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Selective Aberrant Functional-Structural Coupling of Multiscale Brain Networks in Subcortical Vascular Mild Cognitive Impairment.

Sat, 09/26/2020 - 12:40
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Selective Aberrant Functional-Structural Coupling of Multiscale Brain Networks in Subcortical Vascular Mild Cognitive Impairment.

Neurosci Bull. 2020 Sep 25;:

Authors: Ma J, Liu F, Yang B, Xue K, Wang P, Zhou J, Wang Y, Niu Y, Zhang J

Abstract
Subcortical vascular mild cognitive impairment (svMCI) is a common prodromal stage of vascular dementia. Although mounting evidence has suggested abnormalities in several single brain network metrics, few studies have explored the consistency between functional and structural connectivity networks in svMCI. Here, we constructed such networks using resting-state fMRI for functional connectivity and diffusion tensor imaging for structural connectivity in 30 patients with svMCI and 30 normal controls. The functional networks were then parcellated into topological modules, corresponding to several well-defined functional domains. The coupling between the functional and structural networks was finally estimated and compared at the multiscale network level (whole brain and modular level). We found no significant intergroup differences in the functional-structural coupling within the whole brain; however, there was significantly increased functional-structural coupling within the dorsal attention module and decreased functional-structural coupling within the ventral attention module in the svMCI group. In addition, the svMCI patients demonstrated decreased intramodular connectivity strength in the visual, somatomotor, and dorsal attention modules as well as decreased intermodular connectivity strength between several modules in the functional network, mainly linking the visual, somatomotor, dorsal attention, ventral attention, and frontoparietal control modules. There was no significant correlation between the altered module-level functional-structural coupling and cognitive performance in patients with svMCI. These findings demonstrate for the first time that svMCI is reflected in a selective aberrant topological organization in multiscale brain networks and may improve our understanding of the pathophysiological mechanisms underlying svMCI.

PMID: 32975745 [PubMed - as supplied by publisher]

Detection of memory- and learning- related brain connectivity changes following trace eyeblink-conditioning using resting-state functional magnetic resonance imaging in the awake rabbit.

Sat, 09/26/2020 - 12:40
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Detection of memory- and learning- related brain connectivity changes following trace eyeblink-conditioning using resting-state functional magnetic resonance imaging in the awake rabbit.

J Comp Neurol. 2020 Sep 25;:

Authors: Bertolino N, Procissi D, Disterhoft JF, Weiss C

Abstract
Animal imaging studies have the potential to further establish resting-state fMRI (rs-fMRI) and enable its validation for clinical use. The rabbit subjects used in this work are an ideal model system for studying learning and behavior and are also an excellent established test subject for awake scanning given their natural tolerance for restraint. We found that analysis of rs-fMRI conducted on a cohort of rabbits undergoing eyeblink conditioning can reveal functional brain connectivity changes associated with learning, and that rs-fMRI can be used to capture differences between subjects with different levels of cognitive performance. rs-fMRI sessions were conducted on a cohort of rabbits before and after trace eyeblink conditioning. MRI results were analyzed using independent component analysis (ICA) and network analysis. Behavioral data were collected with standard methods using an infrared reflective sensor aimed at the cornea to detect blinks. Behavioral results were analyzed, and a median split was used to create two groups of rabbits based on their performance. The cohort of rabbits undergoing eyeblink conditioning exhibited increased functional connectivity in cingulate cortex, retrosplenial cortex and thalamus consistent with brain reorganization associated with increased learning. Differences in the striatum and right cerebellum were also identified between rabbits in the top or bottom halves of the group as measured by the behavioral assay. Thus, rs-fMRI can provide not only a tool to detect and monitor functional brain changes associated with learning, but also to discriminate between different levels of cognitive performance. This article is protected by copyright. All rights reserved.

PMID: 32975314 [PubMed - as supplied by publisher]

Converging Resting State Networks Unravels Potential Remote Effects of Transcranial Magnetic Stimulation for Major Depression.

Sat, 09/26/2020 - 12:40
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Converging Resting State Networks Unravels Potential Remote Effects of Transcranial Magnetic Stimulation for Major Depression.

Front Psychiatry. 2020;11:836

Authors: Ishida T, Dierks T, Strik W, Morishima Y

Abstract
Despite being a commonly used protocol to treat major depressive disorder (MDD), the underlying mechanism of repetitive transcranial magnetic stimulation (rTMS) on dorsolateral prefrontal cortex (DLPFC) remains unclear. In the current study, we investigated the resting-state fMRI data of 100 healthy subjects by exploring three overlapping functional networks associated with the psychopathologically MDD-related areas (the nucleus accumbens, amygdala, and ventromedial prefrontal cortex). Our results showed that these networks converged at the bilateral DLPFC, which suggested that rTMS over DLPFC might improve MDD by remotely modulating the MDD-related areas synergistically. Additionally, they functionally converged at the DMPFC and bilateral insula which are known to be associated with MDD. These two areas could also be potential targets for rTMS treatment. Dynamic causal modelling (DCM) and Granger causality analysis (GCA) revealed that all pairwise connections among bilateral DLPFC, DMPFC, bilateral insula, and three psychopathologically MDD-related areas contained significant causality. The DCM results also suggested that most of the functional interactions between MDD-related areas and bilateral DLPFC, DMPFC, and bilateral insula can predominantly be explained by the effective connectivity from the psychopathologically MDD-related areas to the rTMS stimulation sites. Finally, we found the conventional functional connectivity to be a more representative measure to obtain connectivity parameters compared to GCA and DCM analysis. Our research helped inspecting the convergence of the functional networks related to a psychiatry disorder. The results identified potential targets for brain stimulation treatment and contributed to the optimization of patient-specific brain stimulation protocols.

