Sex and disease-related alterations of anterior insula functional connectivity in chronic abdominal pain.
J Neurosci. 2014 Oct 22;34(43):14252-9
Authors: Hong JY, Kilpatrick LA, Labus JS, Gupta A, Katibian D, Ashe-McNalley C, Stains J, Heendeniya N, Smith SR, Tillisch K, Naliboff B, Mayer EA
Resting-state functional magnetic resonance imaging has been used to investigate intrinsic brain connectivity in healthy subjects and patients with chronic pain. Sex-related differences in the frequency power distribution within the human insula (INS), a brain region involved in the integration of interoceptive, affective, and cognitive influences, have been reported. Here we aimed to test sex and disease-related alterations in the intrinsic functional connectivity of the dorsal anterior INS. The anterior INS is engaged during goal-directed tasks and modulates the default mode and executive control networks. By comparing functional connectivity of the dorsal anterior INS in age-matched female and male healthy subjects and patients with irritable bowel syndrome (IBS), a common chronic abdominal pain condition, we show evidence for sex and disease-related alterations in the functional connectivity of this region: (1) male patients compared with female patients had increased positive connectivity of the dorsal anterior INS bilaterally with the medial prefrontal cortex (PFC) and dorsal posterior INS; (2) female patients compared with male patients had greater negative connectivity of the left dorsal anterior INS with the left precuneus; (3) disease-related differences in the connectivity between the bilateral dorsal anterior INS and the dorsal medial PFC were observed in female subjects; and (4) clinical characteristics were significantly correlated to the insular connectivity with the dorsal medial PFC in male IBS subjects and with the precuneus in female IBS subjects. These findings are consistent with the INS playing an important role in modulating the intrinsic functional connectivity of major networks in the resting brain and show that this role is influenced by sex and diagnosis.
PMID: 25339739 [PubMed - in process]
Large-scale functional brain network changes in taxi drivers: Evidence from resting-state fMRI.
Hum Brain Mapp. 2014 Oct 23;
Authors: Wang L, Liu Q, Shen H, Li H, Hu D
Driving a car in the environment is a complex behavior that involves cognitive processing of visual information to generate the proper motor outputs and action controls. Previous neuroimaging studies have used virtual simulation to identify the brain areas that are associated with various driving-related tasks. Few studies, however, have focused on the specific patterns of functional organization in the driver's brain. The aim of this study was to assess differences in the resting-state networks (RSNs) of the brains of drivers and nondrivers. Forty healthy subjects (20 licensed taxi drivers, 20 nondrivers) underwent an 8-min resting-state functional MRI acquisition. Using independent component analysis, three sensory (primary and extrastriate visual, sensorimotor) RSNs and four cognitive (anterior and posterior default mode, left and right frontoparietal) RSNs were retrieved from the data. We then examined the group differences in the intrinsic brain activity of each RSN and in the functional network connectivity (FNC) between the RSNs. We found that the drivers had reduced intrinsic brain activity in the visual RSNs and reduced FNC between the sensory RSNs compared with the nondrivers. The major finding of this study, however, was that the FNC between the cognitive and sensory RSNs became more positively or less negatively correlated in the drivers relative to that in the nondrivers. Notably, the strength of the FNC between the left frontoparietal and primary visual RSNs was positively correlated with the number of taxi-driving years. Our findings may provide new insight into how the brain supports driving behavior. Hum Brain Mapp, 2014. © 2014 Wiley Periodicals, Inc.
PMID: 25338709 [PubMed - as supplied by publisher]
Opposite Neural Trajectories of Apolipoprotein E ϵ4 and ϵ2 Alleles with Aging Associated with Different Risks of Alzheimer's Disease.
