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Altered spontaneous functional activity of the right precuneus and cuneus in patients with persistent postural-perceptual dizziness.

Thu, 07/18/2019 - 18:32

Altered spontaneous functional activity of the right precuneus and cuneus in patients with persistent postural-perceptual dizziness.

Brain Imaging Behav. 2019 Jul 16;:

Authors: Li K, Si L, Cui B, Ling X, Shen B, Yang X

Abstract
Persistent postural-perceptual dizziness (PPPD) is a functional vestibular disorder, and is the most common cause of chronic vestibular syndrome. However, the pathogenesis of PPPD is currently unclear. This study aimed to analyze the changes of brain spontaneous functional activities in PPPD patients during the resting state, and to explore the underlying pathogenesis of PPPD, particularly the abnormal integration of visual and vestibular information. Ten PPPD patients and 10 healthy controls were enrolled from January to June 2018, and baseline data were collected from all subjects. Videonystagmography (VNG), the vestibular caloric test, the video head impulse test (vHIT) and vestibular evoked myogenic potentials (VEMPs) were measured to exclude peripheral vestibular lesions. Functional MRI (fMRI) was conducted in PPPD patients and healthy controls. The amplitude of low frequency fluctuation (ALFF) and regional homogeneity (ReHo), and functional connectivity were calculated to explore changes in brain spontaneous functional activity during the resting state. Compared with healthy controls, ALFF and ReHo values in the right precuneus and cuneus were significantly lower in PPPD patients (both P < 0.05). Further seed-based functional connectivity analysis showed decreased functional connectivity between precuneus, cuneus and left precentral gyrus (P < 0.05). Our findings suggest that the spontaneous functional activity of cuneus and precuneus in PPPD patients were altered, potentially leading to abnormal integration of visual and vestibular information. Weakened functional connectivity between the precuneus and the precentral gyrus may be associated with aggravated symptoms during upright posture, active or passive movements.

PMID: 31313022 [PubMed - as supplied by publisher]

Greater Anteroposterior Default Mode Network Functional Connectivity in Long-Term Elderly Yoga Practitioners.

Thu, 07/18/2019 - 18:32

Greater Anteroposterior Default Mode Network Functional Connectivity in Long-Term Elderly Yoga Practitioners.

Front Aging Neurosci. 2019;11:158

Authors: Santaella DF, Balardin JB, Afonso RF, Giorjiani GM, Sato JR, Lacerda SS, Amaro E, Lazar S, Kozasa EH

Abstract
Large-scale brain networks exhibit changes in functional connectivity during the aging process. Recent literature data suggests that Yoga and other contemplative practices may revert, at least in part, some of the aging effects in brain functional connectivity, including the Default Mode Network (DMN). The aim of this cross-sectional investigation was to compare resting-state functional connectivity of the medial prefrontal cortex (MPFC) and posterior cingulate cortex-precuneus (PCC-Precuneus) in long-term elderly Yoga practitioners and healthy paired Yoga-naïve controls. Two paired groups: yoga (Y-20 women, Hatha Yoga practitioners; practicing a minimum of twice a week with a frequency of at least 8 years) and a control group (C-20 women, Yoga-naïve, matched by age, years of formal education, and physical activity) were evaluated for: Mini Mental State Examination (MMSE), Beck Depression Inventory (BDI), Instrumental Activities of Daily Living (IADL), and open-eyes resting-state functional magnetic resonance imaging (fMRI)-seed to voxel connectivity analysis (CONN toolbox 17.f) with pre-processing-realignment and unwarping, slice-timing correction, segmentation, normalization, outlier detection, and spatial filtering. The analysis included a priori regions of interest (ROI) of DMN main nodes-MPFC and PCC-Precuneus. There was no difference between groups in terms of: age, years of formal education, MMSE, BDI and IADL. The Yoga group had a higher correlation between MPFC and the right angular gyrus (AGr), compared to the controls. Elderly women with at least 8 years of yoga practice presented greater intra-network anteroposterior brain functional connectivity of the DMN. This finding may contribute to the understanding of the influences of practicing Yoga for a healthier cognitive aging process.

PMID: 31312135 [PubMed]

Resting-state functional magnetic resonance imaging (fMRI) and functional connectivity density mapping in patients with corneal ulcer.

Wed, 07/17/2019 - 21:31

Resting-state functional magnetic resonance imaging (fMRI) and functional connectivity density mapping in patients with corneal ulcer.