PMID: 32973580 [PubMed]

Delayed Functional Networks Development and Altered Fast Oscillation Dynamics in a Rat Model of Cortical Malformation.

Sat, 09/26/2020 - 12:40
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Delayed Functional Networks Development and Altered Fast Oscillation Dynamics in a Rat Model of Cortical Malformation.

Front Neurosci. 2020;14:711

Authors: Kim MJ, Yum MS, Jo Y, Lee M, Kim EJ, Shim WH, Ko TS

Abstract
Malformations of cortical development (MCD) is associated with a wide range of developmental delay and drug resistant epilepsy in children. By using resting-state functional magnetic resonance imaging (RS-fMRI) and event-related spectral perturbation (ERSP) of cortical electroencephalography (EEG) data, we tried to investigate the neural changes of spatiotemporal functional connectivity (FC) and fast oscillation (FO) dynamics in a rat model of methylazoxymethanol (MAM)-induced MCD. A total of 28 infant rats with prenatal exposure to MAM and those of age matched 28 controls with prenatal saline exposure were used. RS-fMRI were acquired at postnatal day 15 (P15) and 29 (P29), and correlation coefficient analysis of eleven region of interests (ROI) was done to find the differences of functional networks between four groups. Two hour-cortical EEGs were also recorded at P15 and P29 and the ERSP of gamma (30-80 Hz) and ripples (80-200 Hz) were analyzed. The rats with MCD showed significantly delayed development of superior colliculus-brainstem network compared to control rats at P15. In contrast to marked maturation of default mode network (DMN) in controls from P15 to P29, there was no clear development in MCD rats. The MCD rats showed significantly higher cortical gamma and ripples-ERSP at P15 and lower cortical ripples-ERSP at P29 than those of control rats. This study demonstrated delayed development of FC and altered cortical FO dynamics in rats with malformed brain. The results should be further investigated in terms of the epileptogenesis and cognitive dysfunction in patients with MCD.

PMID: 32973422 [PubMed]

Evidence for modulation of EEG microstate sequence by vigilance level.

Fri, 09/25/2020 - 11:20

Evidence for modulation of EEG microstate sequence by vigilance level.

Neuroimage. 2020 Sep 21;:117393

Authors: Krylova M, Alizadeh S, Izyurov I, Teckentrup V, Chang C, van derMeer J, Erb M, Kroemer N, Koenig T, Walter M, Jamalabadi H

Abstract
The momentary global functional state of the brain is reflected in its electric field configuration and cluster analytical approaches have consistently shown four configurations, referred to as EEG microstate classes A to D. Changes in microstate parameters are associated with a number of neuropsychiatric disorders, task performance, and mental state establishing their relevance for cognition. However, the common practice to use eye-closed resting state data to assess the temporal dynamics of microstate parameters might induce systematic confounds related to vigilance levels. Here, we studied the dynamics of microstate parameters in two independent data sets and showed that the parameters of microstates are strongly associated with vigilance level assessed both by EEG power analysis and fMRI global signal. We found that the duration and contribution of microstate class C, as well as transition probabilities towards microstate class C were positively associated with vigilance, whereas the sign was reversed for microstate classes A and B. Furthermore, in looking for the origins of the correspondence between microstates and vigilance level, we found Granger-causal effects of vigilance levels on microstate sequence parameters. Collectively, our findings suggest that duration and occurrence of microstates have a different origin and possibly reflect different physiological processes. Finally, our findings indicate the need for taking vigilance levels into consideration in resting-sate EEG investigations.

PMID: 32971266 [PubMed - as supplied by publisher]

Oral contraceptive use, especially during puberty, alters resting state functional connectivity.

Fri, 09/25/2020 - 11:20

Oral contraceptive use, especially during puberty, alters resting state functional connectivity.

Horm Behav. 2020 Sep 21;:104849

Authors: Sharma R, Fang Z, Smith A, Ismail N

Abstract
Millions of women worldwide use oral contraceptives (OCs), often starting during puberty/adolescence. It is, however, unknown how OC use during this critical period of development affects the brain. The objective of the current study was to examine resting state functional connectivity (FC) in the default mode network (DMN), central executive network (CEN), salience network (SN), reward network (RN), and subcortical limbic network of the brain using independent component analysis (ICA) between pubertal- and adult-onset OC users (n = 27) and naturally cycling women (n = 48). It was hypothesized that OC use would result in network-specific increases and decreases in FC and that pubertal-onset OC use would result in differences to the aforementioned networks compared to adult-onset OC use. Pubertal-onset OC use is related to heightened FC in the SN compared to adult-onset OC users. In general, OC use also increases connectivity in the SN, CEN, RN, and subcortical limbic network compared to NC women. No significant differences in connectivity were observed in the DMN between OC users and NC women. These findings provide a mechanistic insight for the altered executive functioning and emotion/reward processing previously seen in OC users, which may then increase their vulnerability to mental health conditions.

PMID: 32971138 [PubMed - as supplied by publisher]

Impact of Cannabis Use on Brain Structure and Function in Suppressed HIV Infection.

