia: A Complex Network Story.

Wed, 01/30/2019 - 13:00

Non-Invasive Brain Stimulation in Dementia: A Complex Network Story.

Neurodegener Dis. 2019 Jan 29;18(5-6):281-301

Authors: Pini L, Manenti R, Cotelli M, Pizzini FB, Frisoni GB, Pievani M

Abstract
Non-invasive brain stimulation (NIBS) is emerging as a promising rehabilitation tool for a number of neurodegenerative diseases. However, the therapeutic mechanisms of NIBS are not completely understood. In this review, we will summarize NIBS results in the context of brain imaging studies of functional connectivity and metabolites to gain insight into the possible mechanisms underlying recovery. We will briefly discuss how the clinical manifestations of common neurodegenerative disorders may be related with aberrant connectivity within large-scale neural networks. We will then focus on recent studies combining resting-state functional magnetic resonance imaging with NIBS to delineate how stimulation of different brain regions induce complex network modifications, both at the local and distal level. Moreover, we will review studies combining magnetic resonance spectroscopy and NIBS to investigate how microscale changes are related to modifications of large-scale networks. Finally, we will re-examine previous NIBS studies in dementia in light of this network perspective. A better understanding of NIBS impact on the functionality of large-scale brain networks may be useful to design beneficial treatments for neurodegenerative disorders.

PMID: 30695786 [PubMed - as supplied by publisher]

Automatic classification and removal of structured physiological noise for resting state functional connectivity MRI analysis.

Wed, 01/30/2019 - 13:00

Automatic classification and removal of structured physiological noise for resting state functional connectivity MRI analysis.

Magn Reson Imaging. 2019 Jan 26;:

Authors: Lee K, Ming Khoo H, Fourcade C, Gotman J, Grova C

Abstract
Resting state functional magnetic resonance imaging is used to study how brain regions are functionally connected by measuring temporal correlation of the fMRI signals, when a subject is at rest. Sparse dictionary learning is used to estimate a dictionary of resting state networks by decomposing the whole brain signals into several temporal features (atoms), each being shared by a set of voxels associated to a network. Recently, we proposed and validated a new method entitled Sparsity-based Analysis of Reliable K-hubness (SPARK), suggesting that connector hubs of brain networks participating in inter-network communication can be identified by counting the number of atoms involved in each voxel (sparse number k). However, such hub analysis can be corrupted by the presence of noise-related atoms, where physiological fluctuations in cardiorespiratory processes may remain even after band-pass filtering and regression of confound signals from the white matter and cerebrospinal fluid. Handling this issue might require manual classification of noisy atoms, which is a time-consuming and subjective task. Motivated by the fact that the physiological fluctuations are often localized in tissues close to large vasculatures, i.e. sagittal sinus, we propose an automatic classification of physiological noise-related atoms for SPARK using spatial priors and a stepwise regression procedure. We measured the degree to which the noise-characteristic time-courses within the mask are explained by each atom, and classified noise-related atoms using a subject-specific threshold estimated using a bootstrap resampling based strategy. Using real data from healthy subjects (N = 25), manual classification of the atoms by two independent reviewers showed the presence of sagittal sinus related noise in 65% of the runs. Applying the same manual classification after the proposed automatic removal method reduced this rate to 19%. A 10-fold cross-validation on real data showed good specificity and accuracy of the proposed automated method in classifying the target noise (area under the ROC curve= 0.89), when compared to the manual classification considered as the reference. We demonstrated decrease in k-hubness values in the voxels involved in the sagittal sinus at both individual and group levels, suggesting a significant improvement of SPARK, which is particularly important when considering clinical applications.

PMID: 30695721 [PubMed - as supplied by publisher]

Resting-state functional MRI demonstrates brain network reorganization in neuromyelitis optica spectrum disorder (NMOSD).

Wed, 01/30/2019 - 13:00

Resting-state functional MRI demonstrates brain network reorganization in neuromyelitis optica spectrum disorder (NMOSD).

