New resting-state fMRI related studies at PubMed

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resting state fMRI; +20 new citations

Wed, 07/01/2020 - 13:49

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Chemogenetic silencing of neurons in the mouse anterior cingulate area modulates neuronal activity and functional connectivity.

Mon, 06/29/2020 - 00:40
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Chemogenetic silencing of neurons in the mouse anterior cingulate area modulates neuronal activity and functional connectivity.

Neuroimage. 2020 Jun 24;:117088

Authors: Peeters LM, Hinz R, Detrez JR, Missault S, De Vos WH, Verhoye M, Van der Linden A, Keliris GA

Abstract
The anterior cingulate area (ACC) is an integral part of the prefrontal cortex in mice and supports cognitive functions, including attentional processes, motion planning and execution as well as remote memory, fear and pain. Previous anatomical and functional imaging studies demonstrated that the ACC is interconnected with numerous brain regions, such as motor and sensory cortices, amygdala and limbic areas, suggesting it serves as a hub in functional networks. However, the exact role of the ACC in regulating functional network activity and connectivity remains to be elucidated. Recently developed neuromodulatory techniques, such as Designer Receptors Exclusively Activated by Designer Drugs (DREADDs) allow for precise control of neuronal activity. In this study, we used an inhibitory kappa-opioid receptor DREADD (KORD) to temporally inhibit neuronal firing in the right ACC of mice and assessed functional network activity and connectivity using non-invasive functional magnetic resonance imaging (MRI). We demonstrated that KORD-induced inhibition of the right ACC induced blood oxygenation-level dependent (BOLD) signal decreases and increases in connected brain regions of both hemispheres. More specifically, altered neuronal activity could be observed in functional brain networks including connections with sensory cortex, thalamus, basolateral amygdala and ventral pallidum, areas involved in attention processes, working memory, fear behavior and reward respectively. Furthermore, these modulations in neuronal activity were associated with decreased intra- and interhemispheric functional connectivity. Our results consolidate the hub role of the mouse ACC in functional networks and further demonstrate that the combination of the DREADD technology and non-invasive functional imaging methods is a valuable tool for unraveling mechanisms of network function and dysfunction by reversible inactivation of selected targets.

PMID: 32592851 [PubMed - as supplied by publisher]

Resting-State Power and Regional Connectivity After Pediatric Mild Traumatic Brain Injury.

Mon, 06/29/2020 - 00:40
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Resting-State Power and Regional Connectivity After Pediatric Mild Traumatic Brain Injury.

J Magn Reson Imaging. 2020 Jun 27;:

Authors: Stephenson DD, Meier TB, Pabbathi Reddy S, Robertson-Benta CR, Hergert DC, Dodd AB, Shaff NA, Ling JM, Oglesbee SJ, Campbell RA, Phillips JP, Sapien RE, Mayer AR

Abstract
BACKGROUND: Physiological recovery from pediatric mild traumatic brain injury (pmTBI) as a function of age remains actively debated, with the majority of studies relying on subjective symptom report rather than objective markers of brain physiology.
PURPOSE: To examine potential abnormalities in fractional amplitude of low-frequency fluctuations (fALFF) or regional homogeniety (ReHo) during resting-state fMRI following pmTBI.
STUDY TYPE: Prospective cohort.
POPULATION: Consecutively recruited pmTBI (N = 105; 8-18 years old) and age- and sex-matched healthy controls (HC; N = 113).
FIELD STRENGTH/SEQUENCE: 3T multiecho gradient T1 -weighted and single-shot gradient-echo echo-planar imaging.
ASSESSMENT: All pmTBI participants were assessed 1 week and 4 months postinjury (HC assessed at equivalent timepoints after the first visit). Comprehensive demographic, clinical, and cognitive batteries were performed in addition to primary investigation of fALFF and ReHo. All pmTBI were classified as "persistent" or "recovered" based on both assessment periods.
STATISTICAL TESTS: Chi-square, nonparametric, and generalized linear models for demographic data. Generalized estimating equations for clinical and cognitive data. Voxelwise general linear models (AFNI's 3dMVM) for fALFF and ReHo assessment.
RESULTS: Evidence of recovery was observed for some, but not all, clinical and cognitive measures at 4 months postinjury. fALFF was increased in the left striatum for pmTBI relative to HC both at 1 week and 4 months postinjury; whereas no significant group differences (P > 0.001) were observed for ReHo. Age-at-injury did not moderate either resting-state metric across groups. In contrast to analyses of pmTBI as a whole, there were no significant (P > 0.001) differences in either fALFF or ReHo in patients with persistent postconcussive symptoms compared to recovered patients and controls at 4 months postinjury.
DATA CONCLUSIONS: Our findings suggest prolonged clinical recovery and alterations in the relative amplitude of resting-state fluctuations up to 4 months postinjury, but no clear relationship with age-at-injury or subjective symptom report.
LEVEL OF EVIDENCE: 1 TECHNICAL EFFICACY: 2.

