New resting-state fMRI related studies at PubMed

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Amplitude of Low Frequency Fluctuation (ALFF) study of the spontaneous brain activities of patients with phantom limb pain.

Sat, 11/24/2018 - 15:00
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Amplitude of Low Frequency Fluctuation (ALFF) study of the spontaneous brain activities of patients with phantom limb pain.

Eur Rev Med Pharmacol Sci. 2018 Nov;22(21):7164-7171

Authors: Du JG, Xiao H, Zuo YX

Abstract
OBJECTIVE: Our objective was to use Amplitude of Low-Frequency Fluctuation (ALFF) method to investigate the changes in spontaneous brain activity in HM patients and their relationships with clinical features.
PATIENTS AND METHODS: This study was set out to observe, using Functional magnetic resonance imaging (fMRI), the changes in spontaneous brain activity in patients with phantom limb pain (PLP). Eleven amputees with PLP closely matched in age, sex, and education in a right side lower limb were scanned using fMRI to measure the amplitude of low-frequency fluctuation (ALFF) and functional connectivity (FC) in the resting state of the brain (GPLP) before use of prosthetic. They were then scanned again after recovering from PLP (GPLPr) after use of artificial limbs. Eleven healthy volunteers (GC) were also scanned.
RESULTS: When compared to GC, GPLP exhibited decreased ALFF in the left inferior parietal lobule, and GPLPr exhibited decreased ALFF in the left precuneus. When compared to GPLP, GC showed positive FC in the part regions of the limbic system structure. When compared to GC, the positive FC in GPLPr was significantly decreased in the midbrain. Finally, when compared to GPLPr, GPLP showed significantly decreased positive FC in the right precuneus and inferior parietal lobe. The central nervous system shows functional changes in the resting state of the brain in patients with PLP, which may indicate the presence of neurobiological changes. The recovery time of the changes may be longer than the pain symptoms of patients.
CONCLUSIONS: The technique of fMRI of the resting network of the brain in patients with PLP may be able to be used to monitor clinical therapeutic effects.

PMID: 30468457 [PubMed - in process]

Shifts in the functional topography of frontal cortex-striatum connectivity in alcohol use disorder.

Sat, 11/24/2018 - 15:00
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Shifts in the functional topography of frontal cortex-striatum connectivity in alcohol use disorder.

Addict Biol. 2018 Nov 23;:

Authors: Gerchen MF, Rentsch A, Kirsch M, Kiefer F, Kirsch P

Abstract
Frontostriatal circuits are centrally involved in the selection of behavioral programs and play a prominent role in alcohol use disorder (AUD) as well as other mental disorders. However, how frontal regions change their striatal connectivity to implement adaptive cognitive control is still not fully understood. Here, we developed an approach for functional magnetic resonance imaging (fMRI) connectivity analysis in which we change the focus from connectivity to individual voxels towards spatial information about the location of strongest functional connectivity. In resting state data of n = 66 participants with AUD and n = 40 healthy controls (HC) we used the approach to estimate frontostriatal connectivity gradients consistent with nonhuman primate tract-tracing studies, characterized for each frontal voxel the striatal peak connectivity location on this gradient (PeaCoG), and tested for group differences and associations with clinical variables. We identified a cluster in the right orbitofrontal cortex (rOFC) with a peak connectivity shift towards ventral striatal regions in AUD. Reduced variability of rOFC striatal peak connectivity in the AUD group suggests a "clamping" to the ventral striatum as the underlying effect. Within the AUD group striatal peak connectivity in the superior frontal gyrus was associated with self-efficacy to abstain from alcohol, in the medial frontal and dorsolateral prefrontal cortex with alcohol dependency, and in the right inferior frontal gyrus with the urge to consume alcohol. Our results demonstrate that the functional topography of frontostriatal circuits exhibits interindividual variability, which provides insight into frontostriatal network adaptations in AUD and potentially other mental disorders.

PMID: 30468293 [PubMed - as supplied by publisher]

fMRI data processing in MRTOOL: to what extent does anatomical registration affect the reliability of functional results?

Sat, 11/24/2018 - 15:00
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fMRI data processing in MRTOOL: to what extent does anatomical registration affect the reliability of functional results?