Neuropsychiatr Dis Treat. 2019;15:1833-1844

Authors: Zhu F, Tang L, Zhu P, Lin Q, Yuan Q, Shi W, Li B, Ye L, Min Y, Su T, Shao Y

Abstract
Purpose: To investigate alternations in spontaneous brain activities reflected by functional connectivity density (FCD) in patients with corneal ulcer (CU) using resting-state functional connectivity (rsFC).
Methods: We recruited 24 patients with CU (12 males, 12 females), and 24 healthy controls (HCs; 12 males, 12 females) matched for age, gender and education status. Functional magnetic resonance imaging examinations were performed on all subjects in a resting state and the following parameters determined: rsFC, long-range FCD (longFCD) and short-range FCD (IFCD). Receiver operating characteristic (ROC) curves were then used to differentiate patients with CU from HCs.
Results: Compared with HCs, CU patients showed significantly reduced rsFC values in the right cerebellum posterior lobe gyrus, right middle frontal gyrus/inferior frontal gyrus/superior frontal gyrus and left inferior parietal lobule/precuneus. Significantly reduced longFCD values were found in the right hippocampus/inferior temporal gyrus and the left inferior temporal gyrus. Moreover, compared with HCs, IFCD values were significantly reduced in the left inferior temporal gyrus/middle temporal gyrus, left limbic lobe/medial frontal gyrus, and left precuneus/limbic lobe, but were significantly increased in the right insula/superior temporal gyrus, left superior temporal gyrus/inferior frontal gyrus/insula, right superior temporal gyrus/postcentral gyrus, and left precentral gyrus.
Conclusions: Patients with CU exhibited alterations in spontaneous brain activities in several brain areas. These novel findings may help to reveal the neuropathological mechanisms underlying CU.
This study provides a direction for further exploration of underlying neural mechanisms of CU and facilitate the clinical diagnosis and treatment of CU.

PMID: 31308676 [PubMed]

Enhanced baseline activity in the left ventromedial putamen predicts individual treatment response in drug-naive, first-episode schizophrenia: Results from two independent study samples.

Wed, 07/17/2019 - 21:31

Enhanced baseline activity in the left ventromedial putamen predicts individual treatment response in drug-naive, first-episode schizophrenia: Results from two independent study samples.

EBioMedicine. 2019 Jul 12;:

Authors: Li H, Guo W, Liu F, Chen J, Su Q, Zhang Z, Fan X, Zhao J

Abstract
BACKGROUND: Antipsychotic medications are the common treatment for schizophrenia. However, reliable biomarkers that can predict individual treatment response are still lacking. The present study aimed to examine whether baseline putamen activity can predict individual treatment response in schizophrenia.
METHODS: Two independent samples of patients with drug-naive, first-episode schizophrenia (32 patients in sample 1 and 44 in sample 2) and matched healthy controls underwent resting-state functional magnetic resonance imaging (fMRI) at baseline. Patients were treated with olanzapine for 8 weeks; symptom severity was assessed using the Positive and Negative Syndrome Scale (PANSS) at baseline and week 8. Fractional amplitude of low frequency fluctuation (fALFF) and pattern classification techniques were used to analyze the data.
FINDINGS: Univariate analysis shows an elevated pre-treatment fALFF in the left ventromedial putamen in both patient samples compared to healthy controls (p's < 0.001). The support vector regression (SVR) analysis suggests a positive relationship between baseline pre-treatment fALFF in the left ventromedial putamen and improvement in positive symptom at week 8 in each patient group using a cross-validated method (r = 0.452, p = .002; r = 0.511, p = .003, respectively).
INTERPRETATION: Our study suggests that elevated pre-treatment mean fALFF in the left ventromedial putamen may predict individual therapeutic response to olanzapine treatment in drug-naive, first-episode patients with schizophrenia. Future studies are needed to confirm whether this finding is generalizable to patients with schizophrenia treated with other antipsychotic medications. FUND: The National Key R&D Program of China and the National Natural Science Foundation of China.

PMID: 31307956 [PubMed - as supplied by publisher]

Changes in volumetric and metabolic parameters relate to differences in exposure to sub-concussive head impacts.

Wed, 07/17/2019 - 21:31

Changes in volumetric and metabolic parameters relate to differences in exposure to sub-concussive head impacts.

J Cereb Blood Flow Metab. 2019 Jul 15;:271678X19862861

Authors: Champagne AA, Coverdale NS, Germuska M, Bhogal AA, Cook DJ

Abstract
Structural and calibrated magnetic resonance imaging data were acquired on 44 collegiate football players prior to the season (PRE), following the first four weeks in-season (PTC) and one month after the last game (POST). Exposure data collected from g-Force accelerometers mounted to the helmet of each player were used to split participants into HIGH (N = 22) and LOW (N = 22) exposure groups, based on the frequency of impacts sustained by each athlete. Significant decreases in grey-matter volume specific to the HIGH group were documented at POST (P = 0.009), compared to baseline. Changes in resting cerebral blood flow (CBF0), corrected for partial volume effects, were observed within the HIGH group, throughout the season (P < 0.0001), suggesting that alterations in perfusion may follow exposure to sub-concussive collisions. Co-localized significant increases in cerebral metabolic rate of oxygen consumption (CMRO2|0) mid-season were also documented in the HIGH group, with respect to both PRE- and POST values. No physiological changes were observed in the LOW group. Therefore, cerebral metabolic demand may be elevated in players with greater exposure to head impacts. These results provide novel insight into the effects of sub-concussive collisions on brain structure and cerebrovascular physiology and emphasize the importance of multi-modal imaging for a complete characterization of cerebral health.

