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Abnormal intrinsic brain functional network dynamics in Parkinson's disease.

Sat, 10/21/2017 - 12:40
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Abnormal intrinsic brain functional network dynamics in Parkinson's disease.

Brain. 2017 Oct 05;:

Authors: Kim J, Criaud M, Cho SS, Díez-Cirarda M, Mihaescu A, Coakeley S, Ghadery C, Valli M, Jacobs MF, Houle S, Strafella AP

Abstract
Parkinson's disease is a neurodegenerative disorder characterized by nigrostriatal dopamine depletion. Previous studies measuring spontaneous brain activity using resting state functional magnetic resonance imaging have reported abnormal changes in broadly distributed whole-brain networks. Although resting state functional connectivity, estimating temporal correlations between brain regions, is measured with the assumption that intrinsic fluctuations throughout the scan are stable, dynamic changes of functional connectivity have recently been suggested to reflect aspects of functional capacity of neural systems, and thus may serve as biomarkers of disease. The present work is the first study to investigate the dynamic functional connectivity in patients with Parkinson's disease, with a focus on the temporal properties of functional connectivity states as well as the variability of network topological organization using resting state functional magnetic resonance imaging. Thirty-one Parkinson's disease patients and 23 healthy controls were studied using group spatial independent component analysis, a sliding windows approach, and graph-theory methods. The dynamic functional connectivity analyses suggested two discrete connectivity configurations: a more frequent, sparsely connected within-network state (State I) and a less frequent, more strongly interconnected between-network state (State II). In patients with Parkinson's disease, the occurrence of the sparsely connected State I dropped by 12.62%, while the expression of the more strongly interconnected State II increased by the same amount. This was consistent with the altered temporal properties of the dynamic functional connectivity characterized by a shortening of the dwell time of State I and by a proportional increase of the dwell time pattern in State II. These changes are suggestive of a reduction in functional segregation among networks and are correlated with the clinical severity of Parkinson's disease symptoms. Additionally, there was a higher variability in the network global efficiency, suggesting an abnormal global integration of the brain networks. The altered functional segregation and abnormal global integration in brain networks confirmed the vulnerability of functional connectivity networks in Parkinson's disease.

PMID: 29053835 [PubMed - as supplied by publisher]

Pregenual Anterior Cingulate Dysfunction Associated with Depression in OCD: An Integrated Multimodal fMRI/(1)H MRS Study.

Sat, 10/21/2017 - 12:40
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Pregenual Anterior Cingulate Dysfunction Associated with Depression in OCD: An Integrated Multimodal fMRI/(1)H MRS Study.

Neuropsychopharmacology. 2017 Oct 20;:

Authors: Tadayonnejad R, Deshpande R, Ajilore O, Moody T, Morfini F, Ly R, O'Neill J, Feusner JD

Abstract
Depression is a commonly-occurring symptom in obsessive-compulsive disorder (OCD), and is associated with worse functional impairment, poorer quality of life, and poorer treatment response. Understanding the underlying neurochemical and connectivity-based brain mechanisms of this important symptom domain in OCD is necessary for development of novel, more globally effective treatments. To investigate biopsychological mechanisms of comorbid depression in OCD, we examined effective connectivity and neurochemical signatures in the pregenual anterior cingulate cortex (pACC), a structure known to be involved in both OCD and depression. Resting-state fMRI and (1)H MRS data were obtained from participants with OCD (n=49) and healthy individuals of equivalent age and sex (n=25). Granger causality based effective (directed) connectivity was used to define causal networks involving the right and left pACC. The interplay between fMRI connectivity, (1)H MRS and clinical data were explored by applying moderation and mediation analyses. We found that the causal influence of the right dorsal anterior midcingulate cortex (daMCC) on the right pACC was significantly lower in the OCD group and showed significant correlation with depressive symptom severity in the OCD group. Lower and moderate levels of glutamate (Glu) in the right pACC significantly moderated the interaction between right daMCC-pACC connectivity and depression severity. Our results suggest a biochemical-connectivity-psychological model of pACC dysfunction contributing to depression in OCD, particularly involving intracingulate connectivity and glutamate levels in the pACC. These findings have implications for potential molecular and network targets for treatment of this multi-faceted psychiatric condition.Neuropsychopharmacology accepted article preview online, 20 October 2017. doi:10.1038/npp.2017.249.

PMID: 29052616 [PubMed - as supplied by publisher]

Changes in cerebellar functional connectivity and autonomic regulation in cancer patients treated with the Neuro Emotional Technique for traumatic stress symptoms.

Sat, 10/21/2017 - 12:40
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Changes in cerebellar functional connectivity and autonomic regulation in cancer patients treated with the Neuro Emotional Technique for traumatic stress symptoms.

