New resting-state fMRI related studies at PubMed

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Task-evoked reconfiguration of the fronto-parietal network is associated with cognitive performance in brain tumor patients.

Thu, 08/29/2019 - 11:00
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Task-evoked reconfiguration of the fronto-parietal network is associated with cognitive performance in brain tumor patients.

Brain Imaging Behav. 2019 Aug 27;:

Authors: De Baene W, Jansma MJ, Schouwenaars IT, Rutten GM, Sitskoorn MM

Abstract
In healthy participants, the strength of task-evoked network reconfigurations is associated with cognitive performance across several cognitive domains. It is, however, unclear whether the capacity for network reconfiguration also plays a role in cognitive deficits in brain tumor patients. In the current study, we examined whether the level of reconfiguration of the fronto-parietal ('FPN') and default mode network ('DMN') during task execution is correlated with cognitive performance in patients with different types of brain tumors. For this purpose, we combined data from a resting state and task-fMRI paradigm in patients with a glioma or meningioma. Cognitive performance was measured using the in-scanner working memory task, as well as an out-of-scanner cognitive flexibility task. Task-evoked changes in functional connectivity strength (defined as the mean of the absolute values of all connections) and in functional connectivity patterns within and between the FPN and DMN did not differ significantly across meningioma and fast (HGG) and slowly growing glioma (LGG) patients. Across these brain tumor patients, a significant and positive correlation was found between the level of task-evoked reconfiguration of the FPN and cognitive performance. This suggests that the capacity for FPN reconfiguration also plays a role in cognitive deficits in brain tumor patients, as was previously found for normal cognitive performance in healthy controls.

PMID: 31456158 [PubMed - as supplied by publisher]

In Trauma-Exposed Individuals, Self-Reported Hyperarousal and Sleep Architecture Predict Resting-State Functional Connectivity in Frontocortical and Paralimbic Regions.

Thu, 08/29/2019 - 11:00
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In Trauma-Exposed Individuals, Self-Reported Hyperarousal and Sleep Architecture Predict Resting-State Functional Connectivity in Frontocortical and Paralimbic Regions.

Biol Psychiatry Cogn Neurosci Neuroimaging. 2019 Jul 09;:

Authors: Seo J, Oliver KI, Daffre C, Moore KN, Lasko NB, Pace-Schott EF

Abstract
BACKGROUND: Symptoms of posttraumatic stress disorder (PTSD) reflect abnormalities in large-scale brain networks. In individuals with recent trauma exposure, we examined associations of seed-based resting-state functional connectivity (rs-FC) with posttraumatic symptoms and sleep. We hypothesized that more severe PTSD symptoms and poorer sleep quality would predict 1) greater rs-FC between fear-related seeds and other fear-related regions and 2) lesser rs-FC between fear-related seeds and emotion-regulatory regions.
METHODS: Seventy-four participants who had experienced a DSM-5 criterion A stressor within the past 2 years and ranged from asymptomatic to fully meeting criteria for PTSD diagnosis underwent 14 days of actigraphy and sleep diaries, a night of ambulatory polysomnography, and a functional magnetic resonance imaging resting-state scan at 3T. rs-FC measures of 5 fear-related seeds and 1 emotion regulatory seed with regions of the anterior cerebrum were correlated with PTSD symptoms, objective and subjective habitual sleep quality, and sleep architecture.
RESULTS: Longer objective habitual sleep onset latency was associated with greater connectivity between fear-related seeds and other regions of the salience network. Greater PTSD symptoms were associated with less connectivity between fear-related seeds and anterior emotion regulatory regions, whereas greater percent slow wave sleep was associated with more connectivity between these regions. However, other objective and subjective measures reflecting better habitual sleep quality were associated with less rs-FC between these regions.
CONCLUSIONS: Longer sleep onset latency predicted greater rs-FC among fear-related areas. More severe PTSD symptoms predicted less rs-FC between fear and fear regulatory regions reflecting putatively reduced top-down fear regulation. Some (e.g., percent slow wave sleep), but not all sleep indices predicted greater top-down fear regulation.

PMID: 31455572 [PubMed - as supplied by publisher]

Endogenous fluctuations in the dopaminergic midbrain drive behavioral choice variability.

Wed, 08/28/2019 - 22:20
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Endogenous fluctuations in the dopaminergic midbrain drive behavioral choice variability.