PMID: 31307284 [PubMed - as supplied by publisher]

Network analysis of whole-brain fMRI dynamics: A new framework based on dynamic communicability.

Tue, 07/16/2019 - 18:30

Network analysis of whole-brain fMRI dynamics: A new framework based on dynamic communicability.

Neuroimage. 2019 Jul 12;:116007

Authors: Gilson M, Kouvaris NE, Deco G, Mangin JF, Poupon C, Lefranc S, Rivière D, Zamora-López G

Abstract
Neuroimaging techniques such as MRI have been widely used to explore the associations between brain areas. Structural connectivity (SC) captures the anatomical pathways across the brain and functional connectivity (FC) measures the correlation between the activity of brain regions. These connectivity measures have been much studied using network theory in order to uncover the distributed organization of brain structures, in particular FC for task-specific brain communication. However, the application of network theory to study FC matrices is often "static" despite the dynamic nature of time series obtained from fMRI. The present study aims to overcome this limitation by introducing a network-oriented analysis applied to whole-brain effective connectivity (EC) useful to interpret the brain dynamics. Technically, we tune a multivariate Ornstein-Uhlenbeck (MOU) process to reproduce the statistics of the whole-brain resting-state fMRI signals, which provides estimates for MOU-EC as well as input properties (similar to local excitabilities). The network analysis is then based on the Green function (or network impulse response) that describes the interactions between nodes across time for the estimated dynamics. This model-based approach provides time-dependent graph-like descriptor, named communicability, that characterize the roles that either nodes or connections play in the propagation of activity within the network. They can be used at both global and local levels, and also enables the comparison of estimates from real data with surrogates (e.g. random network or ring lattice). In contrast to classical graph approaches to study SC or FC, our framework stresses the importance of taking the temporal aspect of fMRI signals into account. Our results show a merging of functional communities over time (in which input properties play a role), moving from segregated to global integration of the network activity. Our formalism sets a solid ground for the analysis and interpretation of fMRI data, including task-evoked activity.

PMID: 31306771 [PubMed - as supplied by publisher]

Functional network connectivity changes in children with attention-deficit hyperactivity disorder: a resting-state fMRI study.

Tue, 07/16/2019 - 18:30

Functional network connectivity changes in children with attention-deficit hyperactivity disorder: a resting-state fMRI study.

Int J Dev Neurosci. 2019 Jul 12;:

Authors: Jiang K, Yi Y, Li L, Li H, Shen H, Zhao F, Xu Y, Zheng A

Abstract
The study aimed to investigate the pathologic mechanism of functional brain regions in attention-deficit hyperactivity disorder (ADHD) patients through making comparisons of normal and ADHD children from the perspective of the network nodes of brain network and the intensity of functional connection between bilateral of hemispheres by resting-state functional magnetic resonance imaging (fMRI). Thirty-five ADHD and forty-two children were examined by resting-state functional magnetic resonance imaging (fMRI) scans. Data analysis was done via the degree centrality (DC) and voxel-mirrored homotopic connectivity (VMHC) approaches. Compared with healthy subjects, the ADHD group exhibited significantly decreased DC values in the right posterior cingulate gyrus, left medial superior frontal gyrus, right inferior parietal gyrus, right middle frontal gyrus, left superior frontal gyrus and right superior frontal gyrus. Children with ADHD also exhibited some areas with increased DC values compared with healthy children. These regions included the cerebellar anterior lobe, right middle occipital cortex, left middle cingulate gyrus and right middle cingulate gyrus. VMHC analysis all revealed positive activation in a range of brain regions when comparing ADHD and normal children, suggesting that the VMHC scores of children with ADHD were higher in the bilateral superior frontal lobe, bilateral middle occipital lobe, and bilateral cerebellar anterior lobes. This work provides a new approach for examining the neural mechanisms underlying ADHD, demonstrating that the DC and VMHC methods enabled more comprehensive analysis that can be cross-checked.

PMID: 31306738 [PubMed - as supplied by publisher]

Tensor clustering on outer-product of Coefficient and Component Matrices of Independent Component Analysis for Reliable Functional Magnetic Resonance Imaging Data Decomposition.

Tue, 07/16/2019 - 18:30

Tensor clustering on outer-product of Coefficient and Component Matrices of Independent Component Analysis for Reliable Functional Magnetic Resonance Imaging Data Decomposition.

