New resting-state fMRI related studies at PubMed

Subscribe to New resting-state fMRI related studies at PubMed feed New resting-state fMRI related studies at PubMed
NCBI: db=pubmed; Term=resting state fMRI
Updated: 1 hour 57 min ago

Characteristics of respiratory measures in young adults scanned at rest, including systematic changes and "missed" deep breaths.

Tue, 10/08/2019 - 10:20

Characteristics of respiratory measures in young adults scanned at rest, including systematic changes and "missed" deep breaths.

Neuroimage. 2019 Oct 04;:116234

Authors: Power JD, Lynch CJ, Dubin MJ, Silver BM, Martin A, Jones RM

Abstract
Breathing rate and depth influence the concentration of carbon dioxide in the blood, altering cerebral blood flow and thus functional magnetic resonance imaging (fMRI) signals. Such respiratory fluctuations can have substantial influence in studies of fMRI signal covariance in subjects at rest, the so-called "resting state functional connectivity" technique. If respiration is monitored during fMRI scanning, it is typically done using a belt about the subject's abdomen to record abdominal circumference. Several measures have been derived from these belt records, including the windowed envelope of the waveform (ENV), the windowed variance in the waveform (respiration variation, RV), and a measure of the amplitude of each breath divided by the cycle time of the breath (respiration volume per time, RVT). Any attempt to gauge respiratory contributions to fMRI signals requires a respiratory measure, but little is known about how these measures compare to each other, or how they perform beyond the small studies in which they were initially proposed. Here, we examine the properties of these measures in hundreds of healthy young adults scanned for an hour each at rest, a subset of the Human Connectome Project chosen for having high-quality physiological records. We find: 1) ENV, RV, and RVT are all correlated, and ENV and RV are more highly correlated to each other than to RVT; 2) respiratory events like deep breaths exhibit characteristic heart rate elevations, fMRI signal changes, head motions, and image quality abnormalities time-locked to large deflections in the belt traces; 3) all measures can "miss" deep breaths; 4) RVT "misses" deep breaths more than ENV or RV; 5) all respiratory measures change systematically over the course of a 14.4-min scan. We discuss the implication of these findings for the literature and ways to move forward in modeling respiratory influences on fMRI scans.

PMID: 31589990 [PubMed - as supplied by publisher]

Meta-analytic and functional connectivity evidence from functional magnetic resonance imaging for an anterior to posterior gradient of function along the hippocampal axis.

Tue, 10/08/2019 - 10:20

Meta-analytic and functional connectivity evidence from functional magnetic resonance imaging for an anterior to posterior gradient of function along the hippocampal axis.

Hippocampus. 2019 Oct 07;:

Authors: Grady CL

Abstract
There is considerable evidence from non-human animal studies that the anterior and posterior regions of the hippocampus have different anatomical connections and support different behavioural functions. Although there are some recent human studies using functional magnetic resonance imaging (fMRI) that have addressed this idea directly in the memory and spatial processing domains and provided support for it, there has been no broader meta-analysis of the fMRI literature to determine if there is consistent evidence for functional dissociations in anterior and posterior hippocampus across all of the different cognitive domains in which the hippocampus participates. The purpose of this review is to address this gap in our knowledge using three approaches. One approach involved PubMed searches to identify relevant fMRI papers reporting hippocampal activation during episodic encoding and retrieval, semantic retrieval, working memory, spatial navigation, simulation/scene construction, transitive inference, and social cognition tasks. The second was to use a large meta-analytic database (neurosynth) to find text terms and coactivation maps associated with the anterior and posterior hippocampal regions identified in the literature search. The third approach was to contrast the resting-state functional connectivity of the anterior and posterior hippocampal regions using a publicly available database that includes a large sample of adults. These three approaches provided converging evidence that not only are cognitive processes differently distributed along the hippocampal axis, but there also are distinct areas coactivated and functionally connected with the anterior and posterior segments. This anterior/posterior distinction involving multiple cognitive domains is consistent with the animal literature and provides strong support from fMRI for the idea of functional dissociations across the long axis of the hippocampus.

PMID: 31589003 [PubMed - as supplied by publisher]

Increased resting-state functional connectivity in suprasellar tumor patients with postoperative visual improvement.

Tue, 10/08/2019 - 10:20

Increased resting-state functional connectivity in suprasellar tumor patients with postoperative visual improvement.

