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Heterogeneity of structural and functional imaging patterns of advanced brain aging revealed via machine learning methods.

Mon, 08/06/2018 - 10:20

Heterogeneity of structural and functional imaging patterns of advanced brain aging revealed via machine learning methods.

Neurobiol Aging. 2018 Jun 15;71:41-50

Authors: Eavani H, Habes M, Satterthwaite TD, An Y, Hsieh MK, Honnorat N, Erus G, Doshi J, Ferrucci L, Beason-Held LL, Resnick SM, Davatzikos C

Abstract
Disentangling the heterogeneity of brain aging in cognitively normal older adults is challenging, as multiple co-occurring pathologic processes result in diverse functional and structural changes. Capitalizing on machine learning methods applied to magnetic resonance imaging data from 400 participants aged 50 to 96 years in the Baltimore Longitudinal Study of Aging, we constructed normative cross-sectional brain aging trajectories of structural and functional changes. Deviations from typical trajectories identified individuals with resilient brain aging and multiple subtypes of advanced brain aging. We identified 5 distinct phenotypes of advanced brain aging. One group included individuals with relatively extensive structural and functional loss and high white matter hyperintensity burden. Another subgroup showed focal hippocampal atrophy and lower posterior-cingulate functional coherence, low white matter hyperintensity burden, and higher medial-temporal connectivity, potentially reflecting high brain tissue reserve counterbalancing brain loss that is consistent with early stages of Alzheimer's disease. Other subgroups displayed distinct patterns. These results indicate that brain changes should not be measured seeking a single signature of brain aging but rather via methods capturing heterogeneity and subtypes of brain aging. Our findings inform future studies aiming to better understand the neurobiological underpinnings of brain aging imaging patterns.

PMID: 30077821 [PubMed - as supplied by publisher]

Inflammation negatively correlates with amygdala-ventromedial prefrontal functional connectivity in association with anxiety in patients with depression: preliminary results.

Sun, 08/05/2018 - 15:40
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Inflammation negatively correlates with amygdala-ventromedial prefrontal functional connectivity in association with anxiety in patients with depression: preliminary results.

Brain Behav Immun. 2018 Aug 01;:

Authors: Mehta ND, Haroon E, Xu X, Woolwine BJ, Li Z, Felger JC

Abstract
Biomarkers of inflammation, including inflammatory cytokines and the acute-phase reactant C-reactive protein (CRP), are reliably increased in a subset of patients with depression, anxiety disorders and post-traumatic stress disorder (PTSD). Administration of innate immune stimuli to laboratory subjects and the associated release of inflammatory cytokines has been shown to affect brain regions involved in fear, anxiety and emotional processing such as the amygdala. However, the role of inflammation in altered circuitry involving amygdala and other brain regions and its subsequent contribution to symptom severity in depression, anxiety disorders and PTSD is only beginning to be explored. Herein, medically-stable, currently unmedicated outpatients with a primary diagnosis of major depressive disorder (MDD; n=48) underwent resting-state functional MRI (rfMRI) to determine whether altered connectivity between the amygdala and whole brain was observed in a subset of patients with high inflammation and symptoms of anxiety. Whole-brain, voxel-wise functional connectivity analysis of the right and left amygdala as a function of inflammation (plasma CRP concentrations) revealed that increased CRP predicted decreased functional connectivity between right amygdala and left ventromedial prefrontal cortex (vmPFC) (corrected p<0.05). Amygdala-vmPFC connectivity was, in turn, negatively correlated with symptoms of anxiety (r=-0.33, df=46, p=0.022). In exploratory analyses, relationships between low amygdala-vmPFC connectivity and high anxiety were only observed in patients with a secondary diagnosis of an anxiety disorder or PTSD (r=-0.54 to -0.87, p<0.05). More work is needed to understand the role of inflammation and its effects on amygdala-vmPFC circuitry and symptoms of anxiety in MDD patients with comorbid anxiety disorders or PTSD.

PMID: 30076980 [PubMed - as supplied by publisher]

Altered neural signatures of interoception in multiple sclerosis.

Sun, 08/05/2018 - 15:40
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Altered neural signatures of interoception in multiple sclerosis.