J Neurosci Methods. 2019 Jul 12;:108359

Authors: Hu G, Zhang Q, Waters AB, Li H, Zhang C, Wu J, Cong F, Nickerson LD

Abstract
BACKGROUND: Stability of spatial components is frequently used as a post-hoc selection criteria for choosing the dimensionality of an independent component analysis (ICA) of functional magnetic resonance imaging (fMRI) data. Although the stability of the ICA temporal courses differs from that of spatial components, temporal stability has not been considered during dimensionality decisions.
NEW METHOD: The current study aims to (1) develop an algorithm to incorporate temporal course stability into dimensionality selection and (2) test the impact of temporal course on the stability of the ICA decomposition of fMRI data via tensor clustering. Resting state fMRI data were analyzed with two popular ICA algorithms, InfomaxICA and FastICA, using our new method and results were compared with model order selection based on spatial or temporal criteria alone.
RESULTS: Hierarchical clustering indicated that the stability of the ICA decomposition incorporating spatiotemporal tensor information performed similarly when compared to current best practice. However, we found that component spatiotemporal stability and convergence of the model varied significantly with model order. Considering both may lead to methodological improvements for determining ICA model order. Selected components were also significantly associated with relevant behavioral variables. Comparison with Existing Method: The Kullback-Leibler information criterion algorithm suggests the optimal model order for group ICA is 40, compared to the proposed method with an optimal model order of 20.
CONCLUSION: The current study sheds new light on the importance of temporal course variability in ICA of fMRI data.

PMID: 31306718 [PubMed - as supplied by publisher]

Structural and functional brain connectomes in patients with systemic lupus erythematosus.

Tue, 07/16/2019 - 18:30

Structural and functional brain connectomes in patients with systemic lupus erythematosus.

Eur J Neurol. 2019 Jul 15;:

Authors: Preziosa P, Rocca MA, Ramirez GA, Bozzolo EP, Canti V, Pagani E, Valsasina P, Moiola L, Rovere-Querini P, Manfredi AA, Filippi M

Abstract
BACKGROUND: Systemic lupus erythematosus (SLE) is an immune-mediated disease that may affect the nervous system. We explored the topographical organization of structural and functional brain connectivity in SLE-patients and its correlation with neuropsychiatric involvement and autoantibody profiles.
METHODS: Graph theoretical analysis was applied to diffusion tensor MRI and resting state fMRI data from 32 SLE-patients and 32 age- and sex-matched healthy controls. Structural and functional connectivity matrices between 116 cortical/subcortical brain regions were estimated using a bivariate correlation analysis, and global and nodal network metrics were calculated.
RESULTS: Structural, but not functional, global network properties (strength, transitivity, global efficiency and path length) were abnormal in SLE-patients vs controls (p<0.0001), especially in patients with anti-double stranded DNA (ADNA) autoantibodies (p=0.03). No difference was found according to neuropsychiatric involvement or antiphospholipid autoantibody (APA) status. SLE-patients and controls shared identical structural hubs and the majority of functional hubs. In SLE-patients, all structural hubs showed reduced strength and clustering coefficient compared to controls (p from 0.001 to <0.0001), especially in patients with ADNA autoantibodies. Only a few differences in functional hub properties were found between SLE-patients and controls. Structural and functional hub measures did not differ according to neuropsychiatric involvement or APA status. Significant correlations were found between clinical, MRI and network measures (r from -0.56 to 0.60, p from 0.0003 to 0.05).
CONCLUSIONS: Abnormalities of global and nodal structural connectivity occur in SLE-patients, especially with ADNA autoantibodies, with a diffuse disruption of structural integrity. Functional network integrity may contribute to preserve clinical functions. This article is protected by copyright. All rights reserved.

PMID: 31306535 [PubMed - as supplied by publisher]

Resting-State fMRI Networks in Children with Tuberous Sclerosis Complex.

Tue, 07/16/2019 - 18:30

Resting-State fMRI Networks in Children with Tuberous Sclerosis Complex.

J Neuroimaging. 2019 Jul 14;:

Authors: Ahtam B, Dehaes M, Sliva DD, Peters JM, Krueger DA, Bebin EM, Northrup H, Wu JY, Warfield SK, Sahin M, Grant PE, TACERN Study Group

Abstract
BACKGROUND AND PURPOSE: There are no published studies examining resting state networks (RSNs) and their relationship with neurodevelopmental metrics in tuberous sclerosis complex (TSC). We aimed to identify major resting-state functional magnetic resonance imaging (rs-fMRI) networks in infants with TSC and correlate network analyses with neurodevelopmental assessments, autism diagnosis, and seizure history.
METHODS: Rs-fMRI data from 34 infants with TSC, sedated with propofol during the scan, were analyzed to identify auditory, motor, and visual RSNs. We examined the correlations between auditory, motor, and visual RSNs at approximately 11.5 months, neurodevelopmental outcome at approximately 18.5 months, and diagnosis of autism spectrum disorders at approximately 36 months of age.
RESULTS: RSNs were obtained in 76.5% (26/34) of infants. We observed significant negative correlations between auditory RSN and auditory comprehension test scores (p = .038; r = -.435), as well as significant positive correlations between motor RSN and gross motor skills test scores (p = .023; r = .564). Significant positive correlations between motor RSNs and gross motor skills (p = .012; r = .754) were observed in TSC infants without autism, but not in TSC infants with autism, which could suggest altered motor processing. There were no significant differences in RSNs according to seizure history.
CONCLUSIONS: Negative correlation between auditory RSN, as well as positive correlation between motor RSN and developmental outcome measures might reflect different brain mechanisms and, when identified, may be helpful in predicting later function. A larger study of TSC patients with a healthy control group is needed before auditory and motor RSNs could be considered as neurodevelopmental outcome biomarkers.

