New resting-state fMRI related studies at PubMed

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Dynamic Functional Connectivity Within the Fronto-Limbic Network Induced by Intermittent Theta-Burst Stimulation: A Pilot Study.

Wed, 10/02/2019 - 16:20

Dynamic Functional Connectivity Within the Fronto-Limbic Network Induced by Intermittent Theta-Burst Stimulation: A Pilot Study.

Front Neurosci. 2019;13:944

Authors: Tang Y, Jiao X, Wang J, Zhu T, Zhou J, Qian Z, Zhang T, Cui H, Li H, Tang X, Xu L, Zhang L, Wei Y, Sheng J, Liu L, Wang J

Abstract
Purpose: The utility of transcranial magnetic stimulation (TMS) has been growing rapidly in both neurocognitive studies and clinical applications in decades. However, it remains unclear how the responses of the stimulated site and the site-related functional network to the external TMS manipulation dynamically change over time.
Methods: A multi-session combining TMS-fMRI experiment was conducted to explore the spatiotemporal effects of TMS within the fronto-limbic network. Ten healthy volunteers were modulated by intermittent theta-burst stimulation (iTBS) at a precise site within the left dorsolateral prefrontal cortex (DLPFC, MNI coordinate [-44 36 20]), navigated by individual structural MRI image. Three-session resting-state fMRI images were acquired before iTBS (TP1), immediately after iTBS (TP2), and 15 min after iTBS (TP3) for each participant. Seventy-four regions of interests (ROIs) within the fronto-limbic network were chosen including the bilateral superior frontal gyrus (SFG), middle frontal gyrus (MidFG), inferior frontal gyrus (IFG), orbital gyrus (OrG), cingulate gyrus (CG), and subcortical nuclei (hippocampus and amygdala). Regional fractional amplitude of low-frequency fluctuation (fALFF) and ROI-to-ROI functional connectivity (FC) were compared among TP1, TP2, and TP3.
Results: The immediate iTBS effect was observed at the stimulated site. FC between the left dorsolateral SFG and left dorsal IFG and between the left rostral IFG and right MidFG increased at TP2 as compared to at TP1 (all FDR-p < 0.05), while FC within the left OrG decreased. The relatively long-term iTBS effect transmitted with decreased FC between the left IFG and right amygdala, increased FC between the left MidFG and left OrG, and decreased FC between bilateral IFG and OrG at TP3 than at TP1 (all FDR-p < 0.05). Meanwhile, mean fALFF values over the left SFG, MidFG, ventral CG, and IFG were significantly increased at TP3 as compared to those at TP2 (all p < 0.05 with Bonferroni correction).
Conclusion: By combining TMS and fMRI, it becomes possible to track the spatiotemporal dynamics of TMS after-effects within the fronto-limbic network. Our findings suggested that the iTBS effect dynamically changed over time from the local neural activation at the stimulated site to its connected remote regions within the fronto-limbic network.

PMID: 31572111 [PubMed]

Altered Cingulate Cortex Functional Connectivity in Normal Aging and Mild Cognitive Impairment.

Wed, 10/02/2019 - 16:20

Altered Cingulate Cortex Functional Connectivity in Normal Aging and Mild Cognitive Impairment.

Front Neurosci. 2019;13:857

Authors: Cera N, Esposito R, Cieri F, Tartaro A

Abstract
Purpose: Resting-state functional Magnetic Resonance Imaging studies revealed that the brain is organized into specialized networks constituted by regions that show a coherent fluctuation of spontaneous activity. Among these networks, the cingulate cortex appears to play a crucial role, particularly in the default mode network, the dorsal attention network and the salience network. In the present study, we mapped the functional connectivity (FC) pattern of different regions of the cingulate cortex: the anterior cingulate cortex, midcingulate cortex and posterior cingulate cortex/retro splenial cortex, which have been in turn divided into a total of 9 subregions. We compared FC patterns of the cingulate subregions in a sample of mild cognitive impairment patients and healthy elderly subjects.
Methods: We enrolled 19 healthy elders (age range: 61-72 y.o.) and 16 Mild cognitive impairment patients (age range 64-87 y.o.). All participants had comparable levels of education (8-10 years) and were neurologically examined to exclude visual and motor impairments, major medical conditions, psychiatric or neurological disorders and consumption of psychotropic drugs. The diagnosis of mild cognitive impairment was performed according to Petersen criteria. Subjects were evaluated with Mini-Mental State Examination, Frontal Assessment Battery, and prose memory (Babcock story) tests. In addition, with functional Magnetic Resonance Imaging, we investigated resting-state network activities.
Results: Healthy elderly, compared to mild cognitive impairment, showed significant increased level of FC for the ventral part of the anterior cingulate cortex in correspondence to the bilateral caudate and ventromedial prefrontal cortex. Moreover, for the midcingulate cortex the healthy elderly group showed increased levels of FC in the somatomotor region, prefrontal cortex, and superior parietal lobule. Meanwhile, the mild cognitive impairment group showed an increased level of FC for the superior frontal gyrus, frontal eye field and orbitofrontal cortex compared to the healthy elderly group.
Conclusion: Our findings indicate that cognitive decline observed in mild cognitive impairment patients damages the global FC of the cingulate cortex, supporting the idea that abnormalities in resting-state activities of the cingulate cortex could be a useful additional tool in order to better understand the brain mechanisms of MCI.

