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Brain Dynamics and Temporal Summation of Pain Predicts Neuropathic Pain Relief from Ketamine Infusion.

Tue, 09/11/2018 - 12:40
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Brain Dynamics and Temporal Summation of Pain Predicts Neuropathic Pain Relief from Ketamine Infusion.

Anesthesiology. 2018 Sep 07;:

Authors: Bosma RL, Cheng JC, Rogachov A, Kim JA, Hemington KS, Osborne NR, Venkat Raghavan L, Bhatia A, Davis KD

Abstract
WHAT WE ALREADY KNOW ABOUT THIS TOPIC: WHAT THIS ARTICLE TELLS US THAT IS NEW: BACKGROUND:: Ketamine is an N-methyl-D-aspartate receptor antagonist that reduces temporal summation of pain and modulates antinociception. Ketamine infusions can produce significant relief of neuropathic pain, but the treatment is resource intensive and can be associated with adverse effects. Thus, it is crucial to select patients who might benefit from this treatment. The authors tested the hypothesis that patients with enhanced temporal summation of pain and the capacity to modulate pain via the descending antinociceptive brain pathway are predisposed to obtain pain relief from ketamine.
METHODS: Patients with refractory neuropathic pain (n = 30) and healthy controls underwent quantitative sensory testing and resting-state functional magnetic resonance imaging and then completed validated questionnaires. Patients then received outpatient intravenous ketamine (0.5 to 2 mg · kg · h; mean dose 1.1 mg · kg · h) for 6 h/day for 5 consecutive days. Pain was assessed 1 month later. Treatment response was defined as greater than or equal to 30% pain relief (i.e., reduction in pain scores). We determined the relationship between our primary outcome measure of pain relief with pretreatment temporal summation of pain and with brain imaging measures of dynamic functional connectivity between the default mode network and the descending antinociceptive brain pathway.
RESULTS: Approximately 50% of patients achieved pain relief (mean ± SD; Responders, 61 ± 35%; Nonresponders, 7 ± 14%). Pretreatment temporal summation was associated with the effect of ketamine (ρ = -0.52, P = 0.003) and was significantly higher in Responders (median [25th, 75th] = 200 [100, 345]) compared with Nonresponders (44 [9, 92]; P = 0.001). Pretreatment dynamic connectivity was also associated with the clinical effect of ketamine (ρ = 0.51, P = 0.004) and was significantly higher in Responders (mean ± SD, 0.55 ± 0.05) compared with Nonresponders (0.51 ± 0.03; P = 0.006). Finally, the dynamic engagement of the descending antinociceptive system significantly mediated the relationship between pretreatment pain facilitation and pain relief (95% CI, 0.005 to 0.065).
CONCLUSIONS: These findings suggest that brain and behavioral measures have the potential to prognosticate and develop ketamine-based personalized pain therapy.

PMID: 30199420 [PubMed - as supplied by publisher]

Problem drinking, alcohol expectancy and thalamic resting-state functional connectivity in non-dependent adult drinkers.

Tue, 09/11/2018 - 12:40
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Problem drinking, alcohol expectancy and thalamic resting-state functional connectivity in non-dependent adult drinkers.

Brain Connect. 2018 Sep 10;:

Authors: Zhornitsky S, Ide J, Wang W, Chao H, Zhang S, Hu S, Krystal J, Li CR

Abstract
Alcohol misuse is associated with thalamic dysfunction. The thalamus comprises subnuclei that relay and integrate information between cortical and subcortical structures. However, it is unclear how the subnuclei contribute to thalamic dysfunctions in problem drinking. We investigated resting-state functional connectivity (rsFC) of thalamic subregions in 107 nondependent drinkers (57 women), using masks delineated by white matter tractography. Thalamus was parcelled into motor, somatosensory, visual, premotor, frontal association, parietal association, and temporal association subregions. Whole-brain linear regression each against Alcohol Use Disorder Identification Test (AUDIT) and positive alcohol expectancy (AE) score with age as a covariate was performed for each seed, for men and women combined and separately. Overall, problem drinking was associated with increased thalamic connectivities whereas AE was associated with a mixed pattern of increased and decreased connectivities. Motor, premotor, somatosensory, and frontal association thalamic connectivity with bilateral caudate head was positively correlated with AUDIT score in men and women combined. Connectivity of the right caudate head with frontal association and premotor thalamus was also positively correlated with AE score in men and women combined. In contrast, motor and premotor thalamic connectivity with a number of cortical and subcortical structures showed sex differences in the correlation each with AUDIT and AE score. In mediation analyses AE score completely mediated the correlation between thalamic - caudate connectivity and AUDIT score, whereas the model where AE led to problem drinking and, in turn, altered thalamic caudate connectivity was not supported. To conclude, thalamic subregional rsFC's showed both shared and distinct changes and sex differences in association with problem drinking and AE. Increased thalamic caudate connectivity may contribute to problem drinking via enhanced AE. The findings suggest the importance of examining thalamic subdivisions and sex in investigating the functional roles of the thalamus in problem drinking.

