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Cerebral resting state markers of biased perception in social anxiety.

Mon, 12/10/2018 - 21:49
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Cerebral resting state markers of biased perception in social anxiety.

Brain Struct Funct. 2018 Dec 01;:

Authors: Kreifelts B, Weigel L, Ethofer T, Brück C, Erb M, Wildgruber D

Abstract
Social anxiety (SA) comprises a multitude of persistent fears around the central element of dreaded negative evaluation and exclusion. This very common anxiety is spectrally distributed among the general population and associated with social perception biases deemed causal in its maintenance. Here, we investigated cerebral resting state markers linking SA and biased social perception. To this end, resting state functional connectivity (RSFC) was assessed as the neurobiological marker in a study population with greatly varying SA using fMRI in the first step of the experiment. One month later the impact of unattended laughter-exemplifying social threat-on a face rating task was evaluated as a measure of biased social perception. Applying a dimensional approach, SA-related cognitive biases tied to the valence, dominance and arousal of the threat signal and their underlying RSFC patterns among central nodes of the cerebral emotion, voice and face processing networks were identified. In particular, the connectivity patterns between the amygdalae and the right temporal voice area met all criteria for a cerebral mediation of the association between SA and the laughter valence-related interpretation bias. Thus, beyond this identification of non-state-dependent cerebral markers of biased perception in SA, this study highlights both a starting point and targets for future research on the causal relationships between cerebral connectivity patterns, SA and biased perception, potentially via neurofeedback methods.

PMID: 30506458 [PubMed - as supplied by publisher]

A Single-Blinded Trial Using Resting-State Functional Magnetic Resonance Imaging of Brain Activity in Patients with Type 2 Diabetes and Painful Neuropathy.

Mon, 12/10/2018 - 21:49
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A Single-Blinded Trial Using Resting-State Functional Magnetic Resonance Imaging of Brain Activity in Patients with Type 2 Diabetes and Painful Neuropathy.

Diabetes Ther. 2018 Nov 30;:

Authors: Zhang Q, Zhang P, Yan R, Xu X, Mao C, Liu X, Li F, Ma J, Ye L, Yao Z, Wu J

Abstract
About two-thirds of patients with painful diabetic neuropathy (PDN) suffer from anxiety and/or depression disorders. However, the pathogenesis of PDN is unclear, in particular with respect to the mechanism associated with the central nervous system. We used the neuroimaging techniques of fraction amplitude of low-frequency fluctuation (fALFF) and regional homogeneity of resting-state functional magnetic resonance imaging (fMRI) to explore the brain activity in patients with PDN. The symptoms, signs and mental conditions of 19 patients with PDN and of 18 patients with non-pain neuropathy were assessed separately and compared. Blood oxygenation level-dependent resting-state fMRI scans of the brain were performed in all 37 patients with neuropathy and in 15 gender- and age-matched healthy controls. Our data showed that patients with PDN had increased insulin resistance (p  = 0.03), increased depression (p  = 0.02) and increased anxiety (p  < 0.001) compared with the controls and that all of these conditions were associated with abnormal spontaneous activities in several regions of the brain, including the somatosensory, cognitive and emotional regions. The duration of diabetes, level of glycated hemoglobin, homeostasis model assessment of insulin resistance and estimated glomerular filtration rate were significantly correlated to abnormal spontaneous activity in patients' brains. These results lead to the conclusion that patients with PDN have abnormal brain activity, indicating that the central nervous system may contribute to painful diabetic neuropathy. TRIAL REGISTRATION: ClinicalTrials.gov identifier NCT03700502.

PMID: 30506341 [PubMed - as supplied by publisher]

Regional cerebral metabolism alterations affect resting-state functional connectivity in major depressive disorder.

Mon, 12/10/2018 - 21:49
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Regional cerebral metabolism alterations affect resting-state functional connectivity in major depressive disorder.