PMID: 32592270 [PubMed - as supplied by publisher]

Individual differences in local functional brain connectivity affect TMS effects on behavior.

Mon, 06/29/2020 - 00:40
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Individual differences in local functional brain connectivity affect TMS effects on behavior.

Sci Rep. 2020 Jun 26;10(1):10422

Authors: Gießing C, Alavash M, Herrmann CS, Hilgetag CC, Thiel CM

Abstract
Behavioral effects of transcranial magnetic stimulation (TMS) often show substantial differences between subjects. One factor that might contribute to these inter-individual differences is the interaction of current brain states with the effects of local brain network perturbation. The aim of the current study was to identify brain regions whose connectivity before and following right parietal perturbation affects individual behavioral effects during a visuospatial target detection task. 20 subjects participated in an fMRI experiment where their brain hemodynamic response was measured during resting state, and then during a visuospatial target detection task following 1 Hz rTMS and sham stimulation. To select a parsimonious set of associated brain regions, an elastic net analysis was used in combination with a whole-brain voxel-wise functional connectivity analysis. TMS-induced changes in accuracy were significantly correlated with the pattern of functional connectivity during the task state following TMS. The functional connectivity of the left superior temporal, angular, and precentral gyri was identified as key explanatory variable for the individual behavioral TMS effects. Our results suggest that the brain must reach an appropriate state in which right parietal TMS can induce improvements in visual target detection. The ability to reach this state appears to vary between individuals.

PMID: 32591568 [PubMed - as supplied by publisher]

Children with developmental coordination disorder show altered functional connectivity compared to peers.

Sat, 06/27/2020 - 11:00

Children with developmental coordination disorder show altered functional connectivity compared to peers.

Neuroimage Clin. 2020 Jun 12;27:102309

Authors: Rinat S, Izadi-Najafabadi S, Zwicker JG

Abstract
Developmental Coordination Disorder (DCD) is a neurodevelopmental disorder that affects a child's ability to learn motor skills and participate in self-care, educational, and leisure activities. The cause of DCD is unknown, but evidence suggests that children with DCD have atypical brain structure and function. Resting-state MRI assesses functional connectivity by identifying brain regions that have parallel activation during rest. As only a few studies have examined functional connectivity in this population, our objective was to compare whole-brain resting-state functional connectivity of children with DCD and typically-developing children. Using Independent Component Analysis (ICA), we compared functional connectivity of 8-12 year old children with DCD (N = 35) and typically-developing children (N = 23) across 19 networks, controlling for age and sex. Children with DCD demonstrate altered functional connectivity between the sensorimotor network and the posterior cingulate cortex (PCC), precuneus, and the posterior middle temporal gyrus (pMTG) (p < 0.0001). Previous evidence suggests the PCC acts as a link between functionally distinct networks. Our results indicate that ineffective communication between the sensorimotor network and the PCC might play a role in inefficient motor learning seen in DCD. The pMTG acts as hub for action-related information and processing, and its involvement could explain some of the functional difficulties seen in DCD. This study increases our understanding of the neurological differences that characterize this common motor disorder.

PMID: 32590334 [PubMed - as supplied by publisher]

Disrupted functional network connectivity predicts cognitive impairment after acute mild traumatic brain injury.

Sat, 06/27/2020 - 11:00
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Disrupted functional network connectivity predicts cognitive impairment after acute mild traumatic brain injury.

CNS Neurosci Ther. 2020 Jun 25;:

Authors: Li F, Lu L, Shang S, Hu L, Chen H, Wang P, Zhang H, Chen YC, Yin X

Abstract
AIMS: This study aimed to detect alterations of brain functional connectivity (FC) in acute mild traumatic brain injury (mTBI) and to estimate the extent to which these FC differences predicted the characteristics of posttraumatic cognitive impairment.
METHODS: Resting-state fMRI data were acquired from acute mTBI patients (n = 50) and healthy controls (HCs) (n = 43). Resting-state networks (RSNs) were established based on independent component analysis (ICA), and functional network connectivity (FNC) analysis was performed. Subsequently, we analyzed the correlations between FNC abnormalities and cognitive impairment outcomes.
RESULTS: Altered FC within the salience network (SN), sensorimotor network (SMN), default mode network (DMN), executive control network (ECN), visual network (VN), and cerebellum network (CN) was found in the mTBI group relative to the HC group. Moreover, different patterns of altered network interactions were found between the mTBI patients and HCs, including the SN-CN, VN-SMN, and ECN-DMN connections. Correlations between functional disconnection and cognitive impairment measurements in acute mTBI patients were also found.
CONCLUSION: This study indicated that widespread FNC impairment and altered integration existed in mTBI patients at acute stage, suggesting that FNC disruption as a biomarker may be applied for the early diagnosis and prediction of cognitive impairment in mTBI.

