Showing papers in "Brain connectivity in 2018"
TL;DR: Results suggest that human PIVC and PIC share cortical and even subcortical connections, Nevertheless, they also differ in their primary connectivity pattern: PivC is linked with posterior parietal and inferior frontal cortex, whereas PIC is link with superior temporal and inferior parietal cortex.
Abstract: The parieto-insular vestibular cortex (PIVC) and the posterior insular cortex (PIC) are key regions of the cortical vestibular network, both located in the midposterior section of the lateral sulcus. Little is known about the structural connectivity pattern of these areas. We used probabilistic fiber tracking based on diffusion-weighted magnetic resonance imaging (MRI) and compared the ipsilateral connectivity of PIVC and PIC. Seed areas for the tracking algorithm were identified in each brain by functional MRI activity during caloric and visual motion stimulation, respectively. Cortical track terminations were investigated by a surface-based approach. Both PIVC and PIC shared ipsilateral connections to the insular/lateral sulcus, superior temporal cortex, and inferior frontal gyrus. However, PIVC showed significantly more connections than PIC with the anterior insula and Heschl's gyrus in both hemispheres and with the precuneus, intraparietal sulcus, and posterior callosum of the right hemisphere. In contrast, PIC connectivity was more pronounced with the supramarginal gyrus and superior temporal sulcus. Subcortical tracks were examined by a region-of-interest-based approach, which was validated on cortico-thalamic motor tracts. Both PIVC and PIC were connected with lateral nuclei of the thalamus and the basal ganglia (primarily putamen). PIVC tracks but not PIC tracks showed a right-hemispheric lateralization in cortical and subcortical connectivity. Overall, these results suggest that human PIVC and PIC share cortical and even subcortical connections. Nevertheless, they also differ in their primary connectivity pattern: PIVC is linked with posterior parietal and inferior frontal cortex, whereas PIC is linked with superior temporal and inferior parietal cortex.
35 citations
TL;DR: Overall, BTs appear to lead to various alterations in FC across different functional networks, and the most common change is a decrease in expected FC strength.
Abstract: Brain tumor (BT) patients often experience reduced cognitive abilities and disrupted adaptive functioning before and after treatment. An innovative approach to understanding the underlying brain networks associated with these outcomes has been to study the brain's functional connectivity (FC), the spatially distributed and temporally correlated activity throughout the brain, and how it can be affected by a tumor. The present review synthesized the extant BT FC literature that utilizes functional magnetic resonance imaging to study FC strength of commonly observed networks during rest and task. A systematic review of English articles using PubMed was conducted. Search terms included brain tumor OR glioma AND functional connectivity, independent component analysis, ICA, psychophysiological interaction, OR PPI. Studies in which participants were diagnosed with BTs as adults that evaluated specific networks of interest using independent component analysis or seed-based component analysis were included. Twenty-five studies met inclusion criteria. BT patients often presented with decreases in FC strength within well-established networks and increases in atypical FC patterns. Network differences were tumor adjacent and distal, and left hemisphere tumors generally had a greater impact on FC. FC alterations often correlated with behavioral or cognitive outcomes when assessed. Overall, BTs appear to lead to various alterations in FC across different functional networks, and the most common change is a decrease in expected FC strength. More longitudinal studies are needed to determine the time course of network alterations across treatment and recovery, the role of medical treatments in BT survivors' FC, and the potential of FC patterns as biomarkers of cognitive outcomes.
34 citations
TL;DR: Connectome disruption was consistent with a pattern of delayed neurodevelopment that may be associated with reduced resilience, adaptability, and flexibility of the brain network and highlight the need for interventions that will prevent or manage cognitive impairment in survivors of pediatric acute lymphoblastic leukemia.
Abstract: Chemotherapeutic agents used to treat acute lymphoblastic leukemia (ALL), the most common cancer affecting young children, have been associated with long-term cognitive impairments that re...
33 citations
TL;DR: A strong presence of alterations in VIS regions less commonly observed in previous reports is identified and provides a step forward in understanding FNC dysfunction in HDgmc.