J Cancer Surviv. 2017 Oct 19;:

Authors: Monti DA, Tobia A, Stoner M, Wintering N, Matthews M, Conklin CJ, Mohamed FB, Chervoneva I, Newberg AB

Abstract
PURPOSE: A growing number of research studies have implicated the cerebellum in emotional processing and regulation, especially with regard to negative emotional memories. However, there currently are no studies showing functional changes in the cerebellum as a result of treatment for traumatic stress symptoms. The Neuro Emotional Technique (NET) is an intervention designed to help improve symptoms related to traumatic stress using an integrative approach that combines emotional, cognitive, and motor processing, with a particular focus on autonomic nervous system regulation. In this study, we evaluated whether the NET intervention alters functional connectivity in the brain of patients with traumatic stress symptoms associated with a cancer-related event. We hypothesized that the NET intervention would reduce emotional and autonomic reactivity and that this would correlate with connectivity changes between the cerebellum and limbic structures as well as the brain stem.
METHODS: We enrolled patients with a prior cancer diagnosis who experienced distressing cancer-related memories associated with traumatic stress symptoms of at least 6 months in duration. Participants were randomized to either the NET intervention or a waitlist control. To evaluate the primary outcome of neurophysiological effects, all participants received resting-state functional blood oxygen level-dependent (BOLD) magnetic resonance imaging (rs-fMRI) before and after the NET intervention. In addition, autonomic reactivity was measured using heart rate response to the traumatic stimulus. Pre/post comparisons were performed between the NET and control groups.
RESULTS: The results demonstrated significant changes in the NET group, as compared to the control group, in the functional connectivity between the cerebellum (including the vermis) and the amygdala, parahippocampus, and brain stem. Likewise, participants receiving the NET intervention had significant reductions in autonomic reactivity based on heart rate response to the traumatic stimulus compared to the control group.
CONCLUSIONS: This study is an initial step towards establishing a neurological signature of treatment effect for the NET intervention. Specifically, functional connectivity between the cerebellum and the amygdala and prefrontal cortex appear to be associated with a reduction in autonomic reactivity in response to distressing cancer-related memories.
IMPLICATIONS FOR CANCER SURVIVORS: This study contributes to the understanding of possible mechanisms by which interventions like NET may help reduce emotional distress in cancer patients who suffer from traumatic stress symptoms.

PMID: 29052102 [PubMed - as supplied by publisher]

The Effect of Low-Frequency Physiological Correction on the Reproducibility and Specificity of Resting-State fMRI Metrics: Functional Connectivity, ALFF, and ReHo.

Sat, 10/21/2017 - 12:40
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The Effect of Low-Frequency Physiological Correction on the Reproducibility and Specificity of Resting-State fMRI Metrics: Functional Connectivity, ALFF, and ReHo.

Front Neurosci. 2017;11:546

Authors: Golestani AM, Kwinta JB, Khatamian YB, Chen JJ

Abstract
The resting-state fMRI (rs-fMRI) signal is affected by a variety of low-frequency physiological phenomena, including variations in cardiac-rate (CRV), respiratory-volume (RVT), and end-tidal CO2 (PETCO2). While these effects have become better understood in recent years, the impact that their correction has on the quality of rs-fMRI measurements has yet to be clarified. The objective of this paper is to investigate the effect of correcting for CRV, RVT and PETCO2 on the rs-fMRI measurements. Nine healthy subjects underwent a test-retest rs-fMRI acquisition using repetition times (TRs) of 2 s (long-TR) and 0.323 s (short-TR), and the data were processed using eight different physiological correction strategies. Subsequently, regional homogeneity (ReHo), amplitude of low-frequency fluctuation (ALFF), and resting-state connectivity of the motor and default-mode networks are calculated for each strategy. Reproducibility is calculated using intra-class correlation and the Dice Coefficient, while the accuracy of functional-connectivity measures is assessed through network separability, sensitivity and specificity. We found that: (1) the reproducibility of the rs-fMRI measures improved significantly after correction for PETCO2; (2) separability of functional networks increased after PETCO2 correction but was not affected by RVT and CRV correction; (3) the effect of physiological correction does not depend on the data sampling-rate; (4) the effect of physiological processes and correction strategies is network-specific. Our findings highlight limitations in our understanding of rs-fMRI quality measures, and underscore the importance of using multiple quality measures to determine the optimal physiological correction strategy.

PMID: 29051724 [PubMed]

Neuronal and behavioral effects of multi-day brain stimulation and memory training.

Sat, 10/21/2017 - 12:40
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Neuronal and behavioral effects of multi-day brain stimulation and memory training.

Neurobiol Aging. 2017 Sep 28;:

Authors: Antonenko D, Külzow N, Sousa A, Prehn K, Grittner U, Flöel A

Abstract
Strategies for memory enhancement, especially for the older population, are of great scientific and public interest. Here, we aimed at investigating neuronal and behavioral effects of transcranial direct current stimulation (tDCS) paired with memory training. Young and older adults were trained on an object-location-memory task on 3 consecutive days with either anodal or sham tDCS. Recall performance was assessed immediately after training, 1 day and 1 month later, as well as performance on trained function and transfer task. Resting-state functional magnetic resonance imaging was conducted at baseline and at 1-day follow-up to analyze functional coupling in the default mode network. Anodal tDCS led to superior recall performance after training, an associated increase in default mode network strength and enhanced trained function and transfer after 1 month. Our findings suggest that tDCS-accompanied multi-day training improves performance on trained material, is associated with beneficial memory network alterations, and transfers to other memory tasks. Our study provides insight into tDCS-induced behavioral and neuronal alterations and will help to develop interventions against age-related cognitive decline.