Brain Imaging Behav. 2018 Nov 22;:

Authors: Ganzetti M, Taberna GA, Mantini D

Abstract
Spatial registration is an essential step in the analysis of fMRI data because it enables between-subject analyses of brain activity, measured either during task performance or in the resting state. In this study, we investigated how anatomical registration with MRTOOL affects the reliability of task-related fMRI activity. We used as a benchmark the results from two other spatial registration methods implemented in SPM12: the Unified Segmentation algorithm and the DARTEL toolbox. Structural alignment accuracy and the impact on functional activation maps were assessed with high-resolution T1-weighted images and a set of task-related functional volumes acquired in 10 healthy volunteers. Our findings confirmed that anatomical registration is a crucial step in fMRI data processing, contributing significantly to the total inter-subject variance of the activation maps. MRTOOL and DARTEL provided greater registration accuracy than Unified Segmentation. Although DARTEL had superior gray matter and white matter tissue alignment than MRTOOL, there were no significant differences between DARTEL and MRTOOL in test-retest reliability. Likewise, we found only limited differences in BOLD activation morphology between MRTOOL and DARTEL. The test-retest reliability of task-related responses was comparable between MRTOOL and DARTEL, and both proved superior to Unified Segmentation. We conclude that MRTOOL, which is suitable for single-subject processing of structural and functional MR images, is a valid alternative to other SPM12-based approaches that are intended for group analysis. MRTOOL now includes a normalization module for fMRI data and is freely available to the scientific community.

PMID: 30467743 [PubMed - as supplied by publisher]

Correspondence Between Resting-State and Episodic Memory-Task Related Networks in Elderly Subjects.

Sat, 11/24/2018 - 15:00
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Correspondence Between Resting-State and Episodic Memory-Task Related Networks in Elderly Subjects.

Front Aging Neurosci. 2018;10:362

Authors: Simon-Vermot L, Taylor ANW, Araque Caballero MÀ, Franzmeier N, Buerger K, Catak C, Janowitz D, Kambeitz-Ilankovic LM, Ertl-Wagner B, Duering M, Ewers M

Abstract
Resting-state fMRI studies demonstrated temporally synchronous fluctuations in brain activity among ensembles of brain regions, suggesting the existence of intrinsic functional networks. A spatial match between some of the resting-state networks and regional brain activation during cognitive tasks has been noted, suggesting that resting-state networks support particular cognitive abilities. However, the spatial match and predictive value of any resting-state network and regional brain activation during episodic memory is only poorly understood. In order to address this research gap, we obtained fMRI acquired both during rest and a face-name association task in 38 healthy elderly subjects. In separate independent component analyses, networks of correlated brain activity during rest or the episodic memory task were identified. For the independent components identified for task-based fMRI, the design matrix of successful encoding or retrieval trials was regressed against the time course of each of the component to identify significantly activated networks. Spatial regression was used to assess the match of resting-state networks against those related to successful memory encoding or retrieval. We found that resting-state networks covering the medial temporal, middle temporal, and frontal areas showed increased activity during successful encoding. Resting-state networks located within posterior brain regions showed increased activity during successful recognition. However, the level of resting-state network connectivity was not predictive of the task-related activity in these networks. These results suggest that a circumscribed number of functional networks detectable during rest become engaged during successful episodic memory. However, higher intrinsic connectivity at rest may not translate into higher network expression during episodic memory.

PMID: 30467476 [PubMed]

Comparison of Resting-State Brain Activation Detected by BOLD, Blood Volume and Blood Flow.

Sat, 11/24/2018 - 15:00
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Comparison of Resting-State Brain Activation Detected by BOLD, Blood Volume and Blood Flow.

Front Hum Neurosci. 2018;12:443

Authors: Zhang K, Huang D, Shah NJ

Abstract
Resting-state brain activity has been widely investigated using blood oxygenation level dependent (BOLD) contrast techniques. However, BOLD signal changes reflect a combination of the effects of cerebral blood flow (CBF), cerebral blood volume (CBV), as well as the cerebral metabolic rate of oxygen (CMRO2). In this study, resting-state brain activation was detected and compared using the following techniques: (a) BOLD, using a gradient-echo echo planar imaging (GE-EPI) sequence; (b) CBV-weighted signal, acquired using gradient and spin echo (GRASE) based vascular space occupancy (VASO); and (c) CBF, using pseudo-continuous arterial spin labeling (pCASL). Reliable brain networks were detected using VASO and ASL, including sensorimotor, auditory, primary visual, higher visual, default mode, salience and left/right executive control networks. Differences between the resting-state activation detected with ASL, VASO and BOLD could potentially be due to the different temporal signal-to-noise ratio (tSNR) and the short post-labeling delay (PLD) in ASL, along with differences in the spin-echo readout of VASO. It is also possible that the dynamics of spontaneous fluctuations in BOLD, CBV and CBF could differ due to biological reasons, according to their location within the brain.

PMID: 30467468 [PubMed]

Cesarean Delivery Impacts Infant Brain Development.

Sat, 11/24/2018 - 15:00
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Cesarean Delivery Impacts Infant Brain Development.

