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The relationship between biological and psychosocial risk factors and resting-state functional connectivity in 2-month-old Bangladeshi infants: a feasibility and pilot study.

Thu, 04/25/2019 - 19:40
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The relationship between biological and psychosocial risk factors and resting-state functional connectivity in 2-month-old Bangladeshi infants: a feasibility and pilot study.

Dev Sci. 2019 Apr 23;:e12841

Authors: Turesky TK, Jensen SKG, Yu X, Kumar S, Wang Y, Sliva DD, Gagoski B, Sanfilippo J, Zöllei L, Boyd E, Haque R, Hafiz Kakon S, Islam N, Petri WA, Nelson CA, Gaab N

Abstract
Childhood poverty has been associated with structural and functional alterations in the developing brain. However, poverty does not alter brain development directly, but acts through associated biological or psychosocial risk factors (e.g., malnutrition, family conflict). Yet few studies have investigated risk factors in the context of infant neurodevelopment, and none have done so in low-resource settings such as Bangladesh, where children are exposed to multiple, severe biological and psychosocial hazards. In this feasibility and pilot study, usable resting-state fMRI data were acquired in infants from extremely poor (n=16) and (relatively) more affluent (n=16) families in Dhaka, Bangladesh. Whole-brain intrinsic functional connectivity (iFC) was estimated using bilateral seeds in the amygdala, where iFC has shown susceptibility to early life stress, and in sensory areas, which have exhibited less susceptibility to early life stress. Biological and psychosocial risk factors were examined for associations with iFC. Three resting-state networks were identified in within-group brain maps: medial temporal/striatal, visual, and auditory networks. Infants from extremely poor families compared to those from more affluent families exhibited greater (i.e., less negative) iFC in precuneus for amygdala seeds; however, no group differences in iFC were observed for sensory area seeds. Height-for-age, a proxy for malnutrition/infection, was not associated with amygdala/precuneus iFC, whereas prenatal family conflict was positively correlated. Findings suggest that it is feasible to conduct infant fMRI studies in low-resource settings. Challenges and practical steps for successful implementations are discussed. This article is protected by copyright. All rights reserved.

PMID: 31016808 [PubMed - as supplied by publisher]

Dynamic-flip-angle ECG-gating with nuisance signal regression improves resting-state BOLD functional connectivity mapping by reducing cardiogenic noise.

Thu, 04/25/2019 - 19:40
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Dynamic-flip-angle ECG-gating with nuisance signal regression improves resting-state BOLD functional connectivity mapping by reducing cardiogenic noise.

Magn Reson Med. 2019 Apr 24;:

Authors: Hu C, Tokoglu F, Scheinost D, Qiu M, Shen X, Peters DC, Galiana G, Constable RT

Abstract
PURPOSE: To investigate an ECG-gated dynamic-flip-angle BOLD sequence with improved robustness against cardiogenic noise in resting-state fMRI.
METHODS: ECG-gating minimizes the cardiogenic noise but introduces T1 -dependent signal variation, which is minimized by combination of a dynamic-flip-angle technique and retrospective nuisance signal regression (NSR) using signals of white matter, CSF, and global average. The technique was studied with simulations in a wide range of T1 and B1 fields and phantom imaging with pre-programmed TR variations. Resting-state fMRI of 20 healthy subjects was acquired with non-gated BOLD (NG), ECG-gated constant-flip-angle BOLD (GCFA), ECG-gated BOLD with retrospective T1 -correction (GRC), and ECG-gated dynamic-flip-angle BOLD (GDFA), all processed by the same NSR method. GDFA was compared to alternative methods over temporal SNR (tSNR), seed-based connectivity, and whole-brain voxelwise connectivity based on intrinsic connectivity distribution (ICD). A previous large-cohort data set (N = 100) was used as a connectivity gold standard.
RESULTS: Simulations and phantom imaging show substantial reduction of the T1 -dependent signal variation with GDFA alone, and further reduction with NSR. The resting-state study shows improved tSNR in the basal brain, comparing GDFA to NG, after both processed with NSR. Furthermore, GDFA significantly improved subcortical-subcortical and cortical-subcortical connectivity for several representative seeds and significantly improved ICD in the brainstem, thalamus, striatum, and prefrontal cortex, compared to the other 3 approaches.
CONCLUSION: GDFA with NSR improves mapping of the resting-state functional connectivity of the basal-brain regions by reducing cardiogenic noise.

PMID: 31016782 [PubMed - as supplied by publisher]

Hierarchical Structured Sparse Learning for Schizophrenia Identification.

Thu, 04/25/2019 - 19:40
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Hierarchical Structured Sparse Learning for Schizophrenia Identification.