Fri, 09/25/2020 - 11:20
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Impact of Cannabis Use on Brain Structure and Function in Suppressed HIV Infection.

J Behav Brain Sci. 2020 Aug;10(8):344-370

Authors: Kallianpur KJ, Birn R, Ndhlovu LC, Souza SA, Mitchell B, Paul R, Chow DC, Kohorn L, Shikuma CM

Abstract
Background: Brain atrophy and cognitive deficits persist among individuals with suppressed HIV disease. The impact of cannabis use is unknown.
Methods: HIV+ and HIV- participants underwent cross-sectional magnetic resonance imaging and neuropsychological testing. Lifetime frequency, duration (years), and recency of cannabis use were self-reported. Relationships of cannabis use to resting-state functional connectivity (RSFC) and to 9 regional brain volumes were assessed with corrections for multiple comparisons. Peripheral blood cytokines and monocyte subsets were measured in the HIV+ group and examined in relation to cannabis exposure.
Results: We evaluated 52 HIV+ [50.8 ± 7.1 years old; 100% on antiretroviral therapy ≥ 3 months; 83% with plasma viral load < 50 copies/mL] and 55 HIV- [54.0 ± 7.5 years old] individuals. Among HIV+ participants, recent cannabis use (within 12 months) was associated with diminished RSFC, including of occipital cortex, controlling for age. Duration of use correlated negatively with volumes of all regions (most strikingly the nucleus accumbens) independently of recent use and intracranial volume. Recent use was associated with larger caudate and white matter volumes and lower soluble vascular cell adhesion molecule-1 and monocyte chemoattractant protein-1 concentrations. Duration of use correlated positively with psychomotor speed. Use > 10 times/lifetime was linked to more somatic symptoms, better executive function, and lower CD14+CD16++ monocyte count.
Conclusion: HIV+ individuals demonstrated opposing associations with cannabis. Recent use may weaken RSFC and prolonged consumption may exacerbate atrophy of the accumbens and other brain regions. More frequent or recent cannabis use may reduce the inflammation and CD14+CD16++ monocytes that facilitate HIV neuroinvasion. HIV-specific cannabis studies are necessary.

PMID: 32968547 [PubMed]

Resting-state functional magnetic resonance imaging of high altitude patients with obstructive sleep apnoea hypopnoea syndrome.

Fri, 09/25/2020 - 11:20
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Resting-state functional magnetic resonance imaging of high altitude patients with obstructive sleep apnoea hypopnoea syndrome.

Sci Rep. 2020 Sep 23;10(1):15546

Authors: Qin Z, Kang D, Feng X, Kong D, Wang F, Bao H

Abstract
The objective of the study was to observe brain function changes in Obstructive Sleep Apnoea Hypopnoea Syndrome (OSAHS) patients at high altitude. Resting-state functional magnetic resonance imaging (rs-fMRI) in patients with OSAHS was assessed using regional homogeneity (ReHo), amplitude of low frequency fluctuation (ALFF) and functional connectivity (FC). In this study, 36 male patients with OSAHS and 38 healthy male subjects were recruited from high-altitude areas, specifically, altitudes of 2,000-3,000 m. OSAHS was diagnosed by polysomnography (PSG). The blood oxygen level-dependent (BOLD) signals of OSAHS patients and healthy controls in the resting state were obtained and compared using ReHo, ALFF and FC methods. The posterior cingulate cortex (PCC) was selected as the seed region in the comparison of FC between the two groups. Compared with the healthy control group, multiple brain functions in the OSAHS patient group were different. There were correlations between the brain function values of some brain regions and demographic data. We also found that in contrast to earlier findings with individuals in plains areas, the brain function at the frontal lobe and the precuneus were higher in OSAHS patients, and the PCC showed higher FC with the left caudate, which may be due to the high-altitude hypoxic environment.

PMID: 32968086 [PubMed - in process]

Altered Functional Connectivity of the Amygdala and Sex Differences in Functional Dyspepsia.

Fri, 09/25/2020 - 11:20
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Altered Functional Connectivity of the Amygdala and Sex Differences in Functional Dyspepsia.

Clin Transl Gastroenterol. 2019 06;10(6):e00046

Authors: Zeng F, Sun R, He Z, Chen Y, Lei D, Yin T, Liu X, Yang Y, Ma P, Qu Y, Zhang D, Lang C, Park J, Lu J, Lan L, Li Z, Gong Q, Liang F, Kong J

Abstract
INTRODUCTION: The influence of sex on the prevalence and clinical manifestations of functional dyspepsia (FD) has recently been a topic of increasing interest. However, brain MRI pathology based on sexual dimorphism in FD has not yet been investigated. The amygdala, which plays a vital role in processing gastrointestinal signals, may be associated with the sex-related pathophysiology of FD.
METHODS: We investigated the resting-state functional connectivity (rsFC) of amygdala subregions in patients with FD and healthy subjects as well as the sex differences between male and female FD patients.
RESULTS: The results showed that FD patients manifested altered rsFC in the basolateral amygdala (BLA) and centromedial amygdala subregions compared with HS and that female FD patients showed increased BLA rsFC with the insula (INS) and decreased BLA rsFC with the medial prefrontal cortex and dorsal lateral prefrontal cortex compared with male FD patients and female HS.
DISCUSSION: Our findings suggest that FD females tend to have more severe dysfunction of cognitive-affective processing among the brain regions associated with the salience network, central executive network, and default mode network.