Proc Natl Acad Sci U S A. 2019 Aug 26;:

Authors: Chew B, Hauser TU, Papoutsi M, Magerkurth J, Dolan RJ, Rutledge RB

Abstract
Human behavior is surprisingly variable, even when facing the same problem under identical circumstances. A prominent example is risky decision making. Economic theories struggle to explain why humans are so inconsistent. Resting-state studies suggest that ongoing endogenous fluctuations in brain activity can influence low-level perceptual and motor processes, but it remains unknown whether endogenous fluctuations also influence high-level cognitive processes including decision making. Here, using real-time functional magnetic resonance imaging, we tested whether risky decision making is influenced by endogenous fluctuations in blood oxygenation level-dependent (BOLD) activity in the dopaminergic midbrain, encompassing ventral tegmental area and substantia nigra. We show that low prestimulus brain activity leads to increased risky choice in humans. Using computational modeling, we show that increased risk taking is explained by enhanced phasic responses to offers in a decision network. Our findings demonstrate that endogenous brain activity provides a physiological basis for variability in complex human behavior.

PMID: 31451671 [PubMed - as supplied by publisher]

Non-negative Matrix Factorization Reveals Resting-State Cortical Alpha Network Abnormalities in the First-Episode Schizophrenia Spectrum.

Wed, 08/28/2019 - 22:20
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Non-negative Matrix Factorization Reveals Resting-State Cortical Alpha Network Abnormalities in the First-Episode Schizophrenia Spectrum.

Biol Psychiatry Cogn Neurosci Neuroimaging. 2019 Jul 06;:

Authors: Phalen H, Coffman BA, Ghuman A, Sejdić E, Salisbury DF

Abstract
BACKGROUND: Little is known about neural oscillatory dynamics in first-episode psychosis. Pathophysiology of functional connectivity can be measured through network activity of alpha oscillations, reflecting long-range communication between distal brain regions.
METHODS: Resting magnetoencephalographic activity was collected from 31 individuals with first-episode schizophrenia spectrum psychosis and 22 healthy control individuals. Activity was projected to the realistic cortical surface, based on structural magnetic resonance imaging. The first principal component of activity in 40 Brodmann areas per hemisphere was Hilbert transformed within the alpha range. Non-negative matrix factorization was applied to single-trial alpha phase-locking values from all subjects to determine alpha networks. Within networks, energy and entropy were compared.
RESULTS: Four cortical alpha networks were pathological in individuals with first-episode schizophrenia spectrum psychosis. The networks involved the bilateral anterior and posterior cingulate; left auditory, medial temporal, and cingulate cortex; right inferior frontal gyrus and widespread areas; and right posterior parietal cortex and widespread areas. Energy and entropy were associated with the Positive and Negative Syndrome Scale total and thought disorder factors for the first three networks. In addition, the left posterior temporal network was associated with positive and negative factors, and the right inferior frontal network was associated with the positive factor.
CONCLUSIONS: Machine learning network analysis of resting alpha-band neural activity identified several aberrant networks in individuals with first-episode schizophrenia spectrum psychosis, including the left temporal, right inferior frontal, right posterior parietal, and bilateral cingulate cortices. Abnormal long-range alpha communication is evident at the first presentation for psychosis and may provide clues about mechanisms of dysconnectivity in psychosis and novel targets for noninvasive brain stimulation.

PMID: 31451387 [PubMed - as supplied by publisher]

Searchlight classification based on Amplitude of Low Frequency Fluctuation and functional connectivity in individuals with obsessive-compulsive symptoms.

Wed, 08/28/2019 - 22:20
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Searchlight classification based on Amplitude of Low Frequency Fluctuation and functional connectivity in individuals with obsessive-compulsive symptoms.

Cogn Neuropsychiatry. 2019 Aug 26;:1-13

Authors: Wang YM, Cai XL, Zhang RT, Wang Y, Madsen KH, Sørensen TA, Møller A, Cheung EFC, Chan RCK