PMID: 30198312 [PubMed - as supplied by publisher]

Neuroscience Information Toolbox: An Open Source Toolbox for EEG-fMRI Multimodal Fusion Analysis.

Tue, 09/11/2018 - 12:40
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Neuroscience Information Toolbox: An Open Source Toolbox for EEG-fMRI Multimodal Fusion Analysis.

Front Neuroinform. 2018;12:56

Authors: Dong L, Luo C, Liu X, Jiang S, Li F, Feng H, Li J, Gong D, Yao D

Abstract
Recently, scalp electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) multimodal fusion has been pursued in an effort to study human brain function and dysfunction to obtain more comprehensive information on brain activity in which the spatial and temporal resolutions are both satisfactory. However, a more flexible and easy-to-use toolbox for EEG-fMRI multimodal fusion is still lacking. In this study, we therefore developed a freely available and open-source MATLAB graphical user interface toolbox, known as the Neuroscience Information Toolbox (NIT), for EEG-fMRI multimodal fusion analysis. The NIT consists of three modules: (1) the fMRI module, which has batch fMRI preprocessing, nuisance signal removal, bandpass filtering, and calculation of resting-state measures; (2) the EEG module, which includes artifact removal, extracting EEG features (event onset, power, and amplitude), and marking interesting events; and (3) the fusion module, in which fMRI-informed EEG analysis and EEG-informed fMRI analysis are included. The NIT was designed to provide a convenient and easy-to-use toolbox for researchers, especially for novice users. The NIT can be downloaded for free at http://www.neuro.uestc.edu.cn/NIT.html, and detailed information, including the introduction of NIT, user's manual and example data sets, can also be observed on this website. We hope that the NIT is a promising toolbox for exploring brain information in various EEG and fMRI studies.

PMID: 30197593 [PubMed]

Alterations of static functional connectivity and dynamic functional connectivity in motor execution regions after stroke.

Mon, 09/10/2018 - 11:40

Alterations of static functional connectivity and dynamic functional connectivity in motor execution regions after stroke.

Neurosci Lett. 2018 Sep 06;:

Authors: Chen J, Sun D, Shi Y, Jin W, Wang Y, Xi Q, Ren C

Abstract
The aims of this study were to examine both static functional connectivity (FC) and dynamic FC alterations in motor execution regions after stroke and to investigate whether the altered static or dynamic FC was associated with the clinical behaviors in stroke patients. Seventy-six stroke patients and 55 healthy controls (HC) were recruited. Static FC and dynamic FC maps were computed based on the seeds of six core regions in motor execution network. Correlation analyses were performed between static or dynamic FC and clinical behavioral scores in stroke patients. Compared with the HC, the stroke patients had significantly higher static FC between the seeds and the precentral or postcentral gyrus, frontal gyrus, inferior parietal lobule, thalamus and insula, and lower static FC between the seeds and the cerebellum and middle temporal gyrus. There were significant differences in dynamic FC between the seeds and precuneus, calcarine gyrus, insula, inferior parietal lobule, precentral gyrus, and middle temporal, frontal or occipital gyrus between the stroke patients and HC. Furthermore, a significant negative correlation was found between the Fugl-Meyer assessment scores and dynamic FC of the ipsilesional primary motor cortex and contralesional precentral gyrus in patients. The current study shows that the patterns of both static FC and dynamic FC changed after stroke, and correlation between motor function and temporal variability in the FC of the precentral gyrus was significant in stroke patients. Our findings indicate that dynamic FC might be a potential indicator for evaluating motor function after stroke.

PMID: 30195973 [PubMed - as supplied by publisher]

Spread of activity following TMS is related to intrinsic resting connectivity to the salience network: A concurrent TMS-fMRI study.

Mon, 09/10/2018 - 11:40

Spread of activity following TMS is related to intrinsic resting connectivity to the salience network: A concurrent TMS-fMRI study.

Cortex. 2018 Jul 30;108:160-172

Authors: Hawco C, Voineskos AN, Steeves JKE, Dickie EW, Viviano JD, Downar J, Blumberger DM, Daskalakis ZJ

Abstract
Transcranial magnetic stimulation (TMS) modulates activity at local and regions distal to the site of simulation. TMS has also been found to modulate brain networks, and it has been hypothesized that functional connectivity may predict the neuronal changes at local and distal sites in response to a TMS pulse. However, a direct relationship between resting connectivity and change in TMS-induced brain activation has yet to be demonstrated. Concurrent TMS-fMRI is a technique to directly measure this spread activity following TMS in real time. In twenty-two participants, resting-state fMRI scans were acquired, followed by four ten minute sessions of concurrent TMS-fMRI over the left dorsolateral prefrontal cortex (DLPFC). Seed-based functional connectivity to the individualized TMS target was examined using the baseline resting fMRI scan data, and the change of activity resulting from TMS was determined using a general linear model (High vs Low intensity TMS). While at the group level the spatial pattern of resting connectivity related to the pattern of TMS-induced cortical changes, there was substantial variability across individuals. This variability was further probed by examining individual's connectivity from the TMS target to six resting state networks. Only connectivity between the salience network (SN) and the TMS target site correlated with the RSC-TMS score. This suggests that resting state connectivity is correlated with TMS-induced changes in activity following DLPFC stimulation, particularly when the DLPFC target interacts with the SN. These results highlight the importance of examining such relationships at the individual level and may help to guide individual treatment in clinical populations.