PMID: 31572106 [PubMed]

Disrupted Brain Entropy And Functional Connectivity Patterns Of Thalamic Subregions In Major Depressive Disorder.

Wed, 10/02/2019 - 16:20

Disrupted Brain Entropy And Functional Connectivity Patterns Of Thalamic Subregions In Major Depressive Disorder.

Neuropsychiatr Dis Treat. 2019;15:2629-2638

Authors: Xue SW, Wang D, Tan Z, Wang Y, Lian Z, Sun Y, Hu X, Wang X, Zhou X

Abstract
Purpose: Entropy analysis of resting-state functional magnetic resonance imaging (R-fMRI) has recently been adopted to characterize brain temporal dynamics in some neuropsychological or psychiatric diseases. Thalamus-related dysfunction might be a potential trait marker of major depressive disorder (MDD), but the abnormal changes in the thalamus based on R-fMRI are still unclear from the perspective of brain temporal dynamics. The aim of this study was to identify local entropy changes and subregional connectivity patterns of the thalamus in MDD patients.
Patients and methods: We measured the sample entropy of the R-fMRI data from 46 MDD patients and 32 matched healthy controls. We employed the Louvain method for the module detection algorithm to automatically identify a functional parcellation of the thalamus and then examined the whole-brain subregional connectivity patterns.
Results: The results indicated that the MDD patients had decreased entropy in the bilateral thalami compared with healthy controls. Increased functional connectivity between the thalamic subregions and the medial part of the superior frontal gyrus (mSFG) was found in MDD patients.
Conclusion: This study showed new evidence about sample entropy changes in MDD patients. The functional connectivity alterations that were widely distributed across almost all the thalamic subregions with the mSFG in MDD suggest a general involvement independent of the location and function of the subregions.

PMID: 31571880 [PubMed]

Multimodal fusion of structural and functional brain imaging in depression using linked independent component analysis.

Wed, 10/02/2019 - 16:20

Multimodal fusion of structural and functional brain imaging in depression using linked independent component analysis.

Hum Brain Mapp. 2019 Oct 01;:

Authors: Maglanoc LA, Kaufmann T, Jonassen R, Hilland E, Beck D, Landrø NI, Westlye LT

Abstract
Previous structural and functional neuroimaging studies have implicated distributed brain regions and networks in depression. However, there are no robust imaging biomarkers that are specific to depression, which may be due to clinical heterogeneity and neurobiological complexity. A dimensional approach and fusion of imaging modalities may yield a more coherent view of the neuronal correlates of depression. We used linked independent component analysis to fuse cortical macrostructure (thickness, area, gray matter density), white matter diffusion properties and resting-state functional magnetic resonance imaging default mode network amplitude in patients with a history of depression (n = 170) and controls (n = 71). We used univariate and machine learning approaches to assess the relationship between age, sex, case-control status, and symptom loads for depression and anxiety with the resulting brain components. Univariate analyses revealed strong associations between age and sex with mainly global but also regional specific brain components, with varying degrees of multimodal involvement. In contrast, there were no significant associations with case-control status, nor symptom loads for depression and anxiety with the brain components, nor any interaction effects with age and sex. Machine learning revealed low model performance for classifying patients from controls and predicting symptom loads for depression and anxiety, but high age prediction accuracy. Multimodal fusion of brain imaging data alone may not be sufficient for dissecting the clinical and neurobiological heterogeneity of depression. Precise clinical stratification and methods for brain phenotyping at the individual level based on large training samples may be needed to parse the neuroanatomy of depression.

PMID: 31571370 [PubMed - as supplied by publisher]

Functional-structural relationship in large-scale brain networks of patients with end stage renal disease after kidney transplantation: A longitudinal study.

Wed, 10/02/2019 - 16:20

Functional-structural relationship in large-scale brain networks of patients with end stage renal disease after kidney transplantation: A longitudinal study.