Cereb Cortex. 2014 Oct 21;
Authors: Shu H, Shi Y, Chen G, Wang Z, Liu D, Yue C, Ward BD, Li W, Xu Z, Chen G, Guo Q, Xu J, Li SJ, Zhang Z
The apolipoprotein E (APOE) ϵ4 allele is a confirmed genetic risk factor and the APOE ϵ2 allele is a protective factor related to late-onset Alzheimer's disease (AD). Intriguingly, recent studies demonstrated similar brain function alterations between APOE ϵ2 and ϵ4 alleles, despite their opposite susceptibilities to AD. To address this apparent discrepancy, we recruited 129 cognitively normal elderly subjects, including 36 ϵ2 carriers, 44 ϵ3 homozygotes, and 49 ϵ4 carriers. All subjects underwent resting-state functional MRI scans. We hypothesized that aging could influence the APOE ϵ2 and ϵ4 allele effects that contribute to their appropriate AD risks differently. Using the stepwise regression analysis, we demonstrated that although both ϵ2 and ϵ4 carriers showed decreased functional connectivity (FC) compared with ϵ3 homozygotes, they have opposite aging trajectories in the default mode network-primarily in the bilateral anterior cingulate cortex. As age increased, ϵ2 carriers showed elevated FC, whereas ϵ4 carriers exhibited decreased FC. Behaviorally, the altered DMN FC positively correlated with information processing speed in both ϵ2 and ϵ4 carriers. It is suggested that the opposite aging trajectories between APOE ϵ2 and ϵ4 alleles in the DMN may reflect the antagonistic pleiotropic properties and associate with their different AD risks.
PMID: 25336599 [PubMed - as supplied by publisher]
The role of neuroimaging in predicting neurodevelopmental outcomes of preterm neonates.
Clin Perinatol. 2014 Mar;41(1):257-83
Authors: Kwon SH, Vasung L, Ment LR, Huppi PS
Magnetic resonance imaging (MRI) is a safe and high-resolution neuroimaging modality that is increasingly used in the neonatal population to assess brain injury and its consequences on brain development. It is superior to cranial ultrasound for the definition of patterns of both white and gray matter maturation and injury and therefore has the potential to provide prognostic information on the neurodevelopmental outcomes of the preterm population. Furthermore, the development of sophisticated MRI strategies, including diffusion tensor imaging, resting state functional connectivity, and magnetic resonance spectroscopy, may increase the prognostic value, helping to guide parental counseling and allocate early intervention services.
PMID: 24524459 [PubMed - indexed for MEDLINE]
Isolated Assessment of Translation or Rotation Severely Underestimates the Effects of Subject Motion in fMRI Data.
PLoS One. 2014;9(10):e106498
Authors: Wilke M
Subject motion has long since been known to be a major confound in functional MRI studies of the human brain. For resting-state functional MRI in particular, data corruption due to motion artefacts has been shown to be most relevant. However, despite 6 parameters (3 for translations and 3 for rotations) being required to fully describe the head's motion trajectory between timepoints, not all are routinely used to assess subject motion. Using structural (n = 964) as well as functional MRI (n = 200) data from public repositories, a series of experiments was performed to assess the impact of using a reduced parameter set (translationonly and rotationonly) versus using the complete parameter set. It could be shown that the usage of 65 mm as an indicator of the average cortical distance is a valid approximation in adults, although care must be taken when comparing children and adults using the same measure. The effect of using slightly smaller or larger values is minimal. Further, both translationonly and rotationonly severely underestimate the full extent of subject motion; consequently, both translationonly and rotationonly discard substantially fewer datapoints when used for quality control purposes ("motion scrubbing"). Finally, both translationonly and rotationonly severely underperform in predicting the full extent of the signal changes and the overall variance explained by motion in functional MRI data. These results suggest that a comprehensive measure, taking into account all available parameters, should be used to characterize subject motion in fMRI.
PMID: 25333359 [PubMed - as supplied by publisher]
Posteromedial hyperactivation during episodic recognition among people with memory decline: findings from the WRAP study.
Brain Imaging Behav. 2014 Oct 21;
Authors: Nicholas CR, Okonkwo OC, Bendlin BB, Oh JM, Asthana S, Rowley HA, Hermann B, Sager MA, Johnson SC
Episodic memory decline is one of the earliest preclinical symptoms of AD, and has been associated with an upregulation in the BOLD response in the prodromal stage (e.g. MCI) of AD. In a previous study, we observed upregulation in cognitively normal (CN) subjects with subclinical episodic memory decline compared to non-decliners. In light of this finding, we sought to determine if a separate cohort of Decliners will show increased brain activation compared to Stable subjects during episodic memory processing, and determine whether the BOLD effect was influenced by cerebral blood flow (CBF) or gray matter volume (GMV). Individuals were classified as a "Decliner" if scores on the Rey Auditory Verbal Learning Test (RAVLT) consistently fell ≥ 1.5 SD below expected intra- or inter-individual levels. FMRI was used to compare activation during a facial recognition memory task in 90 Stable (age = 59.1) and 34 Decliner (age = 62.1, SD = 5.9) CN middle-aged adults and 10 MCI patients (age = 72.1, SD = 9.4). Arterial spin labeling and anatomical T1 MRI were used to measure resting CBF and GMV, respectively. Stables and Decliners performed similarly on the episodic recognition memory task and significantly better than MCI patients. Compared to Stables, Decliners showed increased BOLD signal in the left precuneus on the episodic memory task that was not explained by CBF or GMV, familial AD risk factors, or neuropsychological measures. These findings suggest that subtle changes in the BOLD signal reflecting altered neural function may be a relatively early phenomenon associated with memory decline.