PMID: 31136362 [PubMed - indexed for MEDLINE]

Altered amplitude of low-frequency fluctuations and regional homogeneity in drug-resistant epilepsy patients with vagal nerve stimulators under different current intensity.

Thu, 09/24/2020 - 16:40
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Altered amplitude of low-frequency fluctuations and regional homogeneity in drug-resistant epilepsy patients with vagal nerve stimulators under different current intensity.

CNS Neurosci Ther. 2020 Sep 23;:

Authors: Zhu J, Xu C, Zhang X, Qiao L, Wang X, Zhang X, Yan X, Ni D, Yu T, Zhang G, Li Y

Abstract
BACKGROUND: The mechanisms of vagal nerve stimulation (VNS) for the treatment of drug-resistant epilepsy (DRE) remain unclear. This study aimed to measure spontaneous brain activity changes caused by VNS in DRE patients using resting-state functional MRI (rs-fMRI).
METHODS: The rs-fMRI scans were performed in 16 DRE patients who underwent VNS surgery. Amplitude of low-frequency fluctuations (ALFF) and regional homogeneity (ReHo) was generated and examined using paired sample t-test to compare activity changes at different current intensity stage. The preoperative and postoperative ALFF/ReHo were also compared in eight responders (≥50% reduction of seizure frequency three months after surgery) and eight nonresponders using paired sample t-test.
RESULTS: The significant ALFF and ReHo changes were shown in various cortical/subcortical structures in patients under different current intensity. After three months of stimulation, responders exhibited increased ALFF in the right middle cingulate gyrus, left parahippocampal gyrus, and left cerebellum, and increased ReHo in the right postcentral gyrus, left precuneus, left postcentral gyrus, right superior parietal gyrus, right precentral gyrus, and right superior frontal gyrus. Nonresponders exhibited decreased ALFF in the left temporal lobe and right cerebellum, increased ALFF in bilateral brainstem, decreased ReHo in bilateral lingual gyri, and increased ReHo in the right middle frontal gyrus and right anterior cingulate gyrus.
CONCLUSIONS: The spontaneous neural activity changes in DRE patients caused by VNS were in an ongoing process. Increased ALFF/ReHo in frontal cortex, cingulate gyri, precentral/postcentral gyri, parahippocampal gyri, precuneus, parietal cortex, and cerebellum may implicate in VNS-induced improvement in seizure frequency.

PMID: 32965801 [PubMed - as supplied by publisher]

Association of Childhood Violence Exposure With Adolescent Neural Network Density.

Thu, 09/24/2020 - 16:40
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Association of Childhood Violence Exposure With Adolescent Neural Network Density.

JAMA Netw Open. 2020 Sep 01;3(9):e2017850

Authors: Goetschius LG, Hein TC, McLanahan SS, Brooks-Gunn J, McLoyd VC, Dotterer HL, Lopez-Duran N, Mitchell C, Hyde LW, Monk CS, Beltz AM

Abstract
Importance: Adverse childhood experiences are a public health issue with negative sequelae that persist throughout life. Current theories suggest that adverse childhood experiences reflect underlying dimensions (eg, violence exposure and social deprivation) with distinct neural mechanisms; however, research findings have been inconsistent, likely owing to variability in how the environment interacts with the brain.
Objective: To examine whether dimensional exposure to childhood adversity is associated with person-specific patterns in adolescent resting-state functional connectivity (rsFC), defined as synchronized activity across brain regions when not engaged in a task.
Design, Setting, and Participants: A sparse network approach in a large sample with substantial representation of understudied, underserved African American youth was used to conduct an observational, population-based longitudinal cohort study. A total of 183 adolescents aged 15 to 17 years from Detroit, Michigan; Toledo, Ohio; and Chicago, Illinois, who participated in the Fragile Families and Child Wellbeing Study were eligible for inclusion. Environmental data from birth to adolescence were collected via telephone and in-person interviews, and neuroimaging data collected at a university lab. The study was conducted from February 1, 1998, to April 26, 2017, and data analysis was performed from January 3, 2019, to May 22, 2020.
Exposures: Composite variables representing violence exposure and social deprivation created from primary caregiver reports on children at ages 3, 5, and 9 years.
Main Outcomes and Measures: Resting-state functional connectivity person-specific network metrics (data-driven subgroup membership, density, and node degree) focused on connectivity among a priori regions of interest in 2 resting-state networks (salience network and default mode) assessed with functional magnetic resonance imaging.
Results: Of the 183 eligible adolescents, 175 individuals (98 girls [56%]) were included in the analysis; mean (SD) age was 15.88 (0.53) years and 127 participants (73%) were African American. Adolescents with high violence exposure were 3.06 times more likely (95% CI, 1.17-8.92) to be in a subgroup characterized by high heterogeneity (few shared connections) and low network density (sparsity). Childhood violence exposure, but not social deprivation, was associated with reduced rsFC density (β = -0.25; 95% CI, -0.41 to -0.05; P = .005), with fewer salience network connections (β = -0.26; 95% CI, -0.43 to -0.08; P = .005) and salience network-default mode connections (β = -0.20; 95% CI, -0.38 to -0.03; P = .02). Violence exposure was associated with node degree of right anterior insula (β = -0.29; 95% CI, -0.47 to -0.12; P = .001) and left inferior parietal lobule (β = -0.26; 95% CI, -0.44 to -0.09; P = .003).
Conclusions and Relevance: The findings of this study suggest that childhood violence exposure is associated with adolescent neural network sparsity. A community-detection algorithm, blinded to child adversity, grouped youth exposed to heightened violence based only on patterns of rsFC. The findings may have implications for understanding how dimensions of adverse childhood experiences impact individualized neural development.

