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Acquisition of Spatial Search Strategies and Reversal Learning in the Morris Water Maze Depend on Disparate Brain Functional Connectivity in Mice.

Sat, 12/29/2018 - 21:48
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Acquisition of Spatial Search Strategies and Reversal Learning in the Morris Water Maze Depend on Disparate Brain Functional Connectivity in Mice.

Cereb Cortex. 2018 Dec 22;:

Authors: Shah D, Verhoye M, Van der Linden A, D'Hooge R

Abstract
Learning has been proposed to coincide with changes in connections between brain regions. In the present study, we used resting-state fMRI (rsfMRI) to map brain-wide functional connectivity (FC) in mice that were trained in the hidden-platform version of the Morris water maze. C57BL6 mice were investigated in a small animal MRI scanner following 2, 10, or 15 days of acquisition learning, or 5 days of reversal learning. Spatial learning coincided with progressive and changing FC between telencephalic regions that have been implemented in spatial learning (such as hippocampus, cingulate, visual, and motor cortex). Search strategy assessment demonstrated that the use of cognitively advanced spatial strategies correlated positively with extensive telencephalic connectivity, whereas non-spatial strategies correlated negatively with connectivity. FC patterns were different and more extensive after reversal learning compared with after extended acquisition learning, which could explain why reversal learning has been shown to be more sensitive to subtle functional defects.

PMID: 30590460 [PubMed - as supplied by publisher]

Spatial dynamics within and between brain functional domains: A hierarchical approach to study time-varying brain function.

Sat, 12/29/2018 - 21:48
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Spatial dynamics within and between brain functional domains: A hierarchical approach to study time-varying brain function.

Hum Brain Mapp. 2018 Dec 26;:

Authors: Iraji A, Fu Z, Damaraju E, DeRamus TP, Lewis N, Bustillo JR, Lenroot RK, Belger A, Ford JM, McEwen S, Mathalon DH, Mueller BA, Pearlson GD, Potkin SG, Preda A, Turner JA, Vaidya JG, van Erp TGM, Calhoun VD

Abstract
The analysis of time-varying activity and connectivity patterns (i.e., the chronnectome) using resting-state magnetic resonance imaging has become an important part of ongoing neuroscience discussions. The majority of previous work has focused on variations of temporal coupling among fixed spatial nodes or transition of the dominant activity/connectivity pattern over time. Here, we introduce an approach to capture spatial dynamics within functional domains (FDs), as well as temporal dynamics within and between FDs. The approach models the brain as a hierarchical functional architecture with different levels of granularity, where lower levels have higher functional homogeneity and less dynamic behavior and higher levels have less homogeneity and more dynamic behavior. First, a high-order spatial independent component analysis is used to approximate functional units. A functional unit is a pattern of regions with very similar functional activity over time. Next, functional units are used to construct FDs. Finally, functional modules (FMs) are calculated from FDs, providing an overall view of brain dynamics. Results highlight the spatial fluidity within FDs, including a broad spectrum of changes in regional associations, from strong coupling to complete decoupling. Moreover, FMs capture the dynamic interplay between FDs. Patients with schizophrenia show transient reductions in functional activity and state connectivity across several FDs, particularly the subcortical domain. Activity and connectivity differences convey unique information in many cases (e.g., the default mode) highlighting their complementarity information. The proposed hierarchical model to capture FD spatiotemporal variations provides new insight into the macroscale chronnectome and identifies changes hidden from existing approaches.

PMID: 30588687 [PubMed - as supplied by publisher]

Bidirectional alterations in ALFF across slow-5 and slow-4 frequencies in the brains of postherpetic neuralgia patients.

Sat, 12/29/2018 - 21:48
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Bidirectional alterations in ALFF across slow-5 and slow-4 frequencies in the brains of postherpetic neuralgia patients.

