New resting-state fMRI related studies at PubMed

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Predictors of Attrition in Longitudinal Neuroimaging Research: Inhibitory Control, Head Movement, and Resting-State Functional Connectivity.

Sat, 11/10/2018 - 11:40

Predictors of Attrition in Longitudinal Neuroimaging Research: Inhibitory Control, Head Movement, and Resting-State Functional Connectivity.

Brain Connect. 2018 Nov 09;:

Authors: Stange JP, Jenkins LM, Bessette KL, Kling LR, Bark J, Shepard R, Hamlat EJ, DelDonno SR, Phan L, Passarotti AM, Ajilore O, Langenecker SA

Abstract
OBJECTIVE: Attrition is a major problem in longitudinal neuroimaging studies, as it may lead to unreliable estimates of the stability of trait-like processes over time, of the identification of risk factors for clinical outcomes, and of the effects of treatment. Identification of characteristics associated with attrition has implications for participant recruitment and participant retention to achieve representative longitudinal samples. We investigated inhibitory control deficits, head motion, and resting-state functional connectivity within the cognitive control network as predictors of attrition.
MATERIALS AND METHODS: Ninety-seven individuals with remitted major depressive disorder or healthy controls completed a functional MRI scan, which included a go/no-go task and resting-state functional connectivity. Approximately two months later, participants were contacted and invited to return for a second scan.
RESULTS: Seventeen individuals were lost to follow-up or declined to participate in the follow-up scan. Worse inhibitory control was correlated with greater movement within the scanner, and each predicted a greater likelihood of attrition, with movement mediating the effects of inhibitory control on attrition. Individuals who dropped out of the study exhibited greater movement than non-dropouts across 9 of the 14 runs of the scan, with medium-to-large effect sizes. Finally, exploratory analyses suggested that attenuated resting-state connectivity with the cognitive control network (particularly in bilateral dorsolateral prefrontal cortex) was associated with greater likelihood of attrition after accounting for head motion at several levels of analysis.
CONCLUSIONS: Inhibitory control and movement within the scanner are associated with attrition, and should be considered for strategic oversampling and participant retention strategies to ensure generalizability of results in longitudinal studies.

PMID: 30411975 [PubMed - as supplied by publisher]

Somatosensory regions show limited functional connectivity differences in youth with Autism Spectrum Disorder.

Sat, 11/10/2018 - 11:40

Somatosensory regions show limited functional connectivity differences in youth with Autism Spectrum Disorder.

Brain Connect. 2018 Nov 09;:

Authors: Cechmanek B, Johnson H, Vazhappilly S, Lebel C, Bray S

Abstract
An estimated 70-90% of children with Autism Spectrum Disorder (ASD) have sensory symptoms, which may present as hyper- or hypo-responsivity in one or more sensory modalities. These sensitivities correlate with social symptoms, activity and social interaction levels. Interestingly, sensory symptoms appear to be most prevalent in late childhood, suggesting a developmental component. While the neural basis of sensory sensitivities remains unclear, atypical functional connectivity of sensory brain regions has been suggested as a potential mechanism. Tactile sensitivities are among the most predictive of social functioning, yet no studies to our knowledge have examined somatosensory functional connectivity in children and adolescents with ASD, when symptoms are typically most prominent. Here, we used human data from the Autism Brain Imaging Data Exchange (ABIDE-I) to assess functional connectivity differences of somatosensory regions during resting state functional magnetic resonance imaging (fMRI), in youth aged 8-15 years. After head-motion exclusion our sample included 67 participants with ASD and 121 typically developing (TD) controls. We additionally examined associations between functional connectivity and age, as well as ASD symptom severity. Together, these seed-based analyses showed limited differences in functional connectivity between groups, either to hypothesized target regions or in terms of global connectivity. Our findings suggest that hyper-or hypo- somatosensory functional connectivity at rest is not a population-level feature in ASD. However, this does not preclude increased variability of somatosensory networks across the ASD population. Further, as sensory sensitivities were not specifically assessed in this sample, future studies may be better able to identify patterns of functional connectivity reflecting individual differences in sensory symptoms.

PMID: 30411970 [PubMed - as supplied by publisher]

Salience network connectivity and social processing in children with nonverbal learning disability or autism spectrum disorder.

Sat, 11/10/2018 - 11:40

Salience network connectivity and social processing in children with nonverbal learning disability or autism spectrum disorder.