AJNR Am J Neuroradiol. 2018 Nov 22;:

Authors: Deoni SC, Adams SH, Li X, Badger TM, Pivik RT, Glasier CM, Ramakrishnaiah RH, Rowell AC, Ou X

Abstract
BACKGROUND AND PURPOSE: The cesarean delivery rate has increased globally in the past few decades. Neurodevelopmental outcomes associated with cesarean delivery are still unclear. This study investigated whether cesarean delivery has any effect on the brain development of offspring.
MATERIALS AND METHODS: A total of 306 healthy children were studied retrospectively. We included 3 cohorts: 2-week-old neonates (cohort 1, n = 32/11 for vaginal delivery/cesarean delivery) and 8-year-old children (cohort 2, n = 37/23 for vaginal delivery/cesarean delivery) studied at Arkansas Children's Hospital, and a longitudinal cohort of 3-month to 5-year-old children (cohort 3, n = 164/39 for vaginal delivery/cesarean delivery) studied independently at Brown University. Diffusion tensor imaging, myelin water fraction imaging, voxel-based morphometry, and/or resting-state fMRI data were analyzed to evaluate white matter integrity, myelination, gray matter volume, and/or functional connectivity, respectively.
RESULTS: While not all MR imaging techniques were shared across the institutions/cohorts, post hoc analyses showed similar results of potential effects of cesarean delivery. The cesarean delivery group in cohort 1 showed significantly lower white matter development in widespread brain regions and significantly lower functional connectivity in the brain default mode network, controlled for a number of potential confounders. No group differences were found in cohort 2 in white matter integrity or gray matter volume. Cohort 3 had significantly different trajectories of white matter myelination between groups, with those born by cesarean delivery having reduced myelin in infancy but normalizing with age.
CONCLUSIONS: Cesarean delivery may influence infant brain development. The impact may be transient because similar effects were not observed in older children. Further prospective and longitudinal studies may be needed to confirm these novel findings.

PMID: 30467219 [PubMed - as supplied by publisher]

Spontaneous cognitive processes and the behavioral validation of time-varying brain connectivity.

Fri, 11/23/2018 - 14:00
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Spontaneous cognitive processes and the behavioral validation of time-varying brain connectivity.

Netw Neurosci. 2018;2(4):397-417

Authors: Kucyi A, Tambini A, Sadaghiani S, Keilholz S, Cohen JR

Abstract
In cognitive neuroscience, focus is commonly placed on associating brain function with changes in objectively measured external stimuli or with actively generated cognitive processes. In everyday life, however, many forms of cognitive processes are initiated spontaneously, without an individual's active effort and without explicit manipulation of behavioral state. Recently, there has been increased emphasis, especially in functional neuroimaging research, on spontaneous correlated activity among spatially segregated brain regions (intrinsic functional connectivity) and, more specifically, on intraindividual fluctuations of such correlated activity on various time scales (time-varying functional connectivity). In this Perspective, we propose that certain subtypes of spontaneous cognitive processes are detectable in time-varying functional connectivity measurements. We define these subtypes of spontaneous cognitive processes and review evidence of their representations in time-varying functional connectivity from studies of attentional fluctuations, memory reactivation, and effects of baseline states on subsequent perception. Moreover, we describe how these studies are critical to validating the use of neuroimaging tools (e.g., fMRI) for assessing ongoing brain network dynamics. We conclude that continued investigation of the behavioral relevance of time-varying functional connectivity will be beneficial both in the development of comprehensive neural models of cognition, and in informing on best practices for studying brain network dynamics.

PMID: 30465033 [PubMed]

Structural and functional brain abnormalities in drug-naive, first-episode, and chronic patients with schizophrenia: a multimodal MRI study.

Fri, 11/23/2018 - 14:00
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Structural and functional brain abnormalities in drug-naive, first-episode, and chronic patients with schizophrenia: a multimodal MRI study.

Neuropsychiatr Dis Treat. 2018;14:2889-2904

Authors: Wu F, Zhang Y, Yang Y, Lu X, Fang Z, Huang J, Kong L, Chen J, Ning Y, Li X, Wu K