PMID: 32965498 [PubMed - as supplied by publisher]

Spontaneously emerging patterns in human visual cortex and their functional connectivity are linked to the patterns evoked by visual stimuli.

Thu, 09/24/2020 - 16:40
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Spontaneously emerging patterns in human visual cortex and their functional connectivity are linked to the patterns evoked by visual stimuli.

J Neurophysiol. 2020 Sep 23;:

Authors: Kim D, Livne T, Metcalf N, Corbetta M, Shulman G

Abstract
The function of spontaneous brain activity is an important issue in neuroscience. Here we test the hypothesis that patterns of spontaneous activity code representational patterns evoked by stimuli. We compared in human visual cortex multi-vertex patterns of spontaneous activity to patterns evoked by ecological visual stimuli (faces, bodies, scenes) and low-level visual features (e.g. phase-scrambled faces). Specifically, we identified regions that preferred particular stimulus categories during localizer scans (e.g. extra-striate body area for bodies), measured multi-vertex patterns for each category during event-related task scans, and then correlated over vertices these stimulus-evoked patterns to the pattern measured on each frame of resting-state scans. The mean correlation coefficient was essentially zero for all regions/stimulus categories, indicating that resting multi-vertex patterns were not biased toward particular stimulus-evoked patterns. However, the spread of correlation coefficients between stimulus-evoked and resting patterns, positive and negative, was significantly greater for the preferred stimulus category of an ROI. The relationship between spontaneous and stimulus-evoked multi-vertex patterns also governed the temporal correlation or functional connectivity of patterns of spontaneous activity between individual regions (pattern-based functional connectivity). Resting multi-vertex patterns related to an object category fluctuated preferentially between ROIs preferring the same category, and fluctuations of the pattern for a category (e.g. body) within its preferred ROIs were largely uncorrelated with fluctuations of the pattern for a disparate category (e.g. scene) within its preferred ROIs. These results support the proposal that spontaneous multi-vertex activity patterns are linked to stimulus-evoked patterns, consistent with a representational function for spontaneous activity.

PMID: 32965156 [PubMed - as supplied by publisher]

Abnormal Regional Spontaneous Neural Activity in Nonarteritic Anterior Ischemic Optic Neuropathy: A Resting-State Functional MRI Study.

Thu, 09/24/2020 - 16:40
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Abnormal Regional Spontaneous Neural Activity in Nonarteritic Anterior Ischemic Optic Neuropathy: A Resting-State Functional MRI Study.

Neural Plast. 2020;2020:8826787

Authors: Guo P, Zhao P, Lv H, Su Y, Liu M, Chen Y, Wang Y, Hua H, Kang S

Abstract
Objective: To explore altered regional neuronal activity in patients with nonarteritic anterior ischemic optic neuropathy (NAION) and its correlation with clinical performances using the regional homogeneity (ReHo) method, which is based on resting-state functional magnetic resonance imaging (fMRI).
Method: Thirty-one patients with NAION (20 males, 11 females) and 31 age- and sex-matched normal controls (NCs) (20 males, 11 females) were enrolled in the study. All patients underwent ophthalmic examination, including eyesight, intraocular pressure measurement, optimal coherence tomography (OCT), visual field analysis, and fMRI scans. After ReHo was calculated, we investigated group differences in results between the patients and NCs. We analyzed the relationship between ReHo values for different brain regions in patients with NAION and intraocular pressure, visual field analysis, and OCT. A receiver operating characteristic (ROC) curve was used to assess the diagnostic ability of the ReHo method.
Results: Compared with NCs, patients with NAION exhibited higher ReHo values in the left middle frontal gyrus, left middle cingulate gyrus, left superior temporal gyrus, and left inferior parietal lobule. Additionally, they exhibited lower ReHo values in the right lingual gyrus, left putamen/lentiform nucleus, and left superior parietal lobule. ReHo values in the left superior parietal lobule were negatively correlated with right retinal nerve fiber layer values (r = -0.462, P = 0.01). The area under the ROC curve for each brain region indicated that the ReHo method is a credible means of diagnosing patient with NAION.
Conclusion: NAION was primarily associated with dysfunction in the default mode network, which may reflect its underlying neural mechanisms.

PMID: 32963518 [PubMed - as supplied by publisher]

Neuroplasticity induced by general anaesthesia: study protocol for a randomised cross-over clinical trial exploring the effects of sevoflurane and propofol on the brain - A 3-T magnetic resonance imaging study of healthy volunteers.

Thu, 09/24/2020 - 16:40
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Neuroplasticity induced by general anaesthesia: study protocol for a randomised cross-over clinical trial exploring the effects of sevoflurane and propofol on the brain - A 3-T magnetic resonance imaging study of healthy volunteers.