Abstract: Huntington's disease (HD) is an inherited brain disorder characterized by progressive motor, cognitive, and behavioral dysfunctions. It is caused by abnormally large trinucleotide cytosine-adenine-guanine (CAG) repeat expansions on exon 1 of the Huntingtin gene. CAG repeat length (CAG-RL) inversely correlates with an earlier age of onset. Region-based studies have shown that HD gene mutation carrier (HDgmc) individuals (CAG-RL ≥36) present functional connectivity alterations in subcortical (SC) and default mode networks. In this analysis, we expand on previous HD studies by investigating associations between CAG-RL and connectivity in the whole brain, as well as between CAG-dependent connectivity and motor and cognitive performances. We used group-independent component analysis on resting-state functional magnetic resonance imaging scans of 261 individuals (183 HDgmc and 78 healthy controls) from the PREDICT-HD study, to obtain whole-brain resting state networks (RSNs). Regression analysis was applied within and between RSNs connectivity (functional network connectivity [FNC]) to identify CAG-RL associations. Connectivity within the putamen RSN is negatively correlated with CAG-RL. The FNC between putamen and insula decreases with increasing CAG-RL, and also shows significant associations with motor and cognitive measures. The FNC between calcarine and middle frontal gyri increased with CAG-RL. In contrast, FNC in other visual (VIS) networks declined with increasing CAG-RL. In addition to observed effects in SC areas known to be related to HD, our study identifies a strong presence of alterations in VIS regions less commonly observed in previous reports and provides a step forward in understanding FNC dysfunction in HDgmc.
32 citations
TL;DR: The results of this study provide robust evidence against the widely held notion of DMN disengagement during goal-oriented, attention-demanding, externally directed tasks and support its involvement in a broader cognitive context with a memory-related role that extends beyond self-referential, internally directed mentation.
Abstract: The default mode network (DMN) is typically associated with off-task internal mentation, or with goal-oriented tasks that require self-referential processing such as autobiographical planning. However, recent reports suggest a broader involvement of the DMN in higher cognition. In line with this view, we report global connectivity changes that are centered on the main DMN hubs of precuneus and posterior cingulate cortex during a functional magnetic resonance imaging-based visuospatial version of the Tower of London planning task. Importantly, functional connectivity of these regions with the left caudate shows a significant relationship with faster reaction time to correct responses only during the high-demand planning condition, thus offering further evidence for the DMN's engagement during visuospatial planning. The results of this study not only provide robust evidence against the widely held notion of DMN disengagement during goal-oriented, attention-demanding, externally directed tasks but also support its involvement in a broader cognitive context with a memory-related role that extends beyond self-referential, internally directed mentation.
31 citations
TL;DR: The results show that the best sparse graphical model, in terms of detection of true connections and having few false-positive connections, is the smoothly clipped absolute deviation (SCAD) estimating method in combination with the Bayesian information criterion (BIC) and cross-validation (CV) selection method.
Abstract: Sparse graphical models are frequently used to explore both static and dynamic functional brain networks from neuroimaging data. However, the practical performance of the models has not been studied in detail for brain networks. In this work, we have two objectives. First, we compare several sparse graphical model estimation procedures and several selection criteria under various experimental settings, such as different dimensions, sample sizes, types of data, and sparsity levels of the true model structures. We discuss in detail the superiority and deficiency of each combination. Second, in the same simulation study, we show the impact of autocorrelation and whitening on the estimation of functional brain networks. We apply the methods to a resting-state functional magnetic resonance imaging (fMRI) data set. Our results show that the best sparse graphical model, in terms of detection of true connections and having few false-positive connections, is the smoothly clipped absolute deviation (SCAD) estimating method in combination with the Bayesian information criterion (BIC) and cross-validation (CV) selection method. In addition, the presence of autocorrelation in the data adversely affects the estimation of networks but can be helped by using the CV selection method. These results question the validity of a number of fMRI studies where inferior graphical model techniques have been used to estimate brain networks.
30 citations
TL;DR: The results suggest that MAAS scores are correlated with the functional connectivity of several brain structures related to attention and involve cross-network functional connectivity.
Abstract: Mindfulness refers to attending to moment-to-moment experiences with acceptance and no judgment. Several scales have been developed to quantify different components of mindfulness. The Mindful Attention Awareness Scale (MAAS) is particularly sensitive to trait mindfulness and is proposed to measure the attentional component of mindfulness. The purpose of this study was to identify the neural correlates of the MAAS in four resting-state networks related to attention-the default mode network (DMN), the salience network (SN), and the left and right central executive network (CEN). Thirty-two university students naive to mindfulness completed the MAAS and later underwent a resting-state functional magnetic resonance imaging scan. Resting-state data were analyzed using an independent component analysis; the scores from the MAAS were covaried to the connectivity maps in an analysis of covariance. The results indicate that variations in MAAS scores correlated with variations in functional connectivity patterns in resting-state networks. Specifically, within the SN and CEN, the MAAS was negatively correlated with functional connectivity in the precuneus, even though the precuneus is a key component of the DMN. Negative correlations in the DMN between the MAAS and the insula and negative correlations in the SN between the MAAS and the posterior cingulate cortex were also observed. These results suggest that MAAS scores (1) are correlated with the functional connectivity of several brain structures related to attention and (2) involve cross-network functional connectivity.