Abstract
Background: Structural and functional brain abnormalities in schizophrenia (SZ) have been widely reported. However, a few studies have investigated both structural and functional characteristics in SZ patients at different stages to understand the neuropathology of SZ.
Methods: In this study, we recruited 44 first-episode drug-naive SZ (FESZ) patients, 44 medicated chronic SZ (CSZ) patients, and 56 normal controls (NCs) and acquired their structural and resting-state functional magnetic resonance imaging (MRI). We then made group comparisons on structural and functional characteristics, including regional gray matter volume (GMV), regional homogeneity, amplitude of low-frequency fluctuation, and degree centrality. A linear support vector machine (SVM) combined with a recursive feature elimination (RFE) algorithm was implemented to discriminate three groups.
Results: Our results indicated that the regional GMV was significantly decreased in patients compared with that in NCs; CSZ patients have more diffused GMV decreases primarily involved in the frontal and temporal lobes when compared with FESZ patients. Both FESZ and CSZ patients showed significant functional alterations compared with NCs; when compared with FESZ patients, CSZ patients showed significant reductions in functional characteristics in several brain regions associated with auditory, visual processing, and sensorimotor functions. Moreover, a linear SVM combined with a RFE algorithm was implemented to discriminate three groups. The accuracies of the three classifiers were 79.80%, 83.16%, and 81.71%, respectively. The performance of classifiers in this study with multimodal MRI was better than that of previous discriminative analyses of SZ patients with single-modal MRI.
Conclusion: Our findings bring new insights into the understanding of the neuropathology of SZ and contribute to stage-specific biomarkers in diagnosis and interventions of SZ.

PMID: 30464473 [PubMed]

Frontostriatal functional connectivity and striatal dopamine synthesis capacity in schizophrenia in terms of antipsychotic responsiveness: an [18F]DOPA PET and fMRI study.

Thu, 11/22/2018 - 13:00
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Frontostriatal functional connectivity and striatal dopamine synthesis capacity in schizophrenia in terms of antipsychotic responsiveness: an [18F]DOPA PET and fMRI study.

Psychol Med. 2018 Nov 21;:1-10

Authors: Kim S, Jung WH, Howes OD, Veronese M, Turkheimer FE, Lee YS, Lee JS, Kim E, Kwon JS

Abstract
BACKGROUND: Given that only a subgroup of patients with schizophrenia responds to first-line antipsychotic drugs, a key clinical question is what underlies treatment response. Observations that prefrontal activity correlates with striatal dopaminergic function, have led to the hypothesis that disrupted frontostriatal functional connectivity (FC) could be associated with altered dopaminergic function. Thus, the aim of this study was to investigate the relationship between frontostriatal FC and striatal dopamine synthesis capacity in patients with schizophrenia who had responded to first-line antipsychotic drug compared with those who had failed but responded to clozapine.
METHODS: Twenty-four symptomatically stable patients with schizophrenia were recruited from Seoul National University Hospital, 12 of which responded to first-line antipsychotic drugs (first-line AP group) and 12 under clozapine (clozapine group), along with 12 matched healthy controls. All participants underwent resting-state functional magnetic resonance imaging and [18F]DOPA PET scans.
RESULTS: No significant difference was found in the total PANSS score between the patient groups. Voxel-based analysis showed a significant correlation between frontal FC to the associative striatum and the influx rate constant of [18F]DOPA in the corresponding region in the first-line AP group. Region-of-interest analysis confirmed the result (control group: R2 = 0.019, p = 0.665; first-line AP group: R2 = 0.675, p < 0.001; clozapine group: R2 = 0.324, p = 0.054) and the correlation coefficients were significantly different between the groups.
CONCLUSIONS: The relationship between striatal dopamine synthesis capacity and frontostriatal FC is different between responders to first-line treatment and clozapine treatment in schizophrenia, indicating that a different pathophysiology could underlie schizophrenia in patients who respond to first-line treatments relative to those who do not.

PMID: 30460891 [PubMed - as supplied by publisher]

An update on advances in magnetic resonance imaging of multiple system atrophy.

Thu, 11/22/2018 - 13:00
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An update on advances in magnetic resonance imaging of multiple system atrophy.

J Neurol. 2018 Nov 20;:

Authors: Chelban V, Bocchetta M, Hassanein S, Haridy NA, Houlden H, Rohrer JD

Abstract
In this review, we describe how different neuroimaging tools have been used to identify novel MSA biomarkers, highlighting their advantages and limitations. First, we describe the main structural MRI changes frequently associated with MSA including the 'hot cross-bun' and 'putaminal rim' signs as well as putaminal, pontine, and middle cerebellar peduncle (MCP) atrophy. We discuss the sensitivity and specificity of different supra- and infratentorial changes in differentiating MSA from other disorders, highlighting those that can improve diagnostic accuracy, including the MCP width and MCP/superior cerebellar peduncle (SCP) ratio on T1-weighted imaging, raised putaminal diffusivity on diffusion-weighted imaging, and increased T2* signal in the putamen, striatum, and substantia nigra on susceptibility-weighted imaging. Second, we focus on recent advances in structural and functional MRI techniques including diffusion tensor imaging (DTI), resting-state functional MRI (fMRI), and arterial spin labelling (ASL) imaging. Finally, we discuss new approaches for MSA research such as multimodal neuroimaging strategies and how such markers may be applied in clinical trials to provide crucial data for accurately selecting patients and to act as secondary outcome measures.