PMID: 25332108 [PubMed - as supplied by publisher]
The effects of antidepressant treatment on resting-state functional brain networks in patients with major depressive disorder.
Hum Brain Mapp. 2014 Oct 21;
Authors: Wang L, Xia M, Li K, Zeng Y, Su Y, Dai W, Zhang Q, Jin Z, Mitchell PB, Yu X, He Y, Si T
Although most knowledge regarding antidepressant effects is at the receptor level, the neurophysiological correlates of these neurochemical changes remain poorly understood. Such an understanding could benefit from elucidation of antidepressant effects at the level of neural circuits, which would be crucial in identifying biomarkers for monitoring treatment efficacy of antidepressants. In this study, we recruited 20 first-episode drug-naive major depressive disorder (MDD) patients and performed resting-state functional magnetic resonance imaging (MRI) scans before and after 8 weeks of treatment with a selective serotonin reuptake inhibitor-escitalopram. Twenty healthy controls (HCs) were also scanned twice with an 8-week interval. Whole-brain connectivity was analyzed using a graph-theory approach-functional connectivity strength (FCS). The analysis of covariance of FCS was used to determine treatment-related changes. We observed significant group-by-time interaction on FCS in the bilateral dorsomedial prefrontal cortex and bilateral hippocampi. Post hoc analyses revealed that the FCS values in the bilateral dorsomedial prefrontal cortex were significantly higher in the MDD patients compared to HCs at baseline and were significantly reduced after treatment; conversely, the FCS values in the bilateral hippocampi were significantly lower in the patients at baseline and were significantly increased after treatment. Importantly, FCS reduction in the dorsomedial prefrontal cortex was significantly correlated with symptomatic improvement. Together, these findings provided evidence that this commonly used antidepressant can selectively modulate the intrinsic network connectivity associated with the medial prefrontal-limbic system, thus significantly adding to our understanding of antidepressant effects at a circuit level and suggesting potential imaging-based biomarkers for treatment evaluation in MDD. Hum Brain Mapp, 2014. © 2014 Wiley Periodicals, Inc.
PMID: 25332057 [PubMed - as supplied by publisher]
Characterizing and Differentiating Brain State Dynamics via Hidden Markov Models.
Brain Topogr. 2014 Oct 21;
Authors: Ou J, Xie L, Jin C, Li X, Zhu D, Jiang R, Chen Y, Zhang J, Li L, Liu T
Functional connectivity measured from resting state fMRI (R-fMRI) data has been widely used to examine the brain's functional activities and has been recently used to characterize and differentiate brain conditions. However, the dynamical transition patterns of the brain's functional states have been less explored. In this work, we propose a novel computational framework to quantitatively characterize the brain state dynamics via hidden Markov models (HMMs) learned from the observations of temporally dynamic functional connectomics, denoted as functional connectome states. The framework has been applied to the R-fMRI dataset including 44 post-traumatic stress disorder (PTSD) patients and 51 normal control (NC) subjects. Experimental results show that both PTSD and NC brains were undergoing remarkable changes in resting state and mainly transiting amongst a few brain states. Interestingly, further prediction with the best-matched HMM demonstrates that PTSD would enter into, but could not disengage from, a negative mood state. Importantly, 84 % of PTSD patients and 86 % of NC subjects are successfully classified via multiple HMMs using majority voting.
PMID: 25331991 [PubMed - as supplied by publisher]
Low- but Not High-Frequency LFP Correlates with Spontaneous BOLD Fluctuations in Rat Whisker Barrel Cortex.