Trials. 2020 Sep 22;21(1):805

Authors: Madsen SS, Møller K, Olsen KS, Vestergaard MB, Lindberg U, Larsson HBW, Mårtensson J, Werner MU, Santos SAG, Asghar MS

Abstract
BACKGROUND: Although used extensively worldwide, the effects of general anaesthesia on the human brain remain largely elusive. Moreover, general anaesthesia may contribute to serious conditions or adverse events such as postoperative cognitive dysfunction and delirium. To understand the basic mechanisms of general anaesthesia, this project aims to study and compare possible de novo neuroplastic changes induced by two commonly used types of general anaesthesia, i.e. inhalation anaesthesia by sevoflurane and intravenously administered anaesthesia by propofol. In addition, we wish to to explore possible associations between neuroplastic changes, neuropsychological adverse effects and subjective changes in fatigue and well-being.
METHODS: This is a randomised, participant- and assessor-blinded, cross-over clinical trial. Thirty healthy volunteers (male:female ratio 1:1) will be randomised to general anaesthesia by either sevoflurane or propofol. Multimodal magnetic resonance imaging (MRI) of the brain will be performed before and after general anaesthesia and repeated after 1 and 8 days. Each magnetic resonance imaging session will be accompanied by cognitive testing and questionnaires on fatigue and well-being. After a wash-out period of 4 weeks, the volunteers will receive the other type of anaesthetic (sevoflurane or propofol), followed by the same series of tests. Primary outcomes: changes in T1-weighted 3D anatomy and diffusion tensor imaging.
SECONDARY OUTCOMES: changes in resting-state functional magnetic resonance imaging, fatigue, well-being, cognitive function, correlations between magnetic resonance imaging findings and the clinical outcomes (questionnaires and cognitive function). Exploratory outcomes: changes in cerebral perfusion and oxygen metabolism, lactate, and response to visual stimuli.
DISCUSSION: To the best of our knowledge, this is the most extensive and advanced series of studies with head-to-head comparison of two widely used methods for general anaesthesia. Recruitment was initiated in September 2019.
TRIAL REGISTRATION: Approved by the Research Ethics Committee in the Capital Region of Denmark, ref. H-18028925 (6 September 2018). EudraCT and Danish Medicines Agency: 2018-001252-35 (23 March 2018). www.clinicaltrials.gov , ID: NCT04125121 . Retrospectively registered on 10 October 2019.

PMID: 32962743 [PubMed - as supplied by publisher]

Cognitive functioning in glioma patients is related to functional connectivity measures of the non-tumoural hemisphere.

Thu, 09/24/2020 - 16:40
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Cognitive functioning in glioma patients is related to functional connectivity measures of the non-tumoural hemisphere.

Eur J Neurosci. 2019 12;50(12):3921-3933

Authors: De Baene W, Rutten GM, Sitskoorn MM

Abstract
Previous studies have shown that cognitive functioning in patients with brain tumour is associated with the functional network characteristics of specific resting-state networks or with whole-brain network characteristics. These studies, however, did not acknowledge the functional contribution of areas in the contralesional, non-tumoural hemisphere, even though these healthy remote areas likely play a critical role in compensating for the loss of function in damaged tissue. In the current study, we examined whether there is an association between cognitive performance and functional network features of the contralesional hemisphere of patients with glioma. We found that local efficiency of the contralesional hemisphere was associated with performance on the reaction time domain, whereas contralesional assortativity was associated with complex attention and cognitive flexibility scores. Our results suggest that a less segregated organization of the contralesional hemisphere is associated with better reaction time scores, whereas a better spread of information over the contralesional hemisphere through mutually interconnected contralesional hubs is associated with better cognitive flexibility and better complex attention scores. These findings urge researchers to recognize the functional contribution of remote, undamaged regions and to focus more on the graph metrics of the contralesional hemisphere in the search for predictors of cognitive functioning in patients with brain tumour.

PMID: 31370107 [PubMed - indexed for MEDLINE]

Intrinsic connectivity of the prefrontal cortex and striato-limbic system respectively differentiate major depressive from generalized anxiety disorder.

Wed, 09/23/2020 - 15:20
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Intrinsic connectivity of the prefrontal cortex and striato-limbic system respectively differentiate major depressive from generalized anxiety disorder.

Neuropsychopharmacology. 2020 Sep 22;:

Authors: Xu X, Dai J, Chen Y, Liu C, Xin F, Zhou X, Zhou F, Stamatakis EA, Yao S, Luo L, Huang Y, Wang J, Zou Z, Vatansever D, Kendrick KM, Zhou B, Becker B