Hum Brain Mapp. 2019 Oct 01;:

Authors: Chen HJ, Wang YF, Wen J, Xu Q, Lu GM, Zhang LJ

Abstract
It is unclear how the brain network changed after kidney transplantation (KT). We explored the patterns of large-scale complex network after KT in end-stage renal disease (ESRD) patients with resting-state functional MRI (rs-fMRI) and diffusion tensor imaging (DTI). Twenty-one ESRD patients (14 men; mean age, 31.5 ± 9.9 years) scheduled for KT and 17 age- and gender-matched healthy controls (HC) (8 men; mean age, 28.9 ± 7.2 years) were enrolled in this study. Each participant underwent rs-fMRI and DTI scans in three time points (pre-KT, 1 and 6 months after KT [for ESRD]). Graph theory analysis was used to characterize the topological properties by using functional and structural network connectivities intergroup correlation analysis was performed between functional/structural MR indexes and clinical markers. Compared with HC, pre-KT ESRD patients showed an altered topological organization in both functional and structural networks. Compared with pre-KT, increased node degree and node efficiency were observed for both functional and structural networks at 1 month after KT (all p < .05), which were further increased at 6 months after KT (p < .05). Both functional and structural networks did not recover completely at 6 months after KT (all p < .05). The patients showed an increased functional-structural connectivity coupling at 1 month after KT compared with HC (p = .041). A trend of progressive recovery of functional and structural connectivity networks was observed in ERSD patients after KT, which did not recover to the normal levels even in 6 months after KT. The study results underlie cognitive function recovery in ESRD patients following KT in the neuropathophysiological perspective.

PMID: 31571368 [PubMed - as supplied by publisher]

Generalizability of machine learning for classification of schizophrenia based on resting-state functional MRI data.

Wed, 10/02/2019 - 16:20

Generalizability of machine learning for classification of schizophrenia based on resting-state functional MRI data.

Hum Brain Mapp. 2019 Oct 01;:

Authors: Cai XL, Xie DJ, Madsen KH, Wang YM, Bögemann SA, Cheung EFC, Møller A, Chan RCK

Abstract
Machine learning has increasingly been applied to classification of schizophrenia in neuroimaging research. However, direct replication studies and studies seeking to investigate generalizability are scarce. To address these issues, we assessed within-site and between-site generalizability of a machine learning classification framework which achieved excellent performance in a previous study using two independent resting-state functional magnetic resonance imaging data sets collected from different sites and scanners. We established within-site generalizability of the classification framework in the main data set using cross-validation. Then, we trained a model in the main data set and investigated between-site generalization in the validated data set using external validation. Finally, recognizing the poor between-site generalization performance, we updated the unsupervised algorithm to investigate if transfer learning using additional unlabeled data were able to improve between-site classification performance. Cross-validation showed that the published classification procedure achieved an accuracy of 0.73 using majority voting across all selected components. External validation found a classification accuracy of 0.55 (not significant) and 0.70 (significant) using the direct and transfer learning procedures, respectively. The failure of direct generalization from one site to another demonstrates the limitation of within-site cross-validation and points toward the need to incorporate efforts to facilitate application of machine learning across multiple data sets. The improvement in performance with transfer learning highlights the importance of taking into account the properties of data when constructing predictive models across samples and sites. Our findings suggest that machine learning classification result based on a single study should be interpreted cautiously.

PMID: 31571320 [PubMed - as supplied by publisher]

Increased cerebellar-default-mode network connectivity at rest in obsessive-compulsive disorder.

Wed, 10/02/2019 - 16:20

Increased cerebellar-default-mode network connectivity at rest in obsessive-compulsive disorder.

Eur Arch Psychiatry Clin Neurosci. 2019 Sep 30;:

Authors: Lv D, Ou Y, Chen Y, Yang R, Zhong Z, Jia C, Sun L, Wang Y, Zhang G, Sun Z, Wang W, Wang Y, Wang X, Guo W, Li P

Abstract
Abnormalities of the cerebellum and default-mode network (DMN) in patients with obsessive-compulsive disorder (OCD) have been widely reported. However, alterations of reciprocal functional connections between the cerebellum and DMN at rest in OCD remain unclear. Forty patients with OCD and 38 gender-, age-, and education-matched healthy controls (HCs) underwent resting-state functional magnetic resonance imaging scan. Seed-based functional connectivity (FC) and support vector machine (SVM) were applied to analyze the imaging data. Compared with HCs, patients with OCD exhibited increased FCs between the left Crus I-left superior medial prefrontal cortex (MPFC) and between the right Crus I-left superior MPFC, left middle MPFC, and left middle temporal gyrus (MTG). A significantly negative correlation was observed between the right Crus I-left MTG connectivity and the Yale-Brown Obsessive-Compulsive Scale compulsion subscale scores in the OCD group (r = - 0.476, p = 0.002, Bonferroni corrected). SVM classification analysis indicated that a combination of the left Crus I-left superior MPFC connectivity and the right Crus I-left middle MPFC connectivity can be used to discriminate patients with OCD from HCs with a sensitivity of 85.00%, specificity of 68.42%, and accuracy of 76.92%. Our study highlights the contribution of the cerebellar-DMN connectivity in OCD pathophysiology and provides new findings to OCD research.

PMID: 31570980 [PubMed - as supplied by publisher]

Aberrant patterns of default-mode network functional connectivity associated with metabolic syndrome: A resting-state study.

Tue, 10/01/2019 - 15:00

Aberrant patterns of default-mode network functional connectivity associated with metabolic syndrome: A resting-state study.