PMID: 29050849 [PubMed - as supplied by publisher]

Structural brain correlates of heart rate variability in a healthy young adult population.

Sat, 10/21/2017 - 12:40
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Structural brain correlates of heart rate variability in a healthy young adult population.

Brain Struct Funct. 2017 Mar;222(2):1061-1068

Authors: Winkelmann T, Thayer JF, Pohlack S, Nees F, Grimm O, Flor H

Abstract
The high frequency component of heart rate variability (HRV) has reliably been shown to serve as an index of autonomic inhibitory control and is increasingly considered as a biomarker of adaptability and health. While several functional neuroimaging studies identified associations between regional cerebral blood flow and HRV, studies on structural brain correlates of HRV are scarce. We investigated whether interindividual differences in HRV are related to brain morphology in healthy humans. Thirty participants underwent HRV recording at rest subsequent to structural magnetic resonance imaging. Cortical reconstruction and subcortical volumetry were performed with the Freesurfer image analysis suite. The amount of resting HRV was positively correlated with the cortical thickness of an area within the right anterior midcingulate cortex (aMCC). Consistent with existing studies implicating forebrain regions in cardiac regulation, our findings show that the thickness of the right aMCC is associated with the degree of parasympathetic regulation of heart rate. Evidence for the neural correlates of interindividual differences in HRV may complement our understanding of the mechanisms underlying the association between HRV and self-regulatory capacity.

PMID: 26801184 [PubMed - indexed for MEDLINE]

Functional connectivity structure of cortical calcium dynamics in anesthetized and awake mice.

Fri, 10/20/2017 - 11:20

Functional connectivity structure of cortical calcium dynamics in anesthetized and awake mice.

PLoS One. 2017;12(10):e0185759

Authors: Wright PW, Brier LM, Bauer AQ, Baxter GA, Kraft AW, Reisman MD, Bice AR, Snyder AZ, Lee JM, Culver JP

Abstract
The interplay between hemodynamic-based markers of cortical activity (e.g. fMRI and optical intrinsic signal imaging), which are an indirect and relatively slow report of neural activity, and underlying synaptic electrical and metabolic activity through neurovascular coupling is a topic of ongoing research and debate. As application of resting state functional connectivity measures is extended further into topics such as brain development, aging and disease, the importance of understanding the fundamental physiological basis for functional connectivity will grow. Here we extend functional connectivity analysis from hemodynamic- to calcium-based imaging. Transgenic mice (n = 7) expressing a fluorescent calcium indicator (GCaMP6) driven by the Thy1 promoter in glutamatergic neurons were imaged transcranially in both anesthetized (using ketamine/xylazine) and awake states. Sequential LED illumination (λ = 454, 523, 595, 640nm) enabled concurrent imaging of both GCaMP6 fluorescence emission (corrected for hemoglobin absorption) and hemodynamics. Functional connectivity network maps were constructed for infraslow (0.009-0.08Hz), intermediate (0.08-0.4Hz), and high (0.4-4.0Hz) frequency bands. At infraslow and intermediate frequencies, commonly used in BOLD fMRI and fcOIS studies of functional connectivity and implicated in neurovascular coupling mechanisms, GCaMP6 and HbO2 functional connectivity structures were in high agreement, both qualitatively and also quantitatively through a measure of spatial similarity. The spontaneous dynamics of both contrasts had the highest correlation when the GCaMP6 signal was delayed with a ~0.6-1.5s temporal offset. Within the higher-frequency delta band, sensitive to slow wave sleep oscillations in non-REM sleep and anesthesia, we evaluate the speed with which the connectivity analysis stabilized and found that the functional connectivity maps captured putative network structure within time window lengths as short as 30 seconds. Homotopic GCaMP6 functional connectivity maps at 0.4-4.0Hz in the anesthetized states show a striking correlated and anti-correlated structure along the anterior to posterior axis. This structure is potentially explained in part by observed propagation of delta-band activity from frontal somatomotor regions to visuoparietal areas. During awake imaging, this spatio-temporal quality is altered, and a more complex and detailed functional connectivity structure is observed. The combined calcium/hemoglobin imaging technique described here will enable the dissociation of changes in ionic and hemodynamic functional structure and neurovascular coupling and provide a framework for subsequent studies of neurological disease such as stroke.

PMID: 29049297 [PubMed - in process]

Salience network dynamics underlying successful resistance of temptation.

Fri, 10/20/2017 - 11:20

Salience network dynamics underlying successful resistance of temptation.