Abstract
Major depressive disorder (MDD) and generalized anxiety disorder (GAD) are highly prevalent and debilitating disorders. The high overlap on the symptomatic and neurobiological level led to ongoing debates about their diagnostic and neurobiological uniqueness. The present study aims to identify common and disorder-specific neuropathological mechanisms and treatment targets in MDD and GAD. To this end we combined categorial and dimensional disorder models with a fully data-driven intrinsic network-level analysis (intrinsic connectivity contrast, ICC) to resting-state fMRI data acquired in 108 individuals (n = 35 and n = 38 unmedicated patients with first-episode GAD, MDD, respectively, and n = 35 healthy controls). Convergent evidence from categorical and dimensional analyses revealed MDD-specific decreased whole-brain connectivity profiles of the medial prefrontal and dorsolateral prefrontal cortex while GAD was specifically characterized by decreased whole-brain connectivity profiles of the putamen and decreased communication of this region with the amygdala. Together, findings from the present data-driven analysis suggest that intrinsic communication of frontal regions engaged in executive functions and emotion regulation represent depression-specific neurofunctional markers and treatment targets whereas dysregulated intrinsic communication of the striato-amygdala system engaged in reinforcement-based and emotional learning processes represent GAD-specific markers.Fig. 1BRAIN AREAS EXHIBITED ALTERATIONS IN ICC ANALYSIS.: a Right medial prefrontal cortex (R_MPFC); b right putamen; c left dorsolateral prefrontal cortex (L_DLPFC); d group differences in R_MPFC; e group differences in right putamen; f group differences in L_DLPFC. R_MPFC right medial prefrontal cortex, L_DLPFC left dorsolateral prefrontal cortex. For visualization, statistical maps are displayed with a threshold of p < 0.005 uncorrected.Fig. 2BRAIN REGIONS SHOWED ABERRANT FUNCTIONAL CONNECTIVITY WITH SEEDS FROM ICC.: a Altered right putamen-right amygdala (centromedial) connectivity and b post hoc group differences. ICC intrinsic connectivity contrast.Fig. 3Associations between (a) the right MPFC and depressive symptom-load; b the left DLPFC and depressive symptom load; c the right putamen and GAD symptom load; and d the right putamen-right amygdala connectivity and GAD symptom load. Scatter plots represented the entire sample pooling the data GAD, MDD, and HC. Diagnostic group membership is color-coded. Vertical axis reflects parameter estimates of corresponding brain areas. *p < 0.05; **p < 0.005, all p values FDR corrected for multiple comparisons. MPFC medial prefrontal cortex, DLPFC dorsolateral prefrontal cortex. Green = HC, blue = MDD, and red = GAD.Fig. 4NeuroSynth decoding of (a) right MPFC, (b) right putamen, and (c) left DLPFC. MPFC medial prefrontal cortex, DLPFC dorsolateral prefrontal cortex.

PMID: 32961541 [PubMed - as supplied by publisher]

A Systematic Review of the Application of Functional Near-InfraredSpectroscopy to the Study of Cerebral Hemodynamics in Healthy Aging.

Wed, 09/23/2020 - 15:20
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A Systematic Review of the Application of Functional Near-InfraredSpectroscopy to the Study of Cerebral Hemodynamics in Healthy Aging.

Neuropsychol Rev. 2020 Sep 22;:

Authors: Yeung MK, Chan AS

Abstract
Positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) studies have shown that healthy aging is associated with functional brain deterioration that preferentially affects the prefrontal cortex. This article reviews the application of an alternative method, functional near-infrared spectroscopy (fNIRS), to the study of age-related changes in cerebral hemodynamics and factors that influence cerebral hemodynamics in the elderly population. We conducted literature searches in PudMed and PsycINFO, and selected only English original research articles that used fNIRS to study healthy individuals with a mean age of ≥ 55 years. All articles were published in peer-reviewed journals between 1977 and May 2019. We synthesized 114 fNIRS studies examining hemodynamic changes that occurred in the resting state and during the tasks of sensation and perception, motor control, semantic processing, word retrieval, attentional shifting, inhibitory control, memory, and emotion and motivation in healthy older adults. This review, which was not registered in a registry, reveals an age-related reduction in resting-state cerebral oxygenation and connectivity in the prefrontal cortex. It also shows that aging is associated with a reduction in functional hemispheric asymmetry and increased compensatory activity in the frontal lobe across multiple task domains. In addition, this article describes the beneficial effects of healthy lifestyles and the detrimental effects of cardiovascular disease risk factors on brain functioning among nondemented older adults. Limitations of this review include exclusion of gray and non-English literature and lack of meta-analysis. Altogether, the fNIRS literature provides some support for various neurocognitive aging theories derived from task-based PET and fMRI studies. Because fNIRS is relatively motion-tolerant and environmentally unconstrained, it is a promising tool for fostering the development of aging biomarkers and antiaging interventions.

PMID: 32959167 [PubMed - as supplied by publisher]

Changes in structural and functional connectivity during two years of fingolimod therapy for multiple sclerosis.

Tue, 09/22/2020 - 14:00
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Changes in structural and functional connectivity during two years of fingolimod therapy for multiple sclerosis.

Magn Reson Imaging. 2020 Sep 18;:

Authors: Bhattacharyya PK, Lowe MJ, Sakaie KE, Li H, Lin J, Fox RJ

Abstract
BACKGROUND: Fingolimod, an oral drug, has been reported to reduce relapse rate in multiple sclerosis (MS). However disease progression may still occur in spite of control of inflammation. Functional imbalances within and between cerebral networks associated with disruption of structural and functional network integrity, have been reported in MS. An effective therapy is expected to stabilize such functional network integrity.
OBJECTIVE: The purpose of this study was to investigate changes in structural and resting-state functional connectivity of motor and cognitive networks, and associated changes in neurologic scores in MS, during 2 years of fingolimod therapy.
METHODS: Twenty five subjects with MS were recruited for this study. Subjects were scanned with diffusion tensor imaging (DTI) and resting-state functional connectivity MRI (fcMRI) scan protocol at 3 T with 6-month interval over a period of 2 years. Neurologic performance scores of motor and cognitive performances were also obtained.
RESULTS: DTI measures worsened during the 1st year and then stabilized; any trend of stabilization of fcMRI was delayed until the 2nd year. While motor performance did not change, cognitive performance showed improvement. Several baseline DTI measures correlated with relevant neurologic scores.
CONCLUSION: Initial worsening of motor and cognitive network was reported after 1 year of treatment, but seems DTI and fcMRI measures seem to stabilize after around one year fingolimod therapy.