Abstract
INTRODUCTION: Investigating obsessive-compulsive symptoms in subclinical populations provides a useful framework for understanding the early development of obsessive-compulsive spectrum disorders. The present study aimed to apply searchlight classification analysis on resting-state functional magnetic resonance imaging data to identify potential brain markers in subclinical individuals with obsessive-compulsive symptoms.
METHODS: In this observational study, 40 college students with high obsessive-compulsive symptom scores and 40 with low obsessive-compulsive symptom scores were recruited from universities in China. We conducted searchlight classification and comparison analysis between the two groups based on Amplitude of Low Frequency Fluctuation (ALFF), fraction ALFF (fALFF) and resting-state functional connectivity using searchlight classification.
RESULTS: We found that the highest accuracy rate in differentiating between the two groups was 85.00%. Significant discriminating features included the ALFF of the left medial superior frontal gyrus and the functional connectivity between the right thalamus and the bilateral medial superior frontal gyrus, and the right putamen, as well as the functional connectivity between the left caudate and the right insula.
CONCLUSIONS: These findings highlight the specific and distinguishing brain functional abnormalities associated with obsessive-compulsive symptoms.

PMID: 31451062 [PubMed - as supplied by publisher]

Functional Connectivity Signatures of Parkinson's Disease.

Wed, 08/28/2019 - 22:20
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Functional Connectivity Signatures of Parkinson's Disease.

J Parkinsons Dis. 2019 Aug 23;:

Authors: Tessitore A, Cirillo M, De Micco R

Abstract
 Resting-state functional magnetic resonance imaging (RS-fMRI) studies have been extensively applied to analyze the pathophysiology of neurodegenerative disorders such as Parkinson's disease (PD). In the present narrative review, we attempt to summarize the most recent RS-fMRI findings highlighting the role of brain networks re-organization and adaptation in the course of PD. We also discuss limitations and potential definition of early functional connectivity signatures to track and predict future PD progression. Understanding the neural correlates and potential predisposing factors of clinical progression and complication will be crucial to guide novel clinical trials and to foster preventive strategies.

PMID: 31450512 [PubMed - as supplied by publisher]

Spontaneous Thoughts and Brain Connectivity: Possible Links Between Early Maltreatment and Later Depression.

Wed, 08/28/2019 - 22:20
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Spontaneous Thoughts and Brain Connectivity: Possible Links Between Early Maltreatment and Later Depression.

J Am Acad Child Adolesc Psychiatry. 2018 09;57(9):634-636

Authors: Cullen KR

Abstract
Maltreatment (MT) during childhood wreaks lasting havoc on the developing central nervous system and is one of the most salient risk factors for numerous psychiatric disorders, including depression.1 Early intervention and prevention strategies to improve outcomes of youth who have experienced MT are sorely needed; advancement in this area will require a deeper understanding of the neurobiological trajectory between the occurrence of MT and the later emergence of illness. One approach is to select neurobiological measures that are known to be impaired in the fully fledged disorder and use them to assess youth with a history of MT who have not yet shown impairment. In depression research, an emerging research area is to study spontaneously generated thoughts that occur while awake but at unstructured times, when thoughts tend to wander. Mind wandering has been linked with intelligence, creative thought generation, and resting-state functional connectivity within the default mode network.2 However, in depression, these wandering thoughts can get stuck on negative content3,4 and could represent a core feature of the illness. Therefore, examination of spontaneously generated thoughts, and their neural correlates, is a promising avenue for research seeking precursors of depression in youth with a history of MT.

PMID: 30196866 [PubMed - indexed for MEDLINE]

Molecular detection of inflammation in cell models using hyperpolarized 13C-pyruvate.

Wed, 08/28/2019 - 22:20
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Molecular detection of inflammation in cell models using hyperpolarized 13C-pyruvate.

Theranostics. 2018;8(12):3400-3407

Authors: Sriram R, Nguyen J, Santos JD, Nguyen L, Sun J, Vigneron S, Van Criekinge M, Kurhanewicz J, MacKenzie JD