30 citations
TL;DR: Activity in the default mode network (DMN) is more complex and less coordinated in CFS, suggesting brain network analysis could be potentially used as a diagnostic biomarker for CFS.
Abstract: The chronic fatigue syndrome (CFS)/myalgic encephalomyelitis is a debilitating disease with unknown pathophysiology and no diagnostic test. This study investigated the default mode network (DMN) to understand the pathophysiology of CFS and to identify potential biomarkers. Using functional MRI (fMRI) collected from 72 subjects (45 CFS and 27 controls) with a temporal resolution of 0.798 sec, we evaluated the DMN using static functional connectivity (FC), dynamic functional connectivity (DFC) and DFC complexity, blood oxygenation level dependent (BOLD) activation maps, and complexity of activity. General linear model univariate analysis was used for intergroup comparison to account for age and gender differences. Hierarchical regression analysis was used to test whether fMRI measures could be used to explain variances of health scores. BOLD signals in the posterior cingulate cortex (PCC), the driving hub in the DMN, were more complex in CFS in both resting state and task (p < 0.05). The FCs betwee...
27 citations
TL;DR: The findings are consistent with a hyperconnectivity hypothesis of the effect of TBI history on functional networks rather than a disconnection hypothesis, demonstrating increased levels of clustering coefficientrather than a decrease as might be expected; however, these results do not account for potential changes in brain structure.
Abstract: Cross-sectional and longitudinal studies in active duty and veteran cohorts have both demonstrated that deployment-acquired traumatic brain injury (TBI) is an independent risk factor for d...
23 citations
TL;DR: A recurrent neural network-based model for identifying individuals based on only a short segment of resting-state functional magnetic resonance imaging data is introduced and neural network features that exhibit the uniqueness of each individual are investigated.
Abstract: Individual identification based on brain function has gained traction in literature. Investigating individual differences in brain function can provide additional insights into the brain. ...
23 citations
TL;DR: Positron emission tomography studies of cerebral blood flow have established a cortical–subcortical pattern of brain activity predictive of syllable rate during phonological/lexical repetition, and the use of propositional language during monologue speech was associated with strong left lateralization.
Abstract: Language has been modeled as a rule governed behavior for generating an unlimited number of novel utterances using phonological, syntactic, and lexical processes. This view of language as essentially propositional is expanding as a contributory role of formulaic expressions (e.g., you know, have a nice day, how are you?) is increasingly recognized. The basic features of the functional anatomy of this language system have been described by studies of brain damage: left lateralization for propositional language and greater right lateralization and basal ganglia involvement for formulaic expressions. Positron emission tomography (PET) studies of cerebral blood flow (CBF) have established a cortical-subcortical pattern of brain activity predictive of syllable rate during phonological/lexical repetition. The same analytic approach was applied to analyzing brain images obtained during spontaneous monologues. Sixteen normal, right-handed, native English speakers underwent PET scanning during several language tasks. Speech rate for the repetition of phonological/lexical items was predicted by increased CBF in the left inferior frontal region and decreased CBF in the head of the right caudate nucleus, replicating previous results. A complementary cortical-subcortical pattern (CBF increased in the right inferior frontal region and decreased in the left caudate) was predictive of the use of speech formulas during monologue speech. The use of propositional language during the monologues was associated with strong left lateralization (increased CBF at the left inferior frontal region and decreased CBF at the right inferior frontal region). Normal communication involves the integration of two language modes, formulaic and novel, that have different neural substrates.
TL;DR: Thalamic subregional rsFCs showed both shared and distinct changes and sex differences in association with problem drinking and AE, suggesting the importance of examining thalamic subdivisions and sex in investigating the functional roles of thalamus in problem drinking.