Brain Behav. 2019 Sep 30;:e01333

Authors: Rashid B, Dev SI, Esterman M, Schwarz NF, Ferland T, Fortenbaugh FC, Milberg WP, McGlinchey RE, Salat DH, Leritz EC

Abstract
INTRODUCTION: Metabolic syndrome (MetS) is a clustering of three or more cardiovascular risk factors (RF), including hypertension, obesity, high cholesterol, or hyperglycemia. MetS and its component RFs are more prevalent in older age, and can be accompanied by alterations in brain structure. Studies have shown altered functional connectivity (FC) in samples with individual RFs as well as in clinical populations that are at higher risk to develop MetS. These studies have indicated that the default mode network (DMN) may be particularly vulnerable, yet little is known about the overall impact of MetS on FC in this network.
METHODS: In this study, we evaluated the integrity of FC to the DMN in participants with MetS relative to non-MetS individuals. Using a seed-based connectivity analysis approach, resting-state functional MRI (fMRI) data were analyzed, and the FC measures among the DMN seed (isthmus of the cingulate) and rest of the brain voxels were estimated.
RESULTS: Participants with MetS demonstrated reduced positive connectivity between the DMN seed and left superior frontal regions, and reduced negative connectivity between the DMN seed and left superior parietal, left postcentral, right precentral, right superior temporal and right superior parietal regions, after accounting for age- and sex-effects.
CONCLUSIONS: Our results suggest that MetS is associated with alterations in FC between the DMN and other regions of the brain. Furthermore, these results indicate that the overall burden of vascular RFs associated with MetS may, in part, contribute to the pathophysiology underlying aberrant FC in the DMN.

PMID: 31568716 [PubMed - as supplied by publisher]

Resting-state functional magnetic resonance imaging versus task-based activity for language mapping and correlation with perioperative cortical mapping.

Tue, 10/01/2019 - 15:00

Resting-state functional magnetic resonance imaging versus task-based activity for language mapping and correlation with perioperative cortical mapping.

Brain Behav. 2019 Sep 30;:e01362

Authors: Lemée JM, Berro DH, Bernard F, Chinier E, Leiber LM, Menei P, Ter Minassian A

Abstract
INTRODUCTION: Preoperative language mapping using functional magnetic resonance imaging (fMRI) aims to identify eloquent areas in the vicinity of surgically resectable brain lesions. fMRI methodology relies on the blood-oxygen-level-dependent (BOLD) analysis to identify brain language areas. Task-based fMRI studies the BOLD signal increase in brain areas during a language task to identify brain language areas, which requires patients' cooperation, whereas resting-state fMRI (rsfMRI) allows identification of functional networks without performing any explicit task through the analysis of the synchronicity of spontaneous BOLD signal oscillation between brain areas. The aim of this study was to compare preoperative language mapping using rsfMRI and task fMRI to cortical mapping (CM) during awake craniotomies.
METHODS: Fifty adult patients surgically treated for a brain lesion were enrolled. All patients had a presurgical language mapping with both task fMRI and rsfMRI. Identified language networks were compared to perioperative language mapping using electric cortical stimulation.
RESULTS: Resting-state fMRI was able to detect brain language areas during CM with a sensitivity of 100% compared to 65.6% with task fMRI. However, we were not able to perform a specificity analysis and compare task-based and rest fMRI with our perioperative setting in the current study. In second-order analysis, task fMRI imaging included main nodes of the SN and main areas involved in semantics were identified in rsfMRI.
CONCLUSION: Resting-state fMRI for presurgical language mapping is easy to implement, allowing the identification of functional brain language network with a greater sensitivity than task-based fMRI, at the cost of some precautions and a lower specificity. Further study is required to compare both the sensitivity and the specificity of the two methods and to evaluate the clinical value of rsfMRI as an alternative tool for the presurgical identification of brain language areas.

PMID: 31568681 [PubMed - as supplied by publisher]

TOMM40 polymorphism is associated with resting-state functional MRI results in patients with Alzheimer's disease.

Tue, 10/01/2019 - 15:00

TOMM40 polymorphism is associated with resting-state functional MRI results in patients with Alzheimer's disease.

Neuroreport. 2019 Nov 06;30(16):1068-1073

Authors: Xiao X, Wei J, Zhang W, Jiao B, Liao X, Pan C, Liu X, Yan X, Tang B, Zhang Y, Wang D, Xing W, Liao W, Shen L