PMID: 31304656 [PubMed - as supplied by publisher]

Infraslow State Fluctuations Govern Spontaneous fMRI Network Dynamics.

Tue, 07/16/2019 - 18:30

Infraslow State Fluctuations Govern Spontaneous fMRI Network Dynamics.

Curr Biol. 2019 Jun 28;:

Authors: Gutierrez-Barragan D, Basson MA, Panzeri S, Gozzi A

Abstract
Spontaneous brain activity as assessed with resting-state fMRI exhibits rich spatiotemporal structure. However, the principles by which brain-wide patterns of spontaneous fMRI activity reconfigure and interact with each other remain unclear. We used a framewise clustering approach to map spatiotemporal dynamics of spontaneous fMRI activity with voxel resolution in the resting mouse brain. We show that brain-wide patterns of fMRI co-activation can be reliably mapped at the group and subject level, defining a restricted set of recurring brain states characterized by rich network structure. Importantly, we document that the identified fMRI states exhibit contrasting patterns of functional activity and coupled infraslow network dynamics, with each network state occurring at specific phases of global fMRI signal fluctuations. Finally, we show that autism-associated genetic alterations entail the engagement of atypical functional states and altered infraslow network dynamics. Our results reveal a novel set of fundamental principles guiding the spatiotemporal organization of resting-state fMRI activity and its disruption in brain disorders.

PMID: 31303490 [PubMed - as supplied by publisher]

Low-Frequency Fluctuations Amplitude Signals Exhibit Abnormalities of Intrinsic Brain Activities and Reflect Cognitive Impairment in Leukoaraiosis Patients.

Tue, 07/16/2019 - 18:30

Low-Frequency Fluctuations Amplitude Signals Exhibit Abnormalities of Intrinsic Brain Activities and Reflect Cognitive Impairment in Leukoaraiosis Patients.

Med Sci Monit. 2019 Jul 14;25:5219-5228

Authors: Wang J, Chen H, Liang H, Wang W, Liang Y, Liang Y, Zhang Y

Abstract
BACKGROUND This study aimed to explore the amplitude of low-frequency fluctuations (ALFF) for whole-brain in leukoaraiosis (LA) patients suffering from cognitive decline or impairment. MATERIAL AND METHODS Patients were selected by employing magnetic resonance imaging (MRI) technique. According to results of the clinical dementia rating and Montreal cognitive assessment (MoCA), patients were divided into 3 groups: LA patients diagnosed as vascular mild-cognitive impairment (LA-VaMCI, n=28), LA patients diagnosed as vascular-dementia (LA-VaD, n=18), and normal individuals (NC, n=28). Executive functions were evaluated by using the Stroop test and Trail Making Test (TMT). The higher scores in TMT test mean greater impairments. Changes for the ALFF were measured by using resting-state functional MRI (rs-fMRI) technique. Correlations between ALFF and cognition scores were analyzed. RESULTS It was found that widespread differences in ALFF were present predominantly in the posterior cingulate cortex/precuneus (PCC/PCu) and in the right inferior temporal gyrus (ITG). Compared with the NC group, ALFF values in PCC/PCu were significantly decreased (F=3.273, P=0.022) and ALFF values were significantly increased (F=2.864, P=0.033) in temporal regions of the LA-VaD patients. ALFF values in LA-VaMCI patients were significantly increased in ITG compared to that in the NC group (F=1.064, P=0.042) and the LA-VaD group (F=2.725, P=0.037). Impairment in executive functions were positively correlated with average ALFF of the left PCu. CONCLUSIONS This research showed that LA patients exhibited abnormal intrinsic-brain activities. Furthermore, altered ALFF was positively correlated with executive function scores.

PMID: 31302662 [PubMed - in process]

The relationship among resting-state brain activity and connectivity, agreeableness and displaced aggression: Two possible mediation models.

Sat, 07/13/2019 - 18:26

The relationship among resting-state brain activity and connectivity, agreeableness and displaced aggression: Two possible mediation models.

J Affect Disord. 2019 Jul 02;256:641-649

Authors: Xiao M, Zhu W, Wei J, Lei X, Xia LX

Abstract
BACKGROUND: Displaced aggression is a specific form of attack prompted by rumination on anger experiences and revenge thought which might lead to expression of anger on innocent people. There is sufficient evidence demonstrating the potential role of agreeableness in reducing displaced aggression in theory. However, little is known about the neural basis of displaced aggression and how agreeableness and the underlying neural mechanisms link to displaced aggression.
METHODS: In this investigation, we examined these issues on 123 college students by assessing resting-state brain activity (i.e. amplitude of low-frequency fluctuation, ALFF) and connectivity (i.e. resting-state functional connectivity, RSFC).
RESULTS: Whole-brain correlation analysis revealed that a higher level of displaced aggression was linked with decreased ALFF in the left dorsomedial prefrontal cortex (dmPFC) and decreased RSFC between the left dmPFC and left ventromedial prefrontal cortex (vmPFC). Mediation analysis further revealed that left dmPFC activity and the left dmPFC-vmPFC connectivity mediated the relationship between agreeableness and displaced aggression, as well as agreeableness mediated the relation between left dmPFC activity and the left dmPFC-vmPFC connectivity and displaced aggression.
LIMITATIONS: Only ALFF and RSFC were used as indicators of brain function in this study. The two mediation models need to be further tested by longitudinal design or experimental methods in further studies.
CONCLUSIONS: This study suggested that dmPFC and vmPFC might be the functional neural markers of displaced aggression and provided two possible mediation models regarding the relationship among the resting-state brain activity and connectivity, agreeableness and displaced aggression.