Abstract
The detection and treatment monitoring of inflammatory states remain challenging in part due to the multifactorial mechanisms of immune activation and spectrum of clinical manifestations. Currently, diagnostic strategies tend to be subjective and limited quantitative tools exist to monitor optimal treatment strategies. Pro-inflammatory M1 polarized macrophages exhibit a distinct metabolic glycolytic phenotype compared to the continuum of M2 polarization states. In the present study, the distinct metabolic phenotypes of resting and activated macrophages were successfully characterized and quantified using hyperpolarized carbon-13 (13C) labeled pyruvate and its metabolic products, i.e. lactate, as a biomarker of resting, disease and treated states. Methods: Mouse macrophage J774A.1 cells were used as a model system in an NMR compatible bioreactor to facilitate dynamic hyperpolarized 13C measurements. The glycolytic metabolism of the cells in the quiescent or resting state were compared with macrophages stimulated by lipopolysaccharide, a classical M1 activator using hyperpolarized 13C labeled pyruvate. Additionally, the activated macrophages were also treated with a non-steroidal anti-inflammatory drug to assess the changes in hyperpolarized lactate signal. The hyperpolarized lactate signals were then correlated using biochemical and molecular assays. Results: We first validated our model system of inflammatory cells by the hallmarks of M1 polarization using steady state metabolic profiling with high resolution NMR in conjunction with nitric oxide Greiss assay, enzyme activity, and mRNA expression. Subsequently, we clearly showed that the cutting edge technology of hyperpolarized 13C NMR can be used to detect elevated lactate levels in M1 polarized macrophages in comparison to control and non-steroidal anti-inflammatory drug treated M2 states. Conclusion: Hyperpolarized 13C lactate has the potential to serve as a biomarker to non-invasively detect and quantify pro-inflammatory state of immune regulatory cells and its response to therapy.

PMID: 29930738 [PubMed - indexed for MEDLINE]

Craving behavioral intervention for internet gaming disorder: remediation of functional connectivity of the ventral striatum.

Wed, 08/28/2019 - 22:20
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Craving behavioral intervention for internet gaming disorder: remediation of functional connectivity of the ventral striatum.

Addict Biol. 2018 01;23(1):337-346

Authors: Zhang JT, Ma SS, Li CR, Liu L, Xia CC, Lan J, Wang LJ, Liu B, Yao YW, Fang XY

Abstract
Psychobehavioral intervention is an effective treatment of Internet addiction, including Internet gaming disorder (IGD). However, the neural mechanisms underlying its efficacy remain unclear. Cortical-ventral striatum (VS) circuitry is a common target of psychobehavioral interventions in drug addiction, and cortical-VS dysfunction has been reported in IGD; hence, the primary aim of the study was to investigate how the VS circuitry responds to psychobehavioral interventions in IGD. In a cross-sectional study, we examined resting-state functional connectivity of the VS in 74 IGD subjects (IGDs) and 41 healthy controls (HCs). In a follow-up craving behavioral intervention (CBI) study, of the 74 IGD subjects, 20 IGD subjects received CBI (CBI+) and 16 IGD subjects did not (CBI-). All participants were scanned twice with similar time interval to assess the effects of CBI. IGD subjects showed greater resting-state functional connectivity of the VS to left inferior parietal lobule (lIPL), right inferior frontal gyrus and left middle frontal gyrus, in positive association with the severity of IGD. Moreover, compared with CBI-, CBI+ showed significantly greater decrease in VS-lIPL connectivity, along with amelioration in addiction severity following the intervention. These findings demonstrated that functional connectivity between VS and lIPL, each presumably mediating gaming craving and attentional bias, may be a potential biomarker of the efficacy of psychobehavioral intervention. These results also suggested that non-invasive techniques such as transcranial magnetic or direct current stimulation targeting the VS-IPL circuitry may be used in the treatment of Internet gaming disorders.

PMID: 27894158 [PubMed - indexed for MEDLINE]

Quantitative Susceptibility Mapping and Resting State Network Analyses in Parkinsonian Phenotypes-A Systematic Review of the Literature.

Tue, 08/27/2019 - 15:00
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Quantitative Susceptibility Mapping and Resting State Network Analyses in Parkinsonian Phenotypes-A Systematic Review of the Literature.

Front Neural Circuits. 2019;13:50

Authors: Pelzer EA, Florin E, Schnitzler A

Abstract
An imbalance of iron metabolism with consecutive aggregation of α-synuclein and axonal degeneration of neurons has been postulated as the main pathological feature in the development of Parkinson's disease (PD). Quantitative susceptibility mapping (QSM) is a new imaging technique, which enables to measure structural changes caused by defective iron deposition in parkinsonian brains. Due to its novelty, its potential as a new imaging technique remains elusive for disease-specific characterization of motor and non-motor symptoms (characterizing the individual parkinsonian phenotype). Functional network changes associated with these symptoms are however frequently described for both magnetoencephalography (MEG) and resting state functional magnetic imaging (rs-fMRI). Here, we performed a systematic review of the current literature about QSM imaging, MEG and rs-fMRI in order to collect existing data about structural and functional changes caused by motor and non-motor symptoms in PD. Whereas all three techniques provide an effect in the motor domain, the understanding of network changes caused by non-motor symptoms is much more lacking for MEG and rs-fMRI, and does not yet really exist for QSM imaging. In order to better understand the influence of pathological iron distribution onto the functional outcome, whole-brain QSM analyses should be integrated in functional analyses (especially for the non-motor domain), to enable a proper pathophysiological interpretation of MEG and rs-fMRI network changes in PD. Herewith, a better understanding of the relationship between neuropathological changes, functional network changes and clinical phenotype might become possible.