PLoS One. 2019;14(1):e0211465

Authors: Bigaut K, Achard S, Hemmert C, Baloglu S, Kremer L, Collongues N, De Sèze J, Kremer S

Abstract
BACKGROUND: The relation between brain functional connectivity of patients with neuromyelitis optica spectrum disorder (NMOSD) and the degree of disability remains unclear.
OBJECTIVE: Compare brain functional connectivity of patients with NMOSD to healthy subjects in resting-state functional MRI (rs-fMRI).
METHODS: We compared the rs-fMRI connectivity in 12 NMOSD patients with 20 healthy subjects matched for age and sex. Graph theory analysis was used to quantify the role of each node using a set of metrics: degree, global efficiency, clustering and modularity. To summarize the abnormal connectivity profile of brain regions in patients compared to healthy subjects, we defined a hub disruption index κ.
RESULTS: Concerning the global organization of networks in NMOSD, a small-world topology was preserved without significant modification concerning all average metrics. However, visual networks and the sensorimotor network showed decreased connectivity with high interindividual variability. The hub disruption index κ was correlated to the Expanded Disability Status Scale (EDSS).
CONCLUSION: These results demonstrate a correlation between disability according to the EDSS and neuronal reorganization using the rs-fMRI graph methodology. The conservation of a normal global topological structure despite local modifications in functional connectivity seems to show brain plasticity in response to the disability.

PMID: 30695058 [PubMed - in process]

Development of spatial orientation skills: an fMRI study.

Wed, 01/30/2019 - 13:00

Development of spatial orientation skills: an fMRI study.

Brain Imaging Behav. 2019 Jan 29;:

Authors: Murias K, Slone E, Tariq S, Iaria G

Abstract
The ability to orient and navigate in spatial surroundings is a cognitive process that undergoes a prolonged maturation with progression of skills, strategies and proficiency over much of childhood. In the present study, we used functional Magnetic Resonance Imaging (fMRI) to investigate the neurological mechanisms underlying the ability to orient in a virtual interior environment in children aged 10 to 12 years of age, a developmental stage in which children start using effective spatial orientation strategies in large-scale surroundings. We found that, in comparison to young adults, children were not as proficient at the spatial orientation task, and revealed increased neural activity in areas of the brain associated with visuospatial processing and navigation (left cuneus and mid occipital area, left inferior parietal region and precuneus, right inferior parietal cortex, right precentral gyrus, cerebellar vermis and bilateral medial cerebellar lobes). When functional connectivity analyses of resting state fMRI data were performed, using seed areas that were associated with performance, increased connectivity was seen in the adults from the right hippocampal/parahippocampal gyrus to the contralateral caudate, the insular cortex, and the posterior supramarginal gyrus; children had increased connectivity from the right paracentral lobule to the right superior frontal gyrus as compared to adults. These findings support the hypothesis that, as children are maturing in their navigation abilities, they are refining and increasing the proficiency of visuospatial skills with a complimentary increase in connectivity of longer-range distributed networks allowing for flexible use of efficient and effective spatial orientation strategies.

PMID: 30694459 [PubMed - as supplied by publisher]

Effective connectivity changes in LSD-induced altered states of consciousness in humans.

Wed, 01/30/2019 - 13:00
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Effective connectivity changes in LSD-induced altered states of consciousness in humans.

Proc Natl Acad Sci U S A. 2019 Jan 28;:

Authors: Preller KH, Razi A, Zeidman P, Stämpfli P, Friston KJ, Vollenweider FX

Abstract
Psychedelics exert unique effects on human consciousness. The thalamic filter model suggests that core effects of psychedelics may result from gating deficits, based on a disintegration of information processing within cortico-striato-thalamo-cortical (CSTC) feedback loops. To test this hypothesis, we characterized changes in directed (effective) connectivity between selected CTSC regions after acute administration of lysergic acid diethylamide (LSD), and after pretreatment with Ketanserin (a selective serotonin 2A receptor antagonist) plus LSD in a double-blind, randomized, placebo-controlled, cross-over study in 25 healthy participants. We used spectral dynamic causal modeling (DCM) for resting-state fMRI data. Fully connected DCM models were specified for each treatment condition to investigate the connectivity between the following areas: thalamus, ventral striatum, posterior cingulate cortex, and temporal cortex. Our results confirm major predictions proposed in the CSTC model and provide evidence that LSD alters effective connectivity within CSTC pathways that have been implicated in the gating of sensory and sensorimotor information to the cortex. In particular, LSD increased effective connectivity from the thalamus to the posterior cingulate cortex in a way that depended on serotonin 2A receptor activation, and decreased effective connectivity from the ventral striatum to the thalamus independently of serotonin 2A receptor activation. Together, these results advance our mechanistic understanding of the action of psychedelics in health and disease. This is important for the development of new pharmacological therapeutics and also increases our understanding of the mechanisms underlying the potential clinical efficacy of psychedelics.

PMID: 30692255 [PubMed - as supplied by publisher]

Insula Functional Connectivity in Schizophrenia: Subregions, Gradients, and Symptoms.

Wed, 01/30/2019 - 13:00
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Insula Functional Connectivity in Schizophrenia: Subregions, Gradients, and Symptoms.