Hum Brain Mapp. 2018 Aug 04;:

Authors: Salamone PC, Esteves S, Sinay VJ, García-Cordero I, Abrevaya S, Couto B, Adolfi F, Martorell M, Petroni A, Yoris A, Torquati K, Alifano F, Legaz A, Cassará FP, Bruno D, Kemp AH, Herrera E, García AM, Ibáñez A, Sedeño L

Abstract
Multiple sclerosis (MS) patients present several alterations related to sensing of bodily signals. However, no specific neurocognitive impairment has yet been proposed as a core deficit underlying such symptoms. We aimed to determine whether MS patients present changes in interoception-that is, the monitoring of autonomic bodily information-a process that might be related to various bodily dysfunctions. We performed two studies in 34 relapsing-remitting, early-stage MS patients and 46 controls matched for gender, age, and education. In Study 1, we evaluated the heartbeat-evoked potential (HEP), a cortical signature of interoception, via a 128-channel EEG system during a heartbeat detection task including an exteroceptive and an interoceptive condition. Then, we obtained whole-brain MRI recordings. In Study 2, participants underwent fMRI recordings during two resting-state conditions: mind wandering and interoception. In Study 1, controls exhibited greater HEP modulation during the interoceptive condition than the exteroceptive one, but no systematic differences between conditions emerged in MS patients. Patients presented atrophy in the left insula, the posterior part of the right insula, and the right anterior cingulate cortex, with abnormal associations between neurophysiological and neuroanatomical patterns. In Study 2, controls showed higher functional connectivity and degree for the interoceptive state compared with mind wandering; however, this pattern was absent in patients, who nonetheless presented greater connectivity and degree than controls during mind wandering. MS patients were characterized by atypical multimodal brain signatures of interoception. This finding opens a new agenda to examine the role of inner-signal monitoring in the body symptomatology of MS.

PMID: 30076770 [PubMed - as supplied by publisher]

Brain network profiling defines functionally specialized cortical networks.

Sun, 08/05/2018 - 15:40
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Brain network profiling defines functionally specialized cortical networks.

Hum Brain Mapp. 2018 Aug 04;:

Authors: Di Plinio S, Ebisch SJH

Abstract
Neuroimaging research made rapid advances in the study of the functional architecture of the brain during the past decade. Many proposals endorsed the relevance of large-scale brain networks, defined as ensembles of brain regions that exhibit highly correlated signal fluctuations. However, analysis methods need further elaboration to define the functional and anatomical extent of specialized subsystems within classical networks with a high reliability. We present a novel approach to characterize and examine the functional proprieties of brain networks. This approach, labeled as brain network profiling (BNP), considers similarities in task-evoked activity and resting-state functional connectivity across biologically relevant brain subregions. To combine task-driven activity and functional connectivity features, principal components were extracted separately for task-related beta values and resting-state functional connectivity z-values (data available from the Human Connectome Project), from 360 brain parcels. Multiple clustering procedures were employed to assess if different clustering methods (Gaussian mixtures; k-means) and/or data structures (task and rest data; only rest data) led to improvements in the replication of the brain architecture. The results indicated that combining information from resting-state functional connectivity and task-evoked activity and using Gaussian mixtures models for clustering produces more reliable results (99% replication across data sets). Moreover, the findings revealed a high-resolution partition of the cerebral cortex in 16 networks with unique functional connectivity and/or task-evoked activity profiles. BNP potentially offers new approaches to advance the investigation of the brain functional architecture.

PMID: 30076763 [PubMed - as supplied by publisher]

The EMIF-AD PreclinAD study: study design and baseline cohort overview.

Sun, 08/05/2018 - 15:40
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The EMIF-AD PreclinAD study: study design and baseline cohort overview.

Alzheimers Res Ther. 2018 Aug 04;10(1):75

Authors: Konijnenberg E, Carter SF, Ten Kate M, den Braber A, Tomassen J, Amadi C, Wesselman L, Nguyen HT, van de Kreeke JA, Yaqub M, Demuru M, Mulder SD, Hillebrand A, Bouwman FH, Teunissen CE, Serné EH, Moll AC, Verbraak FD, Hinz R, Pendleton N, Lammertsma AA, van Berckel BNM, Barkhof F, Boomsma DI, Scheltens P, Herholz K, Visser PJ

Abstract
BACKGROUND: Amyloid pathology is the pathological hallmark in Alzheimer's disease (AD) and can precede clinical dementia by decades. So far it remains unclear how amyloid pathology leads to cognitive impairment and dementia. To design AD prevention trials it is key to include cognitively normal subjects at high risk for amyloid pathology and to find predictors of cognitive decline in these subjects. These goals can be accomplished by targeting twins, with additional benefits to identify genetic and environmental pathways for amyloid pathology, other AD biomarkers, and cognitive decline.
METHODS: From December 2014 to October 2017 we enrolled cognitively normal participants aged 60 years and older from the ongoing Manchester and Newcastle Age and Cognitive Performance Research Cohort and the Netherlands Twins Register. In Manchester we included single individuals, and in Amsterdam monozygotic twin pairs. At baseline, participants completed neuropsychological tests and questionnaires, and underwent physical examination, blood sampling, ultrasound of the carotid arteries, structural and resting state functional brain magnetic resonance imaging, and dynamic amyloid positron emission tomography (PET) scanning with [18F]flutemetamol. In addition, the twin cohort underwent lumbar puncture for cerebrospinal fluid collection, buccal cell collection, magnetoencephalography, optical coherence tomography, and retinal imaging.
RESULTS: We included 285 participants, who were on average 74.8 ± 9.7 years old, 64% female. Fifty-eight participants (22%) had an abnormal amyloid PET scan.
CONCLUSIONS: A rich baseline dataset of cognitively normal elderly individuals has been established to estimate risk factors and biomarkers for amyloid pathology and future cognitive decline.