Neuropsychology. 2018 Nov 08;:

Authors: Margolis AE, Pagliaccio D, Thomas L, Banker S, Marsh R

Abstract
OBJECTIVE: Nonverbal learning disability (NVLD) is a putative neurodevelopmental disorder characterized by spatial processing deficits as well as social deficits similar to those characteristic of autism spectrum disorder (ASD). Nonetheless, NVLD may be a distinct disorder that is differentially associated with the functioning and connectivity of the salience (SN) and default mode (DMN) networks that support social processing. Thus, we sought to assess and compare connectivity across these networks in children with NVLD, ASD, and typically developing children.
METHOD: Resting-state fMRI data were examined in 17 children with NVLD, 17 children with ASD selected from the Autism Brain Imaging Data Exchange (ABIDE), and 40 TD children (20 from ABIDE). Average DMN and SN functional connectivity and pairwise region-to-region connectivity were compared across groups. Associations with social impairment and IQ were assessed.
RESULTS: Children with NVLD showed reduced connectivity between SN regions (anterior insula to anterior cingulate and to rostral prefrontal cortex [rPFC]), whereas children with ASD showed greater connectivity between SN regions (supramarginal gyrus to rPFC) relative to the other groups. Both clinical groups showed higher levels of parent-reported social problems, which related to altered SN connectivity in the NVLD group. No differences were detected in overall average connectivity within or between networks.
CONCLUSIONS: The social deficits common across children with NVLD and ASD may derive from distinct alterations in connectivity within the SN. Such findings represent the first step toward identifying a neurobiological signature of NVLD. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

PMID: 30411904 [PubMed - as supplied by publisher]

Innovative imaging methods in heart failure: a shifting paradigm in cardiac assessment. Position statement on behalf of the Heart Failure Association of the European Society of Cardiology.

Sat, 11/10/2018 - 11:40

Innovative imaging methods in heart failure: a shifting paradigm in cardiac assessment. Position statement on behalf of the Heart Failure Association of the European Society of Cardiology.

Eur J Heart Fail. 2018 Nov 09;:

Authors: Čelutkienė J, Plymen CM, Flachskampf FA, de Boer RA, Grapsa J, Manka R, Anderson L, Garbi M, Barberis V, Filardi PP, Gargiulo P, Zamorano JL, Lainscak M, Seferovic P, Ruschitzka F, Rosano GMC, Nihoyannopoulos P

Abstract
Myriad advances in all fields of cardiac imaging have stimulated and reflected new understanding of cardiac performance, myocardial damage and the mechanisms of heart failure. In this paper, the Heart Failure Association assesses the potential usefulness of innovative imaging modalities in enabling more precise diagnostic and prognostic evaluation, as well as in guiding treatment strategies. Many new methods have gradually penetrated clinical practice and are on their way to becoming a part of routine evaluation. This paper focuses on myocardial deformation and three-dimensional ultrasound imaging; stress tests for the evaluation of contractile and filling function; the progress of magnetic resonance techniques; molecular imaging and other sound innovations. The Heart Failure Association aims to highlight the ways in which paradigms have shifted in several areas of cardiac assessment. These include reassessing of the simplified concept of ejection fraction and implementation of the new parameters of cardiac performance applicable to all heart failure phenotypes; switching from two-dimensional to more accurate and reproducible three-dimensional ultrasound volumetric evaluation; greater tissue characterization via recently developed magnetic resonance modalities; moving from assessing cardiac function and congestion at rest to assessing it during stress; from invasive to novel non-invasive hybrid techniques depicting coronary anatomy and myocardial perfusion; as well as from morphometry to the imaging of pathophysiologic processes such as inflammation and apoptosis. This position paper examines the specific benefits of imaging innovations for practitioners dealing with heart failure aetiology, risk stratification and monitoring, and, in addition, for scientists involved in the development of future research.

PMID: 30411833 [PubMed - as supplied by publisher]

A practical protocol for measurements of spinal cord functional connectivity.

Sat, 11/10/2018 - 11:40
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A practical protocol for measurements of spinal cord functional connectivity.

Sci Rep. 2018 Nov 08;8(1):16512

Authors: Barry RL, Conrad BN, Smith SA, Gore JC

Abstract
Resting state functional magnetic resonance imaging (fMRI) has been used to study human brain function for over two decades, but only recently has this technique been successfully translated to the human spinal cord. The spinal cord is structurally and functionally unique, so resting state fMRI methods developed and optimized for the brain may not be appropriate when applied to the cord. This report therefore investigates the relative impact of different acquisition and processing choices (including run length, echo time, and bandpass filter width) on the detectability of resting state spinal cord networks at 3T. Our results suggest that frequencies beyond 0.08 Hz should be included in resting state analyses, a run length of ~8-12 mins is appropriate for reliable detection of the ventral (motor) network, and longer echo times - yet still shorter than values typically used for fMRI in the brain - may increase the detectability of the dorsal (sensory) network. Further studies are required to more fully understand and interpret the nature of resting state spinal cord networks in health and in disease, and the protocols described in this report are designed to assist such studies.