Cereb Cortex. 2014 Oct 20;
Authors: Lu H, Wang L, Rea WW, Brynildsen JK, Jaime S, Zuo Y, Stein EA, Yang Y
Resting-state magnetic resonance imaging (rsMRI) is thought to reflect ongoing spontaneous brain activity. However, the precise neurophysiological basis of rsMRI signal remains elusive. Converging evidence supports the notion that local field potential (LFP) signal in the high-frequency range correlates with fMRI response evoked by a task (e.g., visual stimulation). It remains uncertain whether this relationship extends to rsMRI. In this study, we systematically modulated LFP signal in the whisker barrel cortex (WBC) by unilateral deflection of rat whiskers. Results show that functional connectivity between bilateral WBC was significantly modulated at the 2 Hz, but not at the 4 or 6 Hz, stimulus condition. Electrophysiologically, only in the low-frequency range (<5 Hz) was the LFP power synchrony in bilateral WBC significantly modulated at 2 Hz, but not at 4- or 6-Hz whisker stimulation, thus distinguishing these 2 experimental conditions, and paralleling the findings in rsMRI. LFP power synchrony in other frequency ranges was modulated in a way that was neither unique to the specific stimulus conditions nor parallel to the fMRI results. Our results support the hypothesis that emphasizes the role of low-frequency LFP signal underlying rsMRI.
PMID: 25331598 [PubMed - as supplied by publisher]
Resting-State Network Complexity and Magnitude Are Reduced in Prematurely Born Infants.
Cereb Cortex. 2014 Oct 20;
Authors: Smyser CD, Snyder AZ, Shimony JS, Mitra A, Inder TE, Neil JJ
Premature birth is associated with high rates of motor and cognitive disability. Investigations have described resting-state functional magnetic resonance imaging (rs-fMRI) correlates of prematurity in older children, but comparable data in the neonatal period remain scarce. We studied 25 term-born control infants within the first week of life and 25 very preterm infants (born at gestational ages ranging from 23 to 29 weeks) without evident structural injury at term equivalent postmenstrual age. Conventional resting-state network (RSN) mapping revealed only modest differences between the term and prematurely born infants, in accordance with previous work. However, clear group differences were observed in quantitative analyses based on correlation and covariance matrices representing the functional MRI time series extracted from 31 regions of interest in 7 RSNs. In addition, the maximum likelihood dimensionality estimates of the group-averaged covariance matrices in the term and preterm infants were 5 and 3, respectively, indicating that prematurity leads to a reduction in the complexity of rs-fMRI covariance structure. These findings highlight the importance of quantitative analyses of rs-fMRI data and suggest a more sensitive method for delineating the effects of preterm birth in infants without evident structural injury.
PMID: 25331596 [PubMed - as supplied by publisher]
Resting State Functional Connectivity Modulation and Sustained Changes after Real-Time fMRI Neurofeedback Training in Depression.
Brain Connect. 2014 Oct 20;
Authors: Yuan H, Young KD, Phillips R, Zotev V, Misaki M, Bodurka J
Amygdala hemodynamic responses to positive stimuli are attenuated in major depressive disorder (MDD) and normalize with remission. Real-time fMRI neurofeedback (rtfMRI-nf) training with the goal of upregulating amygdala activity during recall of happy autobiographical memories (AMs) has been suggested, and recently explored, as a novel therapeutic approach which resulted in improvement in self-reported mood in depressed subjects. In the present study we assessed the possibility of sustained brain changes as well as the neuromodulatory effects of rtfMRI-nf training of the amygdala during recall of positive AMs in MDD and matched healthy subjects. MDD and healthy subjects went through one visit of rtfMRI neurofeedback training. Subjects were assigned to receive active neurofeedback from the left amygdala or from a control region putatively not modulated by AM recall or emotion regulation, i.e. the left horizontal segment of the intraparietal sulcus. To assess lasting effects of neurofeedback in MDD, the resting state functional connectivity before and after rtfMRI-nf in 27 depressed subjects, as well as in 27 matched healthy subjects before rtfMRI-nf was measured. Results show that abnormal hypo-connectivity with left amygdala in MDD is reversed after rtfMRI-nf training by recalling positive AMs. Although such neuromodulatory changes are observed in both MDD groups receiving feedback from respective active and control brain regions, only in the active group are larger decreases of depression severity associated with larger increases of amygdala connectivity and a significant, positive correlation is found between the connectivity changes and the days after neurofeedback. Additionally, active neurofeedback training of the amygdala enhances connectivity with temporal cortical regions including the hippocampus. These results demonstrate lasting brain changes induced by amygdala rtfMRI-nf training and suggest the importance of reinforcement learning in rehabilitating emotion regulation in depression.