PMID: 30460448 [PubMed - as supplied by publisher]

Resting State Connectivity Between Medial Temporal Lobe Regions and Intrinsic Cortical Networks Predicts Performance in a Path Integration Task.

Thu, 11/22/2018 - 13:00
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Resting State Connectivity Between Medial Temporal Lobe Regions and Intrinsic Cortical Networks Predicts Performance in a Path Integration Task.

Front Hum Neurosci. 2018;12:415

Authors: Izen SC, Chrastil ER, Stern CE

Abstract
Humans differ in their individual navigational performance, in part because successful navigation relies on several diverse abilities. One such navigational capability is path integration, the updating of position and orientation during movement, typically in a sparse, landmark-free environment. This study examined the relationship between path integration abilities and functional connectivity to several canonical intrinsic brain networks. Intrinsic networks within the brain reflect past inputs and communication as well as structural architecture. Individual differences in intrinsic connectivity have been observed for common networks, suggesting that these networks can inform our understanding of individual spatial abilities. Here, we examined individual differences in intrinsic connectivity using resting state magnetic resonance imaging (rsMRI). We tested path integration ability using a loop closure task, in which participants viewed a single video of movement in a circle trajectory in a sparse environment, and then indicated whether the video ended in the same location in which it started. To examine intrinsic brain networks, participants underwent a resting state scan. We found that better performance in the loop task was associated with increased connectivity during rest between the central executive network (CEN) and posterior hippocampus, parahippocampal cortex (PHC) and entorhinal cortex. We also found that connectivity between PHC and the default mode network (DMN) during rest was associated with better loop closure performance. The results indicate that interactions between medial temporal lobe (MTL) regions and intrinsic networks that involve prefrontal cortex (PFC) are important for path integration and navigation.

PMID: 30459579 [PubMed]

Disentangling Multispectral Functional Connectivity With Wavelets.

Thu, 11/22/2018 - 13:00
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Disentangling Multispectral Functional Connectivity With Wavelets.

Front Neurosci. 2018;12:812

Authors: Billings JCW, Thompson GJ, Pan WJ, Magnuson ME, Medda A, Keilholz S

Abstract
The field of brain connectomics develops our understanding of the brain's intrinsic organization by characterizing trends in spontaneous brain activity. Linear correlations in spontaneous blood-oxygen level dependent functional magnetic resonance imaging (BOLD-fMRI) fluctuations are often used as measures of functional connectivity (FC), that is, as a quantity describing how similarly two brain regions behave over time. Given the natural spectral scaling of BOLD-fMRI signals, it may be useful to represent BOLD-fMRI as multiple processes occurring over multiple scales. The wavelet domain presents a transform space well suited to the examination of multiscale systems as the wavelet basis set is constructed from a self-similar rescaling of a time and frequency delimited kernel. In the present study, we utilize wavelet transforms to examine fluctuations in whole-brain BOLD-fMRI connectivity as a function of wavelet spectral scale in a sample (N = 31) of resting healthy human volunteers. Information theoretic criteria measure relatedness between spectrally-delimited FC graphs. Voxelwise comparisons of between-spectra graph structures illustrate the development of preferential functional networks across spectral bands.

PMID: 30459548 [PubMed]

White matter injury predicts disrupted functional connectivity and microstructure in very preterm born neonates.

Thu, 11/22/2018 - 13:00
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White matter injury predicts disrupted functional connectivity and microstructure in very preterm born neonates.

Neuroimage Clin. 2018 Nov 13;:

Authors: Duerden EG, Halani S, Ng K, Guo T, Foong J, Glass TJA, Chau V, Branson HM, Sled JG, Whyte HE, Kelly EN, Miller SP

Abstract
OBJECTIVE: To determine whether the spatial extent and location of early-identified punctate white matter injury (WMI) is associated with regionally-specific disruptions in thalamocortical-connectivity in very-preterm born neonates.
METHODS: 37 very-preterm born neonates (median gestational age: 28.1 weeks; interquartile range [IQR]: 27-30) underwent early MRI (median age 32.9 weeks; IQR: 32-35), and WMI was identified in 13 (35%) neonates. Structural T1-weighted, resting-state functional Magnetic Resonance Imaging (rs-fMRI, n = 34) and Diffusion Tensor Imaging (DTI, n = 31) sequences were acquired using 3 T-MRI. A probabilistic map of WMI was developed for the 13 neonates demonstrating brain injury. A neonatal atlas was applied to the WMI maps, rs-fMRI and DTI analyses to extract volumetric, functional and microstructural data from regionally-specific brain areas. Associations of thalamocortical-network strength and alterations in fractional anisotropy (FA, a measure of white-matter microstructure) with WMI volume were assessed in general linear models, adjusting for age at scan and cerebral volumes.
RESULTS: WMI volume in the superior (β = -0.007; p = .02) and posterior corona radiata (β = -0.01; p = .01), posterior thalamic radiations (β = -0.01; p = .005) and superior longitudinal fasciculus (β = -0.02; p = .001) was associated with reduced connectivity strength between thalamus and parietal resting-state networks. WMI volume in the left (β = -0.02; p = .02) and right superior corona radiata (β = -0.03; p = .008), left posterior corona radiata (β = -0.03; p = .01), corpus callosum (β = -0.11; p < .0001) and right superior longitudinal fasciculus (β = -0.02; p = .02) was associated with functional connectivity strength between thalamic and sensorimotor networks. Increased WMI volume was also associated with decreased FA values in the corpus callosum (β = -0.004, p = .015).
CONCLUSIONS: Regionally-specific alterations in early functional and structural network complexity resulting from WMI may underlie impaired outcomes.