PMID: 30075734 [PubMed - in process]

Human amygdala functional network development: A cross-sectional study from 3 months to 5 years of age.

Sat, 08/04/2018 - 14:40
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Human amygdala functional network development: A cross-sectional study from 3 months to 5 years of age.

Dev Cogn Neurosci. 2018 Jul 21;34:63-74

Authors: Gabard-Durnam LJ, O'Muircheartaigh J, Dirks H, Dean DC, Tottenham N, Deoni S

Abstract
Although the amygdala's role in shaping social behavior is especially important during early post-natal development, very little is known of amygdala functional development before childhood. To address this gap, this study uses resting-state fMRI to examine early amygdalar functional network development in a cross-sectional sample of 80 children from 3-months to 5-years of age. Whole brain functional connectivity with the amygdala, and its laterobasal and superficial sub-regions, were largely similar to those seen in older children and adults. Functional distinctions between sub-region networks were already established. These patterns suggest many amygdala functional circuits are intact from infancy, especially those that are part of motor, visual, auditory and subcortical networks. Developmental changes in connectivity were observed between the laterobasal nucleus and bilateral ventral temporal and motor cortex as well as between the superficial nuclei and medial thalamus, occipital cortex and a different region of motor cortex. These results show amygdala-subcortical and sensory-cortex connectivity begins refinement prior to childhood, though connectivity changes with associative and frontal cortical areas, seen after early childhood, were not evident in this age range. These findings represent early steps in understanding amygdala network dynamics across infancy through early childhood, an important period of emotional and cognitive development.

PMID: 30075348 [PubMed - as supplied by publisher]

Key Brain Network Nodes Show Differential Cognitive Relevance and Developmental Trajectories during Childhood and Adolescence.

Sat, 08/04/2018 - 14:40
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Key Brain Network Nodes Show Differential Cognitive Relevance and Developmental Trajectories during Childhood and Adolescence.

eNeuro. 2018 Jul-Aug;5(4):

Authors: Kolskår KK, Alnæs D, Kaufmann T, Richard G, Sanders AM, Ulrichsen KM, Moberget T, Andreassen OA, Nordvik JE, Westlye LT

Abstract
Human adolescence is a period of rapid changes in cognition and goal-directed behavior, and it constitutes a major transitional phase towards adulthood. One of the mechanisms suggested to underlie the protracted maturation of functional brain networks, is the increased network integration and segregation enhancing neural efficiency. Importantly, the increasing coordinated network interplay throughout development is mediated through functional hubs, which are highly connected brain areas suggested to be pivotal nodes for the regulation of neural activity. To elucidate brain hub development during childhood and adolescence, we estimated voxel-wise eigenvector centrality (EC) using functional magnetic resonance imaging (fMRI) data from two different psychological contexts (resting state and a working memory task), in a large cross-sectional sample (n = 754) spanning the age from 8 to 22 years, and decomposed the maps using independent component analysis (ICA). Our results reveal significant age-related centrality differences in cingulo-opercular, visual, and sensorimotor network nodes during both rest and task performance, suggesting that common neurodevelopmental processes manifest across different mental states. Supporting the functional significance of these developmental patterns, the centrality of the cingulo-opercular node was positively associated with task performance. These findings provide evidence for protracted maturation of hub properties in specific nodes of the brain connectome during the course of childhood and adolescence and suggest that cingulo-opercular centrality is a key factor supporting neurocognitive development.

PMID: 30073200 [PubMed - in process]

Functional Connectivity of Chronic Cocaine Use Reveals Progressive Neuroadaptations in Neocortical, Striatal, and Limbic Networks.