PMID: 30410122 [PubMed - in process]

Altered functional connectivity between sub-regions in the thalamus and cortex in schizophrenia patients measured by resting state BOLD fMRI at 7T.

Sat, 11/10/2018 - 11:40
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Altered functional connectivity between sub-regions in the thalamus and cortex in schizophrenia patients measured by resting state BOLD fMRI at 7T.

Schizophr Res. 2018 Nov 05;:

Authors: Hua J, Blair NIS, Paez A, Choe A, Barber AD, Brandt A, Lim IAL, Xu F, Kamath V, Pekar JJ, van Zijl PCM, Ross CA, Margolis RL

Abstract
The thalamus is a small brain structure that relays neuronal signals between subcortical and cortical regions. Abnormal thalamocortical connectivity in schizophrenia has been reported in previous studies using blood-oxygenation-level-dependent (BOLD) functional MRI (fMRI) performed at 3T. However, anatomically the thalamus is not a single entity, but is subdivided into multiple distinct nuclei with different connections to various cortical regions. We sought to determine the potential benefit of using the enhanced sensitivity of BOLD fMRI at ultra-high magnetic field (7T) in exploring thalamo-cortical connectivity in schizophrenia based on subregions in the thalamus. Seeds placed in thalamic subregions of 14 patients and 14 matched controls were used to calculate whole-brain functional connectivity. Our results demonstrate impaired thalamic connectivity to the prefrontal cortex and the cerebellum, but enhanced thalamic connectivity to the motor/sensory cortex in schizophrenia. This altered functional connectivity significantly correlated with disease duration in the patients. Remarkably, comparable effect sizes observed in previous 3T studies were detected in the current 7T study with a heterogeneous and much smaller cohort, providing evidence that ultra-high field fMRI may be a powerful tool for measuring functional connectivity abnormalities in schizophrenia. Further investigation with a larger cohort is merited to validate the current findings.

PMID: 30409697 [PubMed - as supplied by publisher]

Anhedonia in Trauma-Exposed Individuals: Functional Connectivity and Decision-Making Correlates.

Sat, 11/10/2018 - 11:40
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Anhedonia in Trauma-Exposed Individuals: Functional Connectivity and Decision-Making Correlates.

Biol Psychiatry Cogn Neurosci Neuroimaging. 2018 Nov;3(11):959-967

Authors: Olson EA, Kaiser RH, Pizzagalli DA, Rauch SL, Rosso IM

Abstract
BACKGROUND: Reward processing deficits have been increasingly associated with trauma exposure and are a core feature of posttraumatic stress disorder (PTSD). While altered resting-state functional connectivity (rsFC) of ventral striatal regions, including the nucleus accumbens (NAcc), has been associated with anhedonia in some stress-related disorders, relationships between NAcc rsFC and anhedonia have not previously been investigated in trauma-exposed individuals. Additionally, relationships between anhedonia and reward-related decision making remain unexplored in relation to trauma exposure. We hypothesized that elevated anhedonia would be associated with altered rsFC between NAcc and default mode network regions and with increased delay discounting.
METHODS: The sample included 51 participants exposed to a DSM-IV PTSD Criterion A event related to community trauma. Participants completed the Clinician Administered PTSD Scale, the Snaith-Hamilton Pleasure Scale, the Beck Depression Inventory, a computerized delay discounting paradigm, and resting-state functional magnetic resonance imaging. rsFC data were analyzed in SPM12 and CONN.
RESULTS: Higher levels of anhedonia were associated with increased rsFC between seed regions of bilateral NAcc and areas of right dorsomedial prefrontal cortex. This relationship remained significant after accounting for Clinician Administered PTSD Scale total scores, Beck Depression Inventory total scores, or diagnostic group in the regression. Additionally, anhedonia was associated with elevated (increased) delay discounting.
CONCLUSIONS: Greater anhedonia was related to higher positive connectivity between NAcc and right dorsomedial prefrontal cortex and to increased delay discounting, i.e., greater preference for smaller immediate versus larger delayed rewards. These findings contribute to a growing body of literature emphasizing the importance of anhedonia in trauma-exposed individuals.

PMID: 30409390 [PubMed - in process]

Functional Magnetic Resonance Imaging in Huntington's Disease.

Sat, 11/10/2018 - 11:40
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Functional Magnetic Resonance Imaging in Huntington's Disease.

Int Rev Neurobiol. 2018;142:381-408

Authors: Gregory S, Scahill RI

Abstract
Huntington's disease is an inherited neurodegenerative condition characterized by motor dysfunction, cognitive impairment and neuropsychiatric disturbance. The effects of the underlying pathology on brain morphology are relatively well understood. Numerous structural Magnetic Resonance Imaging (MRI) studies have demonstrated macrostructural change with widespread striatal and cortical atrophy and microstructural white matter loss in premanifest and manifest HD gene carriers. However, disease effects on brain function are less well characterized. Functional MRI provides an opportunity to examine differences in brain activity either in response to a particular task or in the brain at rest. There is increasing evidence that HD gene carriers exhibit altered activation patterns and functional connectivity between brain regions in response to the neurodegenerative process. Here we review the growing literature in this area and critically evaluate the utility of this imaging modality.