Soc Cogn Affect Neurosci. 2017 Oct 18;:

Authors: Steimke R, Nomi JS, Calhoun VD, Stelzel C, Paschke LM, Gaschler R, Goschke T, Walter H, Uddin LQ

Abstract
Self-control and the ability to resist temptation are critical for successful completion of long-term goals. Contemporary models in cognitive neuroscience emphasize the primary role of prefrontal cognitive control networks in aligning behavior with such goals. Here we use gaze pattern analysis and dynamic functional connectivity fMRI data to explore how individual differences in the ability to resist temptation are related to intrinsic brain dynamics of the cognitive control and salience networks. Behaviorally, individuals exhibit greater gaze distance from target location (e.g. higher distractibility) during presentation of tempting erotic images compared with neutral images. Individuals whose intrinsic dynamic functional connectivity patterns gravitate towards configurations in which salience detection systems are less strongly coupled with visual systems resist tempting distractors more effectively. The ability to resist tempting distractors was not significantly related to intrinsic dynamics of the cognitive control network. These results suggest that susceptibility to temptation is governed in part by individual differences in salience network dynamics, and provide novel evidence for involvement of brain systems outside canonical cognitive control networks in contributing to individual differences in self-control.

PMID: 29048582 [PubMed - as supplied by publisher]

Re-Establishing Brain Networks in Patients with ESRD after Successful Kidney Transplantation.

Fri, 10/20/2017 - 11:20
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Re-Establishing Brain Networks in Patients with ESRD after Successful Kidney Transplantation.

Clin J Am Soc Nephrol. 2017 Oct 18;:

Authors: Chen HJ, Wen J, Qi R, Zhong J, Schoepf UJ, Varga-Szemes A, Lesslie VW, Kong X, Wang YF, Xu Q, Zhang Z, Li X, Lu GM, Zhang LJ

Abstract
BACKGROUND AND OBJECTIVES: Cognition in ESRD may be improved by kidney transplantation, but mechanisms are unclear. We explored patterns of resting-state networks with resting-state functional magnetic resonance imaging among patients with ESRD before and after kidney transplantation.
DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Thirty-seven patients with ESRD scheduled for kidney transplantation and 22 age-, sex-, and education-matched healthy subjects underwent resting-state functional magnetic resonance imaging. Patients were imaged before and 1 and 6 months after kidney transplantation. Functional connectivity of seven resting-state subnetworks was evaluated: default mode network, dorsal attention network, central executive network, self-referential network, sensorimotor network, visual network, and auditory network. Mixed effects models tested associations of ESRD, kidney transplantation, and neuropsychological measurements with functional connectivity.
RESULTS: Compared with controls, pretransplant patients showed abnormal functional connectivity in six subnetworks. Compared with pretransplant patients, increased functional connectivity was observed in the default mode network, the dorsal attention network, the central executive network, the sensorimotor network, the auditory network, and the visual network 1 and 6 months after kidney transplantation (P=0.01). Six months after kidney transplantation, no significant difference in functional connectivity was observed for the dorsal attention network, the central executive network, the auditory network, or the visual network between patients and controls. Default mode network and sensorimotor network remained significantly different from those in controls when assessed 6 months after kidney transplantation. A relationship between functional connectivity and neuropsychological measurements was found in specific brain regions of some brain networks.
CONCLUSIONS: The recovery patterns of resting-state subnetworks vary after kidney transplantation. The dorsal attention network, the central executive network, the auditory network, and the visual network recovered to normal levels, whereas the default mode network and the sensorimotor network did not recover completely 6 months after kidney transplantation. Neural resting-state functional connectivity was lower among patients with ESRD compared with control subjects, but it significantly improved with kidney transplantation. Resting-state subnetworks exhibited variable recovery, in some cases to levels that were no longer significantly different from those of normal controls.

PMID: 29046290 [PubMed - as supplied by publisher]

Neural network alterations across eating disorders: a narrative review of fMRI studies.

Fri, 10/20/2017 - 11:20
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Neural network alterations across eating disorders: a narrative review of fMRI studies.

Curr Neuropharmacol. 2017 Oct 17;:

Authors: Steward T, Menchón JM, Jiménez-Murcia S, Soriano-Mas C, Fernández-Aranda F

Abstract
Functional magnetic resonance imaging (fMRI) has provided insight on how neural abnormalities are related to the symptomatology of the eating disorders (EDs): anorexia nervosa (AN), bulimia nervosa (BN), and binge eating disorder (BED). More specifically, an increasingly growing number of brain imaging studies has shed light on how functionally connected brain networks contribute not only to disturbed eating behavior, but also to transdiagnostic alterations in body/interoceptive perception, reward processing and executive functions. This narrative review aims to summarize recent advances in fMRI studies of patients with EDs by highlighting studies investigating network alterations that are shared across EDs. Findings on reward processing in both AN and BN patients point to the presence of altered sensitivity to salient food stimuli in striatal regions and to the possibility of hypothalamic inputs being overridden by top-down cognitive control regions. Additionally, innovative new lines of research suggest that increased activations in fronto-striatal circuits are strongly associated with the maintenance of restrictive eating habits in AN patients. Although significantly fewer studies have been carried out in patients with BN and BED, aberrant neural responses to both food cues and anticipated food receipt appear to occur in these populations. These altered responses, coupled with diminished recruitment of prefrontal cognitive control circuitry, are believed to contribute to the binge eating of palatable foods. Results from functional network connectivity studies are diverse, but findings tend to converge on indicating disrupted resting-state connectivity in executive networks, the default-mode network and the salience network across EDs.