Abstract: Alcohol misuse is associated with thalamic dysfunction. The thalamus comprises subnuclei that relay and integrate information between cortical and subcortical structures. However, it is unclear how the subnuclei contribute to thalamic dysfunctions in problem drinking. We investigated resting-state functional connectivity (rsFC) of thalamic subregions in 107 nondependent drinkers (57 women), using masks delineated by white matter tractography. Thalamus was parceled into motor, somatosensory, visual, premotor, frontal association, parietal association, and temporal association subregions. Whole-brain linear regression, each against Alcohol Use Disorders Identification Test (AUDIT) and positive alcohol expectancy (AE) score with age as a covariate, was performed for each seed, for men and women combined, and separately. Overall, problem drinking was associated with increased thalamic connectivities, whereas AE was associated with a mixed pattern of increased and decreased connectivities. Motor, premotor, somatosensory, and frontal association thalamic connectivity with bilateral caudate head was positively correlated with AUDIT score in men and women combined. Connectivity of the right caudate head with frontal association and premotor thalamus was also positively correlated with AE score in men and women combined. In contrast, motor and premotor thalamic connectivity with a number of cortical and subcortical structures showed sex differences in the correlation each with AUDIT and AE score. In mediation analyses, AE score completely mediated the correlation between thalamic caudate connectivity and AUDIT score, whereas the model where AE contributed to problem drinking and, in turn, altered thalamic caudate connectivity was not supported. To conclude, thalamic subregional rsFCs showed both shared and distinct changes and sex differences in association with problem drinking and AE. Increased thalamic caudate connectivity may contribute to problem drinking via enhanced AE. The findings suggest the importance of examining thalamic subdivisions and sex in investigating the functional roles of thalamus in problem drinking.
TL;DR: To study the behavior of the generalized Ising model around criticality, calculation of the dimensionality and critical exponents was performed for the first time, by introducing a new concept of distance based on structural connectivity.
Abstract: There is accumulating evidence that spontaneous fluctuations of the brain are sustained by a structural architecture of axonal fiber bundles. Various models have been used to investigate this structure-function relationship. In this work, we implemented the Ising model using the number of fibers between each pair of brain regions as input. The output of the Ising model simulations on a structural connectome was then compared with empirical functional connectivity data. A simpler two-dimensional classical Ising model was used as the baseline model for comparison purpose. Thermodynamic properties, such as the magnetic susceptibility and the specific heat, illustrated a phase transition from an ordered phase to a disordered phase at the critical temperature. Despite the differences between the two models, the lattice Ising model and the Ising model implemented on a structural connectome (the generalized Ising model) exhibited similar patterns of global properties. To study the behavior of the generalized Ising model around criticality, calculation of the dimensionality and critical exponents was performed for the first time, by introducing a new concept of distance based on structural connectivity. Same value inside the fitting error was found for the dimensionality in both models suggesting similar behavior of the models around criticality.
TL;DR: Experimental results suggest that the tissue property, measured by FA, in olfactory regions is structurally modulated by PD with a mechanism that is different from other brain regions.
Abstract: Many nonmotor symptoms (e.g., hyposmia) appear years before the cardinal motor features of Parkinson's disease (PD). It is thus desirable to be able to use noninvasive brain imaging methods, such as magnetic resonance imaging (MRI), to detect brain abnormalities in early PD stages. Among the MRI modalities, diffusion-tensor imaging (DTI) is suitable for detecting changes in brain tissue structure due to neurological diseases. The main purpose of this study was to investigate whether DTI signals measured from brain regions involved in early stages of PD differ from those of healthy controls. To answer this question, we analyzed whole-brain DTI data of 30 early-stage PD patients and 30 controls using improved region of interest-based analysis methods. Results showed that (i) the fractional anisotropy (FA) values in the olfactory tract (connected with the olfactory bulb: one of the first structures affected by PD) are lower in PD patients than healthy controls; (ii) FA values are higher in PD patients than healthy controls in the following brain regions: corticospinal tract, cingulum (near hippocampus), and superior longitudinal fasciculus (temporal part). Experimental results suggest that the tissue property, measured by FA, in olfactory regions is structurally modulated by PD with a mechanism that is different from other brain regions.
TL;DR: It is concluded that Sle patients in general and neuropsychiatric SLE patients in particular experience altered brain connectivity and these patterns may be due both to direct neuronal damage and compensatory mechanisms through neuronal rewiring and recruitment and may partly explain neuroPsychiatric symptoms in S LE patients.