PMID: 25329241 [PubMed - as supplied by publisher]
Developmental Resting State Functional Connectivity for Clinicians.
Curr Behav Neurosci Rep. 2014 Sep 1;1(3):161-169
Authors: Hulvershorn LA, Cullen KR, Francis M, Westlund M
Resting state functional magnetic imaging (fMRI) is a novel means to examine functional brain networks. It allows investigators to identify functional networks defined by distinct, spontaneous signal fluctuations. Resting state functional connectivity (RSFC) studies examining child and adolescent psychiatric disorders are being published with increasing frequency, despite concerns about the impact of motion on findings. Here we review important RSFC findings on typical brain development and recent publications of child and adolescent psychiatric disorders. We close with a summary of the major findings and current strengths and limitations of RSFC studies.
PMID: 25328859 [PubMed - as supplied by publisher]
[Functional connectivity in ischemia stroke motor aphasia patients during resting state].
Zhonghua Yi Xue Za Zhi. 2014 Jul 15;94(27):2135-8
Authors: Wang W, Wang M, Liu H, Yuan B, Wang J, Li H, Zhou X, Wang X, Tao J, Li J
OBJECTIVE: To investigate the changes of Broca's area functional connectivity in ischemia stroke patients with motor aphasia during resting state using functional magnetic resonance imaging (fMRI).
METHODS: The functional connectivity of Broca's area was analyzed by observing the correlation between low frequency signal fluctuations in Broca's area and those in all brain regions.
RESULTS: In the normal controls group, there was multiple brain area positively correlated with Broca's area during resting state. The patients group compared with controls group, the functional connectivity between Broca's area and adjacent brain regions around its is most significant, and its controlateral brain area correlated with Broca's area reduced, but some cerebellum, occipital lobe, middle temporal gyrus and corpus callosum spenium correlated with Broca's area strengthened.
CONCLUSION: There is a wide range of motor function of language network during resting state. The right anterior cingulate gyrus, knee of corpus callosum and hemisphere play an important part in motor language function network. The enhancement functional connectivity between the adjacent brain regions surrounding Broca's area, the right cerebellum, occipital lobe, middle temporal gyrus and spenium of corpus callosum and Broca's area may be one compensatory mechanism remodeling for the language recover of ischemia stroke patients with motor aphasia.
PMID: 25327862 [PubMed - in process]
Functional connectivity density and balance in young patients with traumatic axonal injury.
Brain Connect. 2014 Oct 18;
Authors: Caeyenberghs K, Siugzdaite R, Drijkoningen D, Marinazzo D, Swinnen S
Background: Our previous study (Caeyenberghs et al., 2012) provided some evidence for the relationship between abnormal structural connectivity and poor balance performance in young traumatic axonal injury (TAI) patients. An enhanced understanding of the functional connectivity following TAI may allow for targeted treatments geared towards improving brain function and postural control. Methods: 12 patients with TAI and 28 normally developing children (aged 9-19 years) performed the Sensory Organisation Test (SOT) protocol of the EquiTest (Neurocom). All participants were scanned using resting state fMRI (rs-fMRI) series along with anatomical scans. We applied 'functional connectivity density mapping' (FCDM), a voxel-wise data-driven method that calculates individual functional connectivity maps to obtain both short-range and long-range FCD. Results: Findings revealed that the TAI group scored generally lower than the control group on the SOT, especially when proprioceptive feedback was compromised. Between-group maps noted significantly decreased long-range FCD in the TAI group in frontal and subcortical regions and significantly increased short-range FCD in frontal regions, left inferior parietal and cerebellar lobules. Moreover, lower balance levels in TAI patients were associated with a lower long-range FCD in left putamen and cerebellar vermis. Conclusion: These findings suggest that long-range connections may be more vulnerable to TAI than short-range connections. Moreover, higher values of short-range FCD may suggest adaptive mechanisms in the TAI group. Finally, this study supports the view that FCDM is a valuable tool for selectively predicting functional motor deficits in TAI patients.
PMID: 25327385 [PubMed - as supplied by publisher]
Lateralized Resting-state Functional Connectivity in the Task-positive and Task-negative Networks.