Int J Med Sci. 2019;16(9):1245-1253

Authors: Ying J, Li C, Yuan T, Jin L, Wang R, Zuo Z, Zhang Y

Abstract
Background and Objective: Large suprasellar tumors often compress the optic chiasm and give rise to visual impairment. Most patients have significantly improved visual function at 1 to 4 months after chiasmal decompression surgery, and only a few individuals regain normal vision at 1 week after surgery. How the recovery of visual function in these patients affects the visual cortex is not fully understood. In this study, we aimed to investigate alterations in brain functional connectivity (FC) in suprasellar tumor patients with visual improvement using resting-state functional magnetic resonance imaging (rs-fMRI). Methods: This longitudinal study was conducted on 13 suprasellar tumor patients who had ophthalmological examinations and rs-fMRI at the following time points: within 1-week preoperation (Pre-op), 1-week postoperation (Post-1w) and 1-month postoperation (Post-1m). The visual impairment score (VIS), local functional correlation (LCOR) and FC values were subjected to one-way ANOVA. Pearson correlation coefficients between changes in the LCOR and clinical factors were calculated. Results: The VIS was significantly decreased at both Post-1w and Post-1m compared to that at Pre-op. Whole-brain analysis of LCOR values showed that the left V1 (primary occipital cortex) was increased significantly at Post-1m compared to that at Pre-op (p < 0.05, FDR corrected). ROI analysis exhibited a significant negative correlation between the LCOR and VIS changes at Post-1m compared to those at Pre-op (p < 0.05, r = - 0.60). FC analysis within the visual network showed that the FC strengths were significantly increased between the left V5 and the left V4, right V3a, left V3, left V2d, and right V5 at Post-1m compared to those at Pre-op (p < 0.05, FDR corrected). Additionally, the FC strengths were significantly increased between the left V5 and the left V1, right orbital-frontal gyrus and left posterior supramarginal gyrus at the whole-brain network level at Post-1m compared to those at Pre-op (p < 0.05, FDR corrected). Conclusions: Postoperative visual improvement can be reflected by the increased FC of the visual cortex at Post-1w and Post-1m, especially at Post-1m. The LCOR value of the left V1 was associated with improved visual outcomes and may be used to objectively assess early visual recovery after chiasmal decompression at Post-1m.

PMID: 31588190 [PubMed - in process]

Applying a network framework to the neurobiology of reading and dyslexia.

Tue, 10/08/2019 - 10:20
Related Articles

Applying a network framework to the neurobiology of reading and dyslexia.

J Neurodev Disord. 2018 12 13;10(1):37

Authors: Bailey SK, Aboud KS, Nguyen TQ, Cutting LE

Abstract
BACKGROUND: There is a substantial literature on the neurobiology of reading and dyslexia. Differences are often described in terms of individual regions or individual cognitive processes. However, there is a growing appreciation that the brain areas subserving reading are nested within larger functional systems, and new network analysis methods may provide greater insight into how reading difficulty arises. Yet, relatively few studies have adopted a principled network-based approach (e.g., connectomics) to studying reading. In this study, we combine data from previous reading literature, connectomics studies, and original data to investigate the relationship between network architecture and reading.
METHODS: First, we detailed the distribution of reading-related areas across many resting-state networks using meta-analytic data from NeuroSynth. Then, we tested whether individual differences in modularity, the brain's tendency to segregate into resting-state networks, are related to reading skill. Finally, we determined whether brain areas that function atypically in dyslexia, as identified by previous meta-analyses, tend to be concentrated in hub regions.
RESULTS: We found that most resting-state networks contributed to the reading network, including those subserving domain-general cognitive skills such as attention and executive function. There was also a positive relationship between the global modularity of an individual's brain network and reading skill, with the visual, default mode and cingulo-opercular networks showing the highest correlations. Brain areas implicated in dyslexia were also significantly more likely to have a higher participation coefficient (connect to multiple resting-state networks) than other areas.
CONCLUSIONS: These results contribute to the growing literature on the relationship between reading and brain network architecture. They suggest that an efficient network organization, i.e., one in which brain areas form cohesive resting-state networks, is important for skilled reading, and that dyslexia can be characterized by abnormal functioning of hub regions that map information between multiple systems. Overall, use of a connectomics framework opens up new possibilities for investigating reading difficulty, especially its commonalities across other neurodevelopmental disorders.

PMID: 30541433 [PubMed - indexed for MEDLINE]

Dissociable Frontostriatal Connectivity: Mechanism and Predictor of the Clinical Efficacy of Capsulotomy in Obsessive-Compulsive Disorder.

Tue, 10/08/2019 - 10:20
Related Articles

Dissociable Frontostriatal Connectivity: Mechanism and Predictor of the Clinical Efficacy of Capsulotomy in Obsessive-Compulsive Disorder.