PMID: 31447651 [PubMed - in process]

A Neurophysiological Event of Arousal Modulation May Underlie fMRI-EEG Correlations.

Tue, 08/27/2019 - 15:00
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A Neurophysiological Event of Arousal Modulation May Underlie fMRI-EEG Correlations.

Front Neurosci. 2019;13:823

Authors: Han F, Gu Y, Liu X

PMID: 31447638 [PubMed]

Cannabis analgesia in chronic neuropathic pain is associated with altered brain connectivity.

Tue, 08/27/2019 - 15:00
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Cannabis analgesia in chronic neuropathic pain is associated with altered brain connectivity.

Neurology. 2018 10 02;91(14):e1285-e1294

Authors: Weizman L, Dayan L, Brill S, Nahman-Averbuch H, Hendler T, Jacob G, Sharon H

Abstract
OBJECTIVE: To characterize the functional brain changes involved in δ-9-tetrahydrocannabinol (THC) modulation of chronic neuropathic pain.
METHODS: Fifteen patients with chronic radicular neuropathic pain participated in a randomized, double-blind, placebo-controlled trial employing a counterbalanced, within-subjects design. Pain assessments and functional resting state brain scans were performed at baseline and after sublingual THC administration. We examined functional connectivity of the anterior cingulate cortex (ACC) and pain-related network dynamics using graph theory measures.
RESULTS: THC significantly reduced patients' pain compared to placebo. THC-induced analgesia was correlated with a reduction in functional connectivity between the anterior cingulate cortex (ACC) and the sensorimotor cortex. Moreover, the degree of reduction was predictive of the response to THC. Graph theory analyses of local measures demonstrated reduction in network connectivity in areas involved in pain processing, and specifically in the dorsolateral prefrontal cortex (DLPFC), which were correlated with individual pain reduction.
CONCLUSION: These results suggest that the ACC and DLPFC, 2 major cognitive-emotional modulation areas, and their connections to somatosensory areas, are functionally involved in the analgesic effect of THC in chronic pain. This effect may therefore be mediated through induction of functional disconnection between regulatory high-order affective regions and the sensorimotor cortex. Moreover, baseline functional connectivity between these brain areas may serve as a predictor for the extent of pain relief induced by THC.

PMID: 30185448 [PubMed - indexed for MEDLINE]

Atrophy in Distributed Networks Predicts Cognition in Alzheimer's Disease and Type 2 Diabetes.

Tue, 08/27/2019 - 15:00
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Atrophy in Distributed Networks Predicts Cognition in Alzheimer's Disease and Type 2 Diabetes.

J Alzheimers Dis. 2018;65(4):1301-1312

Authors: Buss SS, Padmanabhan J, Saxena S, Pascual-Leone A, Fried PJ

Abstract
BACKGROUND: Alzheimer's disease (AD) and type 2 diabetes (T2DM) are common causes of cognitive decline among older adults and share strong epidemiological links. Distinct patterns of cortical atrophy are observed in AD and T2DM, but robust comparisons between structure-function relationships across these two disease states are lacking.
OBJECTIVE: To compare how atrophy within distributed brain networks is related to cognition across the spectrum of cognitive aging.
METHODS: The relationship between structural MRI changes and cognition was studied in 22 mild-to-moderate AD, 28 T2DM, and 27 healthy participants. Cortical thickness measurements were obtained from networks of interest (NOIs) matching the limbic, default, and frontoparietal resting-state networks. Composite cognitive scores capturing domains of global cognition, memory, and executive function were created. Associations between cognitive scores and the NOIs were assessed using linear regression, with age as a covariate. Within-network General Linear Model (GLM) analysis was run in Freesurfer 6.0 to visualize differences in patterns of cortical atrophy related to cognitive function in each group. A secondary analysis examined hemispheric differences in each group.
RESULTS: Across all groups, cortical atrophy within the limbic NOI was significantly correlated with Global Cognition (p = 0.009) and Memory Composite (p = 0.002). Within-network GLM analysis and hemispheric analysis revealed qualitatively different patterns of atrophy contributing to cognitive dysfunction between AD and T2DM.
CONCLUSION: Brain network atrophy is related to cognitive function across AD, T2DM, and healthy participants. Differences in cortical atrophy patterns were seen between AD and T2DM, highlighting neuropathological differences.