J Pain Res. 2019;12:39-47

Authors: Gu L, Hong S, Jiang J, Liu J, Cao X, Huang Q, Zeng X, Zhou F, Zhang D

Abstract
Purpose: Postherpetic neuralgia (PHN) detrimentally affects brain function. Recent studies have suggested that frequency-dependent changes in electroencephalography in chronic pain patients and blood oxygenation level dependent (BOLD) fluctuations can reflect neuronal activity in different frequencies. The current study aimed to investigate PHN-related brain oscillatory activity in a specific frequency band by using the amplitude of low-frequency fluctuation (ALFF) method.
Materials and methods: ALFF changes were analyzed across different frequencies (slow-4 band: 0.027-0.073 Hz; slow-5 band: 0.01-0.027 Hz; and typical band: 0.01-0.08 Hz) in the brains of PHN patients and compared with those in the brains of healthy controls (HCs) during resting-state fMRI. Eighteen HCs and PHN patients underwent fMRI scanning.
Results: In the typical band, compared with HCs, PHN patients showed prominently decreased ALFF in the right prefrontal cortex (Brodmann area 10/46) and increased ALFF in the bilateral brain stem/cerebellum anterior lobe (BS/CAL). In the slow-4 band, PHN patients exhibited significantly decreased ALFF in the bilateral cuneus/lingual gyrus and the right prefrontal cortex. In the slow-5 band, PHN patients presented significantly increased ALFF in the bilateral BS/CAL and left parieto-occipital cortex. Moreover, the increased ALFF in the left parieto-occipital cortex in the slow-5 band was positively correlated with VAS scores (P=0.022), and the increased ALFF in the bilateral BS/CAL in the slow-5 band was positively correlated with disease duration (P=0.020).
Conclusion: Our results suggested that the intrinsic brain activity of PHN patients was abnormal and frequency dependent, especially the bidirectional alteration in ALFF across the slow-4 and slow-5 frequencies in the brains of PHN patients.

PMID: 30588078 [PubMed]

Modular reconfiguration of an auditory control brain network supports adaptive listening behavior.

Sat, 12/29/2018 - 21:48
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Modular reconfiguration of an auditory control brain network supports adaptive listening behavior.

Proc Natl Acad Sci U S A. 2018 Dec 26;:

Authors: Alavash M, Tune S, Obleser J

Abstract
Speech comprehension in noisy, multitalker situations poses a challenge. Successful behavioral adaptation to a listening challenge often requires stronger engagement of auditory spatial attention and context-dependent semantic predictions. Human listeners differ substantially in the degree to which they adapt behaviorally and can listen successfully under such circumstances. How cortical networks embody this adaptation, particularly at the individual level, is currently unknown. We here explain this adaptation from reconfiguration of brain networks for a challenging listening task (i.e., a linguistic variant of the Posner paradigm with concurrent speech) in an age-varying sample of n = 49 healthy adults undergoing resting-state and task fMRI. We here provide evidence for the hypothesis that more successful listeners exhibit stronger task-specific reconfiguration (hence, better adaptation) of brain networks. From rest to task, brain networks become reconfigured toward more localized cortical processing characterized by higher topological segregation. This reconfiguration is dominated by the functional division of an auditory and a cingulo-opercular module and the emergence of a conjoined auditory and ventral attention module along bilateral middle and posterior temporal cortices. Supporting our hypothesis, the degree to which modularity of this frontotemporal auditory control network is increased relative to resting state predicts individuals' listening success in states of divided and selective attention. Our findings elucidate how fine-tuned cortical communication dynamics shape selection and comprehension of speech. Our results highlight modularity of the auditory control network as a key organizational principle in cortical implementation of auditory spatial attention in challenging listening situations.

PMID: 30587584 [PubMed - as supplied by publisher]

Resting-state brain entropy in schizophrenia.

Mon, 12/24/2018 - 09:21
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Resting-state brain entropy in schizophrenia.

Compr Psychiatry. 2018 Dec 04;89:16-21

Authors: Xue SW, Yu Q, Guo Y, Song D, Wang Z

Abstract
BACKGROUND: The human brain presents ongoing temporal fluctuations whose dynamic range indicates the capacity of information processing and can be approximately quantified with entropy. Using functional magnetic resonance imaging (fMRI), recent studies have shown a stable distribution pattern of temporal brain entropy (tBEN) in healthy subjects, which may be affected by neuropsychiatric diseases such as schizophrenia. Assessing tBEN may reciprocally provide a new tool to characterize those disorders.
METHODS: The current study aimed to identify tBEN changes in schizophrenia patients using publicly available data from the Centers of Biomedical Research Excellence (COBRE) project. Forty-three schizophrenia patients and 59 sex- and age-matched healthy control subjects were included, and tBEN was calculated from their resting-state fMRI scans.
RESULTS: Compared with healthy controls, patients showed decreased tBEN in the right middle prefrontal cortex, bilateral thalamus, right hippocampus and bilateral caudate and increased tBEN in the left lingual gyrus, left precuneus, right fusiform face area and right superior occipital gyrus. In schizophrenia patients, tBEN in the left cuneus and middle occipital gyrus was negatively correlated with the positive and negative syndrome scores (PANSS). Age of onset was inversely correlated with tBEN in the right fusiform gyrus and left insula.
CONCLUSION: Our findings demonstrate a detrimental tBEN reduction in schizophrenia that is related to clinical characteristics. The tBEN increase in a few regions might be a result of tBEN redistribution across the whole brain in schizophrenia.

PMID: 30576960 [PubMed - as supplied by publisher]

Contributions of default mode network stability and deactivation to adolescent task engagement.