PMID: 30409260 [PubMed - in process]

Functional MRI in Atypical Parkinsonisms.

Sat, 11/10/2018 - 11:40
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Functional MRI in Atypical Parkinsonisms.

Int Rev Neurobiol. 2018;142:149-173

Authors: Agosta F, Sarasso E, Filippi M

Abstract
The present chapter reports the current knowledge on the use of functional MRI (fMRI) in patients with atypical parkinsonisms, including Multiple System Atrophy, Corticobasal Syndrome and Progressive Supranuclear Palsy syndrome. Both resting state functional connectivity and task-based brain activity abnormalities are reported in atypical parkinsonisms relative to healthy controls and Parkinson's disease patients. Functional alterations were observed earlier than structural damage and may help to make early diagnosis. The chapter also examines the few longitudinal evidence on fMRI changes in patients with these conditions. The potential use of fMRI techniques in aiding the differential diagnosis, accurately measuring disease progression and assessing the effectiveness of therapeutic interventions is discussed.

PMID: 30409252 [PubMed - in process]

Test-retest reliability of task-based and resting-state blood oxygen level dependence and cerebral blood flow measures.

Fri, 11/09/2018 - 17:00
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Test-retest reliability of task-based and resting-state blood oxygen level dependence and cerebral blood flow measures.

PLoS One. 2018;13(11):e0206583

Authors: Holiga Š, Sambataro F, Luzy C, Greig G, Sarkar N, Renken RJ, Marsman JC, Schobel SA, Bertolino A, Dukart J

Abstract
Despite their wide-spread use, only limited information is available on the comparative test-retest reliability of task-based functional and resting state magnetic resonance imaging measures of blood oxygen level dependence (tb-fMRI and rs-fMRI) and cerebral blood flow (CBF) using arterial spin labeling. This information is critical to designing properly powered longitudinal studies. Here we comprehensively quantified and compared the test-retest reliability and reproducibility performance of 8 commonly applied fMRI tasks, 6 rs-fMRI metrics and CBF in 30 healthy volunteers. We find large variability in test-retest reliability performance across the different tb-fMRI paradigms and rs-fMRI metrics, ranging from poor to excellent. A larger extent of activation in tb-fMRI is linked to higher between-subject reliability of the respective task suggesting that differences in the amount of activation may be used as a first reliability estimate of novel tb-fMRI paradigms. For rs-fMRI, a good reliability of local activity estimates is paralleled by poor performance of global connectivity metrics. Evaluated CBF measures provide in general a good to excellent test-reliability matching or surpassing the best performing tb-fMRI and rs-fMRI metrics. This comprehensive effort allows for direct comparisons of test-retest reliability between the evaluated MRI domains and measures to aid the design of future tb-fMRI, rs-fMRI and CBF studies.

PMID: 30408072 [PubMed - in process]

Classification of Alzheimer's Disease, Mild Cognitive Impairment and Normal Control Subjects Using Resting-State fMRI Based Network Connectivity Analysis.

Fri, 11/09/2018 - 17:00
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Classification of Alzheimer's Disease, Mild Cognitive Impairment and Normal Control Subjects Using Resting-State fMRI Based Network Connectivity Analysis.

IEEE J Transl Eng Health Med. 2018;6:1801009

Authors: Wang Z, Zheng Y, Zhu DC, Bozoki AC, Li T

Abstract
This paper proposes a robust method for the Alzheimer's disease (AD), mild cognitive impairment (MCI), and normal control subject classification under size limited fMRI data samples by exploiting the brain network connectivity pattern analysis. First, we select the regions of interest (ROIs) within the default mode network and calculate the correlation coefficients between all possible ROI pairs to form a feature vector for each subject. Second, we propose a regularized linear discriminant analysis (LDA) approach to reduce the noise effect due to the limited sample size. The feature vectors are then projected onto a one-dimensional axis using the proposed regularized LDA. Finally, an AdaBoost classifier is applied to carry out the classification task. The numerical analysis demonstrates that the purposed approach can increase the classification accuracy significantly. Our analysis confirms the previous findings that the hippocampus and the isthmus of the cingulate cortex are closely involved in the development of AD and MCI.

PMID: 30405975 [PubMed]

Multimodal Neuroimaging Approach to Variability of Functional Connectivity in Disorders of Consciousness: A PET/MRI Pilot Study.