Neuroinformatics. 2019 Apr 23;:

Authors: Wang M, Hao X, Huang J, Wang K, Shen L, Xu X, Zhang D, Liu M

Abstract
Fractional amplitude of low-frequency fluctuation (fALFF) has been widely used for resting-state functional magnetic resonance imaging (rs-fMRI) based schizophrenia (SZ) diagnosis. However, previous studies usually measure the fALFF within low-frequency fluctuation (from 0.01 to 0.08Hz), which cannot fully cover the complex neural activity pattern in the resting-state brain. In addition, existing studies usually ignore the fact that each specific frequency band can delineate the unique spontaneous fluctuations of neural activities in the brain. Accordingly, in this paper, we propose a novel hierarchical structured sparse learning method to sufficiently utilize the specificity and complementary structure information across four different frequency bands (from 0.01Hz to 0.25Hz) for SZ diagnosis. The proposed method can help preserve the partial group structures among multiple frequency bands and the specific characters in each frequency band. We further develop an efficient optimization algorithm to solve the proposed objective function. We validate the efficacy of our proposed method on a real SZ dataset. Also, to demonstrate the generality of the method, we apply our proposed method on a subset of Alzheimer's Disease Neuroimaging Initiative (ADNI) database. Experimental results on both datasets demonstrate that our proposed method achieves promising performance in brain disease classification, compared with several state-of-the-art methods.

PMID: 31016571 [PubMed - as supplied by publisher]

Dissociable effects of cannabis with and without cannabidiol on the human brain's resting-state functional connectivity.

Wed, 04/24/2019 - 22:37
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Dissociable effects of cannabis with and without cannabidiol on the human brain's resting-state functional connectivity.

J Psychopharmacol. 2019 Apr 23;:269881119841568

Authors: Wall MB, Pope R, Freeman TP, Kowalczyk OS, Demetriou L, Mokrysz C, Hindocha C, Lawn W, Bloomfield MA, Freeman AM, Feilding A, Nutt DJ, Curran HV

Abstract
BACKGROUND: Two major constituents of cannabis are Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD). THC is the main psychoactive component; CBD may buffer the user against the harmful effects of THC.
AIMS: We examined the effects of two strains of cannabis and placebo on the human brain's resting-state networks using fMRI.
METHODS: Seventeen healthy volunteers (experienced with cannabis, but not regular users) underwent three drug treatments and scanning sessions. Treatments were cannabis containing THC (Cann-CBD; 8 mg THC), cannabis containing THC with CBD (Cann+CBD; 8 mg THC + 10 mg CBD), and matched placebo cannabis. Seed-based resting-state functional connectivity analyses were performed on three brain networks: the default mode (DMN; defined by positive connectivity with the posterior cingulate cortex: PCC+), executive control (ECN; defined by negative connectivity with the posterior cingulate cortex: PCC-) and salience (SAL; defined by positive connectivity with the anterior insula: AI+) network.
RESULTS: Reductions in functional connectivity (relative to placebo) were seen in the DMN (PCC+) and SAL (AI+) networks for both strains of cannabis, with spatially dissociable effects. Across the entire salience network (AI+), Cann-CBD reduced connectivity relative to Cann+CBD. The PCC in the DMN was specifically disrupted by Cann-CBD, and this effect correlated with subjective drug effects, including feeling 'stoned' and 'high'.
CONCLUSIONS: THC disrupts the DMN, and the PCC is a key brain region involved in the subjective experience of THC intoxication. CBD restores disruption of the salience network by THC, which may explain its potential to treat disorders of salience such as psychosis and addiction.

PMID: 31013455 [PubMed - as supplied by publisher]

Altered functional connectivity of dentate nucleus in parkinsonian and cerebellar variants of multiple system atrophy.

Wed, 04/24/2019 - 22:37
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Altered functional connectivity of dentate nucleus in parkinsonian and cerebellar variants of multiple system atrophy.

Brain Imaging Behav. 2019 Apr 23;:

Authors: Yang H, Wang N, Luo X, Lv H, Liu H, Fan G

Abstract
The cerebellum is known to influence cerebral cortical activity via cerebello-thalamo-cortical (CTC) circuits and thereby may be implicated in the pathophysiology of multiple system atrophy (MSA). As the aim of this study, we investigated the abnormalities of corticocerebellar functional connectivity (FC) in patients with two variants of MSA. Resting-state functional magnetic resonance imaging (rs-fMRI) studies were obtained from 55 patients with MSA, including Parkinsonian (MSAp, n = 29) and cerebellar (MSAc, n = 26) variants. We also examined a similar number of healthy controls (HC, n = 51). Seed-based connectivity analysis was performed to assess alterations in CTC circuits. Relations between FC and clinical scores were assessed as well. Compared with the HC group, diminished FC was evident from bilateral dentate nucleus (DN) to motor cortex, bilateral basal ganglia, right cerebellum, default mode network (DMN), and limbic system in patients with MSAc. Patients with MSAp (vs HC subjects) showed less FC from left DN to right putamen, DMN, and limbic systems. Reduced FC was also demonstrated from left DN to DMN in patients with MSAc (vs MSAp), as well as from right DN to right cerebellum, DMN, basal ganglia, motor cortex, and limbic systems. In addition, the extent of FC from right DN to right cerebellum negatively correlated with Unified Parkinson's Disease Rating Scale-III scores in patients with MSA, while showing a positive association with Montreal Cognitive Assessment scores. The FC of DN was similarly altered in patients with MSAc and MSAp, although right cerebellar and motor cortical changes were more widespread in the MSAc group. There may be differing mechanisms of cerebellar functional activity responsible for motor and cognitive impairment, which should be further investigated.