Abstract: To investigate resting-state functional connectivity of lupus patients and associated subgroups according to the ACR NPSLE case definitions (ACR ad hoc). In addition, we investigated whether or not the observed alterations correlated with disease duration, the systemic lupus erythematosus (SLE)-Disease Activity Index-2000 (SLEDAI-2k), and Systemic Lupus International Collaborating Clinical/ACR organ damage index (SDI)-scores. Anatomical 3T magnetic resonance imaging (MRI) and resting-state functional MRI were performed in 61 female lupus patients (mean age = 37.0 years, range = 18.2-52.0 years) and 20 gender- and age-matched controls (mean age = 36.2 years, range = 23.3-52.2 years) in conjunction with clinical examination and laboratory testing. Whole-brain voxelwise functional connectivity analysis with permutation testing was performed to extract network components that differed in lupus patients relative to healthy controls (HCs). Lupus patients exhibited both inter- and intranetwork hypo- and hyperconnectivity involving several crucial networks. We found reduced connectivity within the default mode network (DMN), the central executive network (CEN), and in-between the DMN and CEN in lupus patients. Increased connectivity was primarily observed within and between the sensory motor network in lupus patients when compared to HCs. Comparing lupus patients with and without neuropsychiatric symptoms, hypoconnectivity was more pronounced in the group with neuropsychiatric complaints. The functional connectivity of SLE patients was both positively and negatively correlated to duration of disease. We conclude that SLE patients in general and neuropsychiatric SLE patients in particular experience altered brain connectivity. These patterns may be due both to direct neuronal damage and compensatory mechanisms through neuronal rewiring and recruitment and may partly explain neuropsychiatric symptoms in SLE patients.
TL;DR: It is shown that GSR leads to a positive shift in the correlation between the BOLD and vigilance measures, which results in a reduction in the spatial extent of negative correlations in widespread brain areas, including the visual cortex, but leads to the appearance of positive correlations in other areas, such as the cingulate gyrus.
Abstract: Global signal regression (GSR) is a commonly used although controversial preprocessing approach in the analysis of resting-state blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) data. Although the effects of GSR on resting-state functional connectivity measures have received much attention, there has been relatively little attention devoted to its effects on studies looking at the relationship between resting-state BOLD measures and independent measures of brain activity. In this study, we used simultaneously acquired electroencephalogram (EEG)-fMRI data in humans to examine the effects of GSR on the correlation between resting-state BOLD fluctuations and EEG vigilance measures. We show that GSR leads to a positive shift in the correlation between the BOLD and vigilance measures. This shift leads to a reduction in the spatial extent of negative correlations in widespread brain areas, including the visual cortex, but leads to the appearance of positive correlations in other areas, such as the cingulate gyrus. The results obtained using GSR are consistent with those of a temporal censoring process in which the correlation is computed using a temporal subset of the data. Since the data from these retained time points are unaffected by the censoring process, this finding suggests that the positive correlations in cingulate gyrus are not simply an artifact of GSR.
TL;DR: It is suggested that brain activation dynamics form a general hierarchy across task and rest, with a small number of dominant general states reflecting basic functional modes and a variety of specific states potentially reflecting a wide variety of cognitive processes.
Abstract: Much of our lives are spent in unconstrained rest states, yet cognitive brain processes are primarily investigated using task-constrained states. It may be possible to utilize the insights gained from experimental control of task processes as reference points for investigating unconstrained rest. To facilitate comparison of rest and task functional magnetic resonance imaging data, we focused on activation amplitude patterns, commonly used for task but not rest analyses. During rest, we identified spontaneous changes in temporally extended whole-brain activation-pattern states. This revealed a hierarchical organization of rest states. The top consisted of two competing states consistent with previously identified "task-positive" and "task-negative" activation patterns. These states were composed of more specific states that repeated over time and across individuals. Contrasting with the view that rest consists of only task-negative states, task-positive states occurred 40% of the time while individuals "rested," suggesting task-focused activity may occur during rest. Together our results suggest that brain activation dynamics form a general hierarchy across task and rest, with a small number of dominant general states reflecting basic functional modes and a variety of specific states potentially reflecting a wide variety of cognitive processes.
TL;DR: This pilot study suggests that cortical activation patterns and the activation order of motor areas differ interindividually and depend on the stimulated motor area and indicates that TMS-activated effective connections or underlying structural connections vary between subjects.
Abstract: The combination of transcranial magnetic stimulation (TMS) and electroencephalography (EEG) enables one to study effective connectivity and activation order in neuronal networks. To charac...
TL;DR: The default mode network (DMN) in Moyamoya disease patients is studied and it is demonstrated that it is possible to mitigate the deleterious effects of arterial arrival time on the assessment of functional connectivity of the DMN, and two techniques to correct errors are proposed.