PMID: 30458986 [PubMed - as supplied by publisher]

Resting State Vagally-Mediated Heart Rate Variability Is Associated With Neural Activity During Explicit Emotion Regulation.

Wed, 11/21/2018 - 12:00
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Resting State Vagally-Mediated Heart Rate Variability Is Associated With Neural Activity During Explicit Emotion Regulation.

Front Neurosci. 2018;12:794

Authors: Steinfurth ECK, Wendt J, Geisler F, Hamm AO, Thayer JF, Koenig J

Abstract
Resting state vagally mediated heart rate variability (vmHRV) is related to difficulties in emotion regulation (ER). The prefrontal cortex (PFC) provides inhibitory control over the amygdala during ER. Previous studies linked vmHRV with activity in the ventromedial PFC (vmPFC) during implicit ER. To date no study examined the relation between vmHRV and brain activity during explicit ER. vmHRV was measured during a 7 min baseline at T1 2-5 days preceding T2. At T2 n = 24 participants (50% female, M age = 24.6 years) viewed neutral or emotional pictures of pleasant or unpleasant valence and were instructed to intensify or to reduce their present emotion using two ER strategies (reappraisal and response modulation) or to passively view the picture. Participants rated the valence of their emotional state from pleasant to unpleasant after ER. Whole-brain fMRI data were collected using a 1.5-T-scanner. We observed an association between resting state vmHRV and brain activation in the PFC and the amygdala during ER of unpleasant emotions. Groups based on vmHRV showed significant differences in the modulation of amygdala activity as a function of ER strategy. In participants with high vmHRV amygdala activity was modulated only when using reappraisal and for low vmHRV participants only when using response modulation. Similar, dorsomedial PFC activity in high vmHRV participants was increased when using reappraisal and in low vmHRV participants when using response modulation to regulate unpleasant emotions. These results suggest that individuals with low vmHRV might have difficulties in recruiting prefrontal brain areas necessary for the modulation of amygdala activity during explicit ER.

PMID: 30455624 [PubMed]

Identifying Respiration-Related Aliasing Artifacts in the Rodent Resting-State fMRI.

Wed, 11/21/2018 - 12:00
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Identifying Respiration-Related Aliasing Artifacts in the Rodent Resting-State fMRI.

Front Neurosci. 2018;12:788

Authors: Pais-Roldán P, Biswal B, Scheffler K, Yu X

Abstract
Resting-state functional magnetic resonance imaging (rs-fMRI) combined with optogenetics and electrophysiological/calcium recordings in animal models is becoming a popular platform to investigate brain dynamics under specific neurological states. Physiological noise originating from the cardiac and respiration signal is the dominant interference in human rs-fMRI and extensive efforts have been made to reduce these artifacts from the human data. In animal fMRI studies, physiological noise sources including the respiratory and cardiorespiratory artifacts to the rs-fMRI signal fluctuation have typically been less investigated. In this article, we demonstrate evidence of aliasing effects into the low-frequency rs-fMRI signal fluctuation mainly due to respiration-induced B0 offsets in anesthetized rats. This aliased signal was examined by systematically altering the fMRI sampling rate, i.e., the time of repetition (TR), in free-breathing conditions and by adjusting the rate of ventilation. Anesthetized rats under ventilation showed a significantly narrower frequency bandwidth of the aliasing effect than free-breathing animals. It was found that the aliasing effect could be further reduced in ventilated animals with a muscle relaxant. This work elucidates the respiration-related aliasing effects on the rs-fMRI signal fluctuation from anesthetized rats, indicating non-negligible physiological noise needed to be taken care of in both awake and anesthetized animal rs-fMRI studies.

PMID: 30455623 [PubMed]

Altered resting-state dorsal anterior cingulate cortex functional connectivity in patients with post-traumatic stress disorder.

Wed, 11/21/2018 - 12:00
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Altered resting-state dorsal anterior cingulate cortex functional connectivity in patients with post-traumatic stress disorder.