Mon, 12/24/2018 - 09:21
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Contributions of default mode network stability and deactivation to adolescent task engagement.

Sci Rep. 2018 Dec 21;8(1):18049

Authors: McCormick EM, Telzer EH

Abstract
Out of the several intrinsic brain networks discovered through resting-state functional analyses in the past decade, the default mode network (DMN) has been the subject of intense interest and study. In particular, the DMN shows marked suppression during task engagement, and has led to hypothesized roles in internally-directed cognition that need to be down-regulated in order to perform goal-directed behaviors. Previous work has largely focused on univariate deactivation as the mechanism of DMN suppression. However, given the transient nature of DMN down-regulation during task, an important question arises: Does the DMN need to be strongly, or more stably suppressed to promote successful task learning? In order to explore this question, 65 adolescents (Mage = 13.32; 21 females) completed a risky decision-making task during an fMRI scan. We tested our primary question by examining individual differences in absolute level of deactivation against the stability of activation across time in predicting levels of feedback learning on the task. To measure stability, we utilized a model-based functional connectivity approach that estimates the stability of activation across time within a region. In line with our hypothesis, the stability of activation in default mode regions predicted task engagement over and above the absolute level of DMN deactivation, revealing a new mechanism by which the brain can suppress the influence of brain networks on behavior. These results also highlight the importance of adopting model-based network approaches to understand the functional dynamics of the brain.

PMID: 30575799 [PubMed - in process]

Long-term reactions to pulsatile tinnitus are marked by weakened short-range functional connectivity within a brain network in the right temporal lobe.

Mon, 12/24/2018 - 09:21
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Long-term reactions to pulsatile tinnitus are marked by weakened short-range functional connectivity within a brain network in the right temporal lobe.

J Magn Reson Imaging. 2018 Dec 21;:

Authors: Zheng W, Peng Z, Pengfei Z, Jing L, Heyu D, Hongxia Y, Yawen L, Zhengyu Z, Shusheng G, Zhenghan Y, Han L, Zhenchang W

Abstract
BACKGROUND: There have been recent efforts to characterize brain functional activity features in patients with pulsatile tinnitus (PT). These efforts have revealed evidence of aberrant functional connectivity (FC) of the right middle temporal gyrus (MTG) in PT patients with prolonged disease duration.
PURPOSE: To assess the possible predictive effect of aberrant FC of MTG in PT patients with prolonged disease duration.
STUDY TYPE: Retrospective.
POPULATION: Thirty-four patients with recent-onset PT (RPTIN), 24 patients with long-term PT (LPTIN), and 35 age-, gender-, and education-matched healthy controls were enrolled.
FIELD STRENGTH/SEQUENCE: 3.0T MRI system and echo-planar imaging (EPI) sequence, 3D brain volume imaging (BRAVO) sequence.
ASSESSMENT: Functional MRI data preprocessing was performed in Data Processing & Analysis for Brain Imaging (DPABI) and Statistical Parametric Mapping (SPM) 8. The FC analyses were conducted using the software REST.
STATISTICAL TESTS: One-way analysis of covariance was conducted between three groups with age and gender as covariates, and post-hoc analysis was used to identify the sources of group effects. Pearson's correlation analysis was conducted for the z-values of altered FC strength in the PT group and the clinical data.
RESULTS: Among hubs belonging to the executive control network, the default mode network (DMN), and limbic network, the strength of FC was mainly decreased in the patient groups compared with normal controls (P < 0.05). Relative to RPTIN patients and normal controls, LPTIN patients were further characterized by significantly decreased FC between several short-range brain regions adjacent to the seed (P < 0.05). Finally, disease duration was negatively correlated with decreased FC between the seed and right fusiform gyrus/parahippocampal gyrus, right inferior frontal gyrus, and right MTG (a brain area adjacent to the seed region).
DATA CONCLUSION: Long-term reactions to PT mainly involved weakened short-range FC, especially within a functional network in the right temporal lobe.
LEVEL OF EVIDENCE: 4 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018.

PMID: 30575157 [PubMed - as supplied by publisher]

Optimization of rs-fMRI parameters in the Seed Correlation Analysis (SCA) in DPARSF toolbox: A preliminary study.

Mon, 12/24/2018 - 09:21
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Optimization of rs-fMRI parameters in the Seed Correlation Analysis (SCA) in DPARSF toolbox: A preliminary study.