Biol Psychiatry. 2018 12 15;84(12):926-936

Authors: Yin D, Zhang C, Lv Q, Chen X, Zeljic K, Gong H, Zhan S, Jin H, Wang Z, Sun B

Abstract
BACKGROUND: Little is known about the neural mechanism and response variability underlying neurosurgical interventions for intractable obsessive-compulsive disorder (OCD).
METHODS: Of 81 OCD patients screened for capsulotomy identified in our institutional database, 36 patients with clinical assessment before and after capsulotomy and imaging data (9 of 36 patients without postoperative imaging data used as an independent test group), and 29 healthy control subjects were retrospectively recruited. Twenty of 36 patients (56%) responded to the lesion procedure (determined as a ≥35% reduction in Yale-Brown Obsessive Compulsive Scale [Y-BOCS] score). Seed-based (i.e., ventral and dorsal caudate, medial dorsal thalamus, and ventral and dorsal putamen) resting-state functional connectivity was used to examine alterations in frontostriatal circuitry after capsulotomy.
RESULTS: The Y-BOCS score significantly decreased (p < .001) after capsulotomy in OCD patients. Functional connectivity between the ventral striatum/nucleus accumbens and the dorsal anterior cingulate cortex was reduced (p < .05, corrected) after the surgical procedure. Moreover, change in connectivity significantly correlated with alteration in Y-BOCS score (r = .41, p = .033). In addition, preoperative connectivity between the dorsal caudate and the dorsal anterior cingulate cortex could differentiate nonresponders from responders and predict changes in Y-BOCS score (R2 = .23, F1,25 = 7.56, p = .011), which was generalized in an independent test group.
CONCLUSIONS: We demonstrated that restoration of ventral frontostriatal connectivity was associated with clinical improvement in refractory OCD, suggesting a therapeutic mechanism of capsulotomy. Moreover, preoperative variations in dorsal frontostriatal connectivity predicted clinical response, which may offer a predictor of treatment outcome.

PMID: 29778276 [PubMed - indexed for MEDLINE]

Insula-Retrosplenial Cortex Overconnectivity Increases Internalizing via Reduced Insight in Autism.

Tue, 10/08/2019 - 10:20
Related Articles

Insula-Retrosplenial Cortex Overconnectivity Increases Internalizing via Reduced Insight in Autism.

Biol Psychiatry. 2018 08 15;84(4):287-294

Authors: Hogeveen J, Krug MK, Elliott MV, Solomon M

Abstract
BACKGROUND: Internalizing symptoms like anxiety and depression are common and impairing in autism spectrum disorder (ASD). Here, we test the hypothesis that aberrant functional connectivity among three brain networks (salience network [SN], default mode network [DMN], and frontoparietal network [FPN]) plays a role in the pathophysiology of internalizing in ASD.
METHODS: We examined the association between resting-state functional connectivity and internalizing in 102 adolescents and young adults with ASD (n = 49) or typical development (n = 53). Seed-to-target functional connectivity was contrasted between adolescents and young adults with ASD and typically developing subjects using a recent parcellation of the human cerebral cortex, and connections that were aberrant in ASD were analyzed dimensionally as a function of parent-reported internalizing symptoms.
RESULTS: Three connections demonstrated robust overconnectivity in ASD: 1) the anterior insula to the retrosplenial cortex (i.e., SN-DMN), 2) the anterior insula to the frontal pole (i.e., SN-FPN), and 3) the dorsolateral prefrontal cortex to the retrosplenial cortex (i.e., FPN-DMN). These differences remained significant after controlling for age, and no age-related effects survived correction. The SN-DMN connection was associated with greater internalizing in ASD, mediated by a bigger difference between self- and parent-reported internalizing. Control analyses found that the other two connections were not associated with internalizing, and SN-DMN connectivity was not associated with a well-matched control measure (externalizing symptoms).
CONCLUSIONS: The present findings provide novel evidence for a specific link between SN-DMN overconnectivity and internalizing in ASD. Further, the mediation results suggest that intact anterior insula-retrosplenial connectivity may play a role in an individual's generating insight into his or her own psychopathology.

PMID: 29523413 [PubMed - indexed for MEDLINE]

Temporal stability of functional brain modules associated with human intelligence.

Mon, 10/07/2019 - 15:40
Related Articles

Temporal stability of functional brain modules associated with human intelligence.

Hum Brain Mapp. 2019 Oct 06;:

Authors: Hilger K, Fukushima M, Sporns O, Fiebach CJ

Abstract
Individual differences in general cognitive ability (i.e., intelligence) have been linked to individual variations in the modular organization of functional brain networks. However, these analyses have been limited to static (time-averaged) connectivity, and have not yet addressed whether dynamic changes in the configuration of brain networks relate to general intelligence. Here, we used multiband functional MRI resting-state data (N = 281) and estimated subject-specific time-varying functional connectivity networks. Modularity optimization was applied to determine individual time-variant module partitions and to assess fluctuations in modularity across time. We show that higher intelligence, indexed by an established composite measure, the Wechsler Abbreviated Scale of Intelligence (WASI), is associated with higher temporal stability (lower temporal variability) of brain network modularity. Post-hoc analyses reveal that subjects with higher intelligence scores engage in fewer periods of extremely high modularity - which are characterized by greater disconnection of task-positive from task-negative networks. Further, we show that brain regions of the dorsal attention network contribute most to the observed effect. In sum, our study suggests that investigating the temporal dynamics of functional brain network topology contributes to our understanding of the neural bases of general cognitive abilities.