Quant Imaging Med Surg. 2018 Oct;8(9):910-924

Authors: Su H, Zuo C, Zhang H, Jiao F, Zhang B, Tang W, Geng D, Guan Y, Shi S

Abstract
Background: 18F-FDG positron emission tomography (PET) is a reliable technique to quantify regional neural glucose metabolism even with major depressive disorder (MDD) heterogeneous features. Previous study proposed that in the resting-state (RS), pairs of brain regions whose regional glucose metabolic rates were significantly correlated were functionally associated. This synchronicity indicates a neuronal metabolic and functional interaction in high energy efficient brain regions. In this study, a multimode method was used to identify the RS-FC patterns based on regional metabolism changes, and to observe its relationship with the severity of depressive symptoms in MDD patients.
Methods: The study enrolled 11 medication-naive MDD patients and 14 healthy subjects. All participants received a static 18F-FDG PET brain scan and a resting-state functional magnetic resonance imaging (RS-fMRI) scan. SPM5 software was used to compare brain metabolism in MDD patients with that in healthy controls, and designated regions with a change in metabolism as regions of interest (ROIs). The glucose metabolism-based regional RS-FC Z values were compared between groups. Then group independent component analysis (ICA) was used to identify the abnormal connectivity nodes in the intrinsic function networks. Finally, the correlation between abnormal RS-FC Z values and the severity of depressive symptoms was evaluated.
Results: Patients with MDD had reduced glucose metabolism in the putamen, claustrum, insular, inferior frontal gyrus, and supramarginal gyrus. The metabolic reduction regions impaired functional connectivity (FC) to key hubs, such as the Inferior frontal gyrus (pars triangular), angular gyrus, calcarine sulcus, middle frontal gyrus (MFG), located in dorsolateral prefrontal cortex (DLPFC)/parietal lobe, salience network (SN), primary visual cortex (V1), and language network respectively. There was no correlation between aberrant connectivity and the severity of clinical symptoms.
Conclusions: This research puts forward a possibility that focal neural activity alteration may share RS-FC dysfunction and be susceptible to hubs in the functional network in MDD. In particular, the metabolism and function profiles of the Inferior frontal gyrus (pars triangularis) should be emphasized in future MDD studies.

PMID: 30505720 [PubMed]

Identification and functional characterization of HIV-associated neurocognitive disorders with large-scale Granger causality analysis on resting-state functional MRI.

Mon, 12/10/2018 - 21:49
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Identification and functional characterization of HIV-associated neurocognitive disorders with large-scale Granger causality analysis on resting-state functional MRI.

Proc SPIE Int Soc Opt Eng. 2018 Feb;10575:

Authors: Chockanathan U, DSouza AM, Abidin AZ, Schifitto G, Wismüller A

Abstract
Resting-state functional MRI (rs-fMRI), coupled with advanced multivariate time-series analysis methods such as Granger causality, is a promising tool for the development of novel functional connectivity biomarkers of neurologic and psychiatric disease. Recently large-scale Granger causality (lsGC) has been proposed as an alternative to conventional Granger causality (cGC) that extends the scope of robust Granger causal analyses to high-dimensional systems such as the human brain. In this study, lsGC and cGC were comparatively evaluated on their ability to capture neurologic damage associated with HIV-associated neurocognitive disorders (HAND). Functional brain network models were constructed from rs-fMRI data collected from a cohort of HIV+ and HIV - subjects. Graph theoretic properties of the resulting networks were then used to train a support vector machine (SVM) model to predict clinically relevant parameters, such as HIV status and neuropsychometric (NP) scores. For the HIV+ /- classification task, lsGC, which yielded a peak area under the receiver operating characteristic curve (AUC) of 0.83, significantly outperformed cGC, which yielded a peak AUC of 0.61, at all parameter settings tested. For the NP score regression task, lsGC, with a minimum mean squared error (MSE) of 0.75, significantly outperformed cGC, with a minimum MSE of 0.84 (p < 0.001, one-tailed paired t-test). These results show that, at optimal parameter settings, lsGC is better able to capture functional brain connectivity correlates of HAND than cGC. However, given the substantial variation in the performance of the two methods at different parameter settings, particularly for the regression task, improved parameter selection criteria are necessary and constitute an area for future research.