PMID: 29046154 [PubMed - as supplied by publisher]

A Modulatory Effect of Brief Passive Exposure to Non-linguistic Sounds on Intrinsic Functional Connectivity: Relevance to Cognitive Performance.

Thu, 10/19/2017 - 10:20

A Modulatory Effect of Brief Passive Exposure to Non-linguistic Sounds on Intrinsic Functional Connectivity: Relevance to Cognitive Performance.

Cereb Cortex. 2017 Oct 17;:1-14

Authors: Koyama MS, Ortiz-Mantilla S, Roesler CP, Milham MP, Benasich AA

Abstract
A growing literature on resting-state fMRI (R-fMRI) has explored the impact of preceding sensory experience on intrinsic functional connectivity (iFC). However, it remains largely unknown how passive exposure to irrelevant auditory stimuli, which is a constant in everyday life, reconfigures iFC. Here, we directly compared pre- and post-exposure R-fMRI scans to examine: 1) modulatory effects of brief passive exposure to repeating non-linguistic sounds on subsequent iFC, and 2) associations between iFC modulations and cognitive abilities. We used an exploratory regional homogeneity (ReHo) approach that indexes local iFC, and performed a linear mixed-effects modeling analysis. A modulatory effect (increase) in ReHo was observed in the right superior parietal lobule (R.SPL) within the parietal attention network. Post hoc seed-based correlation analyses provided further evidence for increased parietal iFC (e.g., R.SPL with the right inferior parietal lobule). Notably, less iFC modulation was associated with better cognitive performance (e.g., word reading). These results suggest that: 1) the parietal attention network dynamically reconfigures its iFC in response to passive (thus irrelevant) non-linguistic sounds, but also 2) minimization of iFC modulation in the same network characterizes better cognitive performance. Our findings may open up new avenues for investigating cognitive disorders that involve impaired sensory processing.

PMID: 29045599 [PubMed - as supplied by publisher]

Early Functional Connectome Integrity and 1-Year Recovery in Comatose Survivors of Cardiac Arrest.

Thu, 10/19/2017 - 10:20

Early Functional Connectome Integrity and 1-Year Recovery in Comatose Survivors of Cardiac Arrest.

Radiology. 2017 Oct 18;:162161

Authors: Sair HI, Hannawi Y, Li S, Kornbluth J, Demertzi A, Di Perri C, Chabanne R, Jean B, Benali H, Perlbarg V, Pekar J, Luyt CE, Galanaud D, Velly L, Puybasset L, Laureys S, Caffo B, Stevens RD, Neuroimaging for Coma Emergence and Recovery (NICER) Consortium

Abstract
Purpose To assess whether early brain functional connectivity is associated with functional recovery 1 year after cardiac arrest (CA). Materials and Methods Enrolled in this prospective multicenter cohort were 46 patients who were comatose after CA. Principal outcome was cerebral performance category at 12 months, with favorable outcome (FO) defined as cerebral performance category 1 or 2. All participants underwent multiparametric structural and functional magnetic resonance (MR) imaging less than 4 weeks after CA. Within- and between-network connectivity was measured in dorsal attention network (DAN), default-mode network (DMN), salience network (SN), and executive control network (ECN) by using seed-based analysis of resting-state functional MR imaging data. Structural changes identified with fluid-attenuated inversion recovery and diffusion-weighted imaging sequences were analyzed by using validated morphologic scales. The association between connectivity measures, structural changes, and the principal outcome was explored with multivariable modeling. Results Patients underwent MR imaging a mean 12.6 days ± 5.6 (standard deviation) after CA. At 12 months, 11 patients had an FO. Patients with FO had higher within-DMN connectivity and greater anticorrelation between SN and DMN and between SN and ECN compared with patients with unfavorable outcome, an effect that was maintained after multivariable adjustment. Anticorrelation of SN-DMN predicted outcomes with higher accuracy than fluid-attenuated inversion recovery or diffusion-weighted imaging scores (area under the receiver operating characteristic curves, respectively, 0.88, 0.74, and 0.71). Conclusion MR imaging-based measures of cerebral functional network connectivity obtained in the acute phase of CA were independently associated with FO at 1 year, warranting validation as early markers of long-term recovery potential in patients with anoxic-ischemic encephalopathy. (©) RSNA, 2017.

PMID: 29043908 [PubMed - as supplied by publisher]

Functional network dysconnectivity as a biomarker of treatment resistance in schizophrenia.

Thu, 10/19/2017 - 10:20

Functional network dysconnectivity as a biomarker of treatment resistance in schizophrenia.