PMID: 32588522 [PubMed - as supplied by publisher]

Patterns of motor recovery and structural neuroplasticity after striatal infarcts.

Sat, 06/27/2020 - 11:00
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Patterns of motor recovery and structural neuroplasticity after striatal infarcts.

Neurology. 2020 Jun 25;:

Authors: Liu H, Peng X, Dahmani L, Wang H, Zhang M, Shan Y, Rong D, Guo Y, Li J, Li N, Wang L, Lin Y, Pan R, Lu J, Wang D

Abstract
OBJECTIVE: To elucidate the timeframe and spatial patterns of cortical reorganization after different stroke-induced basal ganglia lesions, we measured cortical thickness at five timepoints over a six-month period. We hypothesized that cortical reorganization would occur very early and that, along with motor recovery, it would vary based on the stroke lesion site.
METHODS: Thirty-three patients with unilateral basal ganglia stroke and 23 healthy control participants underwent MRI scanning and behavioral testing. To further decrease heterogeneity, we split patients into two groups according to whether or not the lesions mainly affect the striatal motor network as defined by resting-state functional connectivity. A priori measures included cortical thickness and motor outcome, as assessed with the Fugl-Meyer scale.
RESULTS: Within 14 days post-stroke, cortical thickness already increased in widespread brain areas (p=0.001), mostly in the frontal and temporal cortices rather than in the motor cortex. Critically, the two groups differed in the severity of motor symptoms (p=0.03) as well as in the cerebral reorganization they exhibited over a period of six months (Dice overlap index=0.16). Specifically, the frontal and temporal regions demonstrating cortical thickening showed minimal overlap between these two groups, indicating different patterns of reorganization.
CONCLUSIONS: Our findings underline the importance of assessing patients early on and of considering individual differences, as patterns of cortical reorganization differ substantially depending on the precise location of damage and occur very soon after stroke. A better understanding of the macrostructural brain changes following stroke and their relationship with recovery may inform individualized treatment strategies.

PMID: 32586896 [PubMed - as supplied by publisher]

Decreased interhemispheric connectivity and increased cortical excitability in unmedicated schizophrenia: A prefrontal interleaved TMS fMRI study.

Fri, 06/26/2020 - 16:00
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Decreased interhemispheric connectivity and increased cortical excitability in unmedicated schizophrenia: A prefrontal interleaved TMS fMRI study.

Brain Stimul. 2020 Jun 22;:

Authors: Webler RD, Hamady C, Molnar C, Johnson K, Bonilha L, Anderson BS, Bruin C, Bohning DE, George MS, Nahas Z

Abstract
BACKGROUND: Prefrontal abnormalities in schizophrenia have consistently emerged from resting state and cognitive neuroimaging studies. However, these correlative findings require causal verification via combined imaging/stimulation approaches. To date, no interleaved transcranial magnetic stimulation and functional magnetic resonance imaging study (TMS fMRI) has probed putative prefrontal cortex abnormalities in schizophrenia.
OBJECTIVE: /Hypothesis: We hypothesized that subjects with schizophrenia would show significant hyperexcitability at the site of stimulation (BA9) and decreased interhemispheric functional connectivity.
METHODS: We enrolled 19 unmedicated subjects with schizophrenia and 22 controls. All subjects underwent brain imaging using a 3T MRI scanner with a SENSE coil. They also underwent a single TMS fMRI session involving motor threshold (rMT) determination, structural imaging, and a parametric TMS fMRI protocol with 10Hz triplet pulses at 0, 80, 100 and 120% rMT. Scanning involved a surface MR coil optimized for bilateral prefrontal cortex image acquisition.
RESULTS: Of the original 41 enrolled subjects, 8 subjects with schizophrenia and 11 controls met full criteria for final data analyses. At equal TMS intensity, subjects with schizophrenia showed hyperexcitability in left BA9 (p=0.0157; max z-score=4.7) and neighboring BA46 (p=0.019; max z-score=4.47). Controls showed more contralateral functional connectivity between left BA9 and right BA9 through increased activation in right BA9 (p=0.02; max z-score=3.4). GM density in subjects with schizophrenia positively correlated with normalized prefrontal to motor cortex ratio of the corresponding distance from skull to cortex ratio (S-BA9/S-MC) (r = 0.83, p=0.004).
CONCLUSIONS: Subjects with schizophrenia showed hyperexcitability in left BA9 and impaired interhemispheric functional connectivity compared to controls. Interleaved TMS fMRI is a promising tool to investigate prefrontal dysfunction in schizophrenia.