PMID: 31011950 [PubMed - as supplied by publisher]

Aberrant Interhemispheric Functional Organization in Children with Dyskinetic Cerebral Palsy.

Wed, 04/24/2019 - 22:37
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Aberrant Interhemispheric Functional Organization in Children with Dyskinetic Cerebral Palsy.

Biomed Res Int. 2019;2019:4362539

Authors: Qin Y, Sun B, Zhang H, Li Y, Zhang T, Luo C, Sun C, Yao D

Abstract
Background: Hemispheric asymmetry is one fundamental principle of neuronal organization. Interhemispheric connectivity and lateralization of intrinsic networks in the resting-state brain demonstrate the interhemispheric functional organization and can be affected by disease processes. This study aims to investigate the interhemispheric organization in children with dyskinetic cerebral palsy (DCP) based on resting-state functional MRI (fMRI).
Methods: 24 children with DCP and 20 healthy children were included. Voxel-mirrored homotopic connectivity (VMHC) was calculated to detect the interhemispheric connectivity, and the lateralization of the resting-state networks was performed to examine the asymmetry of the intrinsic networks of brain.
Results: Decreased interhemispheric connectivity was found at visual, motor, and motor-control related regions in children with DCP, while high cognitive related networks including the central executive network, the frontoparietal network, and the salience network represented decreased asymmetry in children with DCP. Abnormal VMHC in visual areas, as well as the altered lateralization in inferior parietal lobule and supplementary motor area, showed correlation with the gross motor function and activities of daily living in children with DCP.
Conclusion: These findings indicate that the interhemispheric functional organization alteration exists in children with DCP, suggesting that abnormal interhemispheric interaction may be a pathophysiological mechanism of motor and cognitive dysfunction of CP.

PMID: 31011574 [PubMed - in process]

Acupuncture Reversible Effects on Altered Default Mode Network of Chronic Migraine Accompanied with Clinical Symptom Relief.

Wed, 04/24/2019 - 22:37
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Acupuncture Reversible Effects on Altered Default Mode Network of Chronic Migraine Accompanied with Clinical Symptom Relief.

Neural Plast. 2019;2019:5047463

Authors: Zou Y, Tang W, Li X, Xu M, Li J

Abstract
Objective: To determine whether and how longitudinal acupuncture modulates the impaired default mode network (DMN) in chronic migraine (CM) patients without aura.
Methods: Resting-state functional magnetic resonance imaging (fMRI) data from 14 CM patients treated with longitudinal pre- and postacupuncture treatment (PPAT) and data of 18 age- and gender-matched healthy controls (HCs) were analyzed using independent component analysis (ICA) and seed-based correlation analysis (SCA) to investigate connectivity within the DMN. Correlation analyses were performed to identify associations between changes in functional connectivity (FC) and in clinical pain based on PPAT observations. The monthly mean visual analog scale (VAS) scores, monthly mean headache attacks, monthly headache days, monthly amount of acute headache medications, and immediate VAS scores were assessed for evaluation of pain.
Results: The decreased FC within the DMN found in the left superior prefrontal gyrus (L_SPFG) and left precuneus (L_PRECUN) of CM patients was returned to the healthy control level after acupuncture treatments. Furthermore, the diminished pairwise FC strengths in some regions of interest (ROIs) within the DMN were also increased, mainly distributed between the right temporal lobe (R_TPL) and left anterior cingulate cortex, between the R_TPL and bilateral superior medial gyrus, and between the R_TPL and right precuneus. Increased z-scores within the DMN (L_SPFG and L_PRECUN) were associated with reduced immediate VAS scores, and increases in z-scores of the L_PRECUN were negatively correlated with reductions in the monthly amount of acute headache medications. However, no association existed between the increased DMN connectivity and reduced monthly mean VAS scores, monthly mean headache attacks, and monthly headache days.
Conclusion: Altered DMN connectivity and its normalization postacupuncture can be employed to monitor CM and its modulating effects. The DMN is useful for understanding the therapeutic mechanisms of acupuncture in CM.

PMID: 31011330 [PubMed - in process]

Altered whole brain functional connectivity pattern homogeneity in medication-free major depressive disorder.

Tue, 04/23/2019 - 22:36
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Altered whole brain functional connectivity pattern homogeneity in medication-free major depressive disorder.