Sat, 08/04/2018 - 14:40
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Functional Connectivity of Chronic Cocaine Use Reveals Progressive Neuroadaptations in Neocortical, Striatal, and Limbic Networks.

eNeuro. 2018 Jul-Aug;5(4):

Authors: Orsini CA, Colon-Perez LM, Heshmati SC, Setlow B, Febo M

Abstract
Brain imaging studies indicate that chronic cocaine users display altered functional connectivity between prefrontal cortical, thalamic, striatal, and limbic regions; however, the use of cross-sectional designs in these studies precludes measuring baseline brain activity prior to cocaine use. Animal studies can circumvent this limitation by comparing functional connectivity between baseline and various time points after chronic cocaine use. In the present study, adult male Long-Evans rats were trained to self-administer cocaine intravenously for 6 h sessions daily over 14 consecutive days. Two additional groups serving as controls underwent sucrose self-administration or exposure to the test chambers alone. Functional magnetic resonance imaging was conducted before self-administration and after 1 and 14 d of abstinence (1d and 14d Abs). After 1d Abs from cocaine, there were increased clustering coefficients in brain areas involved in reward seeking, learning, memory, and autonomic and affective processing, including amygdala, hypothalamus, striatum, hippocampus, and thalamus. Similar changes in clustering coefficient after 1d Abs from sucrose were evident in predominantly thalamic brain regions. Notably, there were no changes in strength of functional connectivity at 1 or 14 d after either cocaine or sucrose self-administration. The results suggest that cocaine and sucrose can change the arrangement of functional connectivity of brain regions involved in cognition and emotion, but that these changes dissipate across the early stages of abstinence. The study also emphasizes the importance of including baseline measures in longitudinal functional neuroimaging designs seeking to assess functional connectivity in the context of substance use.

PMID: 30073194 [PubMed - in process]

The Connectivity Fingerprint of the Human Frontal Cortex, Subthalamic Nucleus, and Striatum.

Sat, 08/04/2018 - 14:40
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The Connectivity Fingerprint of the Human Frontal Cortex, Subthalamic Nucleus, and Striatum.

Front Neuroanat. 2018;12:60

Authors: Isaacs BR, Forstmann BU, Temel Y, Keuken MC

Abstract
Within the cortico basal ganglia (BG)-thalamic network, the direct and indirect pathways comprise of projections from the cortex to the striatum (STR), whereas the hyperdirect pathway(s) consist of cortical projections toward the subthalamic nucleus (STN). Each pathway possesses a functionally distinct role for action selection. The current study quantified and compared the structural connectivity between 17 distinct cortical areas with the STN and STR using 7 Tesla diffusion weighted magnetic resonance imaging (dMRI) and resting-state functional MRI (rs-fMRI) in healthy young subjects. The selection of these cortical areas was based on a literature search focusing on animal tracer studies. The results indicate that, relative to other cortical areas, both the STN and STR showed markedly weaker structural connections to areas assumed to be essential for action inhibition such as the inferior frontal cortex pars opercularis. Additionally, the cortical connectivity fingerprint of the STN and STR indicated relatively strong connections to areas related to voluntary motor initiation such as the cingulate motor area and supplementary motor area. Overall the results indicated that the cortical-STN connections were sparser compared to the STR. There were two notable exceptions, namely for the orbitofrontal cortex and ventral medial prefrontal cortex, where a higher tract strength was found for the STN. These two areas are thought to be involved in reward processing and action bias.

PMID: 30072875 [PubMed]

Combining gray matter volume in the cuneus and the cuneus-prefrontal connectivity may predict early relapse in abstinent alcohol-dependent patients.

Sat, 08/04/2018 - 14:40
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Combining gray matter volume in the cuneus and the cuneus-prefrontal connectivity may predict early relapse in abstinent alcohol-dependent patients.

PLoS One. 2018;13(5):e0196860

Authors: Wang J, Fan Y, Dong Y, Ma M, Dong Y, Niu Y, Jiang Y, Wang H, Wang Z, Wu L, Sun H, Cui C

Abstract
BACKGROUND: Developing more effective strategies to prevent relapse remains one of the major challenges of treating substance dependence. Previous studies have identified brain abnormalities in abstinent alcoholics. However, whether these persistent brain deficits in abstinence could predict early relapse to alcohol use has not been well established. This study aimed to identify biomarkers of relapse vulnerability by investigating persistent brain abnormalities in abstinent alcohol-dependent patients.
METHODS: Brain imaging and impulsive behavior data were collected from 56 abstinent alcohol-dependent male inpatients and 33 age-matched male healthy controls. Voxel-based morphometry was used to investigate the differences of grey matter volume between the groups. The resting-state functional connectivity was examined using brain areas with gray matter deficits as seed regions. A preliminary prospective study design was used to classify patients into abstainers and relapsers after a 62-day average abstinence period.
RESULTS: Compared with healthy controls, both relapsers and abstainers exhibited significantly reduced gray matter volume in the cuneus. Functional connectivity analysis revealed that relapsers relative to abstainers demonstrated increased cuneus-centered negative functional connectivity within a network of brain regions which are involved in executive control and salience. Abnormal gray matter volume in the left cuneus and the functional connectivity between the right cuneus and bilateral dorsolateral prefrontal cortex could successfully predict relapse during the 3-month follow-up period.
CONCLUSIONS: Findings suggest that the abnormal gray matter volume in the cuneus and resting-state cuneus-prefrontal functional connectivity may play an important role in poor treatment outcomes in alcoholics and serve as useful neural markers of relapse vulnerability.

