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

Sat, 09/26/2020 - 22:50
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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 - 22:50
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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 - 22:50
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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 - 22:50
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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 - 22:49
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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 - 22:49
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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]

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

Fri, 09/25/2020 - 22:49
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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 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 - 22:48
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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]

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

Thu, 09/24/2020 - 22:48
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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 - 22:48
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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]

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

Wed, 09/23/2020 - 22:47
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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 - 22:47
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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]

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

Tue, 09/22/2020 - 22:46
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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]

Respiratory-related brain pulsations are increased in epilepsy-a two-centre functional MRI study.

Tue, 09/22/2020 - 22:46
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Respiratory-related brain pulsations are increased in epilepsy-a two-centre functional MRI study.

Brain Commun. 2020;2(2):fcaa076

Authors: Kananen J, Helakari H, Korhonen V, Huotari N, Järvelä M, Raitamaa L, Raatikainen V, Rajna Z, Tuovinen T, Nedergaard M, Jacobs J, LeVan P, Ansakorpi H, Kiviniemi V

Abstract
Resting-state functional MRI has shown potential for detecting changes in cerebral blood oxygen level-dependent signal in patients with epilepsy, even in the absence of epileptiform activity. Furthermore, it has been suggested that coefficient of variation mapping of fast functional MRI signal may provide a powerful tool for the identification of intrinsic brain pulsations in neurological diseases such as dementia, stroke and epilepsy. In this study, we used fast functional MRI sequence (magnetic resonance encephalography) to acquire ten whole-brain images per second. We used the functional MRI data to compare physiological brain pulsations between healthy controls (n = 102) and patients with epilepsy (n = 33) and furthermore to drug-naive seizure patients (n = 9). Analyses were performed by calculating coefficient of variation and spectral power in full band and filtered sub-bands. Brain pulsations in the respiratory-related frequency sub-band (0.11-0.51 Hz) were significantly (P < 0.05) increased in patients with epilepsy, with an increase in both signal variance and power. At the individual level, over 80% of medicated and drug-naive seizure patients exhibited areas of abnormal brain signal power that correlated well with the known clinical diagnosis, while none of the controls showed signs of abnormality with the same threshold. The differences were most apparent in the basal brain structures, respiratory centres of brain stem, midbrain and temporal lobes. Notably, full-band, very low frequency (0.01-0.1 Hz) and cardiovascular (0.8-1.76 Hz) brain pulses showed no differences between groups. This study extends and confirms our previous results of abnormal fast functional MRI signal variance in epilepsy patients. Only respiratory-related brain pulsations were clearly increased with no changes in either physiological cardiorespiratory rates or head motion between the subjects. The regional alterations in brain pulsations suggest that mechanisms driving the cerebrospinal fluid homeostasis may be altered in epilepsy. Magnetic resonance encephalography has both increased sensitivity and high specificity for detecting the increased brain pulsations, particularly in times when other tools for locating epileptogenic areas remain inconclusive.

PMID: 32954328 [PubMed]

Subthalamic nucleus deep brain stimulation modulates two distinct neurocircuits.

Mon, 09/21/2020 - 22:45
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Subthalamic nucleus deep brain stimulation modulates two distinct neurocircuits.

Ann Neurol. 2020 Sep 20;:

Authors: Shen L, Jiang C, Hubbard CS, Ren J, He C, Wang D, Dahmani L, Guo Y, Liu Y, Xu S, Meng F, Zhang J, Liu H, Li L

Abstract
OBJECTIVE: Current understanding of the neuromodulatory effects of deep brain stimulation (DBS) on large-scale brain networks remains elusive, largely due to the lack of techniques that can reveal DBS-induced activity at the whole-brain level. Using a novel 3T-MRI compatible stimulator, we investigated whole-brain effects of subthalamic nucleus (STN) stimulation in patients with Parkinson's disease.
METHODS: Fourteen patients received STN-DBS treatment and participated in a block-design fMRI experiment, wherein stimulations were delivered during "ON" blocks interleaved with "OFF" blocks. FMRI responses to low-frequency(60Hz) and high-frequency(130Hz) STN-DBS were measured 1-, 3-, 6-, and 12-months post-surgery. To ensure reliability, multiple runs (48min) of fMRI data were acquired at each post-surgical visit. Pre-surgical resting-state fMRI (30min) data were also acquired.
RESULTS: Two neurocircuits showed highly replicable, but distinct responses to STN-DBS. A circuit involving the globus pallidus internus (GPi), thalamus, and deep cerebellar nuclei was significantly activated, while another circuit involving the primary motor cortex (M1), putamen, and cerebellum showed DBS-induced deactivation. These two circuits were dissociable in terms of their DBS-induced responses and resting-state functional connectivity. The GPi-circuit was frequency-dependent, selectively responding to high-frequency stimulation, whereas the M1-circuit was responsive in a time-dependent manner, showing enhanced deactivation over time. Finally, activation of the GPi-circuit was associated with overall motor improvement, whereas M1-circuit deactivation was related to reduced bradykinesia.
INTERPRETATION: Concurrent DBS-fMRI using 3T revealed two distinct circuits that responded differentially to STN-DBS and were related to divergent symptoms, a finding that may provide novel insights into the neural mechanisms underlying DBS. This article is protected by copyright. All rights reserved.