Schizophr Res. 2017 Oct 14;:

Authors: McNabb CB, Tait RJ, McIlwain ME, Anderson VM, Suckling J, Kydd RR, Russell BR

Abstract
Schizophrenia may develop from disruptions in functional connectivity regulated by neurotransmitters such as dopamine and acetylcholine. The modulatory effects of these neurotransmitters might explain how antipsychotics attenuate symptoms of schizophrenia and account for the variable response to antipsychotics observed in clinical practice. Based on the putative mechanisms of antipsychotics and evidence of disrupted connectivity in schizophrenia, we hypothesised that functional network connectivity, as assessed using network-based statistics, would exhibit differences between treatment response subtypes of schizophrenia and healthy controls. Resting-state functional MRI data were obtained from 17 healthy controls as well as individuals with schizophrenia who responded well to first-line atypical antipsychotics (first-line responders; FLR, n=18), had failed at least two trials of antipsychotics but responded to clozapine (treatment-resistant schizophrenia; TRS, n=18), or failed at least two trials of antipsychotics and a trial of clozapine (ultra-treatment-resistant schizophrenia; UTRS, n=16). Data were pre-processed using the Advanced Normalization Toolkit and BrainWavelet Toolbox. Network connectivity was assessed using the Network-Based Statistics toolbox in Matlab. ANOVA revealed a significant difference in functional connectivity between groups that extended between cerebellar and parietal regions to the frontal cortex (p<0.05). Post-hoc t-tests revealed weaker network connectivity in individuals with UTRS compared with healthy controls but no other differences between groups. Results demonstrated distinct differences in functional connectivity between individuals with UTRS and healthy controls. Future work must determine whether these changes occur prior to the onset of treatment and if they can be used to predict resistance to antipsychotics during first-episode psychosis.

PMID: 29042073 [PubMed - as supplied by publisher]

Quantitative, functional MRI and neurophysiological markers in a case of Gerstmann-Sträussler-Scheinker syndrome.

Thu, 10/19/2017 - 10:20

Quantitative, functional MRI and neurophysiological markers in a case of Gerstmann-Sträussler-Scheinker syndrome.

Funct Neurol. 2017 Jul/Sep;32(3):153-158

Authors: Marino S, Morabito R, De Salvo S, Bonanno L, Bramanti A, Pollicino P, Giorgianni R, Bramanti P

Abstract
Gerstmann-Sträussler-Scheinker syndrome (GSS) is an inherited autosomal dominant prion disease, caused by a codon 102 proline to leucine substitution (P102L) in the prion protein gene (PRNP). We describe the case of a 40-year-old male, affected by a slowly progressive gait disturbance, leg weakness and cognitive impairment. Genomic DNA revealed a point mutation of PRNP at codon 102, resulting in P102L, and the diagnosis of GSS was confirmed. Somatosensory evoked potentials showed alterations of principal parameters, particularly in the right upper and lower limbs. Laser-evoked potentials were indicative of nociceptive system impairment, especially in the right upper and lower limbs. Conventional magnetic resonance imaging (MRI) revealed marked atrophy of the vermis and cerebellar hemispheres and mild atrophy of the middle cerebellar peduncles and brainstem, as confirmed by a brain volume automatic analysis. Resting-state functional MRI showed increased functional connectivity in the bilateral visual cortex, and decreased functional connectivity in the bilateral frontal pole and supramarginal and precentral gyrus. Albeit limited to a single case, this is the first study to assess structural and functional connectivity in GSS using a multimodal approach.

PMID: 29042004 [PubMed - in process]

Resting-State Functional Connectivity in Combat Veterans Suffering from Impulsive Aggression.

Thu, 10/19/2017 - 10:20
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Resting-State Functional Connectivity in Combat Veterans Suffering from Impulsive Aggression.

Soc Cogn Affect Neurosci. 2017 Oct 12;:

Authors: Varkevisser T, Gladwin TE, Heesink L, van Honk J, Geuze E

Abstract
Impulsive aggression is common amongst military personnel after deployment, and may arise because of impaired top-down regulation of the amgydala by prefrontal regions. This study sought to further explore this hypothesis via resting-state functional connectivity analyses in impulsively aggressive combat veterans. Male combat veterans with (n = 28) and without (n = 30) impulsive aggression problems underwent resting-state fMRI. Functional connectivity analyses were conducted with the following seed-regions: basolateral amygdala (BLA), centromedial amygdala (CeM), anterior cingulate cortex (ACC), and anterior insular cortex (AIC). Regions-of-interest analyses focused on the orbitofrontal cortex and periaqueductal gray, and yielded no significant results. In exploratory cluster analyses, we observed reduced functional connectivity between the (bilateral) BLA and left dorsolateral prefrontal cortex (DLPFC) in the impulsive aggression group, relative to combat controls. This finding indicates that combat-related impulsive aggression may be marked by weakened functional connectivity between the amygdala and prefrontal regions, already in the absence of explicit emotional stimuli. Group-differences in functional connectivity were also observed between the (bilateral) ACC and left cuneus, which may be related to heightened vigilance to potentially threatening visual cues, as well as between the left AIC and right temporal pole, possibly related to negative memory association in impulsive aggression.