PMID: 32585355 [PubMed - as supplied by publisher]

The relationship between individual variation in macroscale functional gradients and distinct aspects of ongoing thought.

Fri, 06/26/2020 - 16:00
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The relationship between individual variation in macroscale functional gradients and distinct aspects of ongoing thought.

Neuroimage. 2020 Jun 22;:117072

Authors: Mckeown B, Strawson WH, Wang HT, Karapanagiotidis T, Vos de Wael R, Benkarim O, Turnbull A, Margulies D, Jefferies E, McCall C, Bernhardt B, Smallwood J

Abstract
Contemporary accounts of ongoing thought recognise it as a heterogeneous and multidimensional construct, varying in both form and content. An emerging body of evidence demonstrates that distinct types of experience are associated with unique neurocognitive profiles, that can be described at the whole-brain level as interactions between multiple large-scale networks. The current study sought to explore the possibility that whole-brain functional connectivity patterns at rest may be meaningfully related to patterns of ongoing thought that occurred over this period. Participants underwent resting-state functional magnetic resonance imaging (rs-fMRI) followed by a questionnaire retrospectively assessing the content and form of their ongoing thoughts during the scan. A non-linear dimension reduction algorithm was applied to the rs-fMRI data to identify components explaining the greatest variance in whole-brain connectivity patterns, and ongoing thought patterns during the resting-state were measured retrospectively at the end of the scan. Multivariate analyses revealed that individuals for whom the connectivity of the sensorimotor system was maximally distinct from the visual system were most likely to report thoughts related to finding solutions to problems or goals and least likely to report thoughts related to the past. These results add to an emerging literature that suggests that unique patterns of experience are associated with distinct distributed neurocognitive profiles and highlight that unimodal systems may play an important role in this process.

PMID: 32585346 [PubMed - as supplied by publisher]

Baseline sensorimotor GABA levels shape neuroplastic processes induced by motor learning in older adults.

Fri, 06/26/2020 - 16:00
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Baseline sensorimotor GABA levels shape neuroplastic processes induced by motor learning in older adults.

Hum Brain Mapp. 2020 Jun 25;:

Authors: King BR, Rumpf JJ, Verbaanderd E, Heise KF, Dolfen N, Sunaert S, Doyon J, Classen J, Mantini D, Puts NAJ, Edden RAE, Albouy G, Swinnen SP

Abstract
Previous research in young adults has demonstrated that both motor learning and transcranial direct current stimulation (tDCS) trigger decreases in the levels of gamma-aminobutyric acid (GABA) in the sensorimotor cortex, and these decreases are linked to greater learning. Less is known about the role of GABA in motor learning in healthy older adults, a knowledge gap that is surprising given the established aging-related reductions in sensorimotor GABA. Here, we examined the effects of motor learning and subsequent tDCS on sensorimotor GABA levels and resting-state functional connectivity in the brains of healthy older participants. Thirty-six older men and women completed a motor sequence learning task before receiving anodal or sham tDCS to the sensorimotor cortex. GABA-edited magnetic resonance spectroscopy of the sensorimotor cortex and resting-state (RS) functional magnetic resonance imaging data were acquired before and after learning/stimulation. At the group level, neither learning nor anodal tDCS significantly modulated GABA levels or RS connectivity among task-relevant regions. However, changes in GABA levels from the baseline to post-learning session were significantly related to motor learning magnitude, age, and baseline GABA. Moreover, the change in functional connectivity between task-relevant regions, including bilateral motor cortices, was correlated with baseline GABA levels. These data collectively indicate that motor learning-related decreases in sensorimotor GABA levels and increases in functional connectivity are limited to those older adults with higher baseline GABA levels and who learn the most. Post-learning tDCS exerted no influence on GABA levels, functional connectivity or the relationships among these variables in older adults.