J Affect Disord. 2019 Apr 08;253:18-25

Authors: Wang L, Yu L, Wu F, Wu H, Wang J

Abstract
BACKGROUND: Many previous studies have revealed abnormal functional connectivity patterns between brain areas underlying the onset of major depressive disorder (MDD) using resting-state functional magnetic resonance imaging (rs-fMRI). However, how to exactly characterize the voxel-wise whole brain functional connectivity pattern changes in MDD remains unclear, which will provide more convincing evidence for localizing the exactly functional connectivity abnormality in MDD.
METHODS: In this study, we employed our newly developed whole brain functional connectivity homogeneity (FcHo) method to identify the voxel-wise changes of functional connectivity patterns in 27 medication-free MDD patients and 34 gender-, age-, and education level-matched healthy controls (HC). Furthermore, seed-based functional connectivity analysis was then used to identify the alteration of corresponding functional connectivity.
RESULTS: Significantly decreased FcHo values in right ventral anterior insula (INS) and medial prefrontal cortex (MPFC) were identified in MDD patients. The ensuing functional connectivity analyses identified decreased functional connectivity between MPFC and left angular gyrus (AG) in MDD patients. Moreover, both decreased FcHo values in INS, MPFC and functional connectivity between MPFC and left AG showed significant negative correlations with Hamilton depression rating scale (HDRS) scores. The FcHo values in INS were also negatively correlated with disease duration. Finally, meta-analysis based functional characterization found that these brain areas are mainly involved in emotion, theory of mind and reward processing.
CONCLUSIONS: Our findings revealed abnormal whole brain FcHo in INS and MPFC and functional interactions between MPFC and AG in MDD and suggested that dysfunctions of INS and MPFC play an important role in the neuropathology of MDD.

PMID: 31009844 [PubMed - as supplied by publisher]

Fractional Amplitude of Low-Frequency Fluctuations and Functional Connectivity in Comatose Patients Subjected to Resting-State Functional Magnetic Resonance Imaging.

Tue, 04/23/2019 - 22:36
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Fractional Amplitude of Low-Frequency Fluctuations and Functional Connectivity in Comatose Patients Subjected to Resting-State Functional Magnetic Resonance Imaging.

Ann Indian Acad Neurol. 2019 Apr-Jun;22(2):203-209

Authors: Huang L, Zheng Y, Zeng Z, Li M, Zhang L, Gao Y

Abstract
Objective: The objective of the study is to investigate the changes of fractional amplitude of low-frequency fluctuations (fALFFs) and functional connectivity (FC) in the brain function of comatose patients with resting-state blood-oxygenation-level-dependent functional magnetic resonance imaging (BOLD-fMRI) and to discuss the underlying neurophysiological mechanism of disease.
Materials and Methods: Resting-state BOLD-fMRI scans were conducted on 20 comatose patients and 20 age-matched and gender-matched controls. The differences of fALFF between two groups were analyzed with two-sample t-test; significant differences of connectivity between groups were acquired to calculate the FC of the precuneus with other brain regions.
Results: Compared to the control group, the comatose patients exhibited a significant reduction in fALFF in various areas, including the right cingulate gyrus, left precuneus, right inferior parietal lobule, right superior parietal lobule, bilateral anterior/posterior central gyrus, middle frontal gyrus, right superior frontal gyrus, right superior temporal gyrus, and the bilateral cerebellar hemispheres (P < 0.05, Alphasim correction). Compared with controls, the brain region FC correlated with the precuneus reduced mainly located in the bilateral inferior parietal lobule, posterior central gyrus, lenticular nucleus, left anterior central gyrus, left medial frontal gyrus, left anterior lobe of the cerebellum, right insula, right transverse temporal gyri, and right thalamus. Regions whose FC increased include the left superior frontal gyrus, left side of the callosum, left superior parietal lobule, and both sides of the cingulate (P < 0.05, Alphasim correction).
Conclusion: Measurements of fALFF and FC obtained by resting-state BOLD-fMRI could provide considerable information for the analysis and evaluation of the brain function of comatose patients from the perspective of local function and global functional network and provide the theoretical basis for the study of coma nerve physiological mechanism.

PMID: 31007434 [PubMed]

Dynamic reconfiguration of the functional brain network after musical training in young adults.

Tue, 04/23/2019 - 01:35
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Dynamic reconfiguration of the functional brain network after musical training in young adults.

Brain Struct Funct. 2019 Apr 20;:

Authors: Li Q, Wang X, Wang S, Xie Y, Li X, Xie Y, Li S

Abstract
Musical performance strongly depends on continuous and dynamic information integration from the motor, sensory and cognitive systems. Musical training is an excellent model to investigate the plasticity of the dynamics in functional brain networks. Here, we compared the dynamics of the resting-state functional brain network in 29 healthy, young adults (13 males) before and after 24 weeks of piano training (all participants had been novices) with the functional brain network of 27 matched participants (13 males) who were also evaluated longitudinally but without any training. The sliding window approach was used to construct the time-varying functional networks, and the dynamics of 13 well-known functional systems were evaluated. The mean nodal flexibility of each functional system, which is a measure that captures changes in the local properties of the network, was calculated. In addition, the intrasystem connections, intersystem connections and their ratio for each functional system were also calculated. We found increased flexibility of the visual and auditory systems in participants after musical training when compared with the controls. Moreover, the visual system showed increased intrasystem and intersystem connections, and the auditory system showed increased intersystem connections and a decreased ratio of the intrasystem and intersystem connections in the training group after musical training. Furthermore, regression analysis revealed a positive correlation between the increased intersystem connections of the visual system and practice time in the training group. Our results indicated that the dynamics of the functional brain network can be changed by musical training, which provided new insights into the brain plasticity and functional architecture of the brain network.