PMID: 30505063 [PubMed]

Methylphenidate's effects on thalamic metabolism and functional connectivity in cannabis abusers and healthy controls.

Mon, 12/10/2018 - 21:49
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Methylphenidate's effects on thalamic metabolism and functional connectivity in cannabis abusers and healthy controls.

Neuropsychopharmacology. 2018 Dec 01;:

Authors: Demiral ŞB, Tomasi D, Wiers CE, Manza P, Shokri-Kojori E, Studentsova Y, Wang GJ, Volkow ND

Abstract
Methylphenidate (MPH) is a first line treatment for ADHD and is also misused as a purported cognitive enhancer, yet its effects on brain function are still poorly understood. Recent functional magnetic resonance imaging (fMRI) studies showed that MPH altered cortico-striatal resting functional connectivity (RFC). Here we investigated the effects of MPH in thalamic connectivity since the thalamus modulates striato-cortical signaling. We hypothesized that MPH would increase thalamic connectivity and metabolism, and that this response would be blunted in cannabis abusers. For this purpose, we measured RFC in seven thalamic nuclei using fMRI and brain glucose metabolism using positron emission tomography (PET) and 18F-fluorodeoxyglucose (FDG) in sixteen healthy controls and thirteen participants with cannabis use disorder (CUD) twice after placebo and after MPH (0.5 mg/kg, iv). MPH significantly increased thalamo-cerebellar connectivity and cerebellar metabolism to the same extent in both groups. Group comparisons revealed that in CUD compared to controls, metabolism in nucleus accumbens was lower for the placebo and MPH measures, that MPH-induced increases in thalamic metabolism were blunted, and that enhanced negative connectivity between thalamus and accumbens in CUD was normalized by MPH (reducing negative connectivity). Our findings identify the thalamus as a target of MPH, which increased its metabolism and connectivity. The reduced metabolism in nucleus accumbens and the disrupted thalamo-accumbens connectivity (enhanced negative connectivity) in CUD is consistent with impaired reactivity of the brain reward's circuit. MPH's normalization of thalamo-accumbens connectivity (reduced negative connectivity) brings forth its potential therapeutic value in CUD, which merits investigation.

PMID: 30504928 [PubMed - as supplied by publisher]

A posterior-anterior distinction between scene perception and scene construction in human medial parietal cortex.

Mon, 12/10/2018 - 21:49
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A posterior-anterior distinction between scene perception and scene construction in human medial parietal cortex.

J Neurosci. 2018 Nov 30;:

Authors: Silson EH, Gilmore AW, Kalinowski SE, Steel A, Kidder A, Martin A, Baker CI

Abstract
Human retrosplenial complex (RSC), located in medial parietal cortex, has been implicated in numerous cognitive functions, including scene perception, spatial navigation, and autobiographical memory retrieval. Recently, a posterior-anterior distinction within RSC was proposed, such that posterior aspects process scene-related visual information (constituting a "medial place area;" MPA), whereas anterior aspects process information that is vividly retrieved from memory, thereby supporting remembering and potentially navigation. Here, we tested this proposed distinction in a single group of participants (both male and female) using fMRI with both perceptual and mnemonic tasks. After completing a resting-state scan, participants performed a task that required constructing scenes from memory and completed a scene-selectivity localizer task. We tested directly perceptual and mnemonic responses in MPA and an anterior, connectivity-defined region (CON), that showed strong functional connectivity with anterior parahippocampal place area (PPA). A double dissociation was observed, such that CON was more strongly activated during scene construction than was MPA, whereas MPA was more perceptually responsive than CON. Further, peak responses from the scene construction task were anterior to perceptual peaks in all but one participant and hemisphere. Finally, through analyses of the posterior-anterior response profiles, we identify the fundus of the parieto-occipital sulcus (POS) as a potential location for the cross-over from perceptual to mnemonic representations and highlight a potential left-hemisphere advantage for mnemonic representations. Collectively, our results support a distinction between posterior and anterior aspects of the "RSC," suggesting that more specific functional-anatomic terms should be used in its place in future work.SIGNIFICANCE STATEMENTThe retrosplenial complex (RSC) has been implicated in vision, spatial cognition and memory. We previously speculated on a potential posterior-anterior distinction within RSC for scene perception and memory-based scene construction/navigation. Here, we tested this distinction through a combination of resting-state, perceptual and mnemonic task data. Consistent with our predictions, we demonstrate that perceptual responses peak consistently posterior of those elicited by memory-based scene construction within the broader RSC. Further, we highlight (1) the fundus of the parieto-occipital sulcus (POS) as a landmark for the transition between these representations, (2) the anterior bank of POS as the point of maximal separation between these representations and (3) identify a potential hemispheric asymmetry in mnemonic representations. These data support functional dissociations within RSC.