Fri, 11/09/2018 - 17:00
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Multimodal Neuroimaging Approach to Variability of Functional Connectivity in Disorders of Consciousness: A PET/MRI Pilot Study.

Front Neurol. 2018;9:861

Authors: Cavaliere C, Kandeepan S, Aiello M, Ribeiro de Paula D, Marchitelli R, Fiorenza S, Orsini M, Trojano L, Masotta O, St Lawrence K, Loreto V, Chronik BA, Nicolai E, Soddu A, Estraneo A

Abstract
Behavioral assessments could not suffice to provide accurate diagnostic information in individuals with disorders of consciousness (DoC). Multimodal neuroimaging markers have been developed to support clinical assessments of these patients. Here we present findings obtained by hybrid fludeoxyglucose (FDG-)PET/MR imaging in three severely brain-injured patients, one in an unresponsive wakefulness syndrome (UWS), one in a minimally conscious state (MCS), and one patient emerged from MCS (EMCS). Repeated behavioral assessment by means of Coma Recovery Scale-Revised and neurophysiological evaluation were performed in the two weeks before and after neuroimaging acquisition, to ascertain that clinical diagnosis was stable. The three patients underwent one imaging session, during which two resting-state fMRI (rs-fMRI) blocks were run with a temporal gap of about 30 min. rs-fMRI data were analyzed with a graph theory approach applied to nine independent networks. We also analyzed the benefits of concatenating the two acquisitions for each patient or to select for each network the graph strength map with a higher ratio of fitness. Finally, as for clinical assessment, we considered the best functional connectivity pattern for each network and correlated graph strength maps to FDG uptake. Functional connectivity analysis showed several differences between the two rs-fMRI acquisitions, affecting in a different way each network and with a different variability for the three patients, as assessed by ratio of fitness. Moreover, combined PET/fMRI analysis demonstrated a higher functional/metabolic correlation for patients in EMCS and MCS compared to UWS. In conclusion, we observed for the first time, through a test-retest approach, a variability in the appearance and temporal/spatial patterns of resting-state networks in severely brain-injured patients, proposing a new method to select the most informative connectivity pattern.

PMID: 30405513 [PubMed]

Increased Inhibition of the Amygdala by the mPFC may Reflect a Resilience Factor in Post-traumatic Stress Disorder: A Resting-State fMRI Granger Causality Analysis.

Fri, 11/09/2018 - 17:00
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Increased Inhibition of the Amygdala by the mPFC may Reflect a Resilience Factor in Post-traumatic Stress Disorder: A Resting-State fMRI Granger Causality Analysis.

Front Psychiatry. 2018;9:516

Authors: Chen F, Ke J, Qi R, Xu Q, Zhong Y, Liu T, Li J, Zhang L, Lu G

Abstract
Purpose: To determine whether effective connectivity of the amygdala is altered in traumatized subjects with and without post-traumatic stress disorder (PTSD). Materials and Methods: Resting-state functional MRI data were obtained for 27 patients with typhoon-related PTSD, 33 trauma-exposed controls (TEC), and 30 healthy controls (HC). Effective connectivity of the bilateral amygdala was examined with Granger causality analysis and then compared between groups by conducting an analysis of variance. Results: Compared to the HC group, both the PTSD group and the TEC group showed increased effective connectivity from the amygdala to the medial prefrontal cortex (mPFC). The TEC group showed increased effective connectivity from the mPFC to the amygdala relative to the HC group. Compared to the TEC group, the PTSD group showed increased effective connectivity from the amygdala to the supplementary motor area (SMA), whereas decreased effective connectivity was detected from the SMA to the amygdala. Both the PTSD group and the TEC group showed decreased effective connectivity from the superior temporal gyrus (STG) to the amygdala relative to the HC group. Compared to the HC group, the TEC group showed increased effective connectivity from the amygdala to the dorsolateral prefrontal cortex (dlPFC), while both the PTSD group and the TEC group showed decreased effective connectivity from the dlPFC to the amygdala. The PTSD group showed decreased effective connectivity from the precuneus to the amygdala relative to both control groups, but increased effective connectivity from the amygdala to the precuneus relative to the HC group. Conclusion: Trauma leads to an increased down-top excitation from the amygdala to the mPFC and less regulation of the amygdala by the dlPFC. The results suggest that increased inhibition of the amygdala by the mPFC may reflect a resilience factor, and altered amygdala-SMA and amygdala-STG effective connectivity may reflect compensatory mechanisms of brain function. These data raise the possibility that insufficient inhibition of the amygdala by the mPFC might lead to PTSD in those who have been exposed to traumatic incidents, and may inform future therapeutic interventions.

PMID: 30405457 [PubMed]

Functional Connectivity Within the Executive Control Network Mediates the Effects of Long-Term Tai Chi Exercise on Elders' Emotion Regulation.