Biol Psychiatry Cogn Neurosci Neuroimaging. 2018 Dec 13;:

Authors: Tian Y, Zalesky A, Bousman C, Everall I, Pantelis C

Abstract
BACKGROUND: The insular cortex is connected to a diverse network of cortical and subcortical areas. This study aimed to investigate whether the diversity in functional connectivity across the insula's topography is altered in individuals with schizophrenia and relates to the clinical symptoms of the disorder.
METHODS: Insula-to-whole-brain functional connectivity was mapped using resting-state functional magnetic resonance imaging at the resolution of voxels in individuals with schizophrenia (n = 49) and healthy comparison individuals (n = 52). Diversity in functional connectivity across the insula's topography was represented as discrete subregions and gradients of continuous variation. Canonical correlation analysis was used to relate interindividual variation in insula connectivity to clinical symptoms.
RESULTS: Insula connectional diversity was parcellated into two subregions: dorsoanterior and ventroposterior. Compared with the healthy comparison group, subjects with schizophrenia were associated with an overall reduction in insula functional connectivity as well as reduced differentiation in connectivity profiles between these subregions. A significant interaction effect between diagnosis and insula subregion indicated that the anterior subregion in schizophrenia was connected with increased strength to the somatosensory, motor, occipital, and parietal cortices, whereas the posterior subregion showed increased connectivity with the thalamus and prefrontal cortex. Insula connectivity with the anterior cingulate and auditory cortices was significantly associated with cognitive impairment, negative symptoms, poor psychosocial functioning, and longer duration of illness (r = .64, p = .03).
CONCLUSIONS: Diversity in functional connectivity across the insula's rostrocaudal axis is reduced in schizophrenia, resulting in reduced differentiation between anterior and posterior insula. Interindividual variation in insula connectivity explains variability in some of the clinical symptoms of schizophrenia.

PMID: 30691966 [PubMed - as supplied by publisher]

Specific Substantial Dysconnectivity in Schizophrenia: A Transdiagnostic Multimodal Meta-analysis of Resting-State Functional and Structural Magnetic Resonance Imaging Studies.

Wed, 01/30/2019 - 13:00
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Specific Substantial Dysconnectivity in Schizophrenia: A Transdiagnostic Multimodal Meta-analysis of Resting-State Functional and Structural Magnetic Resonance Imaging Studies.

Biol Psychiatry. 2018 Dec 11;:

Authors: Brandl F, Avram M, Weise B, Shang J, Simões B, Bertram T, Hoffmann Ayala D, Penzel N, Gürsel DA, Bäuml J, Wohlschläger AM, Vukadinovic Z, Koutsouleris N, Leucht S, Sorg C

Abstract
BACKGROUND: This study investigated characteristic large-scale brain changes in schizophrenia. Numerous imaging studies have demonstrated brain changes in schizophrenia, particularly aberrant intrinsic functional connectivity (iFC) of ongoing brain activity, measured by resting-state functional magnetic resonance imaging, and aberrant gray matter volume (GMV) of distributed brain regions, measured by structural magnetic resonance imaging. It is unclear, however, which iFC changes are specific to schizophrenia compared with those of other disorders and whether such specific iFC changes converge with GMV changes. To address this question of specific substantial dysconnectivity in schizophrenia, we performed a transdiagnostic multimodal meta-analysis of resting-state functional and structural magnetic resonance imaging studies in schizophrenia and other psychiatric disorders.
METHODS: Multiple databases were searched up to June 2017 for whole-brain seed-based iFC studies and voxel-based morphometry studies in schizophrenia, major depressive disorder, bipolar disorder, addiction, and anxiety. Coordinate-based meta-analyses were performed to detect 1) schizophrenia-specific hyperconnectivity or hypoconnectivity of intrinsic brain networks (compared with hyperconnectivity or hypoconnectivity of each other disorder both separately and combined across comparisons) and 2) the overlap between dysconnectivity and GMV changes (via multimodal conjunction analysis).
RESULTS: For iFC meta-analysis, 173 publications comprising 4962 patients and 4575 control subjects were included, and for GMV meta-analysis, 127 publications comprising 6311 patients and 6745 control subjects were included. Disorder-specific iFC dysconnectivity in schizophrenia (consistent across comparisons with other disorders) was found for limbic, frontoparietal executive, default mode, and salience networks. Disorder-specific dysconnectivity and GMV reductions converged in insula, lateral postcentral cortex, striatum, and thalamus.
CONCLUSIONS: Results demonstrated specific substantial dysconnectivity in schizophrenia in insula, lateral postcentral cortex, striatum, and thalamus. Data suggest that these regions are characteristic targets of schizophrenia.