PMID: 30195825 [PubMed - as supplied by publisher]

State-independent alterations of intrinsic brain network in current and remitted depression.

Sun, 09/09/2018 - 10:20
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State-independent alterations of intrinsic brain network in current and remitted depression.

Prog Neuropsychopharmacol Biol Psychiatry. 2018 Sep 04;:

Authors: Dong D, Ming Q, Zhong X, Pu W, Zhang X, Jiang Y, Gao Y, Sun X, Wang X, Yao S

Abstract
BACKGROUND: It has been proposed that state-independent, or trait, neurobiological alterations across illness phases may contribute to the high recurrence of major depressive disorder (MDD). Although intrinsic brain network abnormalities have been implicated consistently in MDD neuropathology, MDD state-independent and -dependent resting-state network alterations have not been clearly studied.
METHODS: Resting-state functional magnetic resonance imaging (fMRI) data were collected from 57 medication-naive first-episode current MDD patients, 35 remitted MDD patients, and 66 healthy controls (HCs). Independent component analysis (ICA) was used to extract subnetworks of the default mode network (DMN), central executive network (CEN), and salience network (SN).
RESULTS: Relative to HCs, the current MDD and remitted MDD groups had decreased intra-intrinsic functional connectivity (iFC) in the dorsal lateral prefrontal cortex (dlPFC) of the left CEN, increased inter-FC between the SN and right CEN (rCEN), and decreased inter-FC between the anterior DMN (aDMN) and rCEN. The altered intra-iFC in the left CEN were correlated negatively with the depressive level in the remitted MDD.
CONCLUSIONS: Hypoactivity of the dlPFC in the left CEN, increased inter-FC between the SN and rCEN, and decreased inter-FC between the aDMN and rCEN may reflect state-independent biomarkers of MDD.

PMID: 30193990 [PubMed - as supplied by publisher]

A resting state fMRI analysis pipeline for pooling inference across diverse cohorts: an ENIGMA rs-fMRI protocol.

Sat, 09/08/2018 - 15:20
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A resting state fMRI analysis pipeline for pooling inference across diverse cohorts: an ENIGMA rs-fMRI protocol.

Brain Imaging Behav. 2018 Sep 06;:

Authors: Adhikari BM, Jahanshad N, Shukla D, Turner J, Grotegerd D, Dannlowski U, Kugel H, Engelen J, Dietsche B, Krug A, Kircher T, Fieremans E, Veraart J, Novikov DS, Boedhoe PSW, van der Werf YD, van den Heuvel OA, Ipser J, Uhlmann A, Stein DJ, Dickie E, Voineskos AN, Malhotra AK, Pizzagalli F, Calhoun VD, Waller L, Veer IM, Walter H, Buchanan RW, Glahn DC, Hong LE, Thompson PM, Kochunov P

Abstract
Large-scale consortium efforts such as Enhancing NeuroImaging Genetics through Meta-Analysis (ENIGMA) and other collaborative efforts show that combining statistical data from multiple independent studies can boost statistical power and achieve more accurate estimates of effect sizes, contributing to more reliable and reproducible research. A meta- analysis would pool effects from studies conducted in a similar manner, yet to date, no such harmonized protocol exists for resting state fMRI (rsfMRI) data. Here, we propose an initial pipeline for multi-site rsfMRI analysis to allow research groups around the world to analyze scans in a harmonized way, and to perform coordinated statistical tests. The challenge lies in the fact that resting state fMRI measurements collected by researchers over the last decade vary widely, with variable quality and differing spatial or temporal signal-to-noise ratio (tSNR). An effective harmonization must provide optimal measures for all quality data. Here we used rsfMRI data from twenty-two independent studies with approximately fifty corresponding T1-weighted and rsfMRI datasets each, to (A) review and aggregate the state of existing rsfMRI data, (B) demonstrate utility of principal component analysis (PCA)-based denoising and (C) develop a deformable ENIGMA EPI template based on the representative anatomy that incorporates spatial distortion patterns from various protocols and populations.

PMID: 30191514 [PubMed - as supplied by publisher]

Altered Structure and Intrinsic Functional Connectivity in Post-stroke Aphasia.

Sat, 09/08/2018 - 15:20
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Altered Structure and Intrinsic Functional Connectivity in Post-stroke Aphasia.