J Neurosci Res. 2018 Dec 21;:

Authors: Karpiel I, Klose U, Drzazga Z

Abstract
There are a number of various methods of resting-state functional magnetic resonance imaging (rs-fMRI) analysis such as independent component analysis, multivariate autoregressive models, or seed correlation analysis however their results depend on arbitrary choice of parameters. Therefore, the aim of this work was to optimize the parameters in the seed correlation analysis using the Data Processing Assistant for Resting-State fMRI (DPARSF) toolbox for rs-fMRI data received from a Siemens Magnetom Skyra 3-Tesla scanner using a whole-brain, gradient-echo echo planar sequence with a 32-channel head coil. Different ranges of the following parameters: amplitude of low-frequency fluctuation (ALFF), Gaussian kernel at FWHM and radius of spherical ROI for 109 regions were tested for 20 healthy volunteers. The highest values of functional connectivity (FC) correlations were found for ALFF 0.01-0.08, spherical ROIs with the 8-mm radius and Gaussian kernel 8 mm at FWHM in all the studied areas that is, Auditory, Sensimotor, Visual, and Default Mode Network. The dominating influence of ALFF and smoothing on values of FC correlations was noted.

PMID: 30575101 [PubMed - as supplied by publisher]

Advances in Resting State Neuroimaging of Mild Cognitive Impairment.

Mon, 12/24/2018 - 09:21
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Advances in Resting State Neuroimaging of Mild Cognitive Impairment.

Front Psychiatry. 2018;9:671

Authors: Lin L, Xing G, Han Y

Abstract
The rapidly increasing number of patients with Alzheimer's disease (AD) worldwide has become a major public concern. Mild cognitive impairment (MCI), characterized with accelerated memory decline than normal aging, is a stage between cognitively unimpaired and dementia. Identification of MCI in the Alzheimer's continuum from normal aging, is important for early diagnosis and improved intervention of AD. The imaging technique has been extensively used for diagnose and understanding the mechanisms of MCI. Firstly, we review the recent progresses in the research framework of MCI depending on the clinical and/or biomarker findings. Secondly, we cover studies that use of rs-fMRI (resting state functional magnetic resonance imaging) for the brain activities and functional connectivity between normal aging and MCI. Other methodologies and multi-modal studies for investigating the mechanism and early diagnosis of MCI are also discussed. Finally, we discuss how genetic and environmental factors such as education could interact with in MCI. Overall, MCI is a heterogeneous state and employing resting state neuroimaging with other AD biomarker approaches will be able to target in the more precise population and AD-related pathology process.

PMID: 30574100 [PubMed]

Investigating Multiple Streams of Consciousness: Using Descriptive Experience Sampling to Explore Internally and Externally Directed Streams of Thought.

Mon, 12/24/2018 - 09:21
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Investigating Multiple Streams of Consciousness: Using Descriptive Experience Sampling to Explore Internally and Externally Directed Streams of Thought.

Front Hum Neurosci. 2018;12:494

Authors: Fernyhough C, Alderson-Day B, Hurlburt RT, Kühn S

Abstract
Research into resting-state cognition has often struggled with the challenge of assessing inner experience in the resting state. We employed Descriptive Experience Sampling (DES), a method aimed at generating detailed and high-fidelity descriptions of experience, to investigate how experience in the resting state can vary between internal, external, and multiple simultaneous streams. Using a large body of experiential and brain activation data acquired from five DES participants, independent raters classified sampled moments of experience according to whether they were internally directed, externally directed, or contained elements of both at the same time. In line with existing models, comparison of internal with external experience samples identified a network of regions associated with the default mode network. Regions of interest resulting from the whole-brain contrasts successfully predicted independent raters' forced-choice categorizations of samples for which experience had a simultaneous internal and external focus. The present study is distinctive in tying neural activations in the resting state to detailed descriptions of specific phenomenology, and in demonstrating how the DES method enables a particularly nuanced analysis of moments of experience, especially their ability simultaneously to incorporate both an internal and an external focus. The study represents an integration of rich phenomenology and characterizations of brain activity, tracing interpretive paths from phenomenology to neural activation and vice versa.

PMID: 30574081 [PubMed]

Altered Default Mode and Sensorimotor Network Connectivity With Striatal Subregions in Primary Insomnia: A Resting-State Multi-Band fMRI Study.

Mon, 12/24/2018 - 09:21
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Altered Default Mode and Sensorimotor Network Connectivity With Striatal Subregions in Primary Insomnia: A Resting-State Multi-Band fMRI Study.