PMID: 30504281 [PubMed - as supplied by publisher]

Neural substrates of cognitive reserve in Alzheimer's disease spectrum and normal aging.

Mon, 12/10/2018 - 21:49
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Neural substrates of cognitive reserve in Alzheimer's disease spectrum and normal aging.

Neuroimage. 2018 Nov 29;:

Authors: Lee DH, Lee P, Seo SW, Roh JH, Oh M, Oh JS, Oh SJ, Kim JS, Jeong Y

Abstract
The concept of cognitive reserve (CR) originated from discrepancies between the degree of brain pathology and the severity of clinical manifestations. CR has been characterized through CR proxies, such as education and occupation complexity; however, such approaches have inherent limitations. Although several methods have been developed to overcome these limitations, they fail to reflect the entire Alzheimer's disease (AD) pathology. Meanwhile, graph theory analysis, one of most powerful and flexible approaches, have established remarkable network properties of the brain. The functional and structural brain networks are damaged in neurodegenerative diseases. Therefore, network analysis has been applied to clarify the characteristics of the disease or give insight. Here, using multimodal neuroimaging, we propose an intuitive model to estimate CR based on its original definition, and explore the neural substrates of CR from the perspective of networks and functional connectivity. A total of 87 subjects (21 AD, 32 mild cognitive impairment, and 34 normal aging) underwent tau and amyloid PET, 3D T1-weighted MR, and resting-state fMRI. We hypothesized CR as a residual of actual cognitive performance and expected performance to be related to quantitative factors, such as AD pathology, demographics, and a genetic factor. Then, we correlated this marker using education and occupation complexity as conventional CR proxies. We validated this marker by testing whether it would modulate the effect of brain pathology on memory function. To examine the neural substrates associated with CR, we performed graph analysis to investigate the association between the CR marker and network measures at different granularities in total subjects, AD spectrum and normal aging, respectively. The CR marker from our model was well associated with education and occupation complexity. More directly, the CR marker was revealed to modify the relationship between brain pathology and memory function among AD spectrum. The CR marker was correlated with the global efficiency of the entire network, nodal clustering coefficient, and local efficiency of the right middle-temporal pole. In connectivity analysis, one cluster of edges centered on right middle-temporal pole was significantly correlated with the CR marker. In subgroup analysis, the network measures of right middle-temporal pole still correlated with the CR marker among AD spectrum. However, right precentral gyrus was revealed to be associated with the CR marker in normal aging. This study demonstrates that our intuitive model using multimodal neuroimaging and network perspective adequately and comprehensively captures CR. From a network perspective, CR is associated with the capacity to process information efficiently in the brain. The right middle-temporal pole was revealed to be a pivotal neural substrate of CR in AD spectrum. These findings foster understanding of AD and will be useful to help identify individuals with vulnerability or resistance to AD pathology, and characterize patients for intervention or drug trials.

PMID: 30503934 [PubMed - as supplied by publisher]

Multi-echo fMRI, resting-state connectivity, and high psychometric schizotypy.

Mon, 12/10/2018 - 21:49
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Multi-echo fMRI, resting-state connectivity, and high psychometric schizotypy.