PMID: 32956806 [PubMed - as supplied by publisher]

Dynamic brain-body coupling of breath-by-breath O2-CO2 exchange ratio with resting state cerebral hemodynamic fluctuations.

Tue, 09/22/2020 - 14:00
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Dynamic brain-body coupling of breath-by-breath O2-CO2 exchange ratio with resting state cerebral hemodynamic fluctuations.

PLoS One. 2020;15(9):e0238946

Authors: Chan ST, Evans KC, Song TY, Selb J, van der Kouwe A, Rosen BR, Zheng YP, Ahn AC, Kwong KK

Abstract
BACKGROUND: The origin of low frequency cerebral hemodynamic fluctuations (CHF) in the resting state remains unknown. Breath-by breath O2-CO2 exchange ratio (bER) has been reported to correlate with the cerebrovascular response to brief breath hold challenge at the frequency range of 0.008-0.03Hz in healthy adults. bER is defined as the ratio of the change in the partial pressure of oxygen (ΔPO2) to that of carbon dioxide (ΔPCO2) between end inspiration and end expiration. In this study, we aimed to investigate the contribution of respiratory gas exchange (RGE) metrics (bER, ΔPO2 and ΔPCO2) to low frequency CHF during spontaneous breathing.
METHODS: Twenty-two healthy adults were included. We used transcranial Doppler sonography to evaluate CHF by measuring the changes in cerebral blood flow velocity (ΔCBFv) in bilateral middle cerebral arteries. The regional CHF were mapped with blood oxygenation level dependent (ΔBOLD) signal changes using functional magnetic resonance imaging. Temporal features and frequency characteristics of RGE metrics during spontaneous breathing were examined, and the simultaneous measurements of RGE metrics and CHF (ΔCBFv and ΔBOLD) were studied for their correlation.
RESULTS: We found that the time courses of ΔPO2 and ΔPCO2 were interdependent but not redundant. The oscillations of RGE metrics were coherent with resting state CHF at the frequency range of 0.008-0.03Hz. Both bER and ΔPO2 were superior to ΔPCO2 in association with CHF while CHF could correlate more strongly with bER than with ΔPO2 in some brain regions. Brain regions with the strongest coupling between bER and ΔBOLD overlapped with many areas of default mode network including precuneus and posterior cingulate.
CONCLUSION: Although the physiological mechanisms underlying the strong correlation between bER and CHF are unclear, our findings suggest the contribution of bER to low frequency resting state CHF, providing a novel insight of brain-body interaction via CHF and oscillations of RGE metrics.

PMID: 32956397 [PubMed - as supplied by publisher]

Diffuse brain connectivity changes in Charcot-Marie-tooth type 1A patients: A resting-state functional MRI study.

Tue, 09/22/2020 - 14:00
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Diffuse brain connectivity changes in Charcot-Marie-tooth type 1A patients: A resting-state functional MRI study.

Eur J Neurol. 2020 Sep 21;:

Authors: Pontillo G, Tozza S, Perillo T, Cocozza S, Dubbioso R, Severi D, Iodice R, Tedeschi E, Elefante A, Brunetti A, Manganelli F, Quarantelli M

Abstract
BACKGROUND: Changes of brain structure and function have been described in peripheral neuropathies. Aim of our study was to systematically investigate possible modifications of major large-scale brain networks using Resting-State functional MRI(RS-fMRI) in CMT1A patients.
METHODS: In this cross-sectional study, we acquired 3T MRI brain scans of right-handed genetically confirmed CMT1A patients and age- and sex-comparable healthy controls. Patients also underwent clinical and electrophysiological examinations assessing neurological impairment. RS-fMRI data were analyzed using a seed-based approach, with thirty-two different seeds sampling the main hubs of default mode(DMN), sensorimotor(SMN), visual(VN), salience(SN), dorsal attention(DAN), frontoparietal(FPN), language(LN) and cerebellar(CN) networks. Between-group differences in terms of functional connectivity(FC) with the explored seeds were tested voxel-wise, correcting for local gray matter density to account for possible structural abnormalities, while the relationship between FC modifications and neurological impairment was investigated using robust correlation analyses.
RESULTS: 18 CMT1A patients (34.0±11.4years;M/F:11/7) were enrolled, along with 20 healthy controls (30.1±10.2years;M/F:11/9). In the CMT group compared to controls, we found clusters of increased FC with the visual cortex(p=0.001), SN(p<6·10-4 ), DAN(p<8·10-5 ) and LN(p<7·10-4 ), along with a single cluster of reduced FC with the visual cortex in the left lentiform nucleus(p=10-6 ). A significant correlation emerged between neurophysiological impairment and increased FC with right temporal language areas(r=0.655,p=0.006), along with an association between walking ability and increased FC with the left supramarginal gyrus(SN)(r=0.620,p=0.006).
CONCLUSIONS: Our data show evidence of diffuse functional reorganization involving multiple large-scale networks in the CMT1A brain, independent of structural modifications and partially correlating with peripheral nerve damage and functional impairment.

PMID: 32955777 [PubMed - as supplied by publisher]

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