PMID: 31006071 [PubMed - as supplied by publisher]

Autoconnectivity: A New Perspective on Human Brain Function.

Tue, 04/23/2019 - 01:35
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Autoconnectivity: A New Perspective on Human Brain Function.

J Neurosci Methods. 2019 Apr 18;:

Authors: Arbabshirani MR, Preda A, Vaidya JG, Potkin SG, Pearlson G, Voyvodic J, Mathalon D, van Erp T, Michael A, Kiehl KA, Turner JA, Calhoun VD

Abstract
BACKGROUND: Autocorrelation (AC) in fMRI time-series is a well-known phenomenon, typically attributed to colored noise and therefore removed from the data. We hypothesize that AC reflects systematic and meaningful signal fluctuations that may be tied to neural activity and provide evidence to support this hypothesis.
NEW METHOD: Each fMRI time-series is modeled as an autoregressive process from which the autocorrelation is quantified. Then, autocorrelation during resting-state fMRI and auditory oddball (AOD) task in schizophrenia and healthy volunteers is examined.
RESULTS: During resting-state, AC was higher in the visual cortex while during AOD task, frontal part of the brain exhibited higher AC in both groups. AC values were significantly lower in specific brain regions in schizophrenia patients (such as thalamus during resting-state) compared to healthy controls in two independent datasets. Moreover, AC values had significant negative correlation with patients' symptoms. AC differences discriminated patients from healthy controls with high accuracy (resting-state).
COMPARISON WITH EXISTING METHODS: Contrary to most prior works, the results suggest AC shows meaningful patterns that are discriminative between patients and controls. Our results are in line with recent works attributing autocorrelation to feedback loop of brain's regulatory circuit.
CONCLUSIONS: Autoconnectivity is cognitive state dependent (resting-state vs. task) and mental state dependent (healthy vs. schizophrenia). The concept of autoconnectivity resembles a recurrent neural network and provides a new perspective of functional integration in the brain. These findings may have important implications for understanding of brain function in health and disease as well as for analysis of fMRI time-series.

PMID: 31005575 [PubMed - as supplied by publisher]

Functional connectivity disruption of the substantia nigra associated with cognitive impairment in acute mild traumatic brain injury.

Tue, 04/23/2019 - 01:35
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Functional connectivity disruption of the substantia nigra associated with cognitive impairment in acute mild traumatic brain injury.

Eur J Radiol. 2019 May;114:69-75

Authors: Lu L, Li F, Ma Y, Chen H, Wang P, Peng M, Chen YC, Yin X

Abstract
PURPOSE: Mild traumatic brain injury is known to have frequent cognitive impairment. Accumulating evidence is pointing to the malfunctioning of the substantia nigra (SN) as an important factor for head trauma. However, it remains unknown whether changes in the SN-based resting state functional connectivity following mTBI at acute stage and its relationship with cognitive function.
MATERIALS AND METHODS: 58 patients with mTBI and 30 age-, gender-, and years of education-matched healthy controls were enrolled in the current study. All of participants received resting state functional magnetic resonance imaging as well as neuropsychological assessment. The resting state functional MR imaging data were analyzed by using a standard seed-based whole-brain correlation method to characterize SN resting state networks. Student t tests were used to perform comparisons. The association between SN resting state networks and performance on neuropsychological measures was also investigated in patients with mTBI by using Pearson rank correlation.
RESULTS: Patients with mTBI at acute stage exhibited reduced left SN-based functional connectivity with right insula and caudate and increased left SN-based functional connectivity with left precuneus and left middle occipital gyrus, and reduced right SN-based functional connectivity with left insula. Increased functional connectivity of left precuneus was negatively associated with neurocognitive functions as well (r = -0.266; P =  0.049).
CONCLUSION: The present study indicated that patients with acute mTBI suffer from disruption in their SN resting state networks. Moreover, abnormal functional connectivity significantly correlated with cognitive function. Taking together, these results may better improve our understanding of the neuropathological mechanism underlying the neurocognitive symptoms associated with acute mTBI.

PMID: 31005180 [PubMed - in process]

Impact of sampling rate on statistical significance for single subject fMRI connectivity analysis.

Sun, 04/21/2019 - 22:34
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Impact of sampling rate on statistical significance for single subject fMRI connectivity analysis.

Hum Brain Mapp. 2019 Apr 19;:

Authors: James O, Park H, Kim SG

Abstract
A typical time series in functional magnetic resonance imaging (fMRI) exhibits autocorrelation, that is, the samples of the time series are dependent. In addition, temporal filtering, one of the crucial steps in preprocessing of functional magnetic resonance images, induces its own autocorrelation. While performing connectivity analysis in fMRI, the impact of the autocorrelation is largely ignored. Recently, autocorrelation has been addressed by variance correction approaches, which are sensitive to the sampling rate. In this article, we aim to investigate the impact of the sampling rate on the variance correction approaches. Toward this end, we first derived a generalized expression for the variance of the sample Pearson correlation coefficient (SPCC) in terms of the sampling rate and the filter cutoff frequency, in addition to the autocorrelation and cross-covariance functions of the time series. Through simulations, we illustrated the importance of the variance correction for a fixed sampling rate. Using the real resting state fMRI data sets, we demonstrated that the data sets with higher sampling rates were more prone to false positives, in agreement with the existing empirical reports. We further demonstrated with single subject results that for the data sets with higher sampling rates, the variance correction strategy restored the integrity of true connectivity.