PMID: 29734343 [PubMed - indexed for MEDLINE]

Polygenic Risk of Spasmodic Dysphonia is Associated With Vulnerable Sensorimotor Connectivity.

Sat, 08/04/2018 - 14:40
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Polygenic Risk of Spasmodic Dysphonia is Associated With Vulnerable Sensorimotor Connectivity.

Cereb Cortex. 2018 Jan 01;28(1):158-166

Authors: Putzel GG, Battistella G, Rumbach AF, Ozelius LJ, Sabuncu MR, Simonyan K

Abstract
Spasmodic dysphonia (SD), or laryngeal dystonia, is an isolated task-specific dystonia of unknown causes and pathophysiology that selectively affects speech production. Using next-generation whole-exome sequencing in SD patients, we computed polygenic risk score from 1804 genetic markers based on a genome-wide association study in another form of similar task-specific focal dystonia, musician's dystonia. We further examined the associations between the polygenic risk score, resting-state functional connectivity abnormalities within the sensorimotor network, and SD clinical characteristics. We found that the polygenic risk of dystonia was significantly associated with decreased functional connectivity in the left premotor/primary sensorimotor and inferior parietal cortices in SD patients. Reduced connectivity of the inferior parietal cortex was correlated with the age of SD onset. The polygenic risk score contained a significant number of genetic variants lying near genes related to synaptic transmission and neural development. Our study identified a polygenic contribution to the overall genetic risk of dystonia in the cohort of SD patients. Associations between the polygenic risk and reduced functional connectivity of the sensorimotor and inferior parietal cortices likely represent an endophenotypic imaging marker of SD, while genes involved in synaptic transmission and neuron development may be linked to the molecular pathophysiology of this disorder.

PMID: 29117296 [PubMed - indexed for MEDLINE]

Dynamic Network Communication in the Human Functional Connectome Predicts Perceptual Variability in Visual Illusion.

Sat, 08/04/2018 - 14:40
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Dynamic Network Communication in the Human Functional Connectome Predicts Perceptual Variability in Visual Illusion.

Cereb Cortex. 2018 Jan 01;28(1):48-62

Authors: Wang Z, Zeljic K, Jiang Q, Gu Y, Wang W, Wang Z

Abstract
Ubiquitous variability between individuals in visual perception is difficult to standardize and has thus essentially been ignored. Here we construct a quantitative psychophysical measure of illusory rotary motion based on the Pinna-Brelstaff figure (PBF) in 73 healthy volunteers and investigate the neural circuit mechanisms underlying perceptual variation using functional magnetic resonance imaging (fMRI). We acquired fMRI data from a subset of 42 subjects during spontaneous and 3 stimulus conditions: expanding PBF, expanding modified-PBF (illusion-free) and expanding modified-PBF with physical rotation. Brain-wide graph analysis of stimulus-evoked functional connectivity patterns yielded a functionally segregated architecture containing 3 discrete hierarchical networks, commonly shared between rest and stimulation conditions. Strikingly, communication efficiency and strength between 2 networks predominantly located in visual areas robustly predicted individual perceptual differences solely in the illusory stimulus condition. These unprecedented findings demonstrate that stimulus-dependent, not spontaneous, dynamic functional integration between distributed brain networks contributes to perceptual variability in humans.

PMID: 29117288 [PubMed - indexed for MEDLINE]

Spontaneous activity in medial orbitofrontal cortex correlates with trait anxiety in healthy male adults.

Fri, 08/03/2018 - 20:00
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Spontaneous activity in medial orbitofrontal cortex correlates with trait anxiety in healthy male adults.

J Zhejiang Univ Sci B. 2018 Aug.;19(8):643-653

Authors: Xue SW, Lee TW, Guo YH

Abstract
Medial orbitofrontal cortex (mOFC) abnormalities have been observed in various anxiety disorders. However, the relationship between mOFC activity and anxiety among the healthy population has not been fully examined. Here, we conducted a resting state functional magnetic resonance imaging (R-fMRI) study with 56 healthy male adults from the Nathan Kline Institute/Rockland Sample (NKI-RS) to examine the relationship between the fractional amplitude of low-frequency fluctuation (fALFF) signals and trait anxiety across the whole brain. A Louvain method for module detection based on graph theory was further employed in the automated functional subdivision to explore subregional correlates of trait anxiety. The results showed that trait anxiety was related to fALFF in the mOFC. Additionally, the resting-state functional connectivity (RSFC) between the right subregions of the mOFC and the precuneus was correlated with trait anxiety. These findings provided evidence about the involvement of the mOFC in anxiety processing among the healthy population.