Neuroimage Clin. 2018 Nov 20;:

Authors: Waltmann M, O'Daly O, Egerton A, McMullen K, Kumari V, Barker GJ, Williams SCR, Modinos G

Abstract
Disrupted striatal functional connectivity is proposed to play a critical role in the development of psychotic symptoms. Previous resting-state functional magnetic resonance imaging (rs-fMRI) studies typically reported disrupted striatal connectivity in patients with psychosis and in individuals at clinical and genetic high risk of the disorder relative to healthy controls. This has not been widely studied in healthy individuals with subclinical psychotic-like experiences (schizotypy). Here we applied the emerging technology of multi-echo rs-fMRI to examine corticostriatal connectivity in this group, which is thought to drastically maximize physiological noise removal and increase BOLD contrast-to-noise ratio. Multi-echo rs-fMRI data (echo times, 12, 28, 44, 60 ms) were acquired from healthy individuals with low (LS, n = 20) and high (HS, n = 19) positive schizotypy as determined with the Oxford-Liverpool Inventory of Feelings and Experiences (O-LIFE). After preprocessing to ensure optimal contrast and removal of non-BOLD signal components, whole-brain functional connectivity from six striatal seeds was compared between the HS and LS groups. Effects were considered significant at cluster-level p < .05 family-wise error correction. Compared to LS, HS subjects showed lower rs-fMRI connectivity between ventromedial prefrontal regions and ventral striatal regions. Lower connectivity was also observed between the dorsal putamen and the hippocampus, occipital regions, as well as the cerebellum. These results demonstrate that subclinical positive psychotic-like experiences in healthy individuals are associated with striatal hypoconnectivity as detected using multi-echo rs-fMRI. Further application of this approach may aid in characterizing functional connectivity abnormalities across the extended psychosis phenotype.

PMID: 30503214 [PubMed - as supplied by publisher]

Spatial characteristics of spontaneous and stimulus-induced individual functional connectivity networks in severe disorders of consciousness.

Mon, 12/10/2018 - 21:49
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Spatial characteristics of spontaneous and stimulus-induced individual functional connectivity networks in severe disorders of consciousness.

Brain Cogn. 2018 Nov 27;:

Authors: Sitaram R, Yu T, Halsband U, Vogel D, Müller F, Lang S, Birbaumer N, Kotchoubey B

Abstract
BACKGROUND: Functional connectivity (fcMRI) analyses of resting state functional magnetic resonance imaging (fMRI) data revealed substantial differences between states of consciousness. The underlying cause-effect linkage, however, remains unknown to the present day. The aim of this study was to examine the relationship between fcMRI measures and Disorders of Consciousness (DOC) in resting state and under adequate stimulation.
METHODS AND FINDINGS: fMRI data from thirteen patients with unresponsive wakefulness syndrome, eight patients in minimally conscious state, and eleven healthy controls were acquired in rest and during the application of nociceptive and emotional acoustic stimuli. We compared spatial characteristics and anatomical topography of seed-based fcMRI networks on group and individual levels. The anatomical topography of fcMRI networks of patients was altered in all three conditions as compared with healthy controls. Spread and distribution of individual fcMRI networks, however, differed significantly between patients and healthy controls in stimulation conditions only. The exploration of individual metric values identified two patients whose spatial metrics did not deviate from metric distributions of healthy controls in a statistically meaningful manner.
CONCLUSIONS: These findings suggest that the disturbance of consciousness in DOC is related to deficits in global topographical network organization rather than a principal inability to establish long-distance connections. In addition, the results question the claim that task-free measurements are particularly valuable as a tool for individual diagnostics in severe neurological disorders. Further studies comparing connectivity indices with outcome of DOC patients are needed to determine the clinical relevance of spatial metrics and stimulation paradigms for individual diagnosis, prognosis and treatment in DOC.

PMID: 30502227 [PubMed - as supplied by publisher]

Reconfigured functional network dynamics in adult moyamoya disease: a resting-state fMRI study.

Thu, 12/06/2018 - 00:12

Reconfigured functional network dynamics in adult moyamoya disease: a resting-state fMRI study.