PMID: 29040723 [PubMed - as supplied by publisher]

Connectome-based Models Predict Separable Components of Attention in Novel Individuals.

Thu, 10/19/2017 - 10:20
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Connectome-based Models Predict Separable Components of Attention in Novel Individuals.

J Cogn Neurosci. 2017 Oct 17;:1-14

Authors: Rosenberg MD, Hsu WT, Scheinost D, Constable RT, Chun MM

Abstract
Although we typically talk about attention as a single process, it comprises multiple independent components. But what are these components, and how are they represented in the functional organization of the brain? To investigate whether long-studied components of attention are reflected in the brain's intrinsic functional organization, here we apply connectome-based predictive modeling (CPM) to predict the components of Posner and Petersen's [Posner, M. I., & Petersen, S. E. The attention system of the human brain. Annual Review of Neuroscience, 13, 25-42, 1990] influential model of attention: alerting (preparing and maintaining alertness and vigilance), orienting (directing attention to a stimulus), and executive control (detecting and resolving cognitive conflict). Participants performed the Attention Network Task (ANT), which measures these three factors, and rested during fMRI scanning. CPMs tested with leave-one-subject-out cross-validation successfully predicted novel individual's overall ANT accuracy, RT variability, and executive control scores from functional connectivity observed during ANT performance. CPMs also generalized to predict participants' alerting scores from their resting-state functional connectivity alone, demonstrating that connectivity patterns observed in the absence of an explicit task contain a signature of the ability to prepare for an upcoming stimulus. Suggesting that significant variance in ANT performance is also explained by an overall sustained attention factor, the sustained attention CPM, a model defined in prior work to predict sustained attentional abilities, predicted accuracy, RT variability, and executive control from task-based data and predicted RT variability from resting-state data. Our results suggest that, whereas executive control may be closely related to sustained attention, the infrastructure that supports alerting is distinct and can be measured at rest. In the future, CPM may be applied to elucidate additional independent components of attention and relationships between the functional brain networks that predict them.

PMID: 29040013 [PubMed - as supplied by publisher]

Comparison of brain connectivity between Internet gambling disorder and Internet gaming disorder: A preliminary study.

Thu, 10/19/2017 - 10:20
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Comparison of brain connectivity between Internet gambling disorder and Internet gaming disorder: A preliminary study.

J Behav Addict. 2017 Oct 17;:1-11

Authors: Bae S, Han DH, Jung J, Nam KC, Renshaw PF

Abstract
Background and aims Given the similarities in clinical symptoms, Internet gaming disorder (IGD) is thought to be diagnostically similar to Internet-based gambling disorder (ibGD). However, cognitive enhancement and educational use of Internet gaming suggest that the two disorders derive from different neurobiological mechanisms. The goal of this study was to compare subjects with ibGD to those with IGD. Methods Fifteen patients with IGD, 14 patients with ibGD, and 15 healthy control subjects were included in this study. Resting-state functional magnetic resonance imaging data for all participants were acquired using a 3.0 Tesla MRI scanner (Philips, Eindhoven, The Netherlands). Seed-based analyses, the three brain networks of default mode, cognitive control, and reward circuitry, were performed. Results Both IGD and ibGD groups demonstrated decreased functional connectivity (FC) within the default-mode network (DMN) (family-wise error p < .001) compared with healthy control subjects. However, the IGD group demonstrated increased FC within the cognitive network compared with both the ibGD (p < .01) and healthy control groups (p < .01). In contrast, the ibGD group demonstrated increased FC within the reward circuitry compared with both IGD (p < .01) and healthy control subjects (p < .01). Discussion and conclusions The IGD and ibGD groups shared the characteristic of decreased FC in the DMN. However, the IGD group demonstrated increased FC within the cognitive network compared with both ibGD and healthy comparison groups.

PMID: 29039224 [PubMed - as supplied by publisher]

A Study of the Brain Abnormalities of Post-Stroke Depression in Frontal Lobe Lesion.

Thu, 10/19/2017 - 10:20
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A Study of the Brain Abnormalities of Post-Stroke Depression in Frontal Lobe Lesion.

Sci Rep. 2017 Oct 16;7(1):13203

Authors: Shi Y, Zeng Y, Wu L, Liu W, Liu Z, Zhang S, Yang J, Wu W

Abstract
Post stroke depression (PSD) is a serious complication of stroke. Brain imaging is an important method of studying the mechanism of PSD. However, few studies have focused on the single lesion location. The aim of this study was to investigate the brain mechanism of frontal lobe PSD using combined voxel-based morphometry (VBM) and functional magnetic resonance imaging (fMRI). In total, 30 first-time ischemic frontal lobe stroke patients underwent T1 weighted MRI and resting-state fMRI scans. Clinical assessments included the 24-item Hamilton Rating Scale for Depression, the National Institutes of Health Stroke Scale, and the Mini-Mental State Examination. In our result, decreased gray matter (GM) volume in patients was observed in the prefrontal cortex, limbic system and motor cortex. The anterior cingulate cortex, selected as a seed to perform connectivity analyses, showed a greatly decreased functional connectivity with the prefrontal cortex, cingulate cortex, and motor cortex, but had an increased functional connectivity with the hippocampus gyrus, parahippocampa gyrus, insular, and amygdala. Stroke lesion location reduces excitability of brain areas in the ipsilateral brain. PSD affects mood through the brain network of the prefrontal-limbic circuit. Some brain networks, including motor cortex and the default mode network, show other characteristics of PSD brain network.