Brain Topogr. 2018 03;31(2):300-310

Authors: Yang M, Yang P, Fan YS, Li J, Yao D, Liao W, Chen H

Abstract
Previous studies have demonstrated that alterations of gray matter exist in post-stroke aphasia (PSA) patients. However, so far, few studies combined structural alterations of gray matter volume (GMV) and intrinsic functional connectivity (iFC) imbalances of resting-state functional MRI to investigate the mechanism underlying PSA. The present study investigated specific regions with GMV abnormality in patients with PSA (n = 17) and age- and sex- matched healthy controls (HCs, n = 20) using voxel-based morphometry. In addition, we examined whether there is a link between abnormal gray matter and altered iFC. Furthermore, we explored the correlations between abnormal iFC and clinical scores in aphasic patients. We found significantly increased GMV in the right superior temporal gyrus, right inferior parietal lobule (IPL)/supramarginal gyrus (SMG), and left middle occipital gyrus. Decreased GMV was found in the right caudate gyrus, bilateral thalami in PSA patients. Patients showed increased remote interregional FC between the right IPL/SMG and right precuneus, right angular gyrus, right superior occipital gyrus; while reduced FC in the right caudate gyrus and supplementary motor area, dorsolateral superior frontal gyrus. Moreover, iFC strength between the left middle occipital gyrus and the left orbital middle frontal gyrus was positively correlated with the performance quotient. We suggest that GMV abnormality contributes to interregional FC in PSA. These results may provide useful information to understand the pathogenesis of post-stroke aphasia.

PMID: 28921389 [PubMed - indexed for MEDLINE]

Association between resting-state brain functional connectivity and cortisol levels in unmedicated major depressive disorder.

Fri, 09/07/2018 - 14:40
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Association between resting-state brain functional connectivity and cortisol levels in unmedicated major depressive disorder.

J Psychiatr Res. 2018 Sep 01;105:55-62

Authors: Wang Y, Chen G, Zhong S, Jia Y, Xia L, Lai S, Zhao L, Huang L, Liu T

Abstract
Disturbed hypothalamus-pituitary-adrenal axis function, which leads to excessive and prolonged hypercortisolemia, is a core feature of major depressive disorder (MDD). However, the relationships between depression, brain structure and function, and cortisol levels are unclear. The current study examined the whole-brain functional connectivity pattern of patients with MDD and evaluated the association between functional connectivity and serum cortisol levels in MDD. A total of 93 unmedicated patients with MDD and 139 healthy control subjects underwent resting-state functional magnetic resonance imaging. Voxel-wise whole-brain connectivity was analyzed by using a graph theory approach: functional connectivity strength (FCS). A seed-based resting-state functional connectivity analysis was further performed to investigate abnormal functional connectivity patterns of those regions with changed FCS. Morning blood samples were drawn for cortisol measurements in some subjects (including 53 MDD patients and 30 controls). The MDD patients had a significantly lower FCS in the left posterior lobes of the cerebellum (mainly lobule Crus II) (p < 0.05, TFCE corrected). The seed-based functional connectivity analysis revealed decreased functional connectivity between the left posterior cerebellum and the left medial orbitofrontal cortex (OFC) (p < 0.05, TFCE corrected). Moreover, the functional connectivity between the left posterior cerebellum and the left medial OFC were significantly positively correlated with the serum cortisol levels in MDD patients. Our results suggest that cerebellar dysconnectivity, in particular distributed cerebellar-OFC functional connectivity, may be associated with serum cortisol levels in MDD patients.

PMID: 30189325 [PubMed - as supplied by publisher]

Functional connectivity analysis of cerebellum using spatially constrained spectral clustering.

Fri, 09/07/2018 - 14:40
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Functional connectivity analysis of cerebellum using spatially constrained spectral clustering.

IEEE J Biomed Health Inform. 2018 Sep 06;:

Authors: Pezoulas VC, Michalopoulos K, Klados M, Micheloyannis S, Bourbakis N, Zervakis M

Abstract
The human cerebellum contains almost fifty percent of the neurons in the brain, although its volume does not exceed ten percent of the total brain volume. The ultimate goal of this study is to derive the functional network of the cerebellum during resting-state and then compare the ensuing group networks between males and females. Towards this direction, a spatially constrained version of the classic spectral clustering algorithm is proposed and then compared against conventional spectral graph theory approaches, such as, spectral clustering, and N-cut, on synthetic data as well as on resting-state fMRI data obtained from the Human Connectome Project (HCP). The extracted atlas was combined with the anatomical atlas of cerebellum resulting to a functional atlas with 46 Regions of Interest (ROIs). As a final step, a gender-based network analysis of cerebellum was performed using the data-driven atlas along with the concept of the Minimum Spanning Trees. The simulation analysis results confirm the dominance of the spatially constrained spectral clustering approach in discriminating activation patterns under noisy conditions. The network analysis results reveal statistically significant differences in the optimal tree organization between males and females. In addition, the dominance of the Left VI lobule in both genders supports the results reported in a previous study of ours. To our knowledge, the extracted atlas comprises the first resting-state atlas of cerebellum based on HCP data.

PMID: 30188842 [PubMed - as supplied by publisher]

Relating resting-state hemodynamic changes to the variable language profiles in post-stroke aphasia.

Fri, 09/07/2018 - 14:40
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Relating resting-state hemodynamic changes to the variable language profiles in post-stroke aphasia.