PMID: 31587450 [PubMed - as supplied by publisher]

A common variant in OXTR rs53576 impacts topological patterns of brain functional networks.

Mon, 10/07/2019 - 15:40
Related Articles

A common variant in OXTR rs53576 impacts topological patterns of brain functional networks.

Eur Child Adolesc Psychiatry. 2019 Oct 05;:

Authors: Wang J, Zhang Y, Zhu D, Yang Z, Liu F, Qin W, Zhu J, Liu B, Jiang T, Yu C

Abstract
A common variant (rs53576, G/A) in the oxytocin receptor (OXTR) gene is associated with individual differences in social behavior and may increase the risk for neuropsychiatric disorders characterized by social impairment, especially autism. Although recent functional magnetic resonance imaging (fMRI) studies have identified functional connectivity alteration in some brain regions in risk A allele carriers, it is currently unknown whether this dysfunctional connectivity causes disruption of the topological properties of brain functional networks. We applied a graph-theoretical analysis to investigate the topological properties of brain networks derived from resting-state fMRI in relation to AA homozygotes versus G allele carriers in 290 cognitive normal young adults. We found both AA homozygotes and G allele carriers demonstrated small-world properties; however, male AA homozygotes showed lower normalized clustering coefficient, small-worldness, and local efficiency compared with male G allele carriers, no differences survived after Bonferroni correction; and the inter-group differences of all three metrics exhibited an allele-load-dependent trend (AA < AG < GG), indicating a randomization shift of their brain functional networks. No significant results were observed in any global measures in female AA homozygotes as compared to female G allele carriers. Our results suggested that the topological patterns of brain functional networks were altered in OXTR rs53576 male homozygotes for the risk A allele compared with male G allele carriers, providing evidence for the disruption of integrity in large-scale intrinsic brain networks in a sex-dimorphic manner.

PMID: 31587084 [PubMed - as supplied by publisher]

Comparison of resting-state functional connectivity in marmosets with tracer-based cellular connectivity.

Mon, 10/07/2019 - 15:40
Related Articles

Comparison of resting-state functional connectivity in marmosets with tracer-based cellular connectivity.

Neuroimage. 2019 Oct 03;:116241

Authors: Hori Y, Schaeffer DJ, Gilbert KM, Hayrynen LK, Cléry JC, Gati JS, Menon RS, Everling S

Abstract
Resting-state functional MRI (RS-fMRI) is widely used to assess how strongly different brain areas are connected. However, this connection obtained by RS-fMRI, which is called functional connectivity (FC), simply refers to the correlation of blood oxygen level-dependent (BOLD) signals across time it has yet to be quantified how accurately FC reflects cellular connectivity (CC). In this study, we elucidated this relationship using RS-fMRI and quantitative tracer data in marmosets. In addition, we also elucidated the effects of distance between two brain regions on the relationship between FC and CC across seed region. To calculate FC, we used full correlation approach that is considered to reflect not only direct (monosynaptic connections) but also indirect pathways (polysynaptic connections). Our main findings are that: (1) overall FC obtained by RS-fMRI was highly correlated with tracer-based CC, but correlation coefficients varied remarkably across seed regions; (2) the strength of FC decreased with increase in the distance between two regions; (3) correlation coefficients between FC and CC after regressing out the effects of the distance between two regions still varied across seed regions, but some regions have strong correlations. These findings suggest that although FC reflects the strength of monosynaptic pathways, it is strongly affected by the distance between regions.

PMID: 31586676 [PubMed - as supplied by publisher]

Connectomics-Based Functional Network Alterations in both Depressed Patients with Suicidal Behavior and Healthy Relatives of Suicide Victims.

Sun, 10/06/2019 - 14:40
Related Articles

Connectomics-Based Functional Network Alterations in both Depressed Patients with Suicidal Behavior and Healthy Relatives of Suicide Victims.