Brain Imaging Behav. 2018 Dec 03;:

Authors: Lei Y, Song B, Chen L, Su J, Zhang X, Ni W, Yu Y, Xu B, Yu L, Gu Y, Mao Y

Abstract
Treatment of vascular cognitive impairment (VCI) in adult moyamoya disease (MMD) is still unclear because of its unveiled neural synchronization. This study introduced a dynamic measurement of connectivity number entropy (CNE) to characterize both spatial and temporal dimensions of network interactions. Fifty-one patients with MMD were recruited (27 with VCI and 24 with intact cognition), as well as 26 normal controls (NCs). Static network properties were first examined to confirm its aberrance in MMD with VCI. Then, the dynamic measurement of CNE was used to detect the deteriorated flexibility of MMD with VCI at global, regional, and network levels. Finally, dynamic reconfiguration of flexible and specialized regions was traced across the three groups. Graph theory analysis indicated that MMD exhibited "small-world" network topology but presented with a deviating pattern from NC as the disease progressed in all topologic metrics of integration, segregation, and small-worldness. Subsequent dynamic analysis showed significant CNE differences among the three groups at both global (p < 0.001) and network levels (default mode network, p = 0.004; executive control network, p = 0.001). Specifically, brain regions related to key aspects of information processing exhibited significant CNE changes across the three groups. Furthermore, CNE values of both flexible and specialized regions changed with impaired cognition. This study not only sheds light on both the static and dynamic organizational principles behind network changes in adult MMD for the first time, but also provides a new methodologic viewpoint to acquire more knowledge of its pathophysiology and treatment direction.

PMID: 30511114 [PubMed - as supplied by publisher]

Abnormal functional connectivity and degree centrality in anterior cingulate cortex in patients with long-term sensorineural hearing loss.

Thu, 12/06/2018 - 00:12

Abnormal functional connectivity and degree centrality in anterior cingulate cortex in patients with long-term sensorineural hearing loss.

Brain Imaging Behav. 2018 Dec 03;:

Authors: Luan Y, Wang C, Jiao Y, Tang T, Zhang J, Lu C, Salvi R, Teng GJ

Abstract
Wide-ranging functional remodeling is involved in sensorineural hearing loss (SNHL), which has been demonstrated to have accumulated risk of cognitive and emotional dysfunction. Anterior cingulate cortex (ACC) has close connections with the auditory area and plays a vital role in regulating the cognitive, emotional and auditory processing. However, the functional reorganization of the ACC and its associations with potential cognitive and emotional impairments involved in SNHL have never been explored. Thirty-five patients with long-term bilateral SNHL and thirty-five well-matched healthy controls were recruited for this study. We analyzed resting-state functional MRI data and neuropsychological test scores from these participants. Functional connectivity of the ACC subdivisions, voxel-wise degree centrality (DC) and intra-/internetwork connectivity were computed to evaluate the functional changes related to cognitive, emotional and multiple sensory functions. ANCOVA and post hoc analyses were conducted to identify differences between normal controls and patients for each measure. Widespread alterations of functional coupling with the subdivisions of the ACC were observed in regions involved in cognitive, emotional and multiple sensory processing, particularly within the cingulo-opercular network (CON), default mode network (DMN) and auditory network (AN) in the SNHL patients. Outstandingly increased DC was found in the ACC. Network analyses showed significant intra- and inter-network hypo-synchronization in the SNHL patients. Importantly, the functional alterations were associated with the anxiety states and the processing speed. The functional reorganization in the ACC and the disturbance of intrinsic multiple network functional connectivity among the CON, DMN, and AN were found in the SNHL patient, which might shed more lights on potential substrates underlying the cognitive and emotional impairments related to the SNHL.

PMID: 30511112 [PubMed - as supplied by publisher]

Dimensional Complexity of the Resting Brain in Healthy Aging, Using a Normalized MPSE.

Thu, 12/06/2018 - 00:12

Dimensional Complexity of the Resting Brain in Healthy Aging, Using a Normalized MPSE.