Neuroimage Clin. 2018;20:611-619

Authors: Zhao Y, Lambon Ralph MA, Halai AD

Abstract
Linking both structural lesions and the functional integrity of remaining brain tissue to patients' behavioural profile may be critical in discovering the limits of behavioural recovery post stroke. In the present study, we explored the relationship between temporal hemodynamic changes and language performance in chronic post-stroke aphasia. We collected detailed language and neuropsychological data for 66 patients with chronic (>1 year) post-stroke aphasia. We used principal component analysis to extract their core language-neuropsychological features. From resting-state fMRI scans in 35 patients, we calculated the lag in the time-course of the intact brain voxels in each patient. Finally, variation across the language-cognitive factors was related to both the patients' structural damage and the time-course changes in each patient's intact tissue. Phonological abilities were correlated with the structural integrity of the left superior temporal, angular gyrus, supramarginal gyrus and arcuate fasciculus regions and hemodynamic advance in the left intra-parietal sulcus. Speech fluency related to integrity of premotor regions, plus hemodynamic advance in the left middle/superior temporal gyrus, left middle occipital gyrus, and right angular gyrus. Semantic performance reflected a combination of medial ventral temporal lobe status and hemodynamic delay in the left posterior middle temporal gyrus. Finally, executive abilities correlated with hemodynamic delay in the left middle/inferior frontal gyrus, right rolandic operculum, bilateral supplementary motor areas/middle cingulum areas, and bilateral thalamus/caudate. Following stroke, patients' patterns of chronic language abilities reflects a combination of structural and functional integrity across a distributed network of brain regions. The correlation between hemodynamic changes and behaviours may have clinical importance.

PMID: 30186765 [PubMed - in process]

A combined study of 18F-FDG PET-CT and fMRI for assessing resting cerebral function in patients with major depressive disorder.

Fri, 09/07/2018 - 14:40
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A combined study of 18F-FDG PET-CT and fMRI for assessing resting cerebral function in patients with major depressive disorder.

Exp Ther Med. 2018 Sep;16(3):1873-1881

Authors: Fu C, Zhang H, Xuan A, Gao Y, Xu J, Shi D

Abstract
The present study investigated changes in the regional cerebral metabolic rates of glucose uptake (rCMRglc) using 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) and regional homogeneity (ReHo), together with resting-state blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI), in patients with major depressive disorder (MDD). In total, 18 patients with untreated MDD and 17 healthy control subjects underwent 18F-FDG PET and BOLD-fMRI scanning. The MDD patients' cerebral changes, measured as rCMRglc and ReHo values, were mapped and statistically analyzed. Compared with the control group, the patients with MDD had a decreased rCMRglc in the bilateral superior, middle and inferior frontal gyrus, in the bilateral superior and middle temporal gyrus, in the bilateral anterior cingulate cortex, in the bilateral putamen and caudate, and in the left pallidum, but an increased rCMRglc in the bilateral hippocampus and left thalamus. The ReHo values in the patient group were decreased in the bilateral superior and middle frontal gyrus, left pallidum, bilateral putamen and left anterior cingulate cortex, but increased in the right hippocampus and thalamus. No statistically significant differences were identified between decreased metabolism and ReHo brain regions of MDD patients (χ2=9.16; P=0.90) and between increased metabolism and ReHo brain regions (χ2=3.96; P=0.27), when comparing activated brain regions of PET and MRI. The standardized uptake values (SUV) of the bilateral superior, middle and inferior frontal gyrus, bilateral superior and middle temporal gyrus, bilateral putamen, the left caudate and pallidum, the left anterior cingulate cortex, and the bilateral hippocampus and thalamus were correlated with the ReHo (r=0.51-0.83; P<0.05). However, no correlation was detected between the SUV and ReHo in the right caudate and anterior cingulate cortex (r=0.41 and 0.37, respectively; P>0.05). Taken together, these results demonstrated that patients with MDD displayed characteristic patterns regarding changes of brain glucose uptake and ReHo in the resting state. Furthermore, 18F-FDG PET may be a more sensitive technique compared with BOLD-fMRI for the identification of brain lesions in patients with MDD.

PMID: 30186413 [PubMed]

Functional Connectivity Alterations in Children with Spastic and Dyskinetic Cerebral Palsy.

Fri, 09/07/2018 - 14:40
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Functional Connectivity Alterations in Children with Spastic and Dyskinetic Cerebral Palsy.

Neural Plast. 2018;2018:7058953

Authors: Qin Y, Li Y, Sun B, He H, Peng R, Zhang T, Li J, Luo C, Sun C, Yao D

Abstract
Cerebral palsy (CP) has long been investigated to be associated with a range of motor and cognitive dysfunction. As the two most common CP subtypes, spastic cerebral palsy (SCP) and dyskinetic cerebral palsy (DCP) may share common and distinct elements in their pathophysiology. However, the common and distinct dysfunctional characteristics between SCP and DCP on the brain network level are less known. This study aims to detect the alteration of brain functional connectivity in children with SCP and DCP based on resting-state functional MRI (fMRI). Resting-state networks (RSNs) were established based on the independent component analysis (ICA), and the functional network connectivity (FNC) was performed on the fMRI data from 16 DCP, 18 bilateral SCP, and 18 healthy children. Compared with healthy controls, altered functional connectivity within the cerebellum network, sensorimotor network (SMN), left frontoparietal network (LFPN), and salience network (SN) were found in DCP and SCP groups. Furthermore, the disconnections of the FNC consistently focused on the visual pathway; covariance of the default mode network (DMN) with other networks was observed both in DCP and SCP groups, while the DCP group had a distinct connectivity abnormality in motor pathway and self-referential processing-related connections. Correlations between the functional disconnection and the motor-related clinical measurement in children with CP were also found. These findings indicate functional connectivity impairment and altered integration widely exist in children with CP, suggesting that the abnormal functional connectivity is a pathophysiological mechanism of motor and cognitive dysfunction of CP.