PMID: 32583940 [PubMed - as supplied by publisher]

Both Stationary and Dynamic Functional Interhemispheric Connectivity Are Strongly Associated With Performance on Cognitive Tests in Multiple Sclerosis.

Fri, 06/26/2020 - 16:00
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Both Stationary and Dynamic Functional Interhemispheric Connectivity Are Strongly Associated With Performance on Cognitive Tests in Multiple Sclerosis.

Front Neurol. 2020;11:407

Authors: Lin SJ, Kolind S, Liu A, McMullen K, Vavasour I, Wang ZJ, Traboulsee A, McKeown MJ

Abstract
Although functional connectivity has been extensively studied in MS, robust estimates of both stationary (static connectivity at the time) and dynamic (connectivity variation across time) functional connectivity has not been commonly evaluated and neither has its association to cognition. In this study, we focused on interhemispheric connections as previous research has shown links between anatomical homologous connections and cognition. We examined functional interhemispheric connectivity (IC) in MS during resting-state functional MRI using both stationary and dynamic strategies and related connectivity measures to processing speed performance. Twenty-five patients with relapsing-remitting MS and 41 controls were recruited. Stationary functional IC was assessed between homologous Regions of Interest (ROIs) using correlation. For dynamic IC, a sliding window approach was used to quantify changes between homologous ROIs across time. We related IC measures to cognitive performance with correlation and regression. Compared to control subjects, MS demonstrated increased IC across homologous regions, which accurately predicted performance on the symbol digit modalities test (SDMT) (R 2 = 0.96) and paced auditory serial addition test (PASAT) (R 2 = 0.59). Dynamic measures were not different between the 2 groups, but dynamic IC was related to PASAT scores. The associations between stationary/dynamic connectivity and cognitive tests demonstrated that different aspects of functional IC were associated with cognitive processes. Processing speed measured in SDMT was associated with static interhemispheric connections and better PASAT performance, which requires working memory, sustain attention, and processing speed, was more related to rigid IC, underlining the neurophysiological mechanism of cognition in MS.

PMID: 32581993 [PubMed]

Distinct Insular Functional Connectivity Changes Related to Mood and Fatigue Improvements in Major Depressive Disorder Following Tai Chi Training: A Pilot Study.

Fri, 06/26/2020 - 16:00
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Distinct Insular Functional Connectivity Changes Related to Mood and Fatigue Improvements in Major Depressive Disorder Following Tai Chi Training: A Pilot Study.

Front Integr Neurosci. 2020;14:25

Authors: Xu A, Zimmerman CS, Lazar SW, Ma Y, Kerr CE, Yeung A

Abstract
Objective: Tai chi (TC), a contemplative practice combining slow movements and deep breathing, has been shown to be clinically effective in alleviating depressive symptoms. Feelings of fatigue or low vitality often accompany major depressive disorder (MDD) though they are commonly overlooked and not well understood neurologically. By using resting state functional connectivity (rs-FC) using the insula as the seed, this study examines the relationship between mood and vitality symptoms in MDD and how they are impacted by TC training. Methods: Patients (N = 16) with MDD participated in a 10-week TC intervention. Self-report scores of vitality (using the SF-36 scale) and depressed mood (using the Beck Depression Inventory) as well as rs-fMRI were collected pre- and post-intervention. A seed-to-voxel approach was used to test whether changes in insular rs-FC were related to therapeutic improvement in MDD-related symptoms resulting from TC practice. Results: We found decreased self-reported depressed mood and increased vitality following the TC intervention. Furthermore, decreases in depressed mood were associated with increased rs-FC between the right anterior insula (AIC) and superior temporal gyrus and caudate (cluster-corrected p < 0.05). Increased vitality was associated with increased rs-FC between the right posterior insula (PIC) and regions associated with sensorimotor processes (cluster-corrected p < 0.05). Conclusion: These results provide support for differential changes in insula connectivity as neural correlates of symptom improvement in MDD.

PMID: 32581734 [PubMed]

Altered coupling of cerebral blood flow and functional connectivity strength in visual and higher order cognitive cortices in primary open angle glaucoma.

Fri, 06/26/2020 - 16:00
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Altered coupling of cerebral blood flow and functional connectivity strength in visual and higher order cognitive cortices in primary open angle glaucoma.