Front Neurosci. 2018;12:917

Authors: Wang L, Wang K, Liu JH, Wang YP

Abstract
Background: Primary insomnia is a high prevalent sleep disorder. Disturbed brain activity during reward, emotional, and cognitive processing have been observed in insomnia patients. Studies have implicated a critical role of the striatum in these dysfunctions. However, there have been no direct investigations on the whole-brain functional connectivity (FC) of the striatum in insomnia. Methods: We analyzed the group differences in the FC images of 6 predefined striatal subregions based on the multi-band resting-state fMRI data of 18 insomnia patients and 16 healthy controls. Results: We found increased positive FC in the bilateral medial frontal gyrus for bilateral dorsal caudate (DC) and left inferior ventral striatum (VS) subregions, but increased negative FC in the bilateral inferior parietal lobe for the left inferior VSi and right dorsal caudal putamen (DCP) subregions, and in the lateral temporal, occipital, and primary sensorimotor areas for the bilateral DC and left superior VS subregions. The FC between the right DCP and right inferior parietal lobe showed significant positive correlation with Pittsburgh Sleep Quality Index (PSQI). Conclusion: The findings indicate disturbed striatal FC with the default mode network (DMN), the visual and somatosensory areas in insomnia, which likely reflects an inappropriate reward or emotional significance attribute to self-reflection, episodic memory, sensory-perception processes. The altered striatal FC might increase the risk of insomnia patients to develop depression and anxiety.

PMID: 30574065 [PubMed]

Regional Homogeneity and Multivariate Pattern Analysis of Cervical Spondylosis Neck Pain and the Modulation Effect of Treatment.

Mon, 12/24/2018 - 09:21
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Regional Homogeneity and Multivariate Pattern Analysis of Cervical Spondylosis Neck Pain and the Modulation Effect of Treatment.

Front Neurosci. 2018;12:900

Authors: Chen J, Wang Z, Tu Y, Liu X, Jorgenson K, Ye G, Lin C, Liu J, Park J, Lang C, Liu B, Kong J

Abstract
Objects: We investigated brain functional alteration in patients with chronic cervical spondylosis neck pain (CSNP) compared to healthy controls (HCs) and the effect of intervention. Methods: 104 CSNP patients and 96 matched HCs were recruited. Patients received 4 weeks of treatment. Resting-state fMRI and Northwick Park Neck Pain Questionnaire (NPQ) were collected before and after treatment. Resting state regional homogeneity (rs-ReHo) and multivariate pattern analysis (MVPA) were applied to (1) investigate rs-ReHo differences between CSNP patients and controls and the effect of longitudinal treatment and (2) classify CSNP patients from HCs and predict clinical outcomes before treatment using MVPA. Results: We found that (1) CSNP patients showed decreased rs-ReHo in the left sensorimotor cortex and right temporo-parietal junction (rTPJ), and rs-ReHo at the rTPJ significantly increased after treatment; (2) rs-ReHo at rTPJ was associated with NPQ at baseline, and pre- and post-treatment rs-ReHo changes at rTPJ were associated with NPQ changes in CSNP patients; and (3) MVPA could discriminate CSNP patients from HCs with 72% accuracy and predict clinical outcomes with a mean absolute error of 19.6%. Conclusion: CSNP patients are associated with dysfunction of the rTPJ and sensorimotor area. Significance: rTPJ plays on important role in the pathophysiology and development of CSNP.

PMID: 30574062 [PubMed]

Changes in default mode network connectivity in different glucose metabolism status and diabetes duration.

Mon, 12/24/2018 - 09:21
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Changes in default mode network connectivity in different glucose metabolism status and diabetes duration.

Neuroimage Clin. 2018 Dec 05;:101629

Authors: Liu H, Liu J, Peng L, Feng Z, Cao L, Liu H, Shen H, Hu D, Zeng LL, Wang W

Abstract
AIMS/HYPOTHESES: It is now generally accepted that diabetes increases the risk for cognitive impairment, but the precise mechanisms are poorly understood. In recent years, resting-state functional magnetic resonance imaging (rs-fMRI) is increasingly used to investigate the neural basis of cognitive dysfunction in type 2 diabetes (T2D) patients. Alterations in brain functional connectivity may underlie diabetes-related cognitive dysfunction and brain damage. The aim of this study was to investigate the changes in default mode network (DMN) connectivity in different glucose metabolism status and diabetes duration.
METHODS: We used a seed-based fMRI analysis to investigate positive and negative DMN connectivity in four groups (39 subjects with normal glucose metabolism [NGM], 23 subjects with impaired glucose metabolism [IGM; i.e., prediabetes], 59 T2D patients with a diabetes duration of <10 years, and 24 T2D patients with a diabetes duration of ≥10 years).
RESULTS: Negative DMN connectivity increased and then regressed with deteriorating glucose metabolism status and extending diabetes duration. DMN connectivity showed a significant correlation with diabetes duration.
CONCLUSION/INTERPRETATION: This study suggests that DMN connectivity may exhibit distinct patterns in different glucose metabolism status and diabetes duration, providing some potential neuroimaging evidence for early diagnosis and further understanding of the pathophysiological mechanisms of diabetic brain damage.