Fri, 11/09/2018 - 17:00
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Functional Connectivity Within the Executive Control Network Mediates the Effects of Long-Term Tai Chi Exercise on Elders' Emotion Regulation.

Front Aging Neurosci. 2018;10:315

Authors: Liu Z, Wu Y, Li L, Guo X

Abstract
Previous research has identified the effects of tai chi exercise on elders' executive control or on their emotion regulation. However, few works have attempted to reveal the relationships between tai chi, executive control, and emotion regulation in the same study. The current resting-state study investigated whether the impact of tai chi on elders' emotion regulation was mediated by the resting-state functional connectivity within the executive control network. A total of 26 elders with long-term tai chi experience and 26 demographically matched healthy elders were recruited. After the resting-state scan, both groups were required to complete a series of questionnaires, including the Five Facets Mindfulness Questionnaire (FFMQ), and a sequential decision task, which offered an index of the subjects' emotion-regulation ability by calculating how their emotional response could be affected by the objective outcomes of their decisions. Compared to the control group, the tai chi group showed higher levels of non-judgment of inner experiences (a component of the FFMQ), stronger emotion-regulation ability, and a weaker resting-state functional connectivity between the dorsolateral prefrontal cortex (DLPFC) and the middle frontal gyrus (MFG). Moreover, the functional connectivity between the DLPFC and the MFG in the tai chi group fully mediated the impact of non-judgment of inner experience on their emotion-regulation ability. These findings highlighted that the modulation of non-judgment of inner experience on long-term tai chi practitioners' emotion regulation was achieved through decreased functional connectivity within the executive control network.

PMID: 30405392 [PubMed]

Eyes-Open and Eyes-Closed Resting States With Opposite Brain Activity in Sensorimotor and Occipital Regions: Multidimensional Evidences From Machine Learning Perspective.

Fri, 11/09/2018 - 17:00
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Eyes-Open and Eyes-Closed Resting States With Opposite Brain Activity in Sensorimotor and Occipital Regions: Multidimensional Evidences From Machine Learning Perspective.

Front Hum Neurosci. 2018;12:422

Authors: Wei J, Chen T, Li C, Liu G, Qiu J, Wei D

Abstract
Studies have demonstrated that there are widespread significant differences in spontaneous brain activity between eyes-open (EO) and eyes-closed (EC) resting states. However, it remains largely unclear whether spontaneous brain activity is effectively related to EO and EC resting states. The amplitude, local functional concordance, inter-hemisphere functional synchronization, and network centrality of spontaneous brain activity were measured by the fraction amplitude of low frequency fluctuation (fALFF), regional homogeneity (ReHo), voxel-mirrored homotopic connectivity (VMHC) and degree centrality (DC), respectively. Using the public Eyes-open/Eyes-closed dataset, we employed the support vector machine (SVM) and bootstrap technique to establish linking models for the fALFF, ReHo, VMHC and DC dimensions. The classification accuracies of linking models are 0.72 (0.59, 0.82), 0.88 (0.79, 0.97), 0.82 (0.74, 0.91) and 0.70 (0.62, 0.79), respectively. Specifically, we observed that brain activity in the EO condition is significantly greater in attentional system areas, including the fusiform gyrus, occipital and parietal cortex, but significantly lower in sensorimotor system areas, including the precentral/postcentral gyrus, paracentral lobule (PCL) and temporal cortex compared to the EC condition from the four dimensions. The results consistently indicated that spontaneous brain activity is effectively related to EO and EC resting states, and the two resting states are of opposite brain activity in sensorimotor and occipital regions. It may provide new insight into the neural substrate of the resting state and help computational neuroscientists or neuropsychologists to choose an appropriate resting state condition to investigate various mental disorders from the resting state functional magnetic resonance imaging (fMRI) technique.

PMID: 30405376 [PubMed]

Default Mode Network Complexity and Cognitive Decline in Mild Alzheimer's Disease.

Fri, 11/09/2018 - 17:00
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Default Mode Network Complexity and Cognitive Decline in Mild Alzheimer's Disease.