Abstract: In resting-state functional MRI (rs-fMRI), functional networks are assessed utilizing the temporal correlation between spontaneous blood oxygen level-dependent signal fluctuations of spatially remote brain regions. Recently, several groups have shown that temporal shifts are present in rs-fMRI maps in patients with cerebrovascular disease due to spatial differences in arterial arrival times, and that this can be exploited to map arrival times in the brain. This suggests that rs-fMRI connectivity mapping may be similarly sensitive to such temporal shifts, and that standard rs-fMRI analysis methods may fail to identify functional connectivity networks. To investigate this, we studied the default mode network (DMN) in Moyamoya disease patients and compared it with normal healthy volunteers. Our results show that using standard independent component analysis (ICA) and seed-based approaches, arterial arrival delays lead to inaccurate incomplete characterization of functional connectivity within the DMN in Moyamoya disease patients. Furthermore, we propose two techniques to correct these errors, for seed-based and ICA methods, respectively. Using these methods, we demonstrate that it is possible to mitigate the deleterious effects of arterial arrival time on the assessment of functional connectivity of the DMN. As these corrections have not been applied to the vast majority of >200 prior rs-fMRI studies in patients with cerebrovascular disease, we suggest that they be interpreted with great caution. Correction methods should be applied in any rs-fMRI connectivity study of subjects expected to have abnormally delayed arterial arrival times.
TL;DR: Although the global signal collects information from all tissue classes, a diverse subset of the BOLD signal's independent components contribute the most to the global signals, confirming the independence of a constituent process that comprises theglobal signal.
Abstract: Global signal regression is a controversial processing step for resting-state functional magnetic resonance imaging, partly because the source of the global blood oxygen level-dependent (B...
TL;DR: Even though participants with PAE exhibit very similar intranetwork functional connectivity patterns as controls, their lower internetworkfunctional connectivity suggests underlying deficits in the functional network brain architecture that may be related to cognitive impairment.
Abstract: Studies of brain structure in fetal alcohol spectrum disorder (FASD) have shown the global and focal effects that prenatal alcohol exposure (PAE) has on the brain, suggesting but not measuring altered function in FASD. This study aimed to (1) identify resting-state functional networks in children and adolescents with FASD, (2) investigate functional connectivity differences compared with healthy controls, and (3) assess the links to cognitive deficits. Participants included 66 children/adolescents with FASD (aged 5.5-18.9 years) and 67 healthy controls (aged 5.8-18.5 years) scanned across four sites as part of the NeuroDevNet study. Six core functional networks with 27 regions of interest (ROIs) were examined using seed-based and ROI-to-ROI analyses. Average seed-based connectivity maps showed significant spatial overlap of positively correlated regions for all six core networks between FASD and controls, but there was less overlap for negatively correlated regions. ROI-to-ROI matrices demonstrated lower internetwork connectivity between regions primarily associated with the salience network (anterior cingulate cortex and bilateral insula), frontal-parietal network (bilateral posterior parietal cortex), and language network (right posterior superior temporal gyrus). Post hoc correlations of the FASD participants without medication revealed a relationship between functional connectivity and performance on two cognitive tests associated with mathematics ability and attention. Even though participants with PAE exhibit very similar intranetwork functional connectivity patterns as controls, their lower internetwork functional connectivity suggests underlying deficits in the functional network brain architecture that may be related to cognitive impairment.
TL;DR: It is shown that accounting for non-Gaussian signal components such as those arising from resting-state neural activity as well as physiological responses and motion artifacts in the null fMRI datasets yields first- and second-level general linear model analysis residuals with nearly uniform and Gaussian sACF.
Abstract: In a recent study, Eklund et al. employed resting-state functional magnetic resonance imaging data as a surrogate for null functional magnetic resonance imaging (fMRI) datasets and posited...
TL;DR: A network-driven approach quantifies the structural topology of the social brain as a whole and can serve as a critical benchmark against which to compare developmental change in social brain topology over time and atypical network topologies that may be a sign or symptom of disorder.