Aust N Z J Psychiatry. 2018 Nov 19;:4867418812674

Authors: Chen HJ, Zhang L, Ke J, Qi R, Xu Q, Zhong Y, Pan M, Li J, Lu GM, Chen F

Abstract
OBJECTIVE:: The brain functional alterations at regional and network levels in post-traumatic stress disorder patients are still unclear. This study explored brain functional alterations at regional and network levels in post-traumatic stress disorder patients with resting-state functional magnetic resonance imaging and evaluated the relationship between brain function and clinical indices in post-traumatic stress disorder.
METHODS:: Amplitude of low-frequency fluctuation and seed-based functional connectivity analyses were conducted among typhoon survivors with ( n = 27) and without post-traumatic stress disorder ( n = 33) and healthy controls ( n = 30) to assess the spontaneous brain activity and network-level brain function. Pearson correlation analyses were performed to examine the association of brain function with clinical symptom and social support.
RESULTS:: Both the post-traumatic stress disorder group and the trauma-exposed control group showed decreased amplitude of low-frequency fluctuation in the dorsal anterior cingulate cortex relative to the healthy control group. The post-traumatic stress disorder group showed increased dorsal anterior cingulate cortex functional connectivity with the right paracentral lobule and bilateral precentral gyrus/postcentral gyrus relative to both control groups. Both traumatized groups exhibited decreased dorsal anterior cingulate cortex functional connectivity with the right hippocampus and left cerebellum relative to the healthy control group. More decreased dorsal anterior cingulate cortex functional connectivity with the right hippocampus was found in the post-traumatic stress disorder group. The Checklist-Civilian Version score positively correlated with functional connectivity between the dorsal anterior cingulate cortex and the right paracentral lobule as well as between the dorsal anterior cingulate cortex and the right precentral gyrus/postcentral gyrus. The social support was associated with functional connectivity between the dorsal anterior cingulate cortex and the bilateral precentral gyrus/postcentral gyrus as well as the dorsal anterior cingulate cortex and the left middle frontal gyrus.
CONCLUSION:: Trauma exposure may result in aberrant local and network-level functional connectivity in individuals with or without post-traumatic stress disorder. Altered amplitude of low-frequency fluctuation in the dorsal anterior cingulate cortex may be a predisposing risk factor for post-traumatic stress disorder development following trauma exposure. More prominent decreased dorsal anterior cingulate cortex functional connectivity with the right hippocampus might be specific in the post-traumatic stress disorder group. Improvement of social support might possibly be significant for post-traumatic stress disorder patients.

PMID: 30453750 [PubMed - as supplied by publisher]

Dysfunctional Limbic Circuitry Underlying Freezing of Gait in Parkinson's Disease.

Wed, 11/21/2018 - 12:00
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Dysfunctional Limbic Circuitry Underlying Freezing of Gait in Parkinson's Disease.

Neuroscience. 2018 03 15;374:119-132

Authors: Gilat M, Ehgoetz Martens KA, Miranda-Domínguez O, Arpan I, Shine JM, Mancini M, Fair DA, Lewis SJG, Horak FB

Abstract
Freezing of gait (FOG) is a poorly understood symptom affecting many patients with Parkinson's disease (PD). Despite growing evidence of a behavioral link between anxiety, attention and FOG in PD, no research to date has investigated the neural mechanisms that might explain this relationship. The present study therefore examined resting-state MRI functional connectivity between the amygdala, striatum and frontoparietal attentional control network in PD patients with (freezers: n = 19) and without FOG (non-freezers: n = 21) in the dopaminergic 'off' state. Functional connectivity was subsequently correlated with an objective measure of FOG severity and a subjective scale of affective disorder within each group. Connectivity between the right amygdala and right putamen was significantly increased in freezers compared to non-freezers (p < 0.01). Furthermore, freezers showed increased anti-coupling between the frontoparietal network and left amygdala (p = 0.011), but reduced anti-coupling between this network and the right putamen (p = 0.027) as compared to non-freezers. Key functional connections between the amygdala, putamen and frontoparietal network were significantly associated with FOG severity and a fear of falling. This study provides the first evidence that dysfunctional fronto-striato-limbic processes may underpin the link between anxiety and FOG in PD. It is proposed that freezers have heightened striato-limbic load and reduced top-down attentional control at rest, which when further challenged by the parallel processing demands of walking may precipitate FOG.

PMID: 29408498 [PubMed - indexed for MEDLINE]

Hormonal Cycle and Contraceptive Effects on Amygdala and Salience Resting-State Networks in Women with Previous Affective Side Effects on the Pill.