PMID: 30149455 [PubMed - indexed for MEDLINE]

Altered hippocampal GABA and glutamate levels and uncoupling from functional connectivity in multiple sclerosis.

Tue, 08/27/2019 - 15:00
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Altered hippocampal GABA and glutamate levels and uncoupling from functional connectivity in multiple sclerosis.

Hippocampus. 2018 11;28(11):813-823

Authors: Gao F, Yin X, Edden RAE, Evans AC, Xu J, Cao G, Li H, Li M, Zhao B, Wang J, Wang G

Abstract
There is growing evidence for dysfunctional glutamatergic excitation and/or gamma-aminobutyric acid (GABA)ergic inhibition in patients with multiple sclerosis (MS). Cognitive impairment may occur during the early stages of MS and hippocampal abnormalities have been suggested as biomarkers. However, researchers have not clearly determined whether changes in hippocampal GABA and glutamate (Glu) levels are associated with cognitive impairment and aberrant neural activity in patients with MS. We used magnetic resonance spectroscopy to measure GABA+ and Glu levels in the left hippocampal region of 29 patients with relapsing-remitting MS and 29 healthy controls (HCs). Resting-state functional connectivity (FC) with the hippocampus was also examined. Compared to HCs, patients exhibited significantly lower GABA+ and Glu levels, which were associated with verbal and visuospatial memory deficits, respectively. Patients also showed decreased FC strengths between the hippocampus and several cortical regions, which are located within the default mode network. Moreover, hippocampal GABA+ levels and Glu/GABA+ ratios correlated with the FC strengths in HCs but not in patients with MS. This study describes a novel method for investigating the complex relationships among excitatory/inhibitory neurotransmitters, brain connectivity and cognition in health and disease. Strategies that modulate Glu and GABA neurotransmission may represent new therapeutic treatments for patients with MS.

PMID: 30069963 [PubMed - indexed for MEDLINE]

Volume and Connectivity of the Ventral Tegmental Area are Linked to Neurocognitive Signatures of Alzheimer's Disease in Humans.

Tue, 08/27/2019 - 15:00
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Volume and Connectivity of the Ventral Tegmental Area are Linked to Neurocognitive Signatures of Alzheimer's Disease in Humans.

J Alzheimers Dis. 2018;63(1):167-180

Authors: De Marco M, Venneri A

Abstract
BACKGROUND: There is an urgent need to identify the earliest biological changes within the neuropathological cascade of Alzheimer's disease (AD) processes. Recent findings in a murine model of AD showed significant preclinical loss of dopaminergic neurons in the ventral tegmental area (VTA), accompanied by reduced hippocampal innervation and declining memory. It is unknown if these observations can be translated in humans.
OBJECTIVE: We tested the hypothesis that VTA volume is associated with the typical clinical markers of AD in a cohort of patients and healthy controls.
METHODS: Structural and resting state functional MRI scans, and neuropsychological scores were acquired for 51 healthy adults, 30 patients with a diagnosis of mild cognitive impairment, and 29 patients with a diagnosis of AD dementia. VTA volume was quantified together with other control nuclei. The association between nuclei volume, hippocampal size, memory performance, and linguistic-executive skills was tested. The effect of VTA functional connectivity was also tested.
RESULTS: VTA size, but not of control nuclei, yielded a strong association with both hippocampal size and memory competence (but not linguistic-executive performance), and this was particularly strong in healthy adults. In addition, functional connectivity between the VTA and hippocampus was significantly associated with both markers of AD.
CONCLUSION: Diminished dopaminergic VTA activity may be crucial for the earliest pathological features of AD and might suggest new strategies for early treatment. Memory encoding processes may represent cognitive operations susceptible to VTA neurodegeneration.

PMID: 29578486 [PubMed - indexed for MEDLINE]

FMRI response to acute psychological stress differentiates patients with psychogenic non-epileptic seizures from healthy controls - A biochemical and neuroimaging biomarker study.