Front Hum Neurosci. 2018;12:451

Authors: Scheel N, Franke E, Münte TF, Madany Mamlouk A

Abstract
Spontaneous fluctuations of resting-state functional connectivity have been studied in many ways, but grasping the complexity of brain activity has been difficult. Dimensional complexity measures, which are based on Eigenvalue (EV) spectrum analyses (e.g., Ω entropy) have been successfully applied to EEG data, but have not been fully evaluated on functional MRI recordings, because only through the recent introduction of fast multiband fMRI sequences, feasable temporal resolutions are reached. Combining the Eigenspectrum normalization of Ω entropy and the scalable architecture of the so called Multivariate Principal Subspace Entropy (MPSE) leads to a new complexity measure, namely normalized MPSE (nMPSE). It allows functional brain complexity analyses at varying levels of EV energy, independent from global shifts in data variance. Especially the restriction of the EV spectrum to the first dimensions, carrying the most prominent data variance, can act as a filter to reveal the most discriminant factors of dependent variables. Here we look at the effects of healthy aging on the dimensional complexity of brain activity. We employ a large open access dataset, providing a great number of high quality fast multiband recordings. Using nMPSE on whole brain, regional, network and searchlight approaches, we were able to find many age related changes, i.e., in sensorimotoric and right inferior frontal brain regions. Our results implicate that research on dimensional complexity of functional MRI recordings promises to be a unique resource for understanding brain function and for the extraction of biomarkers.

PMID: 30510506 [PubMed]

Replication of Resting State-Task Network Correspondence and Novel Findings on Brain Network Activation During Task fMRI in the Human Connectome Project Study.

Thu, 12/06/2018 - 00:12

Replication of Resting State-Task Network Correspondence and Novel Findings on Brain Network Activation During Task fMRI in the Human Connectome Project Study.

Sci Rep. 2018 Dec 03;8(1):17543

Authors: Nickerson LD

Abstract
There have been many recent reports highlighting a crisis in replication and reliability of research in psychology, neuroscience, and neuroimaging. After a series of reports uncovered various methodological problems with functional magnetic resonance imaging (fMRI) research, considerable attention has been given to principles and practices to improve reproducibility of neuroimaging findings, including promotion of openness, transparency, and data sharing. However, much less attention has been given to use of open access neuroimaging datasets to conduct replication studies. A major barrier to reproducing neuroimaging studies is their high cost, in money and labor, and utilizing such datasets is an obvious solution for breaking down this barrier. The Human Connectome Project (HCP) is an open access dataset consisting of extensive neurological, behavioral, and genetics assessments and neuroimaging data from over 1,100 individuals. In the present study, findings supporting the replication of a highly cited neuroimaging study that showed correspondence between resting state and task brain networks, and novel findings on activation of brain networks during task performance that arose with this exercise are presented as a demonstration of use of the HCP for replication studies.

PMID: 30510165 [PubMed - in process]

Combining resting state functional MRI with intraoperative cortical stimulation to map the mentalizing network.

Wed, 12/05/2018 - 10:53
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Combining resting state functional MRI with intraoperative cortical stimulation to map the mentalizing network.

Neuroimage. 2018 Nov 27;:

Authors: Yordanova YN, Cochereau J, Duffau H, Herbet G

Abstract
OBJECTIVE: To infer the face-based mentalizing network from resting-state functional MRI (rsfMRI) using a seed-based correlation analyses with regions of interest identified during intraoperative cortical electrostimulation.
METHODS: We retrospectively included 23 patients in whom cortical electrostimulation induced transient face-based mentalizing impairment during 'awake' craniotomy for resection of a right-sided diffuse low-grade glioma. Positive stimulation sites were recorded and transferred to the patients' preoperative normalized MRI, and then used as seeds for subsequent seed-to-voxel functional connectivity analyses. The analyses, conducted with an uncorrected voxel-level p-value of 0.001 and a false-discovery-rate cluster-level p-value of 0.05, allowed identification of the cortical structures, functionally coupled with the mentalizing-related sites.
RESULTS: Two clusters of responsive stimulations were identified intraoperatively - one in the right dorsolateral prefrontal cortex (dlPFC, n = 13) and the other in the right inferior frontal gyrus (IFG, n = 10). A whole group level analysis revealed that stimulation sites correlated mainly with voxels located in the pars triangularis of the IFG, the dorsolateral and dorsomedial prefrontal cortices, the temporo-parietal junction, the posterior superior temporal sulcus, and the posterior inferior temporal/fusiform gyrus. Other analyses, taking into consideration the location of the responsive sites (IFG versus dlPFC cluster), highlighted only minor differences between both groups.
CONCLUSIONS: The present study successfully demonstrated the involvement of a large-scale neural network in the face-based mentalizing that perfectly matches networks, classically identified using task-based fMRI paradigms. We thus validated the combination of rsfMRI and stimulation mapping as a powerful approach to identify functional networks in brain-damaged patients.