J Cereb Blood Flow Metab. 2020 Jun 24;:271678X20935274

Authors: Wang Q, Qu X, Chen W, Wang H, Huang C, Li T, Wang N, Xian J

Abstract
Primary open-angle glaucoma (POAG) has been suggested to be a neurodegenerative disease associated with altered cerebral vascular hemodynamics and widespread disruption of neuronal activity within the visual, working memory, attention and executive networks. We hypothesized that disturbed neurovascular coupling in visual and higher order cognitive cortices exists in POAG patients and correlates with glaucoma stage and visual field defects. Through multimodal magnetic resonance imaging, we evaluated the cerebral blood flow (CBF)-functional connectivity strength (FCS) correlations of the whole gray matter and CBF/FCS ratio per voxel for all subjects. Compared with normal controls, POAG patients showed reduced global CBF-FCS coupling and altered CBF/FCS ratios, predominantly in regions in the visual cortex, salience network, default mode network, and dorsal attentional network. The CBF/FCS ratio was negatively correlated with glaucoma stage, and positively correlated with visual field defects in the lingual gyrus in POAG patients. Moreover, early brain changes were detected in early POAG. These findings indicate neurovascular coupling dysfunction might exist in the visual and higher order cognitive cortices in POAG patients and its clinical relevance. The results may contribute to the monitoring of POAG progression and provide insight into the pathophysiology of the neurodegenerative process in POAG.

PMID: 32580669 [PubMed - as supplied by publisher]

Brain networks of rats under anesthesia using resting-state fMRI: comparison with dead rats, random noise and generative models of networks.

Thu, 06/25/2020 - 15:00
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Brain networks of rats under anesthesia using resting-state fMRI: comparison with dead rats, random noise and generative models of networks.

J Neural Eng. 2020 Jun 24;:

Authors: Becq GGJC, Barbier E, Achard S

Abstract
ObjectiveConnectivity networks are crucial to understand the brain resting-state activity using functional magnetic resonance imaging (rs-fMRI). Alterations of these brain networks may highlight important findings concerning the resilience of the brain to different disorders. The focus of this paper is to evaluate the robustness of brain network estimations, discriminate them under anesthesia and compare them to generative models.ApproachThe extraction of brain functional connectivity (FC) networks is difficult and biased due the properties of the data: low signal to noise ratio, high dimension low sample size. We propose to use wavelet correlations to assess FC between brain areas under anesthesia using four anesthetics (isoflurane, etomidate, medetomidine, urethane). The networks are then deduced from the functional connectivity matrices by applying statistical thresholds computed using the number of samples at a given scale of wavelet decomposition. Graph measures are extracted and extensive comparisons with generative models of structured networks are conducted.Main resultsThe sample size and filtering are critical to obtain significant correlations values and thereby detect connections between regions. This is necessary to construct networks different from random ones as shown using rs-fMRI brain networks of dead rats. Brain networks under anesthesia on rats have topological features that are mixing small-world, scale-free and random networks. Betweenness centrality indicates that hubs are present in brain networks obtained from anesthetized rats but locations of these hubs are altered by anesthesia.SignificanceUnderstanding the effects of anesthesia on brain areas is of particular importance in the context of animal research since animal models are commonly used to explore functions, evaluate lesions or illnesses, and test new drugs. More generally, results indicate that the use of correlations in the context of fMRI signals is robust but must be treated with caution. Solutions are proposed in order to control spurious correlations by setting them to zero.

PMID: 32580176 [PubMed - as supplied by publisher]

Differences of connectivity between ESRD patients with PD and HD.

Thu, 06/25/2020 - 15:00
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Differences of connectivity between ESRD patients with PD and HD.

Brain Behav. 2020 Jun 24;:e01708

Authors: Park BS, Seong M, Ko J, Park SH, Kim YW, Hwan Kim I, Park JH, Lee YJ, Park S, Park KM

Abstract
OBJECTIVES: The aim of this study was to investigate alterations in structural and functional brain connectivity between patients with end-stage renal disease (ESRD) who were undergoing peritoneal dialysis (PD) and hemodialysis (HD).
METHODS: We enrolled 40 patients with ESRD who were undergoing PD (20 patients) and HD (20 patients). We also enrolled healthy participants as a control group. All of the subjects underwent diffusion tensor imaging (DTI) and resting-state functional magnetic resonance imaging (rs-fMRI). Using data from the structural and functional connectivity matrix based on DTI and rs-fMRI, we calculated several network measures using graph theoretical analysis.
RESULTS: The measures of global structural connectivity were significantly different between the patients with ESRD who were undergoing PD and healthy subjects. The global efficiency and local efficiency in the patients with PD were significantly decreased compared with those in healthy participants. However, all of the measures of global structural connectivity in the patients with HD were not different from those in healthy participants. Conversely, in the global functional connectivity, the characteristic path length was significantly increased and the small-worldness index was decreased in patients with HD. However, the measures of the global functional connectivity in the patients with PD were not different from those in healthy subjects.
CONCLUSION: This study revealed that alterations in structural and functional connectivity in patients who were undergoing PD and HD were different than those in healthy controls. These findings suggest that brain networks may be affected by different types of renal replacement therapy.