Wed, 11/21/2018 - 12:00
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Hormonal Cycle and Contraceptive Effects on Amygdala and Salience Resting-State Networks in Women with Previous Affective Side Effects on the Pill.

Neuropsychopharmacology. 2018 02;43(3):555-563

Authors: Engman J, Sundström Poromaa I, Moby L, Wikström J, Fredrikson M, Gingnell M

Abstract
The mechanisms linking ovarian hormones to negative affect are poorly characterized, but important clues may come from the examination of the brain's intrinsic organization. Here, we studied the effects of both the menstrual cycle and oral contraceptives (OCs) on amygdala and salience network resting-state functional connectivity using a double-blind, randomized, and placebo-controlled design. Hormone levels, depressive symptoms, and resting-state functional connectivity were measured in 35 healthy women (24.9±4.2 years) who had previously experienced OC-related negative affect. All participants were examined in the follicular phase of a baseline cycle and in the third week of the subsequent cycle during treatment with either a combined OC (30 μg ethinyl estradiol/0.15 mg levonorgestrel) or placebo. The latter time point targeted the midluteal phase in placebo users and steady-state ethinyl estradiol and levonorgestrel concentrations in OC users. Amygdala and salience network connectivity generally increased with both higher endogenous and synthetic hormone levels, although amygdala-parietal cortical connectivity decreased in OC users. When in the luteal phase, the naturally cycling placebo users demonstrated higher connectivity in both networks compared with the women receiving OCs. Our results support a causal link between the exogenous administration of synthetic hormones and amygdala and salience network connectivity. Furthermore, they suggest a similar, potentially stronger, association between the natural hormonal variations across the menstrual cycle and intrinsic network connectivity.

PMID: 28741624 [PubMed - indexed for MEDLINE]

Arithmetic learning modifies the functional connectivity of the fronto-parietal network.

Tue, 11/20/2018 - 17:20
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Arithmetic learning modifies the functional connectivity of the fronto-parietal network.

Cortex. 2018 Jul 31;111:51-62

Authors: Zhao H, Li X, Karolis V, Feng Y, Niu H, Butterworth B

Abstract
How Resting-State Functional Connectivity (RSFC) is modified by learning is an important but rarely asked question. Here we used functional near-infrared spectroscopy (fNIRS) to measure changes in RSFC after learning novel subtraction and multiplication facts by forty-one young adult volunteers. We also measured changes in regional hemoglobin concentration. Fronto-parietal RSFC was modified by arithmetic learning and the fronto-parietal RSFC configuration before learning predicted the effectiveness of arithmetic learning. We also found a significant learning effect indicated by a monotonic decrease in reaction time and an increase in accuracy. Regional task-dependent oxy-hemoglobin concentration differentiated subtraction from multiplication learning supporting previous fMRI findings. These results suggest the sensitivity and importance of fronto-parietal connectivity to arithmetic learning.

PMID: 30453223 [PubMed - as supplied by publisher]

Resting-state functional connectivity after concussion is associated with clinical recovery.

Tue, 11/20/2018 - 17:20
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Resting-state functional connectivity after concussion is associated with clinical recovery.

Hum Brain Mapp. 2018 Nov 19;:

Authors: Kaushal M, España LY, Nencka AS, Wang Y, Nelson LD, McCrea MA, Meier TB

Abstract
There has been a recent call for longitudinal imaging studies to better characterize the time course of physiological recovery following sport-related concussion (SRC) and its relationship with clinical recovery. To address this, we evaluated changes to resting-state functional connectivity (rs-FC) of the whole-brain network following SRC and explored associations between rs-FC and measures of clinical outcome. High school and collegiate football athletes were enrolled during preseason. Athletes that suffered SRC (N = 62) were assessed across the acute (within 48 hr) and sub-acute (days 8, 15, and 45) phases. Matched football athletes without concussion served as controls (N = 60) and participated in similar visits. Multi-band resting-state fMRI was used to assess whole-brain rs-FC at each visit using network-based statistic and average nodal strength from regions of interest defined using a common whole-brain parcellation. Concussed athletes had elevated symptoms, psychological distress, and oculomotor, balance, and memory deficits at 48 hr postconcussion relative to controls, with diminished yet significant elevations in symptoms and psychological distress at 8 days. Both rs-FC analyses showed that concussed athletes had a global increase in connectivity at 8 days postconcussion relative to controls, with no differences at the 48-hr, 15-day, or 45-day visits. Further analysis revealed the group effect at the 8-day visit was driven by the large minority of concussed athletes still symptomatic at their visit; asymptomatic concussed athletes did not differ from controls. Findings from this large-scale, prospective study suggest whole-brain rs-FC alterations following SRC are delayed in onset but associated with the presence of self-reported symptoms.

PMID: 30451340 [PubMed - as supplied by publisher]

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