PMID: 31004386 [PubMed - as supplied by publisher]

Dependence of resting-state fMRI fluctuation amplitudes on cerebral cortical orientation relative to the direction of B0 and anatomical axes.

Sat, 04/20/2019 - 22:33
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Dependence of resting-state fMRI fluctuation amplitudes on cerebral cortical orientation relative to the direction of B0 and anatomical axes.

Neuroimage. 2019 Apr 16;:

Authors: Viessmann O, Scheffler K, Bianciardi M, Wald LL, Polimeni JR

Abstract
Functional magnetic resonance imaging (fMRI) is now capable of sub-millimetre scale measurements over the entire human brain, however with such high resolutions each voxel is influenced by the local fine-scale details of the cerebral cortical vascular anatomy. The cortical vasculature is structured with the pial vessels lying tangentially along the grey matter surface, intracortical diving arterioles and ascending venules running perpendicularly to the surface, and a randomly oriented capillary network within the parenchyma. It is well-known that the amplitude of the blood-oxygenation level dependent (BOLD) signal emanating from a vessel depends on its orientation relative to the B0field. Thus the vascular geometric hierarchy will impart an orientation dependence to the BOLD signal amplitudes and amplitude differences due to orientation differences constitute a bias for interpreting neuronal activity. Here, we demonstrate a clear effect of cortical orientation to B0in the resting-state BOLD-fMRI amplitude (quantified as the coefficient of temporal signal variation) for 1.1 mm, isotropic data at 7T and 2 mm, isotropic at 3T. The maximum bias, i.e. the fluctuation amplitude difference between regions where cortex is perpendicular to vs. parallel to B0, is about +70% at the pial surface at 7T and +11% at 3T. The B0orientation bias declines with cortical depth, becomes progressively smaller closer to the white matter surface, but then increases again to a local maximum within the white matter just beneath the cortical grey matter, suggesting a distinct tangential network of white matter vessels that also generate a BOLD orientation effect. We further found significant (negative) biases with the cortex orientation to the anterior-posterior anatomical axis of the head: a maximum negative bias of about -30% at the pial surface at 7T and about -13% at 3T. The amount of signal variance explained by the low frequency drift, motion and the respiratory cycle also showed a cortical orientation dependence; only the cardiac cycle induced signal variance was independent of cortical orientation, suggesting that the cardiac induced component of the image time-series fluctuations is not related to a significant change in susceptibility. Although these orientation effects represent a signal bias, and are likely to be a nuisance in high-resolution analyses, they may help characterize the vascular influences on candidate fMRI acquisitions and, thereby, may be exploited to improve the neuronal specificity of fMRI.

PMID: 31002965 [PubMed - as supplied by publisher]

Spontaneous variation in electrocorticographic resting state connectivity.

Sat, 04/20/2019 - 22:33
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Spontaneous variation in electrocorticographic resting state connectivity.

Brain Connect. 2019 Apr 19;:

Authors: Casimo K, Madhyastha TM, Ko A, Brown AB, Grassia F, Ojemann J, Weaver K

Abstract
Prior studies using fMRI, electroencephalography, and magnetoencephalography have observed not only structured patterns in resting state functional connectivity, but also spontaneous longitudinal variation in connectivity patterns not specifically linked to a task. In this first study using electrocorticography, we characterized spontaneous, inter-session variation in resting state functional connectivity not linked to a task. We evaluated pairwise connectivity between electrodes using three measures (phase locking value, amplitude correlation, and coherence) for six canonical frequency bands, aimed at capturing different characteristics of time-evolving signals. We grouped electrodes into ten functional brain regions and used intraclass correlation to estimate longitudinal stability across pairwise connections. We found that stronger phase locking (PLV ≥0.4) in theta through gamma bands and strong correlation in all bands (R^2s ≥0.6) is linked to substantial stability (ICC ≥0.6), but that stability is not necessarily linked to strong phase locking or amplitude correlation. There was no notable link between strong connectivity and high ICC in coherence. In individual regions' phase locking, we note that all within-region connections are markedly stable across frequencies. Additionally, we examined broad patterns of interactions across several functional regions: parahippocampal-entorhinal cortex is characterized by stable yet weak functional connectivity except self-connections. Dorsolateral prefrontal cortex connectivity is weak and unstable, also except self-connections. Inferior parietal lobule has little stability within narrow connectivity bounds. We confirm prior studies linking functional connectivity strength and inter-session variability in resting state connectivity, and extend those findings into higher frequencies than other modalities, with greater spatial specificity than scalp electrophysiology. We suggest that further studies quantitatively compare electrocorticography to other modalities and/or use these findings as a baseline to capture functional connectivity and functional dynamics linked to perturbations attributable to a task or disease state.