Mon, 08/26/2019 - 14:00
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FMRI response to acute psychological stress differentiates patients with psychogenic non-epileptic seizures from healthy controls - A biochemical and neuroimaging biomarker study.

Neuroimage Clin. 2019 Aug 06;24:101967

Authors: Allendorfer JB, Nenert R, Hernando KA, DeWolfe JL, Pati S, Thomas AE, Billeaud N, Martin RC, Szaflarski JP

Abstract
We investigated psychological stress response in the brain regions involved in emotion-motor-executive control in psychogenic non-epileptic seizures (PNES). 12 PNES patients and 12 healthy controls (HCs) underwent stress task and resting state functional MRI (fMRI), mood and quality of life (QOL) assessments, and measurements of salivary cortisol, alpha-amylase, and heart rate. Group differences were assessed, and we correlated beta values from a priori selected brain regions showing stress task fMRI group differences with other stress response measures. We also used the regions showing stress task fMRI group differences as seeds for resting state functional connectivity (rs-FC) analysis. Mood and QOL were worse in PNES versus HCs. Physiological and assessment measures were similar except 'Planful Problem Solving' coping that was greater for HCs (p = .043). Perceived stress associated negatively with heart rate change (rs = -0.74, p = .0063). There was stress fMRI hyporeactivity in left/right amygdala and left hippocampus in PNES versus HCs (corrected p < .05). PNES exhibited a positive association between alpha-amylase change and right amygdala activation (rs = 0.71, p = .010). PNES versus HCs exhibited greater right amygdala rs-FC to left precentral and inferior/middle frontal gyri (corrected p < .05). Our findings of fMRI hyporeactivity to psychological stress, along with greater emotion-motor-executive control network rs-FC in PNES when compared to HCs suggest a dysregulation in stress response circuitry in PNES.

PMID: 31446314 [PubMed - as supplied by publisher]

Anosognosia and default mode subnetwork dysfunction in Alzheimer's disease.

Sun, 08/25/2019 - 13:00
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Anosognosia and default mode subnetwork dysfunction in Alzheimer's disease.

Hum Brain Mapp. 2019 Aug 24;:

Authors: Antoine N, Bahri MA, Bastin C, Collette F, Phillips C, Balteau E, Genon S, Salmon E

Abstract
Research on the neural correlates of anosognosia in Alzheimer's disease varied according to methods and objectives: they compared different measures, used diverse neuroimaging modalities, explored connectivity between brain networks, addressed the role of specific brain regions or tried to give support to theoretical models of unawareness. We used resting-state fMRI connectivity with two different seed regions and two measures of anosognosia in different patient samples to investigate consistent modifications of default mode subnetworks and we aligned the results with the Cognitive Awareness Model. In a first study, patients and their relatives were presented with the Memory Awareness Rating Scale. Anosognosia was measured as a patient-relative discrepancy score and connectivity was investigated with a parahippocampal seed. In a second study, anosognosia was measured in patients with brain amyloid (taken as a disease biomarker) by comparing self-reported rating with memory performance, and connectivity was examined with a hippocampal seed. In both studies, anosognosia was consistently related to disconnection within the medial temporal subsystem of the default mode network, subserving episodic memory processes. Importantly, scores were also related to disconnection between the medial temporal and both the core subsystem (participating to self-reflection) and the dorsomedial subsystem of the default mode network (the middle temporal gyrus that might subserve a personal database in the second study). We suggest that disparity in connectivity within and between subsystems of the default mode network may reflect impaired functioning of pathways in cognitive models of awareness.

PMID: 31444942 [PubMed - as supplied by publisher]

What can we learn from fMRI capture of visual hallucinations in Parkinson's disease?

Sun, 08/25/2019 - 13:00
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What can we learn from fMRI capture of visual hallucinations in Parkinson's disease?