PMID: 30691673 [PubMed - as supplied by publisher]

Catechol-O-methyltransferase polymorphism is associated with the cortico-cerebellar functional connectivity of executive function in children with attention-deficit/hyperactivity disorder.

Wed, 01/30/2019 - 13:00
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Catechol-O-methyltransferase polymorphism is associated with the cortico-cerebellar functional connectivity of executive function in children with attention-deficit/hyperactivity disorder.

Sci Rep. 2017 07 07;7(1):4850

Authors: Mizuno Y, Jung M, Fujisawa TX, Takiguchi S, Shimada K, Saito DN, Kosaka H, Tomoda A

Abstract
The cerebellum, although traditionally considered a motor structure, has been increasingly recognized to play a role in regulating executive function, the dysfunction of which is a factor in attention-deficit/hyperactivity disorder (ADHD). Additionally, catechol-O-methyltransferase (COMT) polymorphism has been reported to be associated with executive function. We examined whether the cortico-cerebellar executive function network is altered in children with ADHD and whether COMT polymorphism is associated with the altered network. Thirty-one children with ADHD and thirty age- and IQ-matched typically developing (TD) controls underwent resting-state functional MRI, and functional connectivity of executive function-related Crus I/II in the cerebellum was analysed. COMT Val158Met genotype data were also obtained from children with ADHD. Relative to TD controls, children with ADHD showed significantly lower functional connectivity of the right Crus I/II with the left dorsolateral prefrontal cortex. Additionally, the functional connectivity of children with ADHD was modulated by COMT polymorphism, with Met-carriers exhibiting significantly lower functional connectivity than the Val/Val genotype. These results suggest the existence of variations, such as ethnic differences, in COMT genetic effects on the cortico-cerebellar executive function network. These variations contribute to heterogeneity in ADHD. Further neuroimaging genetics study might lead to the development of fundamental therapies that target ADHD pathophysiology.

PMID: 28687733 [PubMed - indexed for MEDLINE]

Resting-state brain fluctuation and functional connectivity dissociate moral injury from posttraumatic stress disorder.

Tue, 01/29/2019 - 18:20

Resting-state brain fluctuation and functional connectivity dissociate moral injury from posttraumatic stress disorder.

Depress Anxiety. 2019 Jan 28;:

Authors: Sun D, Phillips RD, Mulready HL, Zablonski ST, Turner JA, Turner MD, McClymond K, Nieuwsma JA, Morey RA

Abstract
Moral injury is closely associated with posttraumatic stress disorder (PTSD) and characterized by disturbances in social and moral cognition. Little is known about the neural underpinnings of moral injury, and whether the neural correlates are different between moral injury and PTSD. A sample of 26 U.S. military veterans (two females: 28-55 years old) were investigated to determine how subjective appraisals of morally injurious events measured by Moral Injury Event Scale (MIES) and PTSD symptoms are differentially related to spontaneous fluctuations indexed by amplitude of low frequency fluctuation (ALFF) as well as functional connectivity during resting-state functional magnetic resonance imaging scanning. ALFF in the left inferior parietal lobule (L-IPL) was positively associated with MIES subscores of transgressions, negatively associated with subscores of betrayals, and not related with PTSD symptoms. Moreover, functional connectivity between the L-IPL and bilateral precuneus was positively related with PTSD symptoms and negatively related with MIES total scores. Our results provide the first evidence that morally injurious events and PTSD symptoms have dissociable neural underpinnings, and behaviorally distinct subcomponents of morally injurious events are different in neural responses. The findings increase our knowledge of the neural distinctions between moral injury and PTSD and may contribute to developing nosology and interventions for military veterans afflicted by moral injury.

PMID: 30690812 [PubMed - as supplied by publisher]

Different Modulation Effects of Tai Chi Chuan and Baduanjin on Resting State Functional Connectivity of the Default Mode Network in Older Adults.

Tue, 01/29/2019 - 18:20

Different Modulation Effects of Tai Chi Chuan and Baduanjin on Resting State Functional Connectivity of the Default Mode Network in Older Adults.