PMID: 31299446 [PubMed - as supplied by publisher]

Disruption of resting-state functional connectivity of right posterior insula in adolescents and young adults with major depressive disorder.

Sat, 07/13/2019 - 18:26

Disruption of resting-state functional connectivity of right posterior insula in adolescents and young adults with major depressive disorder.

J Affect Disord. 2019 Jul 02;257:23-30

Authors: Hu L, Xiao M, Ai M, Wang W, Chen J, Tan Z, Cao J, Kuang L

Abstract
BACKGROUND: The neural basis of Major Depressive Disorder (MDD) which is a clinical syndrome characterized by emotional and cognitive impairments is poorly understood. Accumulating evidence has suggested that the insula is an important substrate underlying the mechanism of MDD. This study aimed to examine the disrupted resting-state brain regional function in insula and to further investigate the associated resting-state functional connectivity (rs-FC) of insula underlie the MDD in adolescents and young adults.
METHODS: We employed 3.0T resting-state functional magnetic resonance imaging (rs-fMRI) to acquire data from 76 adolescents and young adults with MDD and 44 age and sex matched healthy control subjects. We employed a regional Amplitude of Low-Frequency Fluctuation (ALFF) analysis to explore local intrinsic neural oscillation alterations in insula and an ALFF-based functional connectivity (FC) approach to detect the potential changes in remote connectivity with insula in adolescents and young adults with MDD.
RESULTS: By applying ALFF analysis, significantly decreased activities were detected in bilateral insula, and in particular in right anterior insular gyrus (MNI; ROI1: 42, 24, -3), right posterior insular gyrus (Montreal Neurological Institute, MNI; ROI2: 36, -9, 15) and left anterior insular gyrus (MNI; ROI3: -36, 12, 9) in patients with MDD compared to the healthy controls (p < 0.05, 1000 permutations, TFCE corrected). With ROI2 as the seed in the subsequent ALFF-based rs-FC analysis, patients with MDD were observed to have significantly reduced FC with bilateral middle occipital gyrus, lingual gyrus, calcarine, postcentral gyrus, precentral gyrus, supramarginal area, superior temporal gyrus and middle cingulate gyrus as compared to the healthy controls (p < 0.05, 1000 permutations, TFCE corrected). No significant differences of FC were detected between the patients and healthy controls when using ROI1 and ROI3 as the seeds. We found no correlations between ALFF or rs-FC values and the severity of depression as estimated by Hamilton Depression Rating Scale (HAM-D).
LIMITATIONS: Clinical information were limited and no significant correlations were found between imaging variables and HAM-D scores, which reduces the power to interpret the present findings. A cross-sectional design was employed in this study so that it is not possible to know whether the abnormal ALFF or altered brain FC of insula reflects a state or trait effect in young people with MDD.
CONCLUSIONS: This study highlights the regional/network interaction abnormalities of insula in adolescents and young adults with MDD, and could provide further insight into understanding the neural pathomechanism of MDD in young patients.

PMID: 31299401 [PubMed - as supplied by publisher]

Thalamic low frequency activity facilitates resting-state cortical interhemispheric MRI functional connectivity.

Sat, 07/13/2019 - 18:26

Thalamic low frequency activity facilitates resting-state cortical interhemispheric MRI functional connectivity.

Neuroimage. 2019 Jul 09;:

Authors: Wang X, Leong ATL, Chan RW, Wu EX

Abstract
Blood-oxygen-level-dependent (BOLD) resting-state functional MRI (rsfMRI) has emerged as a valuable tool to map complex brain-wide functional networks, predict cognitive performance and identify biomarkers for neurological diseases. However, interpreting these findings poses challenges, as the neural basis of rsfMRI connectivity remains poorly understood. The thalamus serves as a relay station and modulates diverse long-range cortical functional integrations, yet few studies directly interrogate its role in brain-wide rsfMRI connectivity. Utilizing a multi-modal approach of rsfMRI, optogenetic stimulation and multi-depth cortical electrophysiology recording, we examined whether and how the somatosensory thalamus contributes to cortical interhemispheric rsfMRI connectivity. We found that low frequency (1 Hz) optogenetic stimulation of somatosensory-specific ventral posteromedial (VPM) thalamocortical excitatory neurons increased the interhemispheric rsfMRI connectivity in all examined sensory cortices, somatosensory, visual and auditory, and the local intrahemispheric BOLD activity at infraslow frequency (0.01-0.1 Hz). In parallel, multi-depth local field potential recordings at bilateral primary somatosensory cortices revealed increased interhemispheric correlations of low frequency neural oscillations (i.e., mainly < 10 Hz) at all cortical layers. Meanwhile, pharmacologically inhibiting VPM thalamocortical neurons decreased interhemispheric rsfMRI connectivity and local intrahemispheric infraslow BOLD activity in all sensory cortices. Taken together, our findings demonstrate that low frequency activities in the thalamo-cortical network contribute to brain-wide rsfMRI connectivity, highlighting the thalamus as a pivotal region that underlies rsfMRI connectivity.