PMID: 31002014 [PubMed - as supplied by publisher]

Aberrant Brain Function in Active-Stage Ulcerative Colitis Patients: A Resting-State Functional MRI Study.

Sat, 04/20/2019 - 22:33
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Aberrant Brain Function in Active-Stage Ulcerative Colitis Patients: A Resting-State Functional MRI Study.

Front Hum Neurosci. 2019;13:107

Authors: Fan W, Zhang S, Hu J, Liu B, Wen L, Gong M, Wang G, Yang L, Chen Y, Chen H, Guo H, Zhang D

Abstract
Background: Patients with ulcerative colitis (UC) usually display cognitive impairments, such as memory loss, attention deficits, and declining executive functions, particularly during the active stage of the disease. However, the potential neurological mechanisms of these symptoms remain unclear. Method: Forty-one patients with mildly to moderately active UC, as well as 42 matched healthy controls, were recruited for an examination using psychological scales, cognitive function tests and resting-state functional magnetic resonance imaging (rs-fMRI). Seed points were identified via analysis of amplitude of low-frequency fluctuation (ALFF), and functional connectivity (FC) was calculated between these seed regions and other voxels in the whole brain. Correlation analyses were performed among clinical indexes, neuropsychological assessments and neuroimaging data. Result: Compared with the healthy controls, patients with UC exhibited lower ALFF values in the bilateral hippocampal/parahippocampal (HIPP/ParaHIPP) region and higher ALFF values in the left posterior cingulate cortex (PCC.L) and left middle frontal gyrus (MFG.L). With HIPP/ParaHIPP as the seed point, the strengths of the FC in the bilateral middle frontal gyri (MFG), anterior cingulate cortex (ACC), and left caudate nucleus (CAU.L) increased; using the PCC.L as the seed point, the strengths of the FC in the middle cingulate cortex (MCC) and the left angular gyrus (AUG.L) increased. These abnormal brain regions were mainly located in the limbic system. By analyzing the correlations between these brain regions and behavioral data, we observed a close correlation between decreased HIPP/ParaHIPP activity and memory loss; increased PCC activity and strength of FC with the AUG.L were related to dysfunction of executive function and attention network in patients with UC. Conclusion: Based on these results, the limbic lobe might be the core of the brain-gut axis (BGA) and play an important role in cognitive impairments, suggesting potential mechanisms for cognitive impairment in patients with UC in the active stage of the disease.

PMID: 31001097 [PubMed]

Sampling Rate Effects on Resting State fMRI Metrics.

Sat, 04/20/2019 - 22:33
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Sampling Rate Effects on Resting State fMRI Metrics.

Front Neurosci. 2019;13:279

Authors: Huotari N, Raitamaa L, Helakari H, Kananen J, Raatikainen V, Rasila A, Tuovinen T, Kantola J, Borchardt V, Kiviniemi VJ, Korhonen VO

Abstract
Low image sampling rates used in resting state functional magnetic resonance imaging (rs-fMRI) may cause aliasing of the cardiorespiratory pulsations over the very low frequency (VLF) BOLD signal fluctuations which reflects to functional connectivity (FC). In this study, we examine the effect of sampling rate on currently used rs-fMRI FC metrics. Ultra-fast fMRI magnetic resonance encephalography (MREG) data, sampled with TR 0.1 s, was downsampled to different subsampled repetition times (sTR, range 0.3-3 s) for comparisons. Echo planar k-space sampling (TR 2.15 s) and interleaved slice collection schemes were also compared against the 3D single shot trajectory at 2.2 s sTR. The quantified connectivity metrics included stationary spatial, time, and frequency domains, as well as dynamic analyses. Time domain methods included analyses of seed-based functional connectivity, regional homogeneity (ReHo), coefficient of variation, and spatial domain group level probabilistic independent component analysis (ICA). In frequency domain analyses, we examined fractional and amplitude of low frequency fluctuations. Aliasing effects were spatially and spectrally analyzed by comparing VLF (0.01-0.1 Hz), respiratory (0.12-0.35 Hz) and cardiac power (0.9-1.3 Hz) FFT maps at different sTRs. Quasi-periodic pattern (QPP) of VLF events were analyzed for effects on dynamic FC methods. The results in conventional time and spatial domain analyses remained virtually unchanged by the different sampling rates. In frequency domain, the aliasing occurred mainly in higher sTR (1-2 s) where cardiac power aliases over respiratory power. The VLF power maps suffered minimally from increasing sTRs. Interleaved data reconstruction induced lower ReHo compared to 3D sampling (p < 0.001). Gradient recalled echo-planar imaging (EPI BOLD) data produced both better and worse metrics. In QPP analyses, the repeatability of the VLF pulse detection becomes linearly reduced with increasing sTR. In conclusion, the conventional resting state metrics (e.g., FC, ICA) were not markedly affected by different TRs (0.1-3 s). However, cardiorespiratory signals showed strongest aliasing in central brain regions in sTR 1-2 s. Pulsatile QPP and other dynamic analyses benefit linearly from short TR scanning.