Soc Cogn Affect Neurosci. 2019 Jan 18;:

Authors: Liu J, Tao J, Liu W, Huang J, Xue X, Li M, Yang M, Zhu J, Lang C, Park J, Tu Y, Wilson G, Chen L, Kong J

Abstract
The default mode network (DMN) plays an importment role in age-related cognitive decline. This study aims to explore the modulation effect of two mind-body interventions (Tai Chi Chuan and Baduanjin) on DMN in elderly individuals. Participants between 50 and 70 years old were recruited and randomized into a Tai Chi Chuan, Baduanjin, or control group. The Wechsler Memory Scale-Chinese Revision (WMS-CR) and resting state fMRI scans were administered at baseline and following 12 weeks of exercise. Seed-based resting state functional connectivity (rsFC) was calculated. We found that: 1) compared to the Baduanjin group, Tai Chi Chuan was significantly associated with increased rsFC between the medial prefrontal cortex (mPFC) and right putamen/caudate; 2) Compared to the control group, Tai Chi Chuan increased posterior cingulate cortex rsFC with the right putamen/caudate, while Baduanjin decreased rsFC between the mPFC and orbital prefrontal gyrus/putamen. Baseline mPFC rsFC with orbital prefrontal gyrus was negatively correlated with VRS. These results suggest that both Tai Chi Chuan and Baduanjin can modulate the DMN, but through different pathways. Elucidating the mechanisms underlying different mind-body interventions may shed light on the development of new methods to prevent age-related diseasesas well as other disorders associated with disrupted DMN.

PMID: 30690554 [PubMed - as supplied by publisher]

Quasi-periodic patterns of brain activity in individuals with attention-deficit/hyperactivity disorder.

Tue, 01/29/2019 - 18:20

Quasi-periodic patterns of brain activity in individuals with attention-deficit/hyperactivity disorder.

Neuroimage Clin. 2019 Jan 19;21:101653

Authors: Abbas A, Bassil Y, Keilholz S

Abstract
Individuals with attention-deficit/hyperactivity disorder have disrupted functional connectivity in the default mode and task positive networks. Traditional fMRI analysis techniques that focus on 'static' changes in functional connectivity have been successful in identifying differences between healthy controls and individuals with ADHD. However, such analyses are unable to explain the mechanisms behind the functional connectivity differences observed. Here, we study dynamic changes in functional connectivity in individuals with ADHD through investigation of quasi-periodic patterns (QPPs). QPPs are reliably recurring low-frequency spatiotemporal patterns in the brain linked to infra-slow electrical activity. They have been shown to contribute to functional connectivity observed through static analysis techniques. We find that QPPs contribute to functional connectivity specifically in regions that are disrupted in individuals with ADHD. Individuals with ADHD also show differences in the spatiotemporal pattern observed within the QPPs. This difference results in a weaker contribution of QPPs to functional connectivity in the default mode and task positive networks. We conclude that quasi-periodic patterns provide insight into the mechanisms behind functional connectivity differences seen in individuals with ADHD. This allows for a better understanding of the etiology of the disorder and development of effective treatments.

PMID: 30690417 [PubMed - as supplied by publisher]

Aberrant resting-state functional connectivity of salience network in first-episode schizophrenia.

Tue, 01/29/2019 - 18:20

Aberrant resting-state functional connectivity of salience network in first-episode schizophrenia.

Brain Imaging Behav. 2019 Jan 28;:

Authors: Huang H, Botao Z, Jiang Y, Tang Y, Zhang T, Tang X, Xu L, Wang J, Li J, Qian Z, Liu X, Wang H, Luo C, Li C, Xu J, Goff D, Wang J

Abstract
The disruption of salience network (SN) has been consistently found in patients with schizophrenia and thought to give rise to specific symptoms. However, the functional dysconnectivity pattern of SN remains unclear in first-episode schizophrenia (FES). Sixty-five patients with FES and sixty-six health controls (HC) were enrolled in this study and underwent resting-state functional magnetic resonance imaging (rs-fMRI). The eleven regions of interest (ROIs) within SN were derived from the peaks of the group independent component analysis (gICA). Seed-based whole-brain functional connectivity (FC) analyses were performed with all SN ROIs as the seeds. Both hyper- and hypo-connectivity of SN were found in the FES. Specifically, the increased FC mainly existed between the SN and cortico-cerebellar sub-circuit and prefrontal cortex, while the reduced FC mainly existed within cortico-striatal-thalamic-cortical (CSTC) sub-circuit. Our findings suggest that FES is associated with pronounced dysregulation of SN, characterized prominently by hyperconnectivity of SN-prefrontal cortex and cerebellum, as well as hypoconnectivity of CSTC sub-circuit of the SN.

PMID: 30689171 [PubMed - as supplied by publisher]

Atypical Frontotemporal Connectivity of Cognitive Empathy in Male Adolescents With Conduct Disorder.

Tue, 01/29/2019 - 18:20
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Atypical Frontotemporal Connectivity of Cognitive Empathy in Male Adolescents With Conduct Disorder.