PMID: 31299370 [PubMed - as supplied by publisher]

Combining Prospective Acquisition CorrEction (PACE) with retrospective correction to reduce motion artifacts in resting state fMRI data.

Sat, 07/13/2019 - 18:26

Combining Prospective Acquisition CorrEction (PACE) with retrospective correction to reduce motion artifacts in resting state fMRI data.

Brain Behav. 2019 Jul 11;:e01341

Authors: Lanka P, Deshpande G

Abstract
BACKGROUND: Head movement in the scanner causes spurious signal changes in the blood-oxygen-level-dependent (BOLD) signal, confounding resting state functional connectivity (RSFC) estimates obtained from functional magnetic resonance imaging (fMRI). We examined the effectiveness of Prospective Acquisition CorrEction (PACE) in reducing motion artifacts in BOLD data.
METHODS: Using PACE-corrected RS-fMRI data obtained from 44 subjects and subdividing them into low- and high-motion cohorts, we investigated voxel-wise motion-BOLD relationships, the distance-dependent functional connectivity artifact and the correlation between head motion and connectivity metrics such as posterior cingulate seed-based connectivity and network degree centrality.
RESULTS: Our results indicate that, when PACE is used in combination with standard retrospective motion correction strategies, it provides two principal advantages over conventional echo-planar imaging (EPI) RS-fMRI data: (a) PACE was effective in eliminating significant negative motion-BOLD relationships, shown to be associated with signal dropouts caused by head motion, and (b) Censoring with a lower threshold (framewise displacement >0.5 mm) and a smaller window around the motion corrupted time point provided qualitatively equivalent reductions in the motion artifact with PACE when compared to a more conservative threshold of 0.2 mm required with conventional EPI data.
CONCLUSIONS: PACE when used in conjunction with retrospective motion correction methods including nuisance signal and motion parameter regression, and censoring, did prove effective in almost eliminating head motion artifacts, even with a lower censoring threshold. Use of a lower censoring threshold could provide substantial savings in data that would otherwise be lost to censoring. Three-dimensional PACE has negligible overhead in terms of scan time, sequence modifications or additional and hence presents an attractive option for head motion correction in high-throughput resting-state BOLD imaging.

PMID: 31297966 [PubMed - as supplied by publisher]

Frequency-specific effects of low-intensity rTMS can persist for up to 2 weeks post-stimulation: A longitudinal rs-fMRI/MRS study in rats.

Sat, 07/13/2019 - 18:26

Frequency-specific effects of low-intensity rTMS can persist for up to 2 weeks post-stimulation: A longitudinal rs-fMRI/MRS study in rats.

Brain Stimul. 2019 Jul 03;:

Authors: Seewoo BJ, Feindel KW, Etherington SJ, Rodger J

Abstract
BACKGROUND: Evidence suggests that repetitive transcranial magnetic stimulation (rTMS), a non-invasive neuromodulation technique, alters resting brain activity. Despite anecdotal evidence that rTMS effects wear off, there are no reports of longitudinal studies, even in humans, mapping the therapeutic duration of rTMS effects.
OBJECTIVE: Here, we investigated the longitudinal effects of repeated low-intensity rTMS (LI-rTMS) on healthy rodent resting-state networks (RSNs) using resting-state functional MRI (rs-fMRI) and on sensorimotor cortical neurometabolite levels using proton magnetic resonance spectroscopy (MRS).
METHODS: Sprague-Dawley rats received 10 min LI-rTMS daily for 15 days (10 Hz or 1 Hz stimulation, n = 9 per group). MRI data were acquired at baseline, after seven days and after 14 days of daily stimulation and at two more timepoints up to three weeks post-cessation of daily stimulation.
RESULTS: 10 Hz stimulation increased RSN connectivity and GABA, glutamine, and glutamate levels. 1 Hz stimulation had opposite but subtler effects, resulting in decreased RSN connectivity and glutamine levels. The induced changes decreased to baseline levels within seven days following stimulation cessation in the 10 Hz group but were sustained for at least 14 days in the 1 Hz group.
CONCLUSION: Overall, our study provides evidence of long-term frequency-specific effects of LI-rTMS. Additionally, the transient connectivity changes following 10 Hz stimulation suggest that current treatment protocols involving this frequency may require ongoing "top-up" stimulation sessions to maintain therapeutic effects.

PMID: 31296402 [PubMed - as supplied by publisher]

Genetic algorithms for feature selection when classifying severe chronic disorders of consciousness.