PMID: 30070087 [PubMed - in process]

Altered Hippocampal GABA and Glutamate Levels and Uncoupling from Functional Connectivity in Multiple Sclerosis.

Fri, 08/03/2018 - 20:00
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Altered Hippocampal GABA and Glutamate Levels and Uncoupling from Functional Connectivity in Multiple Sclerosis.

Hippocampus. 2018 Aug 01;:

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. This article is protected by copyright. All rights reserved.

PMID: 30069963 [PubMed - as supplied by publisher]

Common and distinct abnormal frontal-limbic system structural and functional patterns in patients with major depression and bipolar disorder.

Fri, 08/03/2018 - 20:00
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Common and distinct abnormal frontal-limbic system structural and functional patterns in patients with major depression and bipolar disorder.

Neuroimage Clin. 2018;20:42-50

Authors: Chen L, Wang Y, Niu C, Zhong S, Hu H, Chen P, Zhang S, Chen G, Deng F, Lai S, Wang J, Huang L, Huang R

Abstract
Major depressive disorder (MDD) and bipolar disorder (BD) are common severe affective diseases. Although previous neuroimaging studies have investigated brain abnormalities in MDD or BD, the structural and functional differences between these two disorders remain unclear. In this study, we adopted a multimodal approach, combining voxel-based morphometry (VBM) and functional connectivity (FC), to study the common and distinct structural and functional alterations in unmedicated MDD and BD patients. The VBM analysis revealed that both the MDD and BD patients showed decreased gray matter volume (GMV) in the left anterior cingulate cortex (ACC_L) and right hippocampus (HIP_R) compared with the healthy controls, and the MDD patients showed decreased GMV in the left superior frontal gyrus (SFG_L) and ACC_L compared with the BD patients. Furthermore, we took these clusters as seed regions to analyze the abnormal resting-state functional connectivity (RSFC) in the patients. We found that both the MDD and BD groups had decreased RSFC between the ACC_L and the left orbitofrontal cortex (OFC_L) and that the MDD group had decreased RSFC between the SFG_L and the HIP_L, compared with the healthy controls. Our results revealed that the MDD and BD patients were more similar than different in GMV and RSFC. These findings indicate that investigating the frontal-limbic system could be useful for understanding the underlying mechanisms of these two disorders.

PMID: 30069426 [PubMed - in process]

Visual cortex neural activity alteration in cervical spondylotic myelopathy patients: a resting-state fMRI study.

Thu, 08/02/2018 - 12:20
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Visual cortex neural activity alteration in cervical spondylotic myelopathy patients: a resting-state fMRI study.

Neuroradiology. 2018 Jul 31;:

Authors: Chen Z, Wang Q, Liang M, Zhao R, Zhu J, Xiong W, Su Z, Yu C, Xue Y

Abstract
PURPOSE: We sought to investigate visual cortex neural activity and functional connectivity (FC) alterations in cervical spondylotic myelopathy (CSM) patients using resting-state fMRI (rs-fMRI) and to explore the relationships of these alterations with visual disorder.
METHODS: Twenty-seven CSM patients and 11 healthy controls were recruited as the study and control groups. The amplitude of low-frequency fluctuations (ALFF) and regional homogeneity (ReHo) values were calculated to represent neural activity, seed-based correlation analysis (SCA) was performed to analyze the FC of visual cortex, and the outcomes were compared between groups. The preoperative best-corrected visual acuity (pre-BCVA) and postoperative BCVA (post-BCVA) of study groups were measured. Correlation analyses of the ALFF/ReHo values with the preoperative and postoperative BCVAs were performed. Correlations of the bilateral BCVAs with the ipsilateral and contralateral visual cortex neural activities were performed.
RESULTS: The ALFF/ReHo values were decreased in the occipital lobe and increased in the cerebellar posterior lobe in the study group (P < 0.05). Increased FC was demonstrated between Brodmann's area 17 and posterior cingulate lobe (P < 0.05). Postoperatively, the BCVAs were ameliorated in 22 oculi dexter (ODs) and 20 oculi sinister (OSs) in the study group. Positive correlations between neural activity in the visual cortex and the preoperative and postoperative BCVAs were detected in the study group. The bilateral BCVAs were positively correlated with either the ipsilateral or contralateral visual cortex neural activity.
CONCLUSION: Both ALFF/ReHo value changes and positive correlations of these changes with BCVA were demonstrated in CSM. The FC between the visual cortex and posterior cingulate lobe was also increased in CSM.