Front Psychol. 2018;9:2778

Authors: Dong D, Jiang Y, Gao Y, Ming Q, Wang X, Yao S

Abstract
Background: It has been suggested that adolescents with conduct disorder (CD) may have a deficit in the affective and cognitive domains empathy, but studies exploring networks within the key brain regions of affective and cognitive empathy in adolescents with CD are lacking. Methods: Functional connectivity (FC) analyses among key brain regions of the affective and cognitive empathy with resting-state functional magnetic resonance imaging (fMRI) were conducted in 30 adolescent boys with CD and 33 demographically matched healthy controls (HCs). Results: Atypical FC within the key brain regions of affective empathy was not observed in CD adolescents. However, we found that CD adolescents showed decreased frontotemporal connectivity within the key brain regions of cognitive empathy in relation to HCs, that is, the FCs between right temporoparietal junction and ventromedial prefrontal cortex as well as dorsomedial prefrontal cortex. Conclusion: These findings may provide insight into neural mechanism underlying a cognitive empathy deficiency of CD adolescents from the perspective of FC.

PMID: 30687205 [PubMed]

Precuneus Dysfunction in Parkinson's Disease With Mild Cognitive Impairment.

Tue, 01/29/2019 - 18:20
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Precuneus Dysfunction in Parkinson's Disease With Mild Cognitive Impairment.

Front Aging Neurosci. 2018;10:427

Authors: Jia X, Li Y, Li K, Liang P, Fu X

Abstract
Background: Mild cognitive impairment (MCI) frequently occurs in Parkinson's disease (PD). Neurovascular changes interact with neurodegenerative processes in PD. However, the deficits of cerebral blood flow (CBF) perfusion and the associated functional connectivity (FC) in PD patients with MCI (PD-MCI) remain unclear. Purpose: This study aimed to explore the specific neurovascular perfusion alterations in PD-MCI compared to PD with normal cognition (PD-NC) and healthy controls (HCs), and to further examine the resultant whole brain FC changes in the abnormal perfusion regions. Methods: Relative CBF (rCBF) was calculated using arterial spin labeling (ASL) in 54 patients with PD (27 patients with PD-NC and 27 patients with PD-MCI) and 25 HCs matched for age and gender ratio, who also underwent the structural MRI, resting-state functional MRI (rs-fMRI) and neuropsychological examinations. The gray matter (GM) changes in PD patients were analyzed using voxel-based morphometry (VBM). The alterations in rCBF perfusion and FC among groups were then analyzed respectively. Additionally, correlations between these alterations and neuropsychological performances were further examined. Results: Compared to HC, left caudate atrophy was detected in patients with PD. In comparison to both PD-NC and HC, patients with PD-MCI specifically exhibited hypoperfusion in the parietal memory network (PMN) in the precuneus (PCu) and decreased PCu-FC in the right striatum. Moreover, PCu perfusion and PCu-FC strengths in the right striatum were positively associated with memory performance in PD-MCI. Conclusions: These findings suggest that the posterior PMN dysfunction underlies memory deficits in PD-MCI.

PMID: 30687078 [PubMed]

Decreased Intrinsic Functional Connectivity in First-Episode, Drug-Naive Adolescents With Generalized Anxiety Disorder.

Tue, 01/29/2019 - 18:20
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Decreased Intrinsic Functional Connectivity in First-Episode, Drug-Naive Adolescents With Generalized Anxiety Disorder.

Front Hum Neurosci. 2018;12:539

Authors: Yang F, Fan L, Zhai T, Lin Y, Wang Y, Ma J, Liao M, Zhang Y, Li L, Su L, Dai Z

Abstract
Generalized anxiety disorder (GAD) is characterized by excessive and uncontrollable worry about everyday life. Prior neuroimaging studies have demonstrated that GAD is associated with disruptions in specific brain regions; however, little is known about the global functional connectivity maps in adolescents with GAD. Here, first-episode, medication-naive, adolescent GAD patients (N = 36) and healthy controls (N = 28) (HCs) underwent resting-state functional MRI (R-fMRI) and completed a package of questionnaires to assess clinical symptoms. Functional connectivity strength and seed-based functional connectivity were employed to investigate the functional connectivity architecture. GAD patients showed reduced functional connectivity strength in right supramarginal gyrus (SMG) and right superior parietal gyrus (SPG) compared with HCs. Further seed-based functional connectivity analysis revealed that GAD patients displayed decreased functional connectivity between right SMG and left fusiform gyrus, inferior temporal gyrus, parahippocampal gyrus, bilateral precuneus and cuneus, and between right SPG and bilateral supplementary motor area and middle cingulate gyrus, as well as between the SMG-based network and the SPG-based network. Moreover, the disrupted intra-network connectivity (i.e., the SMG-based network and the SPG-based network) and inter-network connectivity between the SMG-based network and the SPG-based network accounted for 25.5% variance of the State and Trait Anxiety Inventory (STAI) and 39.5% variance of the trait subscale of STAI. Our findings highlight the abnormal functional architecture in the SMG-based network and the SPG-based network in GAD, providing novel insights into the pathological mechanisms of this disorder.