PMID: 32951262 [PubMed - as supplied by publisher]

The longitudinal association between externalizing behavior and frontoamygdalar resting-state functional connectivity in late adolescence and young adulthood.

Mon, 09/21/2020 - 22:45

The longitudinal association between externalizing behavior and frontoamygdalar resting-state functional connectivity in late adolescence and young adulthood.

J Child Psychol Psychiatry. 2020 Sep 20;:

Authors: Thijssen S, Collins PF, Weiss H, Luciana M

Abstract
BACKGROUND: Externalizing behavior has been attributed, in part, to decreased frontolimbic control over amygdala activation. However, little is known about developmental trajectories of frontoamygdalar functional connectivity and its relation to externalizing behavior. The present study addresses this gap by examining longitudinal associations between adolescent and adult externalizing behavior and amygdala-anterior cingulate cortex (ACC) and amygdala-orbitofrontal cortex (OFC) resting-state functional connectivity in a sample of 111 typically developing participants aged 11-23 at baseline.
METHODS: Participants completed two-to-four data waves spaced approximately two years apart, resulting in a total of 309 data points. At each data wave, externalizing behavior was measured using the Externalizing Behavior Broadband Scale from the Achenbach Youth/Adult Self-Report questionnaire. Resting-state fMRI preprocessing was performed using FSL. Amygdala functional connectivity was examined using AFNI. The longitudinal association between externalizing behavior and amygdala-ACC/OFC functional connectivity was examined using linear mixed effect models in R.
RESULTS: Externalizing behavior was associated with increased amygdala-ACC and amygdala-OFC resting-state functional connectivity across adolescence and young adulthood. For amygdala-ACC connectivity, externalizing behavior at baseline primarily drove this association, whereas for amygdala-OFC functional connectivity, change in externalizing behavior relative to baseline drove the main effect of externalizing behavior on amygdala-OFC functional connectivity. No evidence was found for differential developmental trajectories of frontoamygdalar connectivity for different levels of externalizing behavior (i.e., age-by-externalizing behavior interaction effect).
CONCLUSIONS: Higher externalizing behavior is associated with increased resting-state attunement between the amygdala and ACC/OFC, perhaps indicating a generally more vigilant state for neural networks important for emotional processing and control.

PMID: 32951240 [PubMed - as supplied by publisher]

Altered dynamic effective connectivity of the default mode network in newly diagnosed drug-naïve juvenile myoclonic epilepsy.

Mon, 09/21/2020 - 22:45
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Altered dynamic effective connectivity of the default mode network in newly diagnosed drug-naïve juvenile myoclonic epilepsy.

Neuroimage Clin. 2020 Sep 11;28:102431

Authors: Zhang Z, Liu G, Zheng W, Shi J, Liu H, Sun Y

Abstract
Juvenile myoclonic epilepsy (JME) has been repeatedly revealed to be associated with brain dysconnectivity in the default mode network (DMN). However, the implicit assumption of stationary and nondirectional functional connectivity (FC) in most previous resting-state fMRI studies raises an open question of JME-related aberrations in dynamic causal properties of FC. Here, we introduces an empirical method incorporating sliding-window approach and a multivariate Granger causality analysis to investigate, for the first time, the reorganization of dynamic effective connectivity (DEC) in DMN for patients with JME. DEC was obtained from resting-state fMRI of 34 patients with newly diagnosed and drug-naïve JME and 34 matched controls. Through clustering analysis, we found two distinct states that characterize the DEC patterns (i.e., a less frequent, strongly connected state (State 1) and a more frequent, weakly connected state (State 2)). Patients showed altered ECs within DMN subnetworks in the State 2, whereas abnormal ECs between DMN subnetworks were found in the State 1. Furthermore, we observed that the causal influence flows of the medial prefrontal cortex and angular gyrus were altered in a manner of state specificity, and associated with disease severity of patients. Overall, our findings extend the dysconnectivity hypothesis in JME from static to dynamic causal FC and demonstrate that aberrant DEC may underlie abnormal brain function in JME at early phase of illness.

PMID: 32950903 [PubMed - as supplied by publisher]

Peripheral inflammation is associated with dysfunctional corticostriatal circuitry and executive dysfunction in bipolar disorder patients.

Mon, 09/21/2020 - 22:45
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Peripheral inflammation is associated with dysfunctional corticostriatal circuitry and executive dysfunction in bipolar disorder patients.