PMID: 30573410 [PubMed - as supplied by publisher]

A concise and persistent feature to study brain resting-state network dynamics: Findings from the Alzheimer's Disease Neuroimaging Initiative.

Sat, 12/22/2018 - 12:09
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A concise and persistent feature to study brain resting-state network dynamics: Findings from the Alzheimer's Disease Neuroimaging Initiative.

Hum Brain Mapp. 2018 Dec 19;:

Authors: Kuang L, Han X, Chen K, Caselli RJ, Reiman EM, Wang Y, Alzheimer's Disease Neuroimaging Initiative

Abstract
Alzheimer's disease (AD) is the most common type of dementia in the elderly with no effective treatment currently. Recent studies of noninvasive neuroimaging, resting-state functional magnetic resonance imaging (rs-fMRI) with graph theoretical analysis have shown that patients with AD and mild cognitive impairment (MCI) exhibit disrupted topological organization in large-scale brain networks. In previous work, it is a common practice to threshold such networks. However, it is not only difficult to make a principled choice of threshold values, but also worse is the discard of potential important information. To address this issue, we propose a threshold-free feature by integrating a prior persistent homology-based topological feature (the zeroth Betti number) and a newly defined connected component aggregation cost feature to model brain networks over all possible scales. We show that the induced topological feature (Integrated Persistent Feature) follows a monotonically decreasing convergence function and further propose to use its slope as a concise and persistent brain network topological measure. We apply this measure to study rs-fMRI data from the Alzheimer's Disease Neuroimaging Initiative and compare our approach with five other widely used graph measures across five parcellation schemes ranging from 90 to 1,024 region-of-interests. The experimental results demonstrate that the proposed network measure shows more statistical power and stronger robustness in group difference studies in that the absolute values of the proposed measure of AD are lower than MCI and much lower than normal controls, providing empirical evidence for decreased functional integration in AD dementia and MCI.

PMID: 30569583 [PubMed - as supplied by publisher]

One-step analysis of brain perfusion and function for acute stroke patients after reperfusion: A resting-state fMRI study.

Sat, 12/22/2018 - 12:09
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One-step analysis of brain perfusion and function for acute stroke patients after reperfusion: A resting-state fMRI study.

J Magn Reson Imaging. 2018 Dec 19;:

Authors: Chen Q, Zhou J, Zhang H, Chen Y, Mao C, Chen X, Ni L, Zhuo Z, Zhang Y, Geng W, Yin X, Lv Y

Abstract
BACKGROUND: Resting-state functional magnetic resonance imaging (rs-fMRI) can noninvasively estimate the perfusion and function of the brain.
PURPOSE: To investigate the perfusion and functional status using rs-fMRI in acute ischemic stroke (AIS) patients after reperfusion therapy.
STUDY TYPE: Prospective.
SUBJECTS: Twenty-five AIS patients who underwent dynamic susceptibility contrast (DSC) upon hospital admission and both rs-fMRI and DSC scans at 24 hours after reperfusion therapy.
FIELD STRENGTH/SEQUENCE: 3T; DSC, rs-fMRI.
ASSESSMENT: The time delay of the blood oxygenation level-dependent (BOLD) signal was calculated using time-shift-analysis (TSA) and compared with the time to peak (TTP) derived from the DSC. For patients who exhibited partial or complete reperfusion in the supratentorial hemisphere, we quantified the function of different regions (healthy tissue, reperfused tissue, not reperfused tissue) by using three rs-fMRI measurements (functional connectivity, the amplitude of low-frequency fluctuation [ALFF] and regional homogeneity [ReHo]). Correlations between the functional measurements and modified Rankin Scale (mRS) scores were calculated.
STATISTICAL TESTS: Dice coefficient (DC) analysis, two-sample t-tests, Pearson correlation coefficient.
RESULTS: Twelve patients who exhibited complete reperfusion on their TTP maps showed no time-delayed areas on the TSA maps. For the remaining 13 patients with partial reperfusion (5/13) or no reperfusion (8/13) on the TTP maps, the TSA detected comparable time-delayed areas. Eleven out of 13 patients showed moderate to good overlap (mean DC, 0.58 ± 0.1) between the TTP and TSA results. Fourteen patients were chosen for functional analyses and most patients (12/14) showed abnormal functional connectivity in the reperfused regions. The reperfused and not reperfused tissues had lower mean ReHo values than those of the healthy tissue (both P < 0.001). The mRS scores showed negative correlation with mean ReHo values of reperfused region (R = -0.523, P = 0.027). DATA CONCLUSION: rs-fMRI might be a useful way to estimate both the perfusion and functional status for AIS patients after reperfusion therapy.
LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018.

PMID: 30569565 [PubMed - as supplied by publisher]

Altered Sensory Insular Connectivity in Chronic Postsurgical Pain Patients.