PMID: 30186320 [PubMed - in process]

Clinical, Anatomical, and Pathological Features in the Three Variants of Primary Progressive Aphasia: A Review.

Fri, 09/07/2018 - 14:40
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Clinical, Anatomical, and Pathological Features in the Three Variants of Primary Progressive Aphasia: A Review.

Front Neurol. 2018;9:692

Authors: Montembeault M, Brambati SM, Gorno-Tempini ML, Migliaccio R

Abstract
Primary progressive aphasias (PPA) are neurodegenerative diseases clinically characterized by an early and relatively isolated language impairment. Three main clinical variants, namely the nonfluent/agrammatic variant (nfvPPA), the semantic variant (svPPA), and the logopenic variant (lvPPA) have been described, each with specific linguistic/cognitive deficits, corresponding anatomical and most probable pathological features. Since the discovery and the development of diagnostic criteria for the PPA variants by the experts in the field, significant progress has been made in the understanding of these diseases. This review aims to provide an overview of the literature on each of the PPA variant in terms of their clinical, anatomical and pathological features, with a specific focus on recent findings. In terms of clinical advancements, recent studies have allowed a better characterization and differentiation of PPA patients based on both their linguistic and non-linguistic profiles. In terms of neuroimaging, techniques such as diffusion imaging and resting-state fMRI have allowed a deeper understanding of the impact of PPA on structural and functional connectivity alterations beyond the well-defined pattern of regional gray matter atrophy. Finally, in terms of pathology, despite significant advances, clinico-pathological correspondence in PPA remains far from absolute. Nonetheless, the improved characterization of PPA has the potential to have a positive impact on the management of patients. Improved reliability of diagnoses and the development of reliable in vivo biomarkers for underlying neuropathology will also be increasingly important in the future as trials for etiology-specific treatments become available.

PMID: 30186225 [PubMed]

Cognitive Reserve Relates to Functional Network Efficiency in Alzheimer's Disease.

Fri, 09/07/2018 - 14:40
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Cognitive Reserve Relates to Functional Network Efficiency in Alzheimer's Disease.

Front Aging Neurosci. 2018;10:255

Authors: Weiler M, Casseb RF, de Campos BM, de Ligo Teixeira CV, Carletti-Cassani AFMK, Vicentini JE, Magalhães TNC, de Almeira DQ, Talib LL, Forlenza OV, Balthazar MLF, Castellano G

Abstract
Alzheimer's disease (AD) is the most common form of dementia, with no means of cure or prevention. The presence of abnormal disease-related proteins in the population is, in turn, much more common than the incidence of dementia. In this context, the cognitive reserve (CR) hypothesis has been proposed to explain the discontinuity between pathophysiological and clinical expression of AD, suggesting that CR mitigates the effects of pathology on clinical expression and cognition. fMRI studies of the human connectome have recently reported that AD patients present diminished functional efficiency in resting-state networks, leading to a loss in information flow and cognitive processing. No study has investigated, however, whether CR modifies the effects of the pathology in functional network efficiency in AD patients. We analyzed the relationship between CR, pathophysiology and network efficiency, and whether CR modifies the relationship between them. Fourteen mild AD, 28 amnestic mild cognitive impairment (aMCI) due to AD, and 28 controls were enrolled. We used education to measure CR, cerebrospinal fluid (CSF) biomarkers to evaluate pathophysiology, and graph metrics to measure network efficiency. We found no relationship between CR and CSF biomarkers; CR was related to higher network efficiency in all groups; and abnormal levels of CSF protein biomarkers were related to more efficient networks in the AD group. Education modified the effects of tau-related pathology in the aMCI and mild AD groups. Although higher CR might not protect individuals from developing AD pathophysiology, AD patients with higher CR are better able to cope with the effects of pathology-presenting more efficient networks despite pathology burden. The present study highlights that interventions focusing on cognitive stimulation might be useful to slow age-related cognitive decline or dementia and lengthen healthy aging.

PMID: 30186154 [PubMed]

Intra- and Inter-Scanner Reliability of Voxel-Wise Whole-Brain Analytic Metrics for Resting State fMRI.

Fri, 09/07/2018 - 14:40
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Intra- and Inter-Scanner Reliability of Voxel-Wise Whole-Brain Analytic Metrics for Resting State fMRI.