Abstract
OBJECTIVE: Translocase of outer mitochondrial membrane 40 (TOMM40) encodes translocase of the outer mitochondrial membrane (TOM), which is associated with mitochondrial dysfunction in Alzheimer's disease (AD). TOMM40 rs157581-G has been reported to increase susceptibility to AD. However, the effect of TOMM40 rs157581-G in resting-state functional MRI (rs-fMRI) on AD has not been studied. Therefore, we aimed to investigate the role of TOMM40 rs157581-G on rs-fMRI results in AD patients.
METHODS: Twenty-four AD patients were divided into two groups based on TOMM40 rs157581-G status, and clinical and imaging data were compared between the groups.
RESULTS: TOMM40 rs157581-G carriers of AD showed decreased regional homogeneity in the left precuneus and decreased amplitude of low-frequency fluctuations in the bilateral temporal poles compared with noncarriers of AD. TOMM40 rs157581-G carriers of AD also showed increased functional connectivity between the right middle occipital gyrus and the left supramarginal gyrus and decreased connectivity between the left superior occipital gyrus and the right transverse temporal gyrus in comparison with TOMM40 rs157581-G noncarriers.
CONCLUSION: We analyzed rs-fMRI characteristics of TOMM40 rs157581-G carriers of AD for the first time, which suggest that TOMM40 rs157581-G plays a harmful role in AD patients.

PMID: 31568198 [PubMed - in process]

Fused Sparse Network Learning for Longitudinal Analysis of Mild Cognitive Impairment.

Tue, 10/01/2019 - 15:00

Fused Sparse Network Learning for Longitudinal Analysis of Mild Cognitive Impairment.

IEEE Trans Cybern. 2019 Sep 30;:

Authors: Yang P, Zhou F, Ni D, Xu Y, Chen S, Wang T, Lei B

Abstract
Alzheimer's disease (AD) is a neurodegenerative disease with an irreversible and progressive process. To understand the brain functions and identify the biomarkers of AD and early stages of the disease [also known as, mild cognitive impairment (MCI)], it is crucial to build the brain functional connectivity network (BFCN) using resting-state functional magnetic resonance imaging (rs-fMRI). Existing methods have been mainly developed using only a single time-point rs-fMRI data for classification. In fact, multiple time-point data is more effective than a single time-point data in diagnosing brain diseases by monitoring the disease progression patterns using longitudinal analysis. In this article, we utilize multiple rs-fMRI time-point to identify early MCI (EMCI) and late MCI (LMCI), by integrating the fused sparse network (FSN) model with parameter-free centralized (PFC) learning. Specifically, we first construct the FSN framework by building multiple time-point BFCNs. The multitask learning via PFC is then leveraged for longitudinal analysis of EMCI and LMCI. Accordingly, we can jointly learn the multiple time-point features constructed from the BFCN model. The proposed PFC method can automatically balance the contributions of different time-point information via learned specific and common features. Finally, the selected multiple time-point features are fused by a similarity network fusion (SNF) method. Our proposed method is evaluated on the public AD neuroimaging initiative phase-2 (ADNI-2) database. The experimental results demonstrate that our method can achieve quite promising performance and outperform the state-of-the-art methods.

PMID: 31567112 [PubMed - as supplied by publisher]

Blood biomarkers are associated with brain function and blood flow following sport concussion.

Tue, 10/01/2019 - 15:00
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Blood biomarkers are associated with brain function and blood flow following sport concussion.

J Neuroimmunol. 2018 06 15;319:1-8

Authors: Di Battista AP, Churchill N, Schweizer TA, Rhind SG, Richards D, Baker AJ, Hutchison MG

Abstract
BACKGROUND: Secondary injury pathophysiology after sport-related concussion (SRC) is poorly understood. Blood biomarkers may be a useful tool for characterizing these processes, yet there are limitations in their application as a single modality. Combining blood biomarker analysis with advanced neuroimaging may help validate their continued utility in brain injury research by elucidating important secondary injury mechanisms. Hence, the purpose of this study was to evaluate co-modulation between peripheral blood biomarkers and advanced functional brain imaging after SRC.
METHODS: Forty-three university level athletes from 7 sports were recruited (16 recently concussed athletes; 15 healthy athletes with no prior history of concussion; 12 healthy athletes with a history of concussion). Seven blood biomarkers were evaluated: s100B, total tau (T-tau), von Willebrand factor (vWF), brain derived neurotrophic factor (BDNF), peroxiredoxin (PRDX)-6, monocyte chemoattractant protein (MCP)-1 and -4. Resting-state functional MRI was employed to assess global neural connectivity (Gconn), and arterial spin labelling was used to evaluate cerebral blood flow (CBF). We tested for concurrent alterations in blood biomarkers and MRI measures of brain function between athlete groups using a non-parametric, bootstrapped resampling framework.
RESULTS: Compared to healthy athletes, recently concussed athletes showed greater concurrent alterations in several peripheral blood biomarker and MRI measures: a decrease in T-Tau and Gconn, a decrease in T-Tau and CBF, a decrease in Gconn with elevated PRDX-6, a decrease in CBF with elevated PRDX-6, and a decrease in Gconn with elevated MCP-4. In addition, compared to healthy athletes with no concussion history, healthy athletes with a history of concussion displayed greater concurrent alterations in blood biomarkers and Gconn; lower GConn covaried with higher blood levels of s100B and MCP-4.
CONCLUSION: We identified robust relationships between peripheral blood biomarkers and MRI measures in both recently concussed athletes and healthy athletes with a history of concussion. The results from this combinatorial approach further support that human concussion is associated with inflammation, oxidative stress, and cellular damage, and that physiological perturbations may extend chronically beyond recovery. Finally, our results support the continued implementation of blood biomarkers as a tool to investigate brain injury, particularly in a multimodal framework.