Sat, 12/22/2018 - 12:09
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Altered Sensory Insular Connectivity in Chronic Postsurgical Pain Patients.

Front Hum Neurosci. 2018;12:483

Authors: Ching YY, Wang C, Tay T, Loke YM, Tang PH, Sng BL, Zhou J

Abstract
Chronic postsurgical pain (CPSP) occurs in up to 50% of individuals after surgeries and 32% after hysterectomy, leading to major adverse effects on quality of life and socioeconomic burden. Little is known about whether and how large-scale neural networks being affected in CPSP, particularly with regard to the functional connectivity (FC) of insula which is known to be the hub of the intrinsic neural network playing a critical role in pain processing. Here, we sought to examine the dynamics of insular FC in the context of noxious stimuli in CPSP patients. To this aim, resting state fMRI data were acquired, before and after acute heat pain stimulation, from 11 individuals with chronic post-hysterectomy pain (CPHP) and 22 age-matched healthy controls (HCs) who had a hysterectomy but without chronic post-surgical pain. We examined whole-brain FC were mapped by seeding at the sensorimotor and chemosensory subfields of the insula and found significant group × stimulation interaction effects. Specifically, the HC group had increased FC between the left sensorimotor insula and right angular and middle occipital gyrus (MOG) and increased FC between the left chemosensory insula and bilateral angular and MOG following pain stimulation. In contrast, such pain stimulation related FC changes were absent in the CPHP group. Furthermore, higher insular FC at baseline and smaller increased insular FC after pain stimulation correlated with clinical pain scores in CPHP patients. Our findings suggest that CPSP is associated with altered dynamics of large-scale functional networks anchored in the insula.

PMID: 30568586 [PubMed]

Disentangling Mathematics from Executive Functions by Investigating Unique Functional Connectivity Patterns Predictive of Mathematics Ability.

Fri, 12/21/2018 - 15:48

Disentangling Mathematics from Executive Functions by Investigating Unique Functional Connectivity Patterns Predictive of Mathematics Ability.

J Cogn Neurosci. 2018 Dec 19;:1-14

Authors: Skagerlund K, Bolt T, Nomi JS, Skagenholt M, Västfjäll D, Träff U, Uddin LQ

Abstract
What are the underlying neurocognitive mechanisms that give rise to mathematical competence? This study investigated the relationship between tests of mathematical ability completed outside the scanner and resting-state functional connectivity (FC) of cytoarchitectonically defined subdivisions of the parietal cortex in adults. These parietal areas are also involved in executive functions (EFs). Therefore, it remains unclear whether there are unique networks for mathematical processing. We investigate the neural networks for mathematical cognition and three measures of EF using resting-state fMRI data collected from 51 healthy adults. Using 10 ROIs in seed to whole-brain voxel-wise analyses, the results showed that arithmetical ability was correlated with FC between the right anterior intraparietal sulcus (hIP1) and the left supramarginal gyrus and between the right posterior intraparietal sulcus (hIP3) and the left middle frontal gyrus and the right premotor cortex. The connection between the posterior portion of the left angular gyrus and the left inferior frontal gyrus was also correlated with mathematical ability. Covariates of EF eliminated connectivity patterns with nodes in inferior frontal gyrus, angular gyrus, and middle frontal gyrus, suggesting neural overlap. Controlling for EF, we found unique connections correlated with mathematical ability between the right hIP1 and the left supramarginal gyrus and between hIP3 bilaterally to premotor cortex bilaterally. This is partly in line with the "mapping hypothesis" of numerical cognition in which the right intraparietal sulcus subserves nonsymbolic number processing and connects to the left parietal cortex, responsible for calculation procedures. We show that FC within this circuitry is a significant predictor of math ability in adulthood.

PMID: 30566368 [PubMed - as supplied by publisher]

Power Spectral Density Analysis of Long-Term Motor Recovery in Patients With Subacute Stroke.

Fri, 12/21/2018 - 15:48

Power Spectral Density Analysis of Long-Term Motor Recovery in Patients With Subacute Stroke.