PMID: 32578955 [PubMed - as supplied by publisher]

Propagation of BOLD Activity Reveals Task-dependent Directed Interactions Across Human Visual Cortex.

Thu, 06/25/2020 - 15:00
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Propagation of BOLD Activity Reveals Task-dependent Directed Interactions Across Human Visual Cortex.

Cereb Cortex. 2020 Jun 24;:

Authors: Gravel N, Renken RJ, Harvey BM, Deco G, Cornelissen FW, Gilson M

Abstract
It has recently been shown that large-scale propagation of blood-oxygen-level-dependent (BOLD) activity is constrained by anatomical connections and reflects transitions between behavioral states. It remains to be seen, however, if the propagation of BOLD activity can also relate to the brain's anatomical structure at a more local scale. Here, we hypothesized that BOLD propagation reflects structured neuronal activity across early visual field maps. To explore this hypothesis, we characterize the propagation of BOLD activity across V1, V2, and V3 using a modeling approach that aims to disentangle the contributions of local activity and directed interactions in shaping BOLD propagation. It does so by estimating the effective connectivity (EC) and the excitability of a noise-diffusion network to reproduce the spatiotemporal covariance structure of the data. We apply our approach to 7T fMRI recordings acquired during resting state (RS) and visual field mapping (VFM). Our results reveal different EC interactions and changes in cortical excitability in RS and VFM, and point to a reconfiguration of feedforward and feedback interactions across the visual system. We conclude that the propagation of BOLD activity has functional relevance, as it reveals directed interactions and changes in cortical excitability in a task-dependent manner.

PMID: 32577717 [PubMed - as supplied by publisher]

Electroacupuncture promotes motor function and functional connectivity in rats with ischemic stroke: an animal resting-state functional magnetic resonance imaging study.

Thu, 06/25/2020 - 15:00
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Electroacupuncture promotes motor function and functional connectivity in rats with ischemic stroke: an animal resting-state functional magnetic resonance imaging study.

Acupunct Med. 2020 Jun 23;:964528420920297

Authors: Li Z, Yang M, Lin Y, Liang S, Liu W, Chen B, Huang S, Li J, Tao J, Chen L

Abstract
BACKGROUND: To evaluate whether electroacupuncture (EA) treatment at LI11 and ST36 could reduce motor impairments and enhance brain functional recovery in a rat model of ischemic stroke.
METHODS: A rat model of middle cerebral artery occlusion (MCAO) was established. EA at LI11 and ST36 was started at 24 h (MCAO + EA group) after ischemic stroke modeling. Untreated model (MCAO) and sham-operated (Sham) groups were included as controls. The neurological deficits of all groups were assessed using modified neurologic severity scores (mNSS) at 24 h and 14 days after MCAO. To further investigate the effect of EA on infarct volume and brain function, functional magnetic resonance imaging was used to estimate the size of the brain lesions and neural activities of each group at 14 days after ischemic stroke.
RESULTS: EA treatment of MCAO rats led to a significant reduction in the infarct volumes accompanied by functional recovery, reflected in improved mNSS outcomes and motor functional performances. Furthermore, functional connectivity between the left motor cortex and left cerebellum posterior lobe, right motor cortex, left striatum and bilateral sensory cortex were decreased in MCAO group but increased after EA treatment.
CONCLUSION: EA at LI11 and ST36 could enhance the functional connectivity between the left motor cortex and the motor function-related brain regions, including the motor cortex, sensory cortex and striatum, in rats. EA exhibits potential as a treatment for ischemic stroke.

PMID: 32576025 [PubMed - as supplied by publisher]

Recurrent neural networks for reconstructing complex directed brain connectivity.

Thu, 06/25/2020 - 15:00
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Recurrent neural networks for reconstructing complex directed brain connectivity.