PMID: 30500423 [PubMed - as supplied by publisher]

Dual-contrast pCASL using simultaneous gradient-echo/spin-echo multiband EPI.

Wed, 12/05/2018 - 10:53
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Dual-contrast pCASL using simultaneous gradient-echo/spin-echo multiband EPI.

Magn Reson Imaging. 2018 Nov 27;:

Authors: Zhang K, Sturm VJ, Buschle LR, Hahn A, Yun SD, Jon Shah N, Bendszus M, Heiland S, Schlemmer HP, Ziener CH, Kurz FT

Abstract
A 2D gradient-echo EPI is commonly employed for arterial spin labeling (ASL) readout to achieve fast whole brain coverage measurements. However, such a readout suffers from susceptibility artifacts induced by magnetic field inhomogeneities. To reduce these susceptibility effects, single-shot spin-echo EPI was proposed to be used for acquisitions in continuous ASL (CASL). To minimize functional and physiological variations, a gradient-echo (GE)/spin-echo (SE) dual-echo EPI readout of the CASL sequence is needed for a comparison between GE- and SE-based determination of cerebral blood flow (CBF). In this study, we employed a simultaneous GE/SE multiband EPI as the readout of a pseudo-CASL (pCASL) sequence. Motor cortex activations derived from a finger-tapping task and functional networks from resting state fMRI were compared for both GE and SE contrasts. Direct comparison of SE and GE contrasts revealed that GE ASL provides an improved sensitivity of functional activity in finger-tapping and in resting-state imaging. SE ASL, on the other hand, suffered less from susceptibility artifacts induced by magnetic field inhomogeneities and pulsatile flow artifacts.

PMID: 30500347 [PubMed - as supplied by publisher]

Measuring abnormal intrinsic brain activities in patients with retinal detachment using amplitude of low-frequency fluctuation: a resting-state fMRI study.

Sun, 12/02/2018 - 10:33

Measuring abnormal intrinsic brain activities in patients with retinal detachment using amplitude of low-frequency fluctuation: a resting-state fMRI study.

Int J Neurosci. 2018 Nov 30;:1-13

Authors: Kang HH, Shu YQ, Yang L, Zhu PW, Li D, Li QH, Min YL, Ye L, Zhou Q, Shao Y

Abstract
OBJECTIVE: The targets of this study was to access the alternations of spontaneous brain activity in RD patients by amplitude of low-frequency fluctuation (ALFF) method and to explore their relationships with clinical behavioral performance.
METHODS: 20 patients with RD (6 males and 14 females), and 20 healthy controls (HCs) (6 males and 14 females) were recruited, and were matched in sex and age. All participants finished the functional magnetic resonance imaging (fMRI) scanning. We applied the ALFF method to detect the spontaneous brain activity. Receiver operating characteristic (ROC) curve was applied to distinguish RD Patients from HCs.
RESULTS: RD patients showed decreased ALFF values in the right occipital lobe and right medial frontal gyrus and increased ALFF values in the right frontal superior orbital and left inferior temporal gyrus when compared with HCs. In RD patients, we did not find any relationship between the mean ALFF values and the clinical behavioral performances.
CONCLUSION: The RD patients exhibited abnormal spontaneous brain activity in vision and vision related brain regions, which might explore potential pathological mechanism of acute vision loss in RD patients.

PMID: 30499735 [PubMed - as supplied by publisher]