Front Neurosci. 2018;12:770

Authors: Grieder M, Wang DJJ, Dierks T, Wahlund LO, Jann K

Abstract
The human resting-state is characterized by spatially coherent brain activity at a low temporal frequency. The default mode network (DMN), one of so-called resting-state networks, has been associated with cognitive processes that are directed toward the self, such as introspection and autobiographic memory. The DMN's integrity appears to be crucial for mental health. For example, patients with Alzheimer's disease or other psychiatric conditions show disruptions of functional connectivity within the brain regions of the DMN. However, in prodromal or early stages of Alzheimer's disease, physiological alterations are sometimes elusive, despite manifested cognitive impairment. While functional connectivity assesses the signal correlation between brain areas, multi-scale entropy (MSE) measures the complexity of the blood-oxygen level dependent signal within an area and thus might show local changes before connectivity is affected. Hence, we investigated alterations of functional connectivity and MSE within the DMN in fifteen mild Alzheimer's disease patients as compared to fourteen controls. Potential associations of MSE with functional connectivity and cognitive abilities [i.e., mini-mental state examination (MMSE)] were assessed. A moderate decrease of DMN functional connectivity between posterior cingulate cortex and right hippocampus in Alzheimer's disease was found, whereas no differences were evident for whole-network functional connectivity. In contrast, the Alzheimer's disease group yielded lower global DMN-MSE than the control group. The most pronounced regional effects were localized in left and right hippocampi, and this was true for most scales. Moreover, MSE significantly correlated with functional connectivity, and DMN-MSE correlated positively with the MMSE in Alzheimer's disease. Most interestingly, the right hippocampal MSE was positively associated with semantic memory performance. Thus, our results suggested that cognitive decline in Alzheimer's disease is reflected by decreased signal complexity in DMN nodes, which might further lead to disrupted DMN functional connectivity. Additionally, altered entropy in Alzheimer's disease found in the majority of the scales indicated a disturbance of both local information processing and information transfer between distal areas. Conclusively, a loss of nodal signal complexity potentially impairs synchronization across nodes and thus preempts functional connectivity changes. MSE presents a putative functional marker for cognitive decline that might be more sensitive than functional connectivity alone.

PMID: 30405347 [PubMed]

Connecting Openness and the Resting-State Brain Network: A Discover-Validate Approach.

Fri, 11/09/2018 - 17:00
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Connecting Openness and the Resting-State Brain Network: A Discover-Validate Approach.

Front Neurosci. 2018;12:762

Authors: Wang J, Hu Y, Li H, Ge L, Li J, Cheng L, Yang Z, Zuo X, Xu Y

Abstract
In personality neuroscience, the openness-brain association has been a topic of interest. Previous studies usually started from difference in openness trait and used it to infer brain functional activity characteristics, but no study has used a "brain-first" research strategy to explore that association based on more objective brain imaging data. In this study, we used a fully data-driven approach to discover and validate the association between openness and the resting-state brain network. We collected data of 120 subjects as a discovery sample and 56 subjects as a validation sample. The Neuroticism Extraversion Openness Five-Factor Inventory (NEO-FFI) was used to measure the personality characteristics of all the subjects. Using an exploratory approach based on independent component analysis of resting-state functional magnetic resonance imaging (fMRI) data, we identified a parietal network that consisted of the precuneus and inferior parietal lobe. The inter-subject similarity of the parietal memory network exhibited significant associations with openness trait, and this association was validated using the 56-subject independent sample. This finding connects the openness trait to the characteristics of a neural network and helps to understand the underlying biology of the openness trait.

PMID: 30405342 [PubMed]

Quasi-periodic patterns of intrinsic brain activity in individuals and their relationship to global signal.

Fri, 11/09/2018 - 17:00
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Quasi-periodic patterns of intrinsic brain activity in individuals and their relationship to global signal.

Neuroimage. 2018 02 15;167:297-308

Authors: Yousefi B, Shin J, Schumacher EH, Keilholz SD

Abstract
Quasiperiodic patterns (QPPs) as reported by Majeed et al., 2011 are prominent features of the brain's intrinsic activity that involve important large-scale networks (default mode, DMN; task positive, TPN) and are likely to be major contributors to widely used measures of functional connectivity. We examined the variability of these patterns in 470 individuals from the Human Connectome Project resting state functional MRI dataset. The QPPs from individuals can be coarsely categorized into two types: one where strong anti-correlation between the DMN and TPN is present, and another where most areas are strongly correlated. QPP type could be predicted by an individual's global signal, with lower global signal corresponding to QPPs with strong anti-correlation. After regression of global signal, all QPPs showed strong anti-correlation between DMN and TPN. QPP occurrence and type was similar between a subgroup of individuals with extremely low motion and the rest of the sample, which shows that motion is not a major contributor to the QPPs. After regression of estimates of slow respiratory and cardiac induced signal fluctuations, more QPPs showed strong anti-correlation between DMN and TPN, an indication that while physiological noise influences the QPP type, it is not the primary source of the QPP itself. QPPs were more similar for the same subjects scanned on different days than for different subjects. These results provide the first assessment of the variability in individual QPPs and their relationship to physiological parameters.

PMID: 29175200 [PubMed - indexed for MEDLINE]

Evaluation of different cerebrospinal fluid and white matter fMRI filtering strategies-Quantifying noise removal and neural signal preservation.