Front Neuroinform. 2018;12:54

Authors: Zhao N, Yuan LX, Jia XZ, Zhou XF, Deng XP, He HJ, Zhong J, Wang J, Zang YF

Abstract
As the multi-center studies with resting-state functional magnetic resonance imaging (RS-fMRI) have been more and more applied to neuropsychiatric studies, both intra- and inter-scanner reliability of RS-fMRI are becoming increasingly important. The amplitude of low frequency fluctuation (ALFF), regional homogeneity (ReHo), and degree centrality (DC) are 3 main RS-fMRI metrics in a way of voxel-wise whole-brain (VWWB) analysis. Although the intra-scanner reliability (i.e., test-retest reliability) of these metrics has been widely investigated, few studies has investigated their inter-scanner reliability. In the current study, 21 healthy young subjects were enrolled and scanned with blood oxygenation level dependent (BOLD) RS-fMRI in 3 visits (V1 - V3), with V1 and V2 scanned on a GE MR750 scanner and V3 on a Siemens Prisma. RS-fMRI data were collected under two conditions, eyes open (EO) and eyes closed (EC), each lasting 8 minutes. We firstly evaluated the intra- and inter-scanner reliability of ALFF, ReHo, and DC. Secondly, we measured systematic difference between two scanning visits of the same scanner as well as between two scanners. Thirdly, to account for the potential difference of intra- and inter-scanner local magnetic field inhomogeneity, we measured the difference of relative BOLD signal intensity to the mean BOLD signal intensity of the whole brain between each pair of visits. Last, we used percent amplitude of fluctuation (PerAF) to correct the difference induced by relative BOLD signal intensity. The inter-scanner reliability was much worse than intra-scanner reliability; Among the VWWB metrics, DC showed the worst (both for intra-scanner and inter-scanner comparisons). PerAF showed similar intra-scanner reliability with ALFF and the best reliability among all the 4 metrics. PerAF reduced the influence of BOLD signal intensity and hence increase the inter-scanner reliability of ALFF. For multi-center studies, inter-scanner reliability should be taken into account.

PMID: 30186131 [PubMed]

Neurobiology of the dorsolateral prefrontal cortex in GAD: Aberrant neurometabolic correlation to hippocampus and relationship to anxiety sensitivity and IQ.

Fri, 09/07/2018 - 14:40
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Neurobiology of the dorsolateral prefrontal cortex in GAD: Aberrant neurometabolic correlation to hippocampus and relationship to anxiety sensitivity and IQ.

J Affect Disord. 2018 03 15;229:1-13

Authors: Coplan JD, Webler R, Gopinath S, Abdallah CG, Mathew SJ

Abstract
INTRODUCTION: The neurometabolism underlying the cognitive and affective symptoms associated with generalized anxiety disorder (GAD) remain poorly understood. After we have linked worry to intelligence in patients with GAD, we hypothesized that aberrant neurometabolic correlations between hippocampus and neocortical regions may underlie a shared substrate in GAD patients for both anxiety sensitivity and intelligence.
METHODS: GAD patients (n = 16; F = 11) and healthy volunteers (n = 16; F = 10) were assessed using 1H-MRSI. Co-axial planes I [hippocampus (HIPP)] and co-axial plane III [dorsolateral prefrontal cortex (DLPFC), central gyrus (CG)] were examined. Using general linear models, we examined resting metabolite concentrations using HIPP as a hub to CG and DLPFC. Neocortical ROIs were related to Anxiety Sensitivity Index (ASI) and Full Scale IQ (FSIQ) in GAD patients versus controls.
RESULTS: Right hippocampal Cho/Cr directly predicted left DLPFC Cho/Cr in GAD (r = 0.75), an effect distinguishable (p = 0.0004) from controls. Left HIPP Cho/Cr positively predicted left CG Cho/Cr in GAD, an effect distinguishable from controls. In patients, both left and right DLPFC Cho/Cr positively predicted ASI but only left DLPFC Cho/Cr inversely predicted IQ. By contrast, IQ in controls correlated directly with left CG Cho/Cr.
LIMITATIONS: Small sample size precluded us from investigating how gender and FSIQ subscales related to neurochemical correlations in the ROIs examined.
CONCLUSIONS: Aberrant resting state neurochemical correlation between left DLPFC and right HIPP may contribute to GAD symptomatology. Unlike controls, in GAD, IQ and worry may share a common yet inverse neurometabolic substrate in left DLPFC.

PMID: 29288871 [PubMed - indexed for MEDLINE]

Motor and language deficits correlate with Resting State Functional Magnetic Resonance Imaging networks in patients with brain tumors.

Wed, 09/05/2018 - 12:00
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Motor and language deficits correlate with Resting State Functional Magnetic Resonance Imaging networks in patients with brain tumors.