Sci Rep. 2019 Oct 04;9(1):14330

Authors: Wagner G, de la Cruz F, Köhler S, Pereira F, Richard-Devantoy S, Turecki G, Bär KJ, Jollant F

Abstract
Understanding the neural mechanisms of suicidal behavior is crucial. While regional brain alterations have previously been reported, knowledge about brain functional connectomics is currently limited. Here, we investigated differences in global topologic network properties and local network-based functional organization in both suicide attempters and suicide relatives. Two independent samples of depressed suicide attempters (N = 42), depressed patient controls (N = 43), healthy controls (N = 66) as well as one sample of healthy relatives of suicide victims (N = 16) and relatives of depressed patients (N = 16) were investigated with functional magnetic resonance imaging in the resting-state condition. Graph theory analyses were performed. Assortativity, clustering coefficients, global efficiency, and rich-club coefficients were calculated. A network-based statistic approach was finally used to examine functional connectivity matrices. In comparison to healthy controls, both patient groups showed significant reduction in assortativity, and decreased functional connectivity in largely central and posterior brain networks. Suicide attempters only differed from patient controls in terms of higher rich-club coefficients for the highest degree nodes. Compared to patient relatives and healthy controls, suicide relatives showed reduced assortativity, reduced clustering coefficients, increased global efficiency, and increased rich-club coefficients for the highest degree nodes. Suicide relatives also showed reduced functional connectivity in one anterior and one posterior sub-network in comparison to healthy controls, and in a largely anterior brain network in comparison to patient relatives. In conclusion, these results suggest that the vulnerability to suicidal behavior may be associated with heritable deficits in global brain functioning - characterized by weak resilience and poor segregation - and in functional organization with reduced connectivities affecting the ventral and dorsal prefrontal cortex, the anterior cingulate, thalamus, striatum, and possibly the insula, fusiform gyrus and the cerebellum.

PMID: 31586117 [PubMed - in process]

Multi-scale dynamics of spontaneous brain activity is associated with walking speed in older adults.

Sat, 10/05/2019 - 13:40
Related Articles

Multi-scale dynamics of spontaneous brain activity is associated with walking speed in older adults.

J Gerontol A Biol Sci Med Sci. 2019 Oct 05;:

Authors: Zhou J, Poole V, Wooten T, Lo OY, Iloputaife I, Manor B, Esterman M, Lipsitz LA

Abstract
BACKGROUND: In older adults, compromised white matter tract integrity within the brain has been linked to impairments in mobility. We contend that poorer integrity disrupts mobility by altering the processing of sensorimotor, cognitive and attentional resources in neural networks. The richness of information processing in a given network can be quantified by calculating the complexity of resting-state fMRI time-series. We hypothesized that: 1) older adults with lower brain complexity, specifically within sensorimotor, executive and attention networks, would exhibit slower walking speed and greater dual-task costs (i.e., DTC); and 2) such complexity would mediate the effect of white matter integrity on these metrics of mobility.
METHOD: Fifty-three older adults completed a walking assessment and a neuroimaging protocol. Brain complexity was quantified by calculating the multiscale entropy of the resting-state fMRI signal within seven previously defined functional networks. The white matter integrity across structures of the corpus callosum was quantified using fractional anisotropy (FA).
RESULTS: Participants with lower resting-state complexity within the sensorimotor, executive and attention networks walked more slowly under single- and dual-task (i.e., walking while performing a serial-subtraction task) conditions (β>0.28, p≤0.01) and had a greater DTC (β<-0.28, p<0.04). Complexity in these networks mediated the influence of the corpus callosum genu on both single- (indirect effects>0.15, 95% CIs=0.02~0.32) and dual-task walking speeds (indirect effects>0.13, 95% CIs=0.02~0.33).
CONCLUSION: These results suggest that the multi-scale dynamics of resting-state brain activity correlate with mobility and mediate the effect of the microstructural integrity in the corpus callosum genu on walking speed in older adults.

PMID: 31585008 [PubMed - as supplied by publisher]

Resting-state fMRI in disorders of consciousness to facilitate early therapeutic intervention.

Sat, 10/05/2019 - 13:40
Related Articles

Resting-state fMRI in disorders of consciousness to facilitate early therapeutic intervention.

Neurol Clin Pract. 2019 Aug;9(4):e33-e35

Authors: Boerwinkle VL, Torrisi SJ, Foldes ST, Marku I, Ranjan M, Wilfong AA, Adelson PD

PMID: 31583195 [PubMed]

Abnormalities of intrinsic regional brain activity in first-episode and chronic schizophrenia: a meta-analysis of resting-state functional MRI

Fri, 10/04/2019 - 12:20
Related Articles

Abnormalities of intrinsic regional brain activity in first-episode and chronic schizophrenia: a meta-analysis of resting-state functional MRI