PMID: 29685283 [PubMed - indexed for MEDLINE]

Multilocus genetic profile in dopaminergic pathway modulates the striatum and working memory.

Tue, 10/01/2019 - 15:00
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Multilocus genetic profile in dopaminergic pathway modulates the striatum and working memory.

Sci Rep. 2018 03 29;8(1):5372

Authors: Wang C, Liu B, Zhang X, Cui Y, Yu C, Jiang T

Abstract
Dopamine is critical in pathophysiology and therapy of schizophrenia. Many studies have reported altered dopaminergic activity in the dorsal but not ventral striatum in schizophrenia. Based on the largest genome-wide association study of schizophrenia to date, we calculated the polygenic risk score (PGRS) of each subject in a healthy general group, including all variations in the set of functionally related genes involved in dopamine neurotransmitter system. We aimed to test whether the genetic variations in the dopaminergic pathway that have been identified as associated with schizophrenia are related to the function of the striatum and to working memory. We found that a higher PGRS was significantly associated with impairment in working memory. Moreover, resting-state functional connectivity analysis revealed that as the polygenic risk score increased, the connections between left putamen and caudate and the default mode network grew stronger, while the connections with the fronto-parietal network grew weaker. Our findings may shed light on the biological mechanism underlying the "dopamine hypothesis" of schizophrenia and provide some implications regarding the polygenic effects on the dopaminergic activity in the risk for schizophrenia.

PMID: 29599495 [PubMed - indexed for MEDLINE]

Resting state functional magnetic resonance imaging in Attention deficit hyperactivity disorder.

Mon, 09/30/2019 - 13:40
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Resting state functional magnetic resonance imaging in Attention deficit hyperactivity disorder.

Radiologia. 2019 Sep 25;:

Authors: Carmona Franceschi MJ, Ascencio Lancheros JL, Ochoa Gómez JF, Rueda Nobmann MT, Donado Gómez JH, Blazicevich Carrillo L

Abstract
OBJECTIVE: To explore whether children and adolescents with attention deficit/hyperactivity disorder (ADHD) have altered the functional connectivity between the executive control network and the default mode network.
METHODS: Exploratory study of a diagnostic test, prospective, case and control design. A total of 56 participants were recruited consecutively (29 inattentive or combined ADHD subtype and 27 controls) between 7 and 16 years old, male, right dominance. DSM-5 was applied as reference test and a battery of neuropsychological tests to confirm the diagnosis and assess comorbidities. Resting state functional magnetic resonance imaging was performed as an index test. The application and evaluation of the tests was blind. The brain regions were chosen a priori and the region of interest technique was used. The functional connectivity of the anterior cingulate cortex (ACC) was evaluated with: the precuneus (P), the posterior cingulate cortex (PCC) and the dorsomedial prefrontal cortex (DMPC).
RESULTS: The functional connectivity in each of the associations evaluated in the patients with ADHD compared with the controls were: P_D=0.41 vs 0.44; CCP_D=0.43 vs 0.53; CPDM_D=0.75 vs. 0.79; P_I=0.40 vs 0.41; CCP_I=0.48 vs 0.53; CPDM_I=0.76 vs. 0.72). D: right side I: left side. Value of p> 0.05.
CONCLUSION: Cerebral functional connectivity at rest is lower in ADHD patients when compared with healthy controls, however, the difference was not statistically significant.

PMID: 31563420 [PubMed - as supplied by publisher]

A dimensional approach to jealousy reveals enhanced fronto-striatal, insula and limbic responses to angry faces.

Sun, 09/29/2019 - 00:00

A dimensional approach to jealousy reveals enhanced fronto-striatal, insula and limbic responses to angry faces.

Brain Struct Funct. 2019 Sep 27;:

Authors: Zheng X, Luo L, Li J, Xu L, Zhou F, Gao Z, Becker B, Kendrick KM

Abstract
Jealousy is a complex social emotion combining the different primary emotions of anger, fear and sadness. Previous evidence has suggested the involvement of fronto-striatal dopaminergic circuitry in pathological jealousy, although little is known about overlaps with the neural representation of primary emotions involved in non-morbid jealousy and the utility of a dimensional neuroimaging approach. In the current study, 85 healthy subjects underwent fMRI during an emotional face recognition paradigm and resting state. A total of 150 faces (happy, angry, fearful, sad, neutral) were presented and subjects required to identify the expression and rate its intensity. Trait jealousy was assessed using the Multidimensional Jealousy Scale. Behavioral results showed that only intensity ratings of angry faces were positively associated with subjects' jealousy scores. During processing of angry versus neutral expression faces, subjects with elevated jealousy exhibited increased activation in the right thalamus, insula, fusiform gyrus and hippocampus, left dorsal striatum, superior parietal lobule and bilateral cerebellum and inferior frontal gyrus after controlling for trait aggression and sex. Functional connectivity between the inferior frontal gyrus and dorsal striatum was also increased. No associations with resting-state functional connectivity were found. Overall, the present study demonstrates an association between exaggerated jealousy and increased intensity ratings of angry faces as well as activity and functional connectivity of the dorsal striatal-inferior frontal circuitry. Thus, increased emotional responsivity to social threat and enhanced activity in limbic regions and dopaminergic fronto-striatal circuitry may be features of both non-morbid and pathological jealousy confirming the utility of a dimensional approach.