J Neuroradiol. 2018 Sep 01;:

Authors: Liouta E, Katsaros VK, Stranjalis G, Leks E, Klose U, Bisdas S

Abstract
BACKGROUND AND PURPOSE: Evidence of preoperative resting state functional magnetic resonance (RS-fMRI) validation by correlating it with clinical preoperative status in brain tumor patients is scarce. Our aim was to validate the functional relevance of RS-fMRI by investigating the association between RS-fMRI and preoperative motor and language function performance in patients with brain tumor.
MATERIALS AND METHODS: 69 patients with brain tumors were prospectively recruited. Patients with tumors near pre-central gyrus (n = 49) underwent assessment for apparent (paresis) and subtle (finger tapping) deficits. Patients with left frontal tumors in the vicinity of the inferior frontal gyrus (n = 29) underwent assessment for gross (aphasia) and mild language (phonological verbal fluency) deficits. RS-fMRI results were extracted by spatial Independent Component Analysis (ICA).
RESULTS: Motor group: paretic patients showed significantly (P = 0.01) decreased BOLD-signal in ipsilesional pre-central gyrus when compared to contralesional one. Significantly (P < 0.01) lower BOLD-signal was also observed in ipsilesional pre-central gyrus of paretics when compared with the non-paretics. In asymptomatic patients, a strong positive correlation (r = 0.68, P < 0.01) between ipsilesional motor cortex BOLD-signal and contralesional finger tapping performance was observed. Language group: patients with aphasia showed significantly (P = 0.01) decreased RS-fMRI BOLD-signal in left BA 44 when compared with non- aphasics. In asymptomatic patients, a strong positive correlation (r = 0.72, P < 0.01) between BA 44 BOLD-signal and phonological fluency performance was observed.
CONCLUSIONS: Our results showed that RS-fMRI BOLD-signal of motor and language networks were significantly affected by the tumors implying the usefulness of the method for assessment of the underlying functions in brain tumors patients.

PMID: 30179690 [PubMed - as supplied by publisher]

Joint representation of connectome-scale structural and functional profiles for identification of consistent cortical landmarks in macaque brain.

Wed, 09/05/2018 - 12:00
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Joint representation of connectome-scale structural and functional profiles for identification of consistent cortical landmarks in macaque brain.

Brain Imaging Behav. 2018 Sep 04;:

Authors: Zhang S, Jiang X, Zhang W, Zhang T, Chen H, Zhao Y, Lv J, Guo L, Howell BR, Sanchez MM, Hu X, Liu T

Abstract
Discovery and representation of common structural and functional cortical architectures has been a significant yet challenging problem for years. Due to the remarkable variability of structural and functional cortical architectures in human brain, it is challenging to jointly represent a common cortical architecture which can comprehensively encode both structure and function characteristics. In order to better understand this challenge and considering that macaque monkey brain has much less variability in structure and function compared with human brain, in this paper, we propose a novel computational framework to apply our DICCCOL (Dense Individualized and Common Connectivity-based Cortical Landmarks) and HAFNI (Holistic Atlases of Functional Networks and Interactions) frameworks on macaque brains, in order to jointly represent structural and functional connectome-scale profiles for identification of a set of consistent and common cortical landmarks across different macaque brains based on multimodal DTI and resting state fMRI (rsfMRI) data. Experimental results demonstrate that 100 consistent and common cortical landmarks are successfully identified via the proposed framework, each of which has reasonably accurate anatomical, structural fiber connection pattern, and functional correspondences across different macaque brains. This set of 100 landmarks offer novel insights into the structural and functional cortical architectures in macaque brains.

PMID: 30178424 [PubMed - as supplied by publisher]

Sex differences in resting-state cerebral activity alterations in internet gaming disorder.

Wed, 09/05/2018 - 12:00
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Sex differences in resting-state cerebral activity alterations in internet gaming disorder.

Brain Imaging Behav. 2018 Sep 04;:

Authors: Sun Y, Wang Y, Han X, Jiang W, Ding W, Cao M, Du Y, Lin F, Xu J, Zhou Y

Abstract
Although evidence has shown that the prevalence rates of Internet gaming disorder (IGD) differ between males and females, few studies have examined whether such sex differences extend to brain function. This study aimed to explore the sex differences in resting-state cerebral activity alterations in IGD. Thirty male participants with IGD (IGDm), 23 female participants with IGD (IGDf), and 30 male and 22 female age-matched healthy controls (HC) underwent resting-state functional MRI. Maps of the amplitude of low-frequency fluctuation (ALFF) and functional connectivity (FC) were constructed. A two-factor ANCOVA model was performed, with sex and diagnosis as the between-subject factors. Then, post hoc pair-wise comparisons were performed using two-sample t-tests within the interaction masks. The Barratt Impulsiveness Scale-11 (BIS-11) was used to assess the behavioral inhibition function. We found that the ALFF values in the orbital part of the left superior frontal gyrus (SFG) were lower in IGDm than in HCm, which were negatively correlated with BIS-11 scores. IGDm also demonstrated lower connectivity between the orbital part of the left SFG and the posterior cingulate cortex (PCC), the right angular gyrus, and the right dorsolateral prefrontal cortex than HCm. Furthermore, IGDm had lower seed connectivity between the orbital part of the left SFG and the PCC than ICDf. Our findings suggest that (1) the altered ALFF values in the orbital part of the left SFG represent a clinically relevant biomarker for the behavioral inhibition function of IGDm; (2) IGD may interact with sex-specific patterns of FC in male and female subjects.

PMID: 30178423 [PubMed - as supplied by publisher]

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