PMID: 30066277 [PubMed - as supplied by publisher]

Abnormal Functional Connectivity Density in Amyotrophic Lateral Sclerosis.

Thu, 08/02/2018 - 12:20
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Abnormal Functional Connectivity Density in Amyotrophic Lateral Sclerosis.

Front Aging Neurosci. 2018;10:215

Authors: Li W, Zhang J, Zhou C, Hou W, Hu J, Feng H, Zheng X

Abstract
Purpose: Amyotrophic lateral sclerosis (ALS) is a motor neuro-degenerative disorder that also damages extra-motor neural pathways. A significant proportion of existing evidence describe alterations in the strengths of functional connectivity, whereas the changes in the density of these functional connections have not been explored. Therefore, our study seeks to identify ALS-induced alternations in the resting-state functional connectivity density (FCD). Methods: Two groups comprising of 38 ALS patients and 35 healthy participants (age and gender matched) were subjected to the resting-state functional magnetic resonance imaging (MRI) scanning. An ultra-fast graph theory method known as FCD mapping was utilized to calculate the voxel-wise short- and long-range FCD values of the brain for each participant. FCD values of patients and controls were compared based on voxels in order to discern cerebral regions that possessed significant FCD alterations. For areas demonstrating a group effect of atypical FCD in ALS, seed-based functional connectivity analysis was then investigated. Partial correlation analyses were carried out between aberrant FCDs and several clinical variables, controlling for age, gender, and total intracranial volume. Results: Patients with ALS were found to have decreased short-range FCD in the primary motor cortex and increased long-range FCD in the premotor cortex. Extra-motor areas that also displayed extensive FCD alterations encompassed the temporal cortex, insula, cingulate gyrus, occipital cortex, and inferior parietal lobule. Seed-based correlation analysis further demonstrated that these regions also possessed disrupted functional connectivity. However, no significant correlations were identified between aberrant FCDs and clinical variables. Conclusion: FCD changes in the regions identified represent communication deficits and impaired functional brain dynamics, which might underlie the motor, motor control, language, visuoperceptual and high-order cognitive deficits in ALS. These findings support the fact that ALS is a disorder affecting multiple systems. We gain a deeper insight of the neural mechanisms underlying ALS.

PMID: 30065647 [PubMed]

Differences in functional connectivity profiles as a predictor of response to anterior thalamic nucleus deep brain stimulation for epilepsy: a hypothesis for the mechanism of action and a potential biomarker for outcomes.

Thu, 08/02/2018 - 12:20
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Differences in functional connectivity profiles as a predictor of response to anterior thalamic nucleus deep brain stimulation for epilepsy: a hypothesis for the mechanism of action and a potential biomarker for outcomes.

Neurosurg Focus. 2018 Aug;45(2):E7

Authors: Middlebrooks EH, Grewal SS, Stead M, Lundstrom BN, Worrell GA, Van Gompel JJ

Abstract
OBJECTIVE Deep brain stimulation (DBS) of the anterior nucleus of the thalamus (ANT) is a promising therapy for refractory epilepsy. Unfortunately, the variability in outcomes from ANT DBS is not fully understood. In this pilot study, the authors assess potential differences in functional connectivity related to the volume of tissue activated (VTA) in ANT DBS responders and nonresponders as a means for better understanding the mechanism of action and potentially improving DBS targeting. METHODS This retrospective analysis consisted of 6 patients who underwent ANT DBS for refractory epilepsy. Patients were classified as responders (n = 3) if their seizure frequency decreased by at least 50%. The DBS electrodes were localized postoperatively and VTAs were computationally generated based on DBS programming settings. VTAs were used as seed points for resting-state functional MRI connectivity analysis performed using a control dataset. Differences in cortical connectivity to the VTA were assessed between the responder and nonresponder groups. RESULTS The ANT DBS responders showed greater positive connectivity with the default mode network compared to nonresponders, including the posterior cingulate cortex, medial prefrontal cortex, inferior parietal lobule, and precuneus. Interestingly, there was also a consistent anticorrelation with the hippocampus seen in responders that was not present in nonresponders. CONCLUSIONS Based on their pilot study, the authors observed that successful ANT DBS in patients with epilepsy produces increased connectivity in the default mode network, which the authors hypothesize increases the threshold for seizure propagation. Additionally, an inhibitory effect on the hippocampus mediated through increased hippocampal γ-aminobutyric acid (GABA) concentration may contribute to seizure suppression. Future studies are planned to confirm these findings.