Sat, 07/13/2019 - 03:26

Genetic algorithms for feature selection when classifying severe chronic disorders of consciousness.

PLoS One. 2019;14(7):e0219683

Authors: Wutzl B, Leibnitz K, Rattay F, Kronbichler M, Murata M, Golaszewski SM

Abstract
The diagnosis and prognosis of patients with severe chronic disorders of consciousness are still challenging issues and a high rate of misdiagnosis is evident. Hence, new tools are needed for an accurate diagnosis, which will also have an impact on the prognosis. In recent years, functional Magnetic Resonance Imaging (fMRI) has been gaining more and more importance when diagnosing this patient group. Especially resting state scans, i.e., an examination when the patient does not perform any task in particular, seems to be promising for these patient groups. After preprocessing the resting state fMRI data with a standard pipeline, we extracted the correlation matrices of 132 regions of interest. The aim was to find the regions of interest which contributed most to the distinction between the different patient groups and healthy controls. We performed feature selection using a genetic algorithm and a support vector machine. Moreover, we show by using only those regions of interest for classification that are most often selected by our algorithm, we get a much better performance of the classifier.

PMID: 31295332 [PubMed - in process]

Network Targeted Approach and Postoperative Resting State Functional MRI are Associated with Seizure Outcome.

Sat, 07/13/2019 - 03:26

Network Targeted Approach and Postoperative Resting State Functional MRI are Associated with Seizure Outcome.

Ann Neurol. 2019 Jul 11;:

Authors: Boerwinkle VL, Cediel EG, Mirea L, Williams K, Kerrigan JF, Lam S, Raskin JS, Desai VR, Wilfong AA, Adelson PD, Curry DJ

Abstract
OBJECTIVE: Postoperative resting state functional MRI in children with intractable epilepsy has not been quantified in relation to seizure outcome. Therefore, its value as a biomarker for epileptogenic pathology is not well understood.
METHODS: In a sample of children with intractable epilepsy who underwent prospective resting state guided epilepsy surgery, post-operative resting state functional MRI was performed 6 to 12 months later. Graded normalization of the post-operative resting state seizure onset zone was compared to seizure outcomes, patient, surgery, and anatomical MRI characteristics.
RESULTS: A total of 64 cases were evaluated. Post-operative rs-fMRI normalization was significantly (p-value <0.001) correlated with seizure reduction, with Spearman rank correlation coefficient of 0.83. Of 39 cases with post-operative resting state seizure onset zone normalization, 38 (97%) became completely seizure free. In contrast, of the 25 cases without complete rs-fMRI SOZ normalization, only 3 (5%) become seizure free. The accuracy of rs-fMRI as a biomarker predicting seizure freedom is 94%, with 96% sensitivity and 93% specificity.
INTERPRETATION: Among seizure localization techniques in pediatric epilepsy, post-operative rs-fMRI normalization has high correlation with seizure freedom. This study shows that pre-operative resting state functional MRI abnormalities can be used as a biomarker of the epileptogenic zone and the post-operative rs-fMRI normalization is a biomarker for seizure onset zone quiescence. This article is protected by copyright. All rights reserved.

PMID: 31294865 [PubMed - as supplied by publisher]

Simultaneous metabolic and functional imaging of the brain using SPICE.

Sat, 07/13/2019 - 03:26

Simultaneous metabolic and functional imaging of the brain using SPICE.

Magn Reson Med. 2019 Jul 11;:

Authors: Guo R, Zhao Y, Li Y, Li Y, Liang ZP

Abstract
PURPOSE: To enable simultaneous high-resolution mapping of brain function and metabolism.
METHODS: An encoding scheme was designed for interleaved acquisition of functional MRI (fMRI) data in echo volume imaging trajectories and MR spectroscopic imaging (MRSI) data in echo-planar spectroscopic imaging trajectories. The scheme eliminates water and lipid suppression and utilizes free induction decay signals to encode both functional and metabolic information with ultrashort TE, short TR, and sparse sampling of k , t -space. A subspace-based image reconstruction method was introduced for processing both the fMRI and MRSI data. The complementary information in the fMRI and MRSI data sets was also utilized to improve image reconstruction in the presence of intrascan head motion, field drift, and tissue susceptibility changes.
RESULTS: In-vivo experimental results were obtained from healthy human subjects in resting-state fMRI/MRSI experiments. In these experiments, the proposed method was able to simultaneously acquire metabolic and functional information from the brain in high resolution. For scans of 6.5 minutes, we achieved 3.0 × 3.0 × 1.8 mm3 spatial resolution for fMRI, 1.9 × 2.5 × 3.0 mm3 nominal spatial resolution for MRSI, and 1.9 × 1.9 × 1.8 mm3 nominal spatial resolution for quantitative susceptibility maps.
CONCLUSION: This work demonstrates the feasibility of simultaneous high-resolution mapping of brain function and metabolism with improved spatial resolution and synergistic image reconstruction.

PMID: 31294487 [PubMed - as supplied by publisher]