PMID: 31560099 [PubMed - as supplied by publisher]

Sex differences in functional and molecular neuroimaging biomarkers of Alzheimer's disease in cognitively normal older adults with subjective memory complaints.

Sun, 09/29/2019 - 00:00
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Sex differences in functional and molecular neuroimaging biomarkers of Alzheimer's disease in cognitively normal older adults with subjective memory complaints.

Alzheimers Dement. 2018 09;14(9):1204-1215

Authors: Cavedo E, Chiesa PA, Houot M, Ferretti MT, Grothe MJ, Teipel SJ, Lista S, Habert MO, Potier MC, Dubois B, Hampel H, INSIGHT-preAD Study Group, Alzheimer Precision Medicine Initiative (APMI)

Abstract
INTRODUCTION: Observational multimodal neuroimaging studies indicate sex differences in Alzheimer's disease pathophysiological markers.
METHODS: Positron emission tomography brain amyloid load, neurodegeneration (hippocampus and basal forebrain volumes adjusted to total intracranial volume, cortical thickness, and 2-deoxy-2-[fluorine-18]fluoro-D-glucose-positron emission tomography metabolism), and brain resting-state functional connectivity were analyzed in 318 cognitively intact older adults from the INSIGHT-preAD cohort (female n = 201, male n = 117). A linear mixed-effects model was performed to investigate sex effects and sex∗apolipoprotein E genotype interaction on each marker as well as sex∗amyloid group interaction for non-amyloid markers.
RESULTS: Men compared with women showed higher anterior cingulate cortex amyloid load (P = .009), glucose hypometabolism in the precuneus (P = .027), posterior cingulate (P < .001) and inferior parietal (P = .043) cortices, and lower resting-state functional connectivity in the default mode network (P = .024). No brain volumetric markers showed differences between men and women. Sex∗apolipoprotein E genotype and sex∗amyloid status interactions were not significant.
DISCUSSION: Our findings suggest that cognitively intact older men compared with women have higher resilience to pathophysiological processes of Alzheimer's disease.

PMID: 30201102 [PubMed - indexed for MEDLINE]

Reduced integration and improved segregation of functional brain networks in Alzheimer's disease.

Sun, 09/29/2019 - 00:00
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Reduced integration and improved segregation of functional brain networks in Alzheimer's disease.

J Neural Eng. 2018 04;15(2):026023

Authors: Kabbara A, Eid H, El Falou W, Khalil M, Wendling F, Hassan M

Abstract
OBJECTIVE: Emerging evidence shows that cognitive deficits in Alzheimer's disease (AD) are associated with disruptions in brain functional connectivity. Thus, the identification of alterations in AD functional networks has become a topic of increasing interest. However, to what extent AD induces disruption of the balance of local and global information processing in the human brain remains elusive. The main objective of this study is to explore the dynamic topological changes of AD networks in terms of brain network segregation and integration.
APPROACH: We used electroencephalography (EEG) data recorded from 20 participants (10 AD patients and 10 healthy controls) during resting state. Functional brain networks were reconstructed using EEG source connectivity computed in different frequency bands. Graph theoretical analyses were performed assess differences between both groups.
MAIN RESULTS: Results revealed that AD networks, compared to networks of age-matched healthy controls, are characterized by lower global information processing (integration) and higher local information processing (segregation). Results showed also significant correlation between the alterations in the AD patients' functional brain networks and their cognitive scores.
SIGNIFICANCE: These findings may contribute to the development of EEG network-based test that could strengthen results obtained from currently-used neurophysiological tests in neurodegenerative diseases.

PMID: 29451125 [PubMed - indexed for MEDLINE]

Large scale networks for human hand-object interaction: Functionally distinct roles for two premotor regions identified intraoperatively.

Fri, 09/27/2019 - 10:20

Large scale networks for human hand-object interaction: Functionally distinct roles for two premotor regions identified intraoperatively.