PMID: 30687052 [PubMed]

Neural Network Connectivity During Post-encoding Rest: Linking Episodic Memory Encoding and Retrieval.

Tue, 01/29/2019 - 18:20
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Neural Network Connectivity During Post-encoding Rest: Linking Episodic Memory Encoding and Retrieval.

Front Hum Neurosci. 2018;12:528

Authors: Risius OJ, Onur OA, Dronse J, von Reutern B, Richter N, Fink GR, Kukolja J

Abstract
Commonly, a switch between networks mediating memory encoding and those mediating retrieval is observed. This may not only be due to differential involvement of neural resources due to distinct cognitive processes but could also reflect the formation of new memory traces and their dynamic change during consolidation. We used resting state fMRI to measure functional connectivity (FC) changes during post-encoding rest, hypothesizing that during this phase, new functional connections between encoding- and retrieval-related regions are created. Interfering and reminding tasks served as experimental modulators to corroborate that the observed FC differences indeed reflect changes specific to post-encoding rest. The right inferior occipital and fusiform gyri (active during encoding) showed increased FC with the left inferior frontal gyrus and the left middle temporal gyrus (MTG) during post-encoding rest. Importantly, the left MTG subsequently also mediated successful retrieval. This finding might reflect the formation of functional connections between encoding- and retrieval-related regions during undisturbed post-encoding rest. These connections were vulnerable to experimental modulation: Cognitive interference disrupted FC changes during post-encoding rest resulting in poorer memory performance. The presentation of reminders also inhibited FC increases but without affecting memory performance. Our results contribute to a better understanding of the mechanisms by which post-encoding rest bridges the gap between encoding- and retrieval-related networks.

PMID: 30687046 [PubMed]

Topological Properties of Resting-State fMRI Functional Networks Improve Machine Learning-Based Autism Classification.

Tue, 01/29/2019 - 18:20
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Topological Properties of Resting-State fMRI Functional Networks Improve Machine Learning-Based Autism Classification.

Front Neurosci. 2018;12:1018

Authors: Kazeminejad A, Sotero RC

Abstract
Automatic algorithms for disease diagnosis are being thoroughly researched for use in clinical settings. They usually rely on pre-identified biomarkers to highlight the existence of certain problems. However, finding such biomarkers for neurodevelopmental disorders such as Autism Spectrum Disorder (ASD) has challenged researchers for many years. With enough data and computational power, machine learning (ML) algorithms can be used to interpret the data and extract the best biomarkers from thousands of candidates. In this study, we used the fMRI data of 816 individuals enrolled in the Autism Brain Imaging Data Exchange (ABIDE) to introduce a new biomarker extraction pipeline for ASD that relies on the use of graph theoretical metrics of fMRI-based functional connectivity to inform a support vector machine (SVM). Furthermore, we split the dataset into 5 age groups to account for the effect of aging on functional connectivity. Our methodology achieved better results than most state-of-the-art investigations on this dataset with the best model for the >30 years age group achieving an accuracy, sensitivity, and specificity of 95, 97, and 95%, respectively. Our results suggest that measures of centrality provide the highest contribution to the classification power of the models.

PMID: 30686984 [PubMed]

Tracking Neural Progenitor Cell Migration in the Rodent Brain Using Magnetic Resonance Imaging.

Tue, 01/29/2019 - 18:20
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Tracking Neural Progenitor Cell Migration in the Rodent Brain Using Magnetic Resonance Imaging.