Abstract: Although a large body of research has identified discrete neuroanatomical regions involved in social cognition and behavior (the "social brain"), the existing findings are based largely on studies of specific brain structures defined within the context of particular tasks or for specific types of social behavior. The objective of the current work was to view these regions as nodes of a larger collective network and to quantitatively characterize both the topology of that network and the relative criticality of its many nodes. Large-scale data mining was performed to generate seed regions of the social brain. High-quality diffusion MRI data of typical adults were used to map anatomical networks of the social brain. Network topology and nodal centrality were analyzed using graph theory. The structural social brain network demonstrates a high degree of global functional integration with strong local segregation. Bilateral dorsomedial prefrontal cortices and amygdala play the most central roles in the network. Strong probabilistic evidence supports modular divisions of the social brain into subnetworks bearing good resemblance to functionally classified clusters. The present network-driven approach quantifies the structural topology of the social brain as a whole. This work can serve as a critical benchmark against which to compare (1) developmental change in social brain topology over time (from infancy through adolescence and beyond) and (2) atypical network topologies that may be a sign or symptom of disorder (as in conditions such as autism, Williams syndrome, schizophrenia, and others).
TL;DR: The results demonstrate that summary metrics describing the clustering of individual time frames have adequate test/retest reliability, and thus, these patterns of brain activation may hold promise for individual-difference research.
Abstract: Dynamic functional connectivity metrics have much to offer to the neuroscience of individual differences of cognition. Yet, despite the recent expansion in dynamic connectivity research, l...
TL;DR: Differences in the pattern of the resting-state frontolimbic connectivity and its associations with performance in ToM tasks between the two study groups might represent a different setup for processing social information in patients with SCH.
Abstract: Patients with schizophrenia (SCH) often demonstrate impairment in social-cognitive functions as well as disturbances in large-scale network connectivity. The ventromedial prefrontal cortex (vmPFC) is a core region of the default mode network, with projections to limbic structures. It plays an important role in social and emotional decision-making. We investigated whether resting-state functional connectivity (FC) relates to the cognitive and affective domains of theory of mind (ToM). Twenty-three SCH patients and 19 healthy controls (HCs) underwent resting-state functional magnetic resonance imaging scanning. vmPFC seed connectivity was correlated with behavioral measures assessing ToM domains. SCH performed less well than HCs in both ToM task domains. An analysis of the resting-state FC revealed that SCH had reduced connectivity from the vmPFC to the subcallosal cortex, right amygdala, and right hippocampus as a function of behavioral scores in both ToM domains. Within-group analyses indicated that in HCs, the performance in ToM was positively associated with frontoamygdalar resting-state connectivity, whereas in SCH, the performance in ToM was negatively associated with the frontosubcallosal connectivity. Differences in the pattern of the resting-state frontolimbic connectivity and its associations with performance in ToM tasks between the two study groups might represent a different setup for processing social information in patients with SCH.
TL;DR: Results suggest that FPN functional architecture may underlie insufficiencies in top-down control in PTSD, with results broadly supporting the notion that networks' functional architecture influences the breakdown of normative functional relationships in PTSD.
Abstract: Posttraumatic stress disorder (PTSD) is associated with disrupted functional connectivity in multiple neural networks. Multinetwork models of PTSD hypothesize that aberrant regional connectivity emerges from broad network-level disruptions. However, few studies have tested how characteristics of network-level organization influence regional functional connectivity in PTSD. This gap in knowledge impacts both our understanding of the pathophysiology of the disorder and the development of network-targeted PTSD treatments. We acquired resting-state imaging from a naturalistic sample of patients with PTSD (n = 42) and healthy controls (n = 42). Group differences in functional connectivity were identified using region of interest analyses and estimations of within- and between neural network activity; PTSD patients demonstrated reduced amygdala-orbitofrontal connectivity and increased default mode network (DMN) connectivity compared with controls. We then used convergence-a novel measure representing the capacity for functional integration-to test whether differences in functional architecture underlie connectivity signatures of PTSD. This approach found that reduced frontoparietal network (FPN) convergence was associated with reduced amygdala-orbitofrontal connectivity. Furthermore, in controls only, increased DMN convergence was associated with reduced DMN-to-salience network connectivity, and increased FPN convergence was associated with reduced FPN-to-ventral attention network connectivity. These results suggest that FPN functional architecture may underlie insufficiencies in top-down control in PTSD, with results broadly supporting the notion that networks' functional architecture influences the breakdown of normative functional relationships in PTSD. This work also indicates the potential of convergence to be applied to clinical populations in future research studies.
TL;DR: The results suggest that children with RDs utilize neural circuits supporting EFs more so than do typical readers to perform a cognitive task and provide a neurobiological explanation for the challenges in EFs shared by children withRDs.