PMID: 31001071 [PubMed]

Patterns of on-task thought in older age are associated with changes in functional connectivity between temporal and prefrontal regions.

Sat, 04/20/2019 - 01:32
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Patterns of on-task thought in older age are associated with changes in functional connectivity between temporal and prefrontal regions.

Brain Cogn. 2019 Apr 15;132:118-128

Authors: Martinon LM, Riby LM, Poerio G, Wang HT, Jefferies E, Smallwood J

Abstract
Humans spend a large proportion of their time engaged in thoughts unrelated to the task being performed, a tendency that declines with age. However, a clear neuro-cognitive account of what underlies this decrease is lacking. This study addresses the possibility that age-related changes in off-task thinking are correlated with changes in the intrinsic organisation of the brain. Laboratory measures of ongoing thought were recorded in young and older individuals, who also participated in a resting state fMRI experiment. Older individuals showed reduced connectivity between the left anterior temporal lobe with prefrontal aspects of the DMN. We found that off-task thinking did not increase when task demands were lower for older adults, which is a pattern repeatedly seen in younger individuals. Finally, we demonstrated that these neural and thought patterns were linked - for younger participants only, reductions in the strength of connectivity were related to a greater shift towards off-task thoughts when task demands decreased. Importantly, in the older individuals, lower connectivity between the same regions was linked to preserved performance on a creativity task. These data suggest that the age-related reduction of off-task thought may be related to reduced communication between temporal and prefrontal DMN regions in ageing.

PMID: 30999087 [PubMed - as supplied by publisher]

Functional Connectivity Pattern in the Core Face Network Reflects Different Mechanisms of Holistic Face Processing Measured by the Whole-Part Effect and Composite-Face Effect.

Sat, 04/20/2019 - 01:32
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Functional Connectivity Pattern in the Core Face Network Reflects Different Mechanisms of Holistic Face Processing Measured by the Whole-Part Effect and Composite-Face Effect.

Neuroscience. 2019 Apr 15;:

Authors: Li J, Song Y, Liu J

Abstract
Holistic face processing is a critical component of face recognition. There are two classical measures of holistic face processing: the whole-part effect (WPE) and composite-face effect (CFE). However, the two effects have demonstrated inconsistent pattern of results in behavioral literature. Here, to address whether the WPE and CFE tap different mechanisms of holistic face processing, we examined the neural basis of the two effects at network level in a large sample of participants. With a voxel-wise global brain connectivity approach based on resting-state fMRI, we calculated the within network connectivity (WNC) of each voxel in the core face network (CFN). We found that a cluster in the right occipital face area (rOFA) showed positive correlation between its WNC and the WPE, while a cluster in the right fusiform face area (rFFA) showed negative correlation between its WNC and the CFE. These results suggested that the WPE was related to integration of the rOFA within the CFN, while the CFE was associated with separation of the rFFA from other CFN regions. Further analyses showed that higher WPE was related to stronger connection between the rOFA and bilateral posterior superior temporal sulcus (pSTS), while larger CFE was associated with weaker connection between the rFFA and bilateral pSTS. In short, our study reveals distinct neural correlates of the two hallmarks of holistic face processing at network level and sheds new light on the different mechanisms of holistic face processing reflected by the two effects.

PMID: 30999034 [PubMed - as supplied by publisher]

Functional connectome from phase synchrony at resting state is a neural fingerprint.

Sat, 04/20/2019 - 01:32
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Functional connectome from phase synchrony at resting state is a neural fingerprint.

Brain Connect. 2019 Apr 18;:

Authors: Zhang R, Kranz G, Lee TMC

Abstract
Coherent oscillatory activity across brain regions provides a variety of individual-specific characteristics, sometimes referred to as a neural fingerprint. This information, however, may not be directly retrieved from raw fMRI time series. In this study, we examined the data of 205 participants who completed two resting-state fMRI scanning sessions, separated by an average of 2.63 years. In the first step, we tested the long-term reliability of functional connectomes derived from amplitude-based functional connectivity (the conventional method) and found that they remained accurate markers (> 85%, p < 0.001, permutation test) for identifying individuals, even after a period longer than 800 days. Using the same data set, we further expanded our exploration of the extent to which two analytic components of oscillatory activity (amplitude envelope and instantaneous phase) may function as reliable fingerprints. Both analytic signals-in particular, the instantaneous phase-were identified as useful indices in shaping functional connectivity fingerprints (86%, p < 0.001, permutation test). Connectivity profiles derived from the ventral attention, frontoparietal, and default mode networks (DMNs) were the largest contributing factors to identification. The current results suggest that neural synchronization tapped by analytical signal from a low-frequency resting-state fMRI BOLD oscillation could be a reliable and useful fingerprint for identifying individuals and might provide an alternative method for characterizing dynamic functional connectivity profiles.

PMID: 30997813 [PubMed - as supplied by publisher]