Brain Connect. 2014 Oct 18;
Authors: Kim E, Di X, Chen P, Biswal BB
Studies on functional brain lateralization using functional magnetic resonance imaging (fMRI) have generally focused on lateralization of local brain regions. We analyzed lateralization of functional connectivity using resting-state fMRI (N=87, right handed) and mapped left- and right- lateralized networks. We divided 402 equally spaced regions of interest (ROI) covering the entire gray matter into 358 task-positive and 44 task-negative ROIs. Lateralized functional connections were obtained using k-means clustering analysis. The right-lateralized functional connections were between the occipital and inferior/middle frontal regions among other connections, whereas the left-lateralized functional connections were among fusiform gyrus, inferior frontal and inferior/superior parietal regions. Within the task-negative network, the left-lateralized connections were mainly between the precuneus and medial prefrontal regions. Specific brain regions exhibited different left- or right-lateralized connections with other regions which suggest the importance of reporting lateralized connections over lateralized seed regions. The mean lateralization indices of the left- and right-lateralized connections were correlated, suggesting that the lateralization of connectivity may result from complementary processes between the lateralized networks. The potential functions of the lateralized networks were discussed.
PMID: 25327308 [PubMed - as supplied by publisher]
The relationship between eye movement and vision develops before birth.
Front Hum Neurosci. 2014;8:775
Authors: Schöpf V, Schlegl T, Jakab A, Kasprian G, Woitek R, Prayer D, Langs G
While the visuomotor system is known to develop rapidly after birth, studies have observed spontaneous activity in vertebrates in visually excitable cortical areas already before extrinsic stimuli are present. Resting state networks and fetal eye movements were observed independently in utero, but no functional brain activity coupled with visual stimuli could be detected using fetal fMRI. This study closes this gap and links in utero eye movement with corresponding functional networks. BOLD resting-state fMRI data were acquired from seven singleton fetuses between gestational weeks 30-36 with normal brain development. During the scan time, fetal eye movements were detected and tracked in the functional MRI data. We show that already in utero spontaneous fetal eye movements are linked to simultaneous networks in visual- and frontal cerebral areas. In our small but in terms of gestational age homogenous sample, evidence across the population suggests that the preparation of the human visuomotor system links visual and motor areas already prior to birth.
PMID: 25324764 [PubMed]
Increased resting state functional connectivity in the fronto-parietal and default mode network in anorexia nervosa.
Front Behav Neurosci. 2014;8:346
Authors: Boehm I, Geisler D, King JA, Ritschel F, Seidel M, Deza Araujo Y, Petermann J, Lohmeier H, Weiss J, Walter M, Roessner V, Ehrlich S
The etiology of anorexia nervosa (AN) is poorly understood. Results from functional brain imaging studies investigating the neural profile of AN using cognitive and emotional task paradigms are difficult to reconcile. Task-related imaging studies often require a high level of compliance and can only partially explore the distributed nature and complexity of brain function. In this study, resting state functional connectivity imaging was used to investigate well-characterized brain networks potentially relevant to understand the neural mechanisms underlying the symptomatology and etiology of AN. Resting state functional magnetic resonance imaging data was obtained from 35 unmedicated female acute AN patients and 35 closely matched healthy controls female participants (HC) and decomposed using spatial group independent component analyses (ICA). Using validated templates, we identified components covering the fronto-parietal "control" network, the default mode network (DMN), the salience network, the visual and the sensory-motor network. Group comparison revealed an increased functional connectivity between the angular gyrus and the other parts of the fronto-parietal network in patients with AN in comparison to HC. Connectivity of the angular gyrus was positively associated with self-reported persistence in HC. In the DMN, AN patients also showed an increased functional connectivity strength in the anterior insula in comparison to HC. Anterior insula connectivity was associated with self-reported problems with interoceptive awareness. This study, with one of the largest sample to date, shows that acute AN is associated with abnormal brain connectivity in two major resting state networks (RSN). The finding of an increased functional connectivity in the fronto-parietal network adds novel support for the notion of AN as a disorder of excessive cognitive control, whereas the elevated functional connectivity of the anterior insula with the DMN may reflect the high levels of self- and body-focused ruminations when AN patients are at rest.
PMID: 25324749 [PubMed]
Discriminative sparse connectivity patterns for classification of fMRI Data.