PMID: 30064322 [PubMed - in process]

Altered connectivity between striatal and extrastriatal regions in patients with schizophrenia on maintenance antipsychotics: an [18 F]fallypride PET and functional MRI study.

Wed, 08/01/2018 - 11:40
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Altered connectivity between striatal and extrastriatal regions in patients with schizophrenia on maintenance antipsychotics: an [18 F]fallypride PET and functional MRI study.

Synapse. 2018 Jul 31;:

Authors: Kim JH, Cumming P, Son YD, Kim HK, Joo YH, Kim JH

Abstract
In addition to probing regional differences in receptor availability, molecular positron emission tomography (PET) is proving useful for investigating perturbations in neurotransmitter networks using interregional correlation analyses. In a multi-modal imaging study, we examined interregional correlations of dopamine D2/3 receptor availability between striatal and extrastriatal regions using [18 F]fallypride high-resolution PET in 11 patients with schizophrenia receiving low-dose maintenance atypical antipsychotics and 14 healthy control subjects, and investigated resting-state functional connectivity in the same subjects using seed-based functional magnetic resonance imaging (fMRI) analysis. In the healthy control group, there were no significant correlations between [18 F]fallypride binding potential (BPND ) in striatal regions and any cortical areas, whereas the patient group showed significant and widespread inter-correlations. Correlations between BPND in striatum, amygdala and insula with cortex were significantly higher in patients than in controls. In seed-based resting-state fMRI analysis, the healthy controls revealed positive and negative functional connectivity patterns, while patients exhibited a pattern of exclusively positive connectivity. Functional connectivity was significantly higher between striatal regions and extrastriatal areas including cortical regions in patients compared to controls. In this first such report, molecular and functional connectivity between striatal and extrastriatal regions was primarily characterized by increased interregional relationships in treated patients with schizophrenia. The results suggest that the spatial organization of D2/3 receptor availability and related functional connectivity are significantly perturbed in stable outpatients on maintenance antipsychotics. Future studies should include antipsychotic-naïve patients to determine if these relationships are illness-related characteristics, or arising due to chronic antipsychotic treatment. This article is protected by copyright. All rights reserved.

PMID: 30063263 [PubMed - as supplied by publisher]

Bariatric surgery in obese patients reduced resting connectivity of brain regions involved with self-referential processing.

Wed, 08/01/2018 - 11:40
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Bariatric surgery in obese patients reduced resting connectivity of brain regions involved with self-referential processing.

Hum Brain Mapp. 2018 Jul 31;:

Authors: Li G, Ji G, Hu Y, Xu M, Jin Q, Liu L, von Deneen KM, Zhao J, Chen A, Cui G, Wang H, Zhao Q, Wu K, Shokri-Kojori E, Tomasi D, Volkow ND, Nie Y, Zhang Y, Wang GJ

Abstract
Obese individuals exhibit brain alterations of resting-state functional connectivity (RSFC) integrity of resting-state networks (RSNs) related to food intake. Bariatric surgery is currently the most effective treatment for combating morbid obesity. How bariatric surgery influences neurocircuitry is mostly unknown. Functional connectivity density (FCD) mapping was employed to calculate local (lFCD)/global (gFCD) voxelwise connectivity metrics in 22 obese participants who underwent functional magnetic resonance imaging before and 1 month after sleeve gastrectomy (SG), and in 19 obese controls (Ctr) without surgery but tested twice (baseline and 1-month later). Two factor (group, time) repeated measures ANOVA was used to assess main and interaction effects in lFCD/gFCD; regions of interest were identified for subsequent seed to voxel connectivity analyses to assess resting-state functional connectivity and to examine association with weight loss. Bariatric surgery significantly decreased lFCD in VMPFC, posterior cingulate cortex (PCC)/precuneus, and dorsal anterior cingulate cortex (dACC)/dorsomedial prefrontal cortex (DMPFC) and decreased gFCD in VMPFC, right dorsolateral prefrontal cortex (DLPFC) and right insula (pFWE  < .05). lFCD decreased in VMPFC and PCC/precuneus correlated with reduction in BMI after surgery. Seed to voxel connectivity analyses showed the VMPFC had stronger connectivity with left DLPFC and weaker connectivity with hippocampus/parahippocampus, and PCC/precuneus had stronger connectivity with right caudate and left DLPFC after surgery. Bariatric surgery significantly decreased FCD in regions involved in self-referential processing (VMPFC, DMPFC, dACC, and precuneus), and interoception (insula), and changes in VMPFC/precuneus were associated with reduction in BMI suggesting a role in improving control of eating behaviors following surgery.

PMID: 30062852 [PubMed - as supplied by publisher]

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