Neurorehabil Neural Repair. 2018 Dec 19;:1545968318818900

Authors: Min YS, Park JW, Jang KE, Lee HJ, Lee J, Lee YS, Jung TD, Chang Y

Abstract
BACKGROUND: Prognostic measures of long-term motor recovery are important in patients with stroke presenting with severe hemiplegia.
OBJECTIVE: We aimed to investigate whether initial power spectral density (PSD) analysis of resting-state functional magnetic resonance (fMRI) data can provide a sensitive prognostic predictor in patients with subacute stroke with severe hand disability.
METHODS: Twelve patients with good recovery, 14 patients with poor recovery, and 12 healthy subjects were included. PSD analysis was performed using resting-state fMRI data. Contralesional and ipsilesional PSD in the motor cortex were measured. Pearson correlation analysis was performed to assess a possible association between the difference in ipsilesional versus contralesional PSD and motor outcomes. A receiver operating characteristic (ROC) curve was constructed to estimate the discriminative value of the difference between the ipsilesional PSD and the contralesional PSD for good versus poor recovery.
RESULTS: There were no differences in PSD between the contralesional and ipsilesional hemispheres in the good recovery group ( P = .77). In contrast, there were significant differences in PSD between the 2 hemispheres in the poor recovery group ( P = .07). The difference in PSD between the 2 hemispheres had a positive correlation with post Brunnstrom stage scores. ROC analysis showed that the difference in PSD between the 2 hemispheres was sensitive in discriminating good versus poor recovery.
CONCLUSION: The present study suggests that PSD in the motor cortex may be a sensitive predictor of late-onset motor recovery following stroke.

PMID: 30565493 [PubMed - as supplied by publisher]

An active cognitive lifestyle as a potential neuroprotective factor in Huntington's disease.

Fri, 12/21/2018 - 15:48
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An active cognitive lifestyle as a potential neuroprotective factor in Huntington's disease.

Neuropsychologia. 2019 Jan;122:116-124

Authors: Garcia-Gorro C, Garau-Rolandi M, Escrichs A, Rodriguez-Dechicha N, Vaquer I, Subira S, Calopa M, Martinez-Horta S, Perez-Perez J, Kulisevsky J, Muñoz E, Santacruz P, Ruiz-Idiago J, Mareca C, de Diego-Balaguer R, Camara E

Abstract
A cognitive stimulating lifestyle has been observed to confer cognitive benefits in multiple neurodegenerative diseases. However, the underlying neurobiological basis of this phenomenon remains unclear. Huntington's disease can provide a suitable model to study the effects and neural mechanisms of cognitive engagement in neurodegeneration. In this study, we investigate the effect of lifestyle factors such as education, occupation and engagement in cognitive activities in Huntington's disease gene carriers on cognitive performance and age of onset as well as the underlying neural changes sustaining these effects, measured by magnetic resonance imaging. Specifically, we analyzed both gray matter volume and the strength of connectivity of the executive control resting-state network. High levels of cognitive engagement were significantly associated with more preserved executive functions, a delay in the appearance of symptoms, reduced volume loss of the left precuneus and the bilateral caudate and a modulation of connectivity strength of anterior cingulate cortex and left angular gyrus with the executive control network. These findings suggest that a cognitively stimulating lifestyle may promote brain maintenance by modulating the executive control resting-state network and conferring protection against neurodegeneration, which results in a delayed onset of symptoms and improved performance in executive functions.

PMID: 30563619 [PubMed - in process]

Experimentally induced subclinical hypothyroidism causes decreased functional connectivity of the cuneus: A resting state fMRI study.

Wed, 12/19/2018 - 17:13
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Experimentally induced subclinical hypothyroidism causes decreased functional connectivity of the cuneus: A resting state fMRI study.

Psychoneuroendocrinology. 2018 Dec 12;102:158-163

Authors: Göbel A, Göttlich M, Heldmann M, Georges R, Nieberding R, Rogge B, Sartorius A, Brabant G, Münte TF

Abstract
OBJECTIVE: The aim of this study was to experimentally evaluate the effects of subclinical mild hypothyroidism on brain network connectivity as determined by resting state fMRI (rsfMRI) which serves as a proxy for global changes in brain function.
METHODS: Fifteen otherwise healthy patients with complete hypothyroidism under stable, long term levothyroxine substitution volunteered for the study. They reduced their pretest levothyroxine dosage by 30% for 52-56 days. Basally and after partial levothyroxine withdrawal, rsfMRI along with a neuropsychological analysis was performed. RsfMRI was subjected to graph-theory-based analysis to investigate whole-brain intrinsic functional connectivity.
RESULTS: The desired subclinical hypothyroidism was achieved in all subjects. This was associated with a significant decrease in resting-state functional connectivity specifically in the cuneus (0.05 FWE corrected at cluster level) which was mainly caused by a weaker functional connectivity to the cerebellum and regions of the default mode network, i.e. the medial prefrontal cortex, the precuneus and the bilateral angular gyri. The decrease in cuneus connectivity was correlated to the increase in TSH serum levels. A working memory task showed a slightly longer reaction time and less accuracy after partial levothyroxine withdrawal.
CONCLUSION: Even short-term partial levothyroxine partial withdrawal leads to deficits in working memory tasks and to a weaker integration of the cuneus within the default mode network.

PMID: 30557763 [PubMed - as supplied by publisher]