Med Image Comput Comput Assist Interv. 2014;17(Pt 3):193-200
Authors: Eavani H, Satterthwaite TD, Gur RE, Gur RC, Davatzikos C
Functional connectivity using resting-state fMRI has emerged as an important research tool for understanding normal brain function as well as changes occurring during brain development and in various brain disorders. Most prior work has examined changes in pairwise functional connectivity values using a multi-variate classification approach, such as Support Vector Machines (SVM). While it is powerful, SVMs produce a dense set of high-dimensional weight vectors as output, which are difficult to interpret, and require additional post-processing to relate to known functional networks. In this paper, we propose a joint framework that combines network identification and classification, resulting in a set of networks, or Sparse Connectivity Patterns (SCPs) which are functionally interpretable as well as highly discriminative of the two groups. Applied to a study of normal development classifying children vs. adults, the proposed method provided accuracy of 76%(AUC= 0.85), comparable to SVM (79%,AUC=0.87), but with dramatically fewer number of features (50 features vs. 34716 for the SVM). More importantly, this leads to a tremendous improvement in neuro-scientific interpretability, which is specially advantageous in such a study where the group differences are wide-spread throughout the brain. Highest-ranked discriminative SCPs reflect increases in long-range connectivity in adults between the frontal areas and posterior cingulate regions. In contrast, connectivity between the bilateral parahippocampal gyri was decreased in adults compared to children.
PMID: 25320799 [PubMed - in process]
Multiple-network classification of childhood autism using functional connectivity dynamics.
Med Image Comput Comput Assist Interv. 2014;17(Pt 3):177-84
Authors: Price T, Wee CY, Gao W, Shen D
Characterization of disease using stationary resting-state functional connectivity (FC) has provided important hallmarks of abnormal brain activation in many domains. Recent studies of resting-state functional magnetic resonance imaging (fMRI), however, suggest there is a considerable amount of additional knowledge to be gained by investigating the variability in FC over the course of a scan. While a few studies have begun to explore the properties of dynamic FC for characterizing disease, the analysis of dynamic FC over multiple networks at multiple time scales has yet to be fully examined. In this study, we combine dynamic connectivity features in a multi-network, multi-scale approach to evaluate the method's potential in better classifying childhood autism. Specifically, from a set of group-level intrinsic connectivity networks (ICNs), we use sliding window correlations to compute intra-network connectivity on the subject level. We derive dynamic FC features for all ICNs over a large range of window sizes and then use a multiple kernel support vector machine (MK-SVM) model to combine a subset of these features for classification. We compare the performance our multi-network, dynamic approach to the best results obtained from single-network dynamic FC features and those obtained from both single- and multi-network static FC features. Our experiments show that integrating multiple networks on different dynamic scales has a clear superiority over these existing methods.
PMID: 25320797 [PubMed - in process]
Large-scale brain network dynamics supporting adolescent cognitive control.
J Neurosci. 2014 Oct 15;34(42):14096-107
Authors: Dwyer DB, Harrison BJ, Yücel M, Whittle S, Zalesky A, Pantelis C, Allen NB, Fornito A
Adolescence is a time when the ability to engage cognitive control is linked to crucial life outcomes. Despite a historical focus on prefrontal cortex functioning, recent evidence suggests that differences between individuals may relate to interactions between distributed brain regions that collectively form a cognitive control network (CCN). Other research points to a spatially distinct and functionally antagonistic system-the default-mode network (DMN)-which typically deactivates during performance of control tasks. This literature implies that individual differences in cognitive control are determined either by activation or functional connectivity of CCN regions, deactivation or functional connectivity of DMN regions, or some combination of both. We tested between these possibilities using a multilevel fMRI characterization of CCN and DMN dynamics, measured during performance of a cognitive control task and during a task-free resting state, in 73 human adolescents. Better cognitive control performance was associated with (1) reduced activation of CCN regions, but not deactivation of the DMN; (2) variations in task-related, but not resting-state, functional connectivity within a distributed network involving both the CCN and DMN; (3) functional segregation of core elements of these two systems; and (4) task-dependent functional integration of a set of peripheral nodes into either one network or the other in response to prevailing stimulus conditions. These results indicate that individual differences in adolescent cognitive control are not solely attributable to the functioning of any single region or network, but are instead dependent on a dynamic and context-dependent interplay between the CCN and DMN.
PMID: 25319705 [PubMed - in process]