Abstract: Children with reading difficulties (RDs) often receive related accommodations in schools, such as additional time for examinations and reading aloud written material. Existing data suggest that these readers share challenges in executive functions (EFs). Our study was designed to determine whether children with RDs have specific challenges in EFs and define neurobiological signatures for such difficulties using magnetic resonance imaging (MRI) data. Reading and EFs abilities were assessed in 8-12-year-old children with RDs and age-matched typical readers. Functional MRI data were acquired during a Stroop task, and functional connectivity of the EFs defined network was calculated in both groups and related to reading ability. Children with RDs showed lower reading and EFs abilities and demonstrated greater functional connectivity between the EFs network and visual, language, and cognitive control regions during the Stroop task, compared to typical readers. Our results suggest that children with RDs utilize neural circuits supporting EFs more so than do typical readers to perform a cognitive task. These results also provide a neurobiological explanation for the challenges in EFs shared by children with RDs and explain challenges this group shares outside of the reading domain.
TL;DR: A large number of brain regions that demonstrate strong functional connectivity in areas related to language and emotion have been identified and these regions are studied in detail in this study.
Abstract: In recent years, there has been strong interest in neuroscience studies to investigate brain organization through networks of brain regions that demonstrate strong functional connectivity ...
TL;DR: Investigation of differences between patients with and without chemotherapy in functional brain networks at rest and during an affective processing functional magnetic resonance imaging (fMRI) task on average >14 years post-treatment reveals that functional hyperconnectivity is widespread, possibly to compensate for the pathophysiological disturbances.
Abstract: Chemotherapy for testicular cancer (TC) has been associated with neurotoxic effects shortly post-treatment Late effects of chemotherapy on brain function in this patient group are still unknown In this study, we investigated differences between patients with and without chemotherapy in functional brain networks at rest and during an affective processing functional magnetic resonance imaging (fMRI) task on average >14 years post-treatment In addition, we report on changes in cognitive functioning during survivorship by comparing present and previous performance on a neuropsychological test battery on average 11 years earlier (3 years post-treatment) Twenty-eight chemotherapy (431 ± 75 years) and 23 surgery-only (482 ± 95 years) TC survivors were examined using neurocognitive tests and 3T-fMRI >10 years after treatment end Brain functional networks were identified using dual regression independent component analysis Task fMRI was analyzed using a block design Standardized domain change scores were calculated for each individual to assess cognitive change TC patients in the chemotherapy group showed functional hyperconnectivity at rest in the precuneus network, sensory and motor function network, executive control network, and the ventral stream network when compared with surgery-only patients Furthermore, hypoactivation was found when performing the affective processing task Cognitive data revealed that both groups showed comparable patterns of change from 3 to 14 years after initial treatment This study provides novel insights on the possible underlying neurobiological mechanisms of late neurotoxic effects of cisplatin-based chemotherapy Present findings reveal that functional hyperconnectivity is widespread, possibly to compensate for the pathophysiological disturbances This concurs with our previous findings of structural hyperconnectivity in white matter Longitudinal multimodal imaging studies are warranted to further investigate the association between long-term structural and functional network connectivity data, as well as its relationship with cognitive changes
TL;DR: Preliminary evidence showed that both the global and nodal graph metrics were affected by the coping strategy in the delta band, suggesting that processes such as emotional load are highly solicited in passive coping individuals.
Abstract: This study aims to investigate the effects of individual differences in trait coping on brain networks at rest using electroencephalography (EEG) data EEG recordings were processed using graph theory analysis Active and passive coping styles were determined according to the factor structure of the Brief Coping Orientation to Problems Experienced questionnaire A structural equation modeling analysis indicated that the influence of coping strategies on quality of life varies in strength and direction In particular, active coping strategies were positively correlated with the psychological dimension Graph measures, at both global and nodal levels, were used to identify the brain network properties in accordance with passive versus active coping styles Preliminary evidence showed that both the global and nodal graph metrics were affected by the coping strategy in the delta band During resting state, passive coping strategy participants had network topology characterized by a high global efficiency, indicating an important level of integration between distant brain areas and a high local efficiency and transitivity, suggesting a high local communication between adjacent regions Various regions, such as the paracentral lobule, posterior cingulate, and other frontal or parietal areas, seemed to play a key role, suggesting that processes such as emotional load are highly solicited in passive coping individuals In active coping participants, the superior temporal gyrus seemed to be of importance when neurons oscillated in the theta and alpha frequencies