J Psychiatry Neurosci. 2019 Oct 03;44(6):180245

Authors: Gong J, Wang J, Luo X, Chen G, Huang H, Huang R, Huang L, Wang Y

Abstract
Background: Resting-state functional MRI (fMRI) studies have provided much evidence for abnormal intrinsic brain activity in schizophrenia, but results have been inconsistent.
Methods: We conducted a meta-analysis of whole-brain, resting-state fMRI studies that explored differences in amplitude of low-frequency fluctuation (ALFF) between people with schizophrenia (including first episode and chronic) and healthy controls.
Results: A systematic literature search identified 24 studies comparing a total of 1249 people with schizophrenia and 1179 healthy controls. Overall, patients with schizophrenia displayed decreased ALFF in the bilateral postcentral gyrus, bilateral precuneus, left inferior parietal gyri and right occipital lobe, and increased ALFF in the right putamen, right inferior frontal gyrus, left inferior temporal gyrus and right anterior cingulate cortex. In the subgroup analysis, patients with first-episode schizophrenia demonstrated decreased ALFF in the bilateral inferior parietal gyri, right precuneus and left medial prefrontal cortex, and increased ALFF in the bilateral putamen and bilateral occipital gyrus. Patients with chronic schizophrenia showed decreased ALFF in the bilateral postcentral gyrus, left precuneus and right occipital gyrus, and increased ALFF in the bilateral inferior frontal gyri, bilateral superior frontal gyrus, left amygdala, left inferior temporal gyrus, right anterior cingulate cortex and left insula.
Limitations: The small sample size of our subgroup analysis, predominantly Asian samples, processing steps and publication bias could have limited the accuracy of the results.
Conclusion: Our comprehensive meta-analysis suggests that findings of aberrant regional intrinsic brain activity during the initial stages of schizophrenia, and much more widespread damage with the progression of disease, may contribute to our understanding of the progressive pathophysiology of schizophrenia.

PMID: 31580042 [PubMed - as supplied by publisher]

Weighted Graph Regularized Sparse Brain Network Construction for MCI Identification.

Fri, 10/04/2019 - 12:20
Related Articles

Weighted Graph Regularized Sparse Brain Network Construction for MCI Identification.

Pattern Recognit. 2019 Jun;90:220-231

Authors: Yu R, Qiao L, Chen M, Lee SW, Fei X, Shen D

Abstract
Brain functional networks (BFNs) constructed from resting-state functional magnetic resonance imaging (rs-fMRI) have been widely applied to the analysis and diagnosis of brain diseases, such as Alzheimer's disease and its prodrome, namely mild cognitive impairment (MCI). Constructing a meaningful brain network based on, for example, sparse representation (SR) is the most essential step prior to the subsequent analysis or disease identification. However, the independent coding process of SR fails to capture the intrinsic locality and similarity characteristics in the data. To address this problem, we propose a novel weighted graph (Laplacian) regularized SR framework, based on which BFN can be optimized by considering both intrinsic correlation similarity and local manifold structure in the data, as well as sparsity prior of the brain connectivity. Additionally, the non-convergence of the graph Laplacian in the self-representation model has been solved properly. Combined with a pipeline of sparse feature selection and classification, the effectiveness of our proposed method is demonstrated by identifying MCI based on the constructed BFNs.

PMID: 31579345 [PubMed]

Strength and Similarity Guided Group-level Brain Functional Network Construction for MCI Diagnosis.

Fri, 10/04/2019 - 12:20
Related Articles

Strength and Similarity Guided Group-level Brain Functional Network Construction for MCI Diagnosis.

Pattern Recognit. 2019 Apr;88:421-430

Authors: Zhang Y, Zhang H, Chen X, Liu M, Zhu X, Lee SW, Shen D

Abstract
Sparse representation-based brain functional network modeling often results in large inter-subject variability in the network structure. This could reduce the statistical power in group comparison, or even deteriorate the generalization capability of the individualized diagnosis of brain diseases. Although group sparse representation (GSR) can alleviate such a limitation by increasing network similarity across subjects, it could, in turn, fail in providing satisfactory separability between the subjects from different groups (e.g., patients vs. controls). In this study, we propose to integrate individual functional connectivity (FC) information into the GSR-based network construction framework to achieve higher between-group separability while maintaining the merit of within-group consistency. Our method was based on an observation that the subjects from the same group have generally more similar FC patterns than those from different groups. To this end, we propose our new method, namely "strength and similarity guided GSR (SSGSR)", which exploits both BOLD signal temporal correlation-based "low-order" FC (LOFC) and inter-subject LOFC-profile similarity-based "high-order" FC (HOFC) as two priors to jointly guide the GSR-based network modeling. Extensive experimental comparisons are carried out, with the rs-fMRI data from mild cognitive impairment (MCI) subjects and healthy controls, between the proposed algorithm and other state-of-the-art brain network modeling approaches. Individualized MCI identification results show that our method could achieve a balance between the individually consistent brain functional network construction and the adequately maintained inter-group brain functional network distinctions, thus leading to a more accurate classification result. Our method also provides a promising and generalized solution for the future connectome-based individualized diagnosis of brain disease.