Neuroimage. 2019 Sep 23;:116215

Authors: Simone L, Fornia L, Viganò L, Sambataro F, Rossi M, Leonetti A, Puglisi G, Howells H, Bellacicca A, Bello L, Cerri G

Abstract
The development of awake intraoperative brain-mapping procedures for resection of brain tumors is of growing interest in neuroscience, because it enables direct testing of brain tissue, previously only possible in non-human primates. In a recent study performed in this setting specific effects can be induced by direct electrical stimulation on different sectors of premotor cortex during the execution of a hand manipulation task. Specifically, direct electrical stimulation applied on a dorsal sector of precentral cortex led to an increase in motor unit recruitment in hand muscles during execution of a hand manipulation task (Recruitment sector). The opposite effect was elicited when electrical stimulation was delivered more ventrally on the precentral cortex (Suppression sector). We studied whether the different effects on motor behavior induced by direct electrical stimulation applied on the two sites of the precentral cortex underlie differences in their functional connectivity with other brain areas, measured using resting state fMRI. Using healthy adults scanned as part of the Human Connectome Project, we computed the functional connectivity of each sector used as seeds. The functional connectivity patterns of the two intraoperative seeds was similar but cross-comparison revealed that the left and right Recruitment sectors had stronger functional connections with the hand region of the sensorimotor cortex, while the right Suppression region displayed stronger functional connectivity with a bilateral set of parieto-frontal areas crucial for the integration of perceptual and cognitive hand-related sensorimotor processes required for goal-related hand actions. Our results suggest that analyzing data obtained in the intraoperative setting with resting state functional magnetic resonance imaging in healthy brains can yield useful insight into the roles of different premotor sectors directly involved in hand-object interaction.

PMID: 31557544 [PubMed - as supplied by publisher]

Resting-state functional magnetic resonance study of primary open-angle glaucoma based on voxelwise brain network degree centrality.

Fri, 09/27/2019 - 10:20

Resting-state functional magnetic resonance study of primary open-angle glaucoma based on voxelwise brain network degree centrality.

Neurosci Lett. 2019 Sep 23;:134500

Authors: Zhang Q, Shu Y, Li X, Xiong C, Li P, Pang Y, Ye W, Yang L, Zeng X, Zhang X

Abstract
OBJECTIVE: To investigate alterations in the functional brain networks of patients with primary open-angle glaucoma (POAG) by using the resting-state functional magnetic resonance imaging (fMRI) voxelwise degree centrality (DC) method.
MATERIALS AND METHODS: Thirteen patients with POAG and thirteen healthy subjects were recruited for this study, and each participant underwent a rs-fMRI scan. The voxelwise DC method was used to assess the features of spontaneous brain activity. The differences in the mean DC across brain regions between the POAG group and the healthy control group were analyzed, and the correlations between the DC values of altered brain regions and various clinical ophthalmic parameters were analyzed in the POAG group.
RESULTS: Compared with healthy controls, patients with POAG exhibited significantly decreased DC values of the left superior frontal gyrus and the left postcentral gyrus as well as significantly increased DC values of the left superior occipital gyrus. In POAG patients, the DC value of the left superior occipital gyrus was significantly positively correlated with age (r = 0.571, P = 0.042) and negatively correlated with the intraocular pressure of the right eye (r=-0.625, P = 0.022). The DC value of the left superior frontal gyrus was significantly positively correlated with the right eye average cup-to-disc ratio (r = 0.683, P = 0.010), vertical cup-to-disc ratio (r = 0.779, P = 0.002), and pattern standard deviation (r = 0.567, P = 0.043).
CONCLUSION: The results showed that altered DC values in three brain regions may reflect the underlying pathological mechanisms of POAG. Decreased DC values of the left superior occipital gyrus could be useful imaging markers for determining the extent of brain damage in POAG patients compared to healthy subjects.

PMID: 31557522 [PubMed - as supplied by publisher]

Psychological Resilience Enhances the Orbitofrontal Network in the Elderly With Mild Cognitive Impairment.

Fri, 09/27/2019 - 10:20
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Psychological Resilience Enhances the Orbitofrontal Network in the Elderly With Mild Cognitive Impairment.

Front Psychiatry. 2019;10:615

Authors: Son SJ, Park B, Choi JW, Roh HW, Kim NR, Sin JE, Kim H, Lim HK, Hong CH

Abstract
Background: It has been suggested that maintaining the efficient organization of the brain's functional connectivity (FC) supports neuroflexibility under neurogenerative stress. This study examined psychological resilience-related FC in 112 older adults with mild cognitive impairment (MCI). Methods: Using a resting-state functional magnetic resonance imaging (fMRI) approach, we investigated reorganization of the orbitofrontal gyrus (OFG)/amygdala (AMG)/hippocampus (HP)/parahippocampal gyrus (PHG) FC according to the different levels of resilience scale. Results: Compared with the low resilient group, the high resilient group had greater connectivity strengths between the left inferior OFG and right superior OFG (P < 0.05, Bonferroni corrected), between the right inferior OFG and left PHG (P < 0.05, Bonferroni corrected), and between the right middle OFG and left PHG (false discovery rate < 0.05). Conclusion: Psychological resilience may be associated with enhancement of the orbitofrontal network in the elderly with MCI.

PMID: 31555158 [PubMed]

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