Brain Imaging Behav. 2019 Aug 23;:

Authors: Dujardin K, Roman D, Baille G, Pins D, Lefebvre S, Delmaire C, Defebvre L, Jardri R

Abstract
With disease progression, patients with Parkinson's disease (PD) may have chronic visual hallucinations (VH). The mechanisms behind this invalidating non-motor symptom remain largely unknown, namely because it is extremely difficult to capture hallucination events. This study aimed to describe the patterns of brain functional changes when VH occur in PD patients. Nine PD patients were enrolled because of their frequent and chronic VH (> 10/day). Patients with severe cognitive decline (MMSE<18) were excluded. Patients were scanned during ON/OFF hallucinatory states and resting-state functional imaging (rs-fMRI) was performed. Data were analyzed in reference to the two-step method, which consists in: (i) a data-driven analysis of per-hallucinatory fMRI data, and (ii) selection of the components of interest based on a post-fMRI interview. The phenomenology of VH ranged from visual spots to distorting faces. First, at the individual level, several VH-related components of interest were identified and integrated in a second-level analysis. Using a random-effects self-organizing-group ICA, we evidenced increased connectivity in visual networks concomitant to VH, encompassing V2, V3 and the fusiform gyri bilaterally. Interestingly, the stability of the default-mode network (DMN) was found positively correlated with VH severity (Spearman's rho = 0.77, p = 0.05). By using a method that does not need online self-report, we showed that VH in PD patients were associated with functional changes in associative visual cortices, possibly linked with strengthened stability of resting-state networks.

PMID: 31444780 [PubMed - as supplied by publisher]

Inconsistency between cortical reorganization and functional connectivity alteration in the sensorimotor cortex following incomplete cervical spinal cord injury.

Sun, 08/25/2019 - 13:00
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Inconsistency between cortical reorganization and functional connectivity alteration in the sensorimotor cortex following incomplete cervical spinal cord injury.

Brain Imaging Behav. 2019 Aug 23;:

Authors: Li X, Chen Q, Zheng W, Chen X, Wang L, Qin W, Li K, Lu J, Chen N

Abstract
The aim of this study was to explore whether there will be any alterations in sensorimotor-related cortex and the possible causes of sensorimotor dysfunction after incomplete cervical spinal cord injury (ICSCI). Structural and resting-state functional magnetic resonance imaging (rs-fMRI) of nineteen ICSCI patients and nineteen healthy controls (HCs) was acquired. Voxel based morphometry (VBM) and tract-based spatial statistics were performed to assess differences in gray matter volume (GMV) and white matter integrity between ICSCI patients and HCs. Whole brain functional connectivity (FC) was analyzed using the results of VBM as seeds. Associations between the clinical variables and the brain changes were studied. Compared with HCs, ICSCI patients demonstrated reduced GMV in the right fusiform gyrus (FG) and left orbitofrontal cortex (OFC) but no changes in areas directly related to sensorimotor function. There were no significant differences in brain white matter. Additionally, the FC in the left primary sensorimotor cortex and cerebellum decreased when the FG and OFC, respectively, were used as seeds. Subsequent relevance analysis suggests a weak positive correlation between the left OFC's GMV and visual analog scale (VAS) scores. In conclusion, brain structural changes following ICSCI occur mainly in certain higher cognitive regions, such as the FG and OFC, rather than in the brain areas directly related to sensation or motor control. The functional areas of the brain that are related to cognitive processing may play an important role in sensorimotor dysfunction through the decreased FC with sensorimotor areas after ICSCI. Therefore, cognition-related functional training may play an important role in rehabilitation of sensorimotor function after ICSCI.

PMID: 31444779 [PubMed - as supplied by publisher]

Effects of Overweight or Obesity on Brain Resting State Functional Connectivity of Children with Autism Spectrum Disorder.

Sun, 08/25/2019 - 13:00
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Effects of Overweight or Obesity on Brain Resting State Functional Connectivity of Children with Autism Spectrum Disorder.

J Autism Dev Disord. 2019 Aug 23;:

Authors: Kahathuduwa CN, West B, Mastergeorge A

Abstract
Evidence on neurophysiological correlates of coexisting autism spectrum disorders (ASD) and overweight/obesity may elucidate mechanisms leading to the observed greater risk of obesity in children with ASD. An exploratory secondary data analysis was performed on resting state functional magnetic resonance imaging (rs-fMRI) data of children downloaded from the ABIDE Preprocessed database (n = 81). Children with isolated ASD showed hypo-connectivity between anterior and posterior default mode network (DMN) (p = 0.003; FWER). Children with coexisting ASD and overweight/obesity showed hyper-connectivity between anterior and posterior DMN (p = 0.015; FWER). More evidence is needed to confirm these contrasting rs-fMRI connectivity profiles and to explicate causal inferences regarding neurophysiological mechanisms associated with coexisting ASD and overweight/obesity.

PMID: 31444629 [PubMed - as supplied by publisher]

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