PMID: 31579344 [PubMed]

Functional Connectivity Alterations in Neuromyelitis Optica Spectrum Disorder : Correlation with Disease Duration and Cognitive Impairment.

Fri, 10/04/2019 - 12:20
Related Articles

Functional Connectivity Alterations in Neuromyelitis Optica Spectrum Disorder : Correlation with Disease Duration and Cognitive Impairment.

Clin Neuroradiol. 2019 Oct 01;:

Authors: Han Y, Liu Y, Zeng C, Luo Q, Xiong H, Zhang X, Li Y

Abstract
PURPOSE: The aim of this study was to investigate resting state functional connectivity alterations within the main brain networks in neuromyelitis optica spectrum disorder (NMOSD) and their associations with disease duration, disability and cognitive dysfunction progression.
METHODS: Resting state functional magnetic resonance imaging (rs-fMRI), clinical and neuropsychological evaluations were obtained from 41 NMOSD patients and 41 healthy controls. Seed-voxel functional connectivity was analyzed in seven major hubs, including the default mode network, dorsal attention network, visual network, sensorimotor network, cerebellar network, thalamic network and reward-emotion network. Abnormalities of functional connectivity and correlations with disease duration, scores of the expanded disability status scale (EDSS), mini-mental state examination (MMSE) and Montreal cognitive assessment (MoCA) were further explored.
RESULTS: Compared with healthy controls, NMOSD patients showed increased functional connectivity in the default mode network, dorsal attention network and thalamic network, while decreased in the visual network and cerebellum networks. At the regional level, increased functional connectivity involved the right superior temporal gyrus, left fusiform gyrus, left inferior parietal lobule, bilateral middle frontal gyrus and right precuneus, whereas functional connectivity was decreased in the right parahippocampal gyrus and left precuneus. Functional connectivity reduction in the right parahippocampal gyrus positively correlated with disease duration (r = 0.488, p = 0.001) and negatively correlated with MoCA scores (r = -0.330, p = 0.035).
CONCLUSION: The study demonstrated functional alterations in the rs-fMRI of NMOSD, which provide a novel insight into the large-scale selective functional reorganization and could be useful to reveal the characteristics of the physiological mechanism.

PMID: 31578601 [PubMed - as supplied by publisher]

Stability of dynamic functional architecture differs between brain networks and states.

Thu, 10/03/2019 - 11:20
Related Articles

Stability of dynamic functional architecture differs between brain networks and states.

Neuroimage. 2019 Sep 29;:116230

Authors: Li L, Lu B, Yan CG

Abstract
Stable representation of information in distributed neural connectivity is critical to function effectively in the world. Despite the dynamic nature of the brain's functional architecture, characterizing its temporal stability within a continuous state has been largely neglected. Here we characterized stability of functional architecture at a dynamic timescale (∼1 min) for each brain voxel by measuring the concordance of dynamic functional connectivity (DFC) over time, compared between association and unimodal regions, and established its reliability using test-retest resting-state fMRI data of adults from an open dataset. After the measure of functional stability was established, we further employed another fMRI open dataset which included movie-watching and resting-state data of children and adolescents, to explore how stability was modified by natural viewing from its intrinsic form, with specific focus on the associative and primary visual cortices. The results showed that high-order association regions, especially the default mode network, demonstrated high stability during resting-state scans, while primary sensory-motor cortices revealed relatively lower stability. During movie watching, stability in the primary visual cortex was decreased, which was associated with larger DFC variation with neighboring regions. By contrast, higher-order regions in the ventral and dorsal visual stream demonstrated increased stability. The distribution of functional stability and its modification describes a profile of the brain's stability property, which may be useful reference for examining distinct mental states and disorders.

PMID: 31577959 [PubMed - as supplied by publisher]

Homotopic region connectivity during concussion recovery: A longitudinal fMRI study.

Thu, 10/03/2019 - 11:20
Related Articles

Homotopic region connectivity during concussion recovery: A longitudinal fMRI study.