Conf Proc IEEE Eng Med Biol Soc. 2019 07;2019:6418-6421

Authors: Duggento A, Guerrisi M, Toschi N

Abstract
While Granger Causality(GC)-based approaches have been widely employed in a vast number of problems in network science, the vast majority of GC applications are based on linear multivariate autoregressive (MVAR) models. However, it is well known that real-life system (and biological networks in particular) exhibit notable nonlinear behavior, hence undermining that validity of MVAR-based approaches to estimating GC (MVAR-GC). In this paper, we define a novel approach to estimating nonlinear, directed within-network interactions based on a specific class of recurrent neural networks (RNN) termed echo-state networks (ESN). We reformulate the classical GC framework in terms of ESN-based models for multivariate signals generated by arbitrarily complex networks, and characterize the ability of our ESN-based Granger Causality (ES-GC) to capture nonlinear causal relations by simulating multivariate coupling in a network of nonlinearly interacting, noisy Duffing oscillators operating in a chaotic regime. Synthetic validation shows a net advantage of ES-GC over all other estimators in detecting nonlinear, causal links. We then explore the structure of EC-GC networks in the human brain in functional MRI data from 1003 healthy subjects scanned at rest at 3T, discovering previously unknown between-network interactions. In summary, ES-GC performs significantly better than commonly used and recently developed GC detection tools, making it a superior tool for the analysis of e.g. multivariate biological networks.

PMID: 31947311 [PubMed - indexed for MEDLINE]

Spontaneous cognition and its relationship to human creativity: a functional connectivity study involving a chain free association task.

Wed, 06/24/2020 - 13:40
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Spontaneous cognition and its relationship to human creativity: a functional connectivity study involving a chain free association task.

Neuroimage. 2020 Jun 20;:117064

Authors: Marron TR, Berant E, Axelrod V, Faust M

Abstract
Resting-state functional connectivity (RSFC) between various brain regions is thought to be associated with creative abilities. Extensive research correlating RSFC with performance on creativity tasks has revealed some of the RSFC patterns characterizing 'the creative brain'. Yet, our understanding of the neurocognitive processes underlying creative thinking still remains limited. This limitation results, in part, from the fact that standard creativity tasks used in these studies do not distinguish between the different modes of cognitive processing that are critical in creative cognition (e.g., spontaneous cognition vs. controlled cognition). In the present fMRI research we address this limitation by using a chain free association task - a task that we have recently refined and validated for the purpose of isolating measures of spontaneous cognition that are relevant for creative thinking (referred to as associative fluency and associative flexibility). In our study, 27 female participants completed standardized creativity tasks, a chain free association task, and an fMRI scan in which RSFC was measured. Our results indicate that higher scores on associative fluency are associated with stronger positive RSFC within the default mode network (DMN; i.e., between DMN regions). Critically, we provide evidence that the previously-identified relationship between performance on creativity tasks and connectivity within the DMN is partially mediated by associative fluency. Thus, our observations suggest that the heightened DMN connectivity observed in 'the creative brain' can be explained, at least to some extent, by spontaneous cognition. Overall, our study identifies unique RSFC patterns that are related specifically to spontaneous cognitive processes involved in creative ideation, thus shedding new light on mechanisms of creative processing.

PMID: 32574810 [PubMed - as supplied by publisher]

The same, but different: Preserved distractor suppression in old age is implemented through an age-specific reactive ventral fronto-parietal network.

Wed, 06/24/2020 - 13:40
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The same, but different: Preserved distractor suppression in old age is implemented through an age-specific reactive ventral fronto-parietal network.

Hum Brain Mapp. 2020 Jun 23;:

Authors: Ashinoff BK, Mayhew SD, Mevorach C

Abstract
Previous studies have shown age-related impairments in the ability to suppress salient distractors. One possibility is that this is mediated by age-related impairments in the recruitment of the left intraparietal sulcus (Left IPS), which has been shown to mediate the suppression of salient distractors in healthy, young participants. Alternatively, this effect may be due to a shift in engagement from proactive control to reactive control, possibly to compensate for age-related impairments in proactive control. Another possibility is that this is due to changes in the functional specificity of brain regions that mediate salience suppression, expressed in changes in spontaneous connectivity of these regions. We assessed these possibilities by having participants engage in a proactive distractor suppression task while in an fMRI scanner. Although we did not find any age-related differences in behavior, the young (N = 15) and older (N = 15) cohorts engaged qualitatively distinctive brain networks to complete the task. Younger participants engaged the predicted proactive control network, including the Left IPS. On the other hand, older participants simultaneously engaged both a proactive and a reactive network, but this was not a consequence of reduced network specificity as resting state functional connectivity was largely comparable in both age groups. Furthermore, improved behavioral performance for older adults was associated with increased resting state functional connectivity between these two networks. Overall, the results of this study suggest that age-related differences in the recruitment of a left lateralized ventral fronto-parietal network likely reflect the specific recruitment of reactive control mechanisms for distractor inhibition.

PMID: 32573907 [PubMed - as supplied by publisher]

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