New resting-state fMRI related studies at PubMed

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Weak correlations between hemodynamic signals and ongoing neural activity during the resting state.

Wed, 12/13/2017 - 15:20
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Weak correlations between hemodynamic signals and ongoing neural activity during the resting state.

Nat Neurosci. 2017 Dec;20(12):1761-1769

Authors: Winder AT, Echagarruga C, Zhang Q, Drew PJ

Abstract
Spontaneous fluctuations in hemodynamic signals in the absence of a task or overt stimulation are used to infer neural activity. We tested this coupling by simultaneously measuring neural activity and changes in cerebral blood volume (CBV) in the somatosensory cortex of awake, head-fixed mice during periods of true rest and during whisker stimulation and volitional whisking. We found that neurovascular coupling was similar across states and that large, spontaneous CBV changes in the absence of sensory input were driven by volitional whisker and body movements. Hemodynamic signals during periods of rest were weakly correlated with neural activity. Spontaneous fluctuations in CBV and vessel diameter persisted when local neural spiking and glutamatergic input were blocked, as well as during blockade of noradrenergic receptors, suggesting a non-neuronal origin for spontaneous CBV fluctuations. Spontaneous hemodynamic signals reflect a combination of behavior, local neural activity, and putatively non-neural processes.

PMID: 29184204 [PubMed - indexed for MEDLINE]

Neural substrates underlying balanced time perspective: A combined voxel-based morphometry and resting-state functional connectivity study.

Wed, 12/13/2017 - 15:20
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Neural substrates underlying balanced time perspective: A combined voxel-based morphometry and resting-state functional connectivity study.

Behav Brain Res. 2017 Aug 14;332:237-242

Authors: Guo Y, Chen Z, Feng T

Abstract
Balanced time perspective (BTP), which is defined as a mental ability to switch flexibly among different time perspectives Zimbardo and Boyd (1999), has been suggested to be a central component of positive psychology Boniwell and Zimbardo (2004). BTP reflects individual's cognitive flexibility towards different time frames, which leads to many positive outcomes, including positive mood, subjective wellbeing, emotional intelligence, fluid intelligence, and executive control. However, the neural basis of BTP is still unclear. To address this question, we quantified individual's deviation from the BTP (DBTP), and investigated the neural substrates of DBTP using both voxel-based morphometry (VBM) and resting-state functional connectivity (RSFC) methods VBM analysis found that DBTP scores were positively correlated with gray matter volume (GMV) in the ventral precuneus. We further found that DBTP scores were negatively associated with RSFCs between the ventral precuneus seed region and medial prefrontal cortex (mPFC), bilateral temporoparietal junction (TPJ), parahippocampa gyrus (PHG), and middle frontal gyrus (MFG). These brain regions found in both VBM and RSFC analyses are commonly considered as core nodes of the default mode network (DMN) that is known to be involved in many functions, including episodic and autobiographical memory, self-related processing, theory of mind, and imagining the future. These functions of the DMN are also essential to individuals with BTP. Taken together, we provide the first evidence for the structural and functional neural basis of BTP, and highlight the crucial role of the DMN in cultivating an individual's BTP.

PMID: 28606629 [PubMed - indexed for MEDLINE]

Resting-State Functional Connectivity Within Medial Prefrontal Cortex Mediates Age Differences in Risk Taking.

Wed, 12/13/2017 - 15:20
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Resting-State Functional Connectivity Within Medial Prefrontal Cortex Mediates Age Differences in Risk Taking.

Dev Neuropsychol. 2017;42(3):187-197

Authors: Yu J, Li R, Guo Y, Fang F, Duan S, Lei X

Abstract
To investigate the association between age-related changes in risk taking and resting-state functional activity, we recorded resting-state scans from both young (n = 26) and older adults (n = 27). In addition, all participants completed two decision-making tasks: the Cambridge Gambling Task and the Balloon Analogue Risk