Brain Behav Immun. 2020 Sep 17;:

Authors: Tseng HH, Hua Chang H, Wei SY, Lu TH, Hsieh YT, Kuang Yang Y, See Chen P

Abstract
Bipolar disorder (BD) has been linked to abnormal frontal and striatal function, and elevated inflammatory responses. However, the impact of peripheral inflammation on the corticostriatal functional connectivity (FC) remains obscure in BD. The current study aimed to explore the association between peripheral inflammation and corticostriatal connectivity in euthymic BD. We recruited 25 euthymic BD patients and 43 healthy controls (HCs) from the community. Resting state functional images were obtained using 3T magnetic resonance imaging (fMRI), and striatal seed-based whole-brain functional connectivity analyses were performed, with the fasting plasma high-sensitivity C-reactive protein (hs-CRP) level entered as a regressor of interest. The participants also completed the Wisconsin Card-Sorting Test (WCST) and the Continuous Performance Test (CPT). The euthymic BD group had a similar hs-CRP level to the HC group, but a significantly poorer cognitive performance. Compared with the HC group, a higher connectivity between the right dorsal caudal putamen (dcP) and the ventral lateral prefrontal cortex (vlPFC) in the BD group was significantly correlated with a higher hs-CRP level. Stronger dcP-vlPFC connectivity was correlated with a lower CPT unmasked d' in the BD group. BD patients might be particularly sensitive to the effects of inflammation on corticostriatal connectivity. The potentially greater sensitivity of BD patients to peripheral inflammation may differentially modulate the cognitive and reward related corticostriatal circuitry, which may contribute to the pathophysiology of cognitive-affective dysregulation in the euthymic state. Anti-inflammatory or other circuit-specific treatment is warranted for individualized treatment in BD.

PMID: 32950621 [PubMed - as supplied by publisher]

Increased functional homotopy of the prefrontal cortex is associated with corpus callosum degeneration and working memory decline.

Sun, 09/20/2020 - 22:42
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Increased functional homotopy of the prefrontal cortex is associated with corpus callosum degeneration and working memory decline.

Neurobiol Aging. 2020 Aug 25;96:68-78

Authors: Avelar-Pereira B, Bäckman L, Wåhlin A, Nyberg L, Salami A

Abstract
Functional homotopy reflects the link between spontaneous activity in a voxel and its counterpart in the opposite hemisphere. Alterations in homotopic functional connectivity (FC) are seen in normal aging, with highest and lowest homotopy being present in sensory-motor and higher-order regions, respectively. Homotopic FC relates to underlying structural connections, but its neurobiological underpinnings remain unclear. The genu of the corpus callosum joins symmetrical parts of the prefrontal cortex (PFC) and is susceptible to age-related degeneration, suggesting that PFC homotopic connectivity is linked to changes in white-matter integrity. We investigated homotopic connectivity changes and whether these were associated with white-matter integrity in 338 individuals. In addition, we examined whether PFC homotopic FC was related to changes in the genu over 10 years and working memory over 5 years. There were increases and decreases in functional homotopy, with the former being prevalent in subcortical and frontal regions. Increased PFC homotopic FC was partially driven by structural degeneration and negatively associated with working memory, suggesting that it reflects detrimental age-related changes.

PMID: 32949903 [PubMed - as supplied by publisher]

Disturbance of thalamic metabolism and its association with regional neural dysfunction and cognitive impairment in minimal hepatic encephalopathy.

Sun, 09/20/2020 - 22:42
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Disturbance of thalamic metabolism and its association with regional neural dysfunction and cognitive impairment in minimal hepatic encephalopathy.

Eur J Radiol. 2020 Aug 29;131:109252

Authors: Chen LH, Shi JY, Zou TX, Zhang L, Gou Y, Lin Y, Chen HJ

Abstract
PURPOSE: To conduct the first investigation on thalamic metabolic alterations in minimal hepatic encephalopathy (MHE) and elucidate their association with intrinsic neural activity change and cognitive dysfunction.
METHODS: Thirty-eight cirrhotic patients [18 with MHE, 20 without MHE (NHE)] and 21 healthy controls (HC) were included, all of whom underwent 1H-magnetic resonance spectroscopy, resting-state functional magnetic resonance imaging (fMRI), as well as cognitive assessment based on the Psychometric Hepatic Encephalopathy Score (PHES). Metabolite ratios in the thalamus were measured, including N-acetyl aspartate (NAA)/creatine (Cr), glutamate plus glutamine (Glx)/Cr, choline (Cho)/Cr, and myo-inositol (mI)/Cr. Intrinsic neural activity was evaluated based on frequency-specific amplitude of low-frequency fluctuations (ALFF) using fMRI signals.
RESULTS: MHE patients showed an increase in Glx/Cr and a decrease in Cho/Cr and mI/Cr, compared with HC. These changes were aggravated from NHE to MHE. Cho/Cr and mI/Cr were positively correlated with regional ALFF derived from the frequency-specific band (0.01-0.027 Hz) and PHES. Receiver operating characteristic curve analysis showed that Cho/Cr and mI/Cr measurements exhibited moderate discrimination ability between NHE and MHE.
CONCLUSION: Our findings provide evidence that MHE is associated with disturbed metabolism in the thalamus, which may contribute to the altered neural activity and underlie the mechanisms of cognitive impairments. MRS measurements in the thalamus could serve as the potential biomarker for diagnosing MHE among cirrhotic patients.

PMID: 32949859 [PubMed - as supplied by publisher]