Front Neurosci. 2018;12:995

Authors: Mallett CL, Shuboni-Mulligan DD, Shapiro EM

Abstract
The study of neurogenesis and neural progenitor cells (NPCs) is important across the biomedical spectrum, from learning about normal brain development and studying disease to engineering new strategies in regenerative medicine. In adult mammals, NPCs proliferate in two main areas of the brain, the subventricular zone (SVZ) and the subgranular zone, and continue to migrate even after neurogenesis has ceased within the rest of the brain. In healthy animals, NPCs migrate along the rostral migratory stream (RMS) from the SVZ to the olfactory bulb, and in diseased animals, NPCs migrate toward lesions such as stroke and tumors. Here we review how MRI-based cell tracking using iron oxide particles can be used to monitor and quantify NPC migration in the intact rodent brain, in a serial and relatively non-invasive fashion. NPCs can either be labeled directly in situ by injecting particles into the lateral ventricle or RMS, where NPCs can take up particles, or cells can be harvested and labeled in vitro, then injected into the brain. For in situ labeling experiments, the particle type, injection site, and image analysis methods have been optimized and cell migration toward stroke and multiple sclerosis lesions has been investigated. Delivery of labeled exogenous NPCs has allowed imaging of cell migration toward more sites of neuropathology, which may enable new diagnostic and therapeutic opportunities for as-of-yet untreatable neurological diseases.

PMID: 30686969 [PubMed]

Cognitive functioning and functional brain networks in postoperative WHO grade I meningioma patients.

Tue, 01/29/2019 - 18:20
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Cognitive functioning and functional brain networks in postoperative WHO grade I meningioma patients.

J Neurooncol. 2018 Dec;140(3):605-613

Authors: van Nieuwenhuizen D, Douw L, Klein M, Peerdeman SM, Heimans JJ, Reijneveld JC, Stam CJ, Hillebrand A

Abstract
INTRODUCTION: Meningioma patients often have subtle cognitive deficits that might be attributed to the tumor itself, to surgical treatment, or to the occurrence of seizures and their treatment. Magnetoencephalography (MEG) analysis of resting-state functional networks (RSNs) could help to understand the neurophysiological basis of cognitive impairment in these patients. We explored the correlation between RSN functional connectivity and topology of functional networks on the one hand, and cognition on the other hand in WHO grade I meningioma patients.
METHODS: Twenty adult WHO grade I meningioma patients who had undergone tumor resection, as well as 20 healthy matched controls, were included. Neuropsychological assessment was done through a standardized test battery. MEG data were recorded, and projected to the anatomical space of the Automated Anatomical Labeling atlas. Functional connectivity (PLI), within the default mode network (DMN) and the bilateral frontoparietal networks were correlated to cognitive performance. Minimum spanning tree (MST) characteristics were correlated with cognitive functioning.
RESULTS: Compared to healthy controls, meningioma patients had lower working memory capacity (p = 0.037). Within the patient group, lower working memory performance was associated with lower DMN connectivity and a lower maximum MST degree in the theta band (resp. p = 0.044 and p = 0.003).
CONCLUSIONS: This study shows that cognitive functioning is correlated with functional connectivity in the default mode network and hub-pathology in WHO grade I meningioma patients. Future longitudinal studies are needed to corroborate these findings and to further investigate the pathophysiology of cognitive deficits and possible changes in functional brain networks in meningioma patients.

PMID: 30219943 [PubMed - indexed for MEDLINE]

Associations of systemic inflammation with frontotemporal functional network connectivity and out-degree social-network size in community-dwelling older adults.

Mon, 01/28/2019 - 11:20

Associations of systemic inflammation with frontotemporal functional network connectivity and out-degree social-network size in community-dwelling older adults.

Brain Behav Immun. 2019 Jan 24;:

Authors: Bang M, Kim J, Kyoon An S, Youm Y, Chey J, Chang Kim H, Park K, Namkoong K, Lee E

Abstract
Increasing evidence suggests that systemic inflammation adversely affects social experiences and behaviors of older adults by changing the functional state of the brain. In this study, we investigated the relationships among systemic inflammation, functional network connectivity (FNC) of the whole brain, and social-network size using complete social-network data of older adults residing in a Korean village. Sixty-one participants were recruited from the Korean Social Life, Health, and Aging Project (KSHAP). Participants underwent a resting-state functional magnetic resonance imaging scan. High sensitivity C-reactive protein (hs-CRP) levels were measured as an inflammation marker. In-degree and out-degree network sizes were calculated based on the total number of intimate social relationships per participant. We demonstrated that hs-CRP levels were associated with decreased frontotemporal FNC. Stronger frontotemporal FNC was significantly correlated with a larger out-degree network size, suggesting that impaired frontotemporal communication in older adults decreases perceived social connectedness with other people. An exploratory mediation analysis supported the observation that increased systemic inflammation contributes to reduced out-degree social-network size among older adults by changing frontotemporal FNC. The present findings provide meaningful insight into the complex relationship between systemic inflammation and social quality of life.

PMID: 30685533 [PubMed - as supplied by publisher]

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