Thu, 11/08/2018 - 16:00
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Evaluation of different cerebrospinal fluid and white matter fMRI filtering strategies-Quantifying noise removal and neural signal preservation.

Hum Brain Mapp. 2018 Nov 07;:

Authors: Bartoň M, Mareček R, Krajčovičová L, Slavíček T, Kašpárek T, Zemánková P, Říha P, Mikl M

Abstract
This study examines the impact of using different cerebrospinal fluid (CSF) and white matter (WM) nuisance signals for data-driven filtering of functional magnetic resonance imaging (fMRI) data as a cleanup method before analyzing intrinsic brain fluctuations. The routinely used temporal signal-to-noise ratio metric is inappropriate for assessing fMRI filtering suitability, as it evaluates only the reduction of data variability and does not assess the preservation of signals of interest. We defined a new metric that evaluates the preservation of selected neural signal correlates, and we compared its performance with a recently published signal-noise separation metric. These two methods provided converging evidence of the unfavorable impact of commonly used filtering approaches that exploit higher numbers of principal components from CSF and WM compartments (typically 5 + 5 for CSF and WM, respectively). When using only the principal components as nuisance signals, using a lower number of signals results in a better performance (i.e., 1 + 1 performed best). However, there was evidence that this routinely used approach consisting of 1 + 1 principal components may not be optimal for filtering resting-state (RS) fMRI data, especially when RETROICOR filtering is applied during the data preprocessing. The evaluation of task data indicated the appropriateness of 1 + 1 principal components, but when RETROICOR was applied, there was a change in the optimal filtering strategy. The suggested change for extracting WM (and also CSF in RETROICOR-corrected RS data) is using local signals instead of extracting signals from a large mask using principal component analysis.

PMID: 30403309 [PubMed - as supplied by publisher]

Two-Year Longitudinal Monitoring of Amnestic Mild Cognitive Impairment Patients with Prodromal Alzheimer's Disease Using Topographical Biomarkers Derived from Functional Magnetic Resonance Imaging and Electroencephalographic Activity.

Thu, 11/08/2018 - 16:00
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Two-Year Longitudinal Monitoring of Amnestic Mild Cognitive Impairment Patients with Prodromal Alzheimer's Disease Using Topographical Biomarkers Derived from Functional Magnetic Resonance Imaging and Electroencephalographic Activity.

J Alzheimers Dis. 2018 Oct 29;:

Authors: Jovicich J, Babiloni C, Ferrari C, Marizzoni M, Moretti DV, Del Percio C, Lizio R, Lopez S, Galluzzi S, Albani D, Cavaliere L, Minati L, Didic M, Fiedler U, Forloni G, Hensch T, Molinuevo JL, Bartrés Faz D, Nobili F, Orlandi D, Parnetti L, Farotti L, Costa C, Payoux P, Rossini PM, Marra C, Schönknecht P, Soricelli A, Noce G, Salvatore M, Tsolaki M, Visser PJ, Richardson JC, Wiltfang J, Bordet R, Blin O, Frisoniand GB

Abstract
Auditory "oddball" event-related potentials (aoERPs), resting state functional magnetic resonance imaging (rsfMRI) connectivity, and electroencephalographic (rsEEG) rhythms were tested as longitudinal functional biomarkers of prodromal Alzheimer's disease (AD). Data were collected at baseline and four follow-ups at 6, 12, 18, and 24 months in amnesic mild cognitive impairment (aMCI) patients classified in two groups: "positive" (i.e., "prodromal AD"; n = 81) or "negative" (n = 63) based on a diagnostic marker of AD derived from cerebrospinal samples (Aβ42/P-tau ratio). A linear mixed model design was used to test functional biomarkers for Group, Time, and Group×Time effects adjusted by nuisance covariates (only data until conversion to dementia was used). Functional biomarkers that showed significant Group effects ("positive" versus "negative", p <  0.05) regardless of Time were 1) reduced rsfMRI connectivity in both the default mode network (DMN) and the posterior cingulate cortex (PCC), both also giving significant Time effects (connectivity decay regardless of Group); 2) increased rsEEG source activity at delta (<4 Hz) and theta (4-8 Hz) rhythms and decreased source activity at low-frequency alpha (8-10.5 Hz) rhythms; and 3) reduced parietal and posterior cingulate source activities of aoERPs. Time×Group effects showed differential functional biomarker progression between groups: 1) increased rsfMRI connectivity in the left parietal cortex of the DMN nodes, consistent with compensatory effects and 2) increased limbic source activity at theta rhythms. These findings represent the first longitudinal characterization of functional biomarkers of prodromal AD relative to "negative" aMCI patients based on 5 serial recording sessions over 2 years.

PMID: 30400088 [PubMed - as supplied by publisher]

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