PLoS One. 2019;14(10):e0221892

Authors: Chong CD, Wang L, Wang K, Traub S, Li J

Abstract
OBJECTIVES: To (i) investigate alterations in homotopic functional connectivity (hfc) in concussed patients relative to healthy controls (HC) and to (ii) interrogate whether hfc in concussed patients normalized during the recovery process. The relationship between symptom recovery and change in hfc was assessed using post-hoc analyses.
METHODS: This study included 15 concussed patients (mean age = 39.1, SD = 10.1; sex: 13 females, 2 males) and 15 HC (mean age = 39.1, SD = 11.7; sex: 13 females, 2 males). Hfc patterns were interrogated using resting-state magnetic resonance imaging (rs-MRI) for 29 a priori selected pain-processing regions. Concussed patients underwent imaging at two time-points; at 1-month post-concussion (mean time following concussion: 28 days, SD = 9.5) and again at 5-months post-concussion (mean time following concussion: 121 days, SD = 13). At both time-points, symptoms associated with concussion were assessed using the Sports Concussion Assessment Tool (SCAT-3).
RESULTS: Concussed patients had significantly weaker hfc in the following six regions 1-month post-concussion compared to HC: middle cingulate, posterior insula, middle occipital, spinal trigeminal nucleus, precentral and the pulvinar. There were no regions of significantly stronger hfc in concussed patients relative to HC. Longitudinally, patients showed significant symptom recovery 5-months post-concussion and had significant strengthening of hfc patterns in seven homotopic ROIs: middle cingulate, posterior insula, middle occipital, secondary somatosensory area, spinal trigeminal nucleus, precentral, and the pulvinar. Post-hoc analyses indicated a significant negative correlation between somatosensory functional connectivity strengthening and symptom severity.
CONCLUSION: At 1-month post-concussion, patients had significantly weaker hfc in a number of pain-processing regions relative to HC. However, over a period of 5-months, region-pair connectivity showed significant recovery and normalization. Those patients with more successful symptom recovery at 5-months post-concussion had more functional somatosensory strengthening, suggesting an association between functional strengthening and post-concussion symptom recovery.

PMID: 31577811 [PubMed - in process]

Power spectrum of resting-state blood-oxygen-level-dependent signal.

Thu, 10/03/2019 - 11:20
Related Articles

Power spectrum of resting-state blood-oxygen-level-dependent signal.

Phys Rev E. 2019 Aug;100(2-1):022418

Authors: Pang JC, Robinson PA

Abstract
Hemodynamic modeling is used to explore the origin, predict, and analyze the power spectrum of the resting-state blood-oxygen-level-dependent (BOLD) signal measured by functional magnetic resonance imaging (fMRI), which has been reported to have a power-law form, i.e., P(f)∝f^{-s}, where P(f) is the power, f is the frequency, and s>0 is the power-law exponent. However, current fMRI experimental paradigms have limited acquisition durations, affecting the spectral resolution of fMRI data at the low-frequency regime. Here, the claimed power-law spectrum is investigated by using a recent hemodynamic model to analytically derive the BOLD power spectrum, with parameters that are related to neurophysiology. The theoretical results show that, for all realistic parameter combinations, the BOLD power spectrum is flat at f≲0.01Hz, has a weak resonance originating from intrinsic oscillations of vasodilatory response, and becomes a power law for high frequencies, all of which is in agreement with an empirical data set that describes the spectrum of one subject and brain region. However, the results are contrary to studies reporting a pure power-law spectrum at f≲0.2Hz. The discrepancy is attributed largely to data averaging employed by current approaches that averages together important properties of the BOLD power spectrum, such as its resonance, that biases the spectrum to only show a power law. Data averaging also reduces the high-frequency power-law exponent relative to individual cases. Overall, this work demonstrates how the model can reproduce BOLD dynamics and further analyze its low-frequency behavior. Moreover, it also uses the model to explain the impact of procedures, such as data averaging, on the reported features of the BOLD power spectrum.

PMID: 31574765 [PubMed - in process]

Individualized functional networks reconfigure with cognitive state.

Wed, 10/02/2019 - 16:20

Individualized functional networks reconfigure with cognitive state.

Neuroimage. 2019 Sep 28;:116233

Authors: Salehi M, Karbasi A, Barron DS, Scheinost D, Constable RT

Abstract
There is extensive evidence that functional organization of the human brain varies dynamically as the brain switches between task demands, or cognitive states. This functional organization also varies across subjects, even when engaged in similar tasks. To date, the functional network organization of the brain has been considered static. In this work we use fMRI data obtained across multiple cognitive states (task-evoked and rest conditions) and across multiple subjects, to measure state- and subject-specific functional network parcellation (the assignment of nodes to networks). Our parcellation approach provides a measure of how node-to-network assignment (NNA) changes across states and across subjects. We demonstrate that the brain's functional networks are not spatially fixed, but that many nodes change their network membership as a function of cognitive state. Such reconfigurations are highly robust and reliable to the extent that they can be used to predict cognitive state with up to 97% accuracy. Our findings suggest that if functional networks are to be defined via functional clustering of nodes, then it is essential to consider that such definitions may be fluid and cognitive-state dependent.

PMID: 31574322 [PubMed - as supplied by publisher]

Pages