PMID: 29038494 [PubMed - in process]

Correlated Disruption of Resting-state fMRI, LPF, and Spike Connectivity Between area 3b and S2 Following Spinal Cord Injury in Monkeys.

Thu, 10/19/2017 - 10:20
Related Articles

Correlated Disruption of Resting-state fMRI, LPF, and Spike Connectivity Between area 3b and S2 Following Spinal Cord Injury in Monkeys.

J Neurosci. 2017 Oct 16;:

Authors: Wu R, Yang PF, Chen LM

Abstract
This study aims to understand how functional connectivity (FC) between areas 3b and S2 alters following input-deprivation and the neuronal basis of disrupted FC of resting state fMRI signals. We combined submillimeter fMRI with microelectrode recordings to localize the deafferented digit regions in areas 3b and S2 by mapping tactile stimulus-evoked fMRI activations before and after cervical dorsal column lesion (DCL) in each male monkey. An average afferents disruption of 97% significantly reduced fMRI, LFP and spike responses to stimuli in both areas. Analysis of resting state fMRI signal correlation, LFP coherence, and spike cross-correlation revealed significantly reduced functional connectivity between deafferented areas 3b and S2. The degrees of reductions in stimulus responsiveness and FC after deafferentation differed across fMRI, LFP, and spiking signals. The reduction of FC was much weaker than that of stimulus-evoked responses. While the largest stimulus-evoked signal drop (∼80%) was observed in LFP signals, the greatest FC reduction was detected in the spiking activity (∼30%). FMRI signals showed mild reductions in stimulus responsiveness (∼25%) and FC (∼20%). The overall deafferentation-induced changes were quite similar in area 3b and S2 across signals. Here we demonstrated that FC strength between area 3b and S2 was much weakened by DCL, and stimulus response reduction and FC disruption in fMRI co-vary with those of LPF and spiking signals in deafferented areas 3b and S2. These findings have important implications for fMRI studies aiming to probe FC alterations in pathological conditions involving deafferentation in humans.Significant statementBy directly comparing fMRI, LPF, and spike signals in both tactile stimulation and resting states before and after severe disruption of dorsal column afferent, we demonstrated that reduction in fMRI responses to stimuli is accompanied by weakened rsfMRI FC in input-deprived and reorganized digit regions in area 3b of the S1 and S2. Concurrent reductions in LFP and spike FC validated the use of rsfMRI signals for probing neural intrinsic FC alterations in pathological deafferented cortex, and indicated that disrupted FC between mesoscale functionally highly related regions may contribute to the behavioral impairments.

PMID: 29038239 [PubMed - as supplied by publisher]

Dynamic functional connectivity impairments in early schizophrenia and clinical high-risk for psychosis.

Thu, 10/19/2017 - 10:20
Related Articles

Dynamic functional connectivity impairments in early schizophrenia and clinical high-risk for psychosis.

Neuroimage. 2017 Oct 13;:

Authors: Du Y, Fryer SL, Fu Z, Lin D, Sui J, Chen J, Damaraju E, Mennigen E, Stuart B, Mathalon DH, Calhoun VD

Abstract
Individuals at clinical high-risk (CHR) for psychosis are characterized by attenuated psychotic symptoms. Only a minority of CHR individuals convert to full-blown psychosis. Therefore, there is a strong interest in identifying neurobiological abnormalities underlying the psychosis risk syndrome. Dynamic functional connectivity (DFC) captures time-varying connectivity over short time scales, and has the potential to reveal complex brain functional organization. Based on resting-state functional magnetic resonance imaging (fMRI) data from 70 healthy controls (HCs), 53 CHR individuals, and 58 early illness schizophrenia (ESZ) patients, we applied a novel group information guided ICA (GIG-ICA) to estimate inherent connectivity states from DFC, and then investigated group differences. We found that ESZ patients showed more aberrant connectivities and greater alterations than CHR individuals. Results also suggested that disease-related connectivity states occurred in CHR and ESZ groups. Regarding the dominant state with the highest contribution to dynamic connectivity, ESZ patients exhibited greater impairments than CHR individuals primarily in the cerebellum, frontal cortex, thalamus and temporal cortex, while CHR and ESZ populations shared common aberrances mainly in the supplementary motor area, parahippocampal gyrus and postcentral cortex. CHR-specific changes were also found in the connections between the superior frontal gyrus and calcarine cortex in the dominant state. Our findings show that CHR individuals generally show an intermediate functional connectivity pattern between HCs and SZ patients but also have unique connectivity alterations.

PMID: 29038030 [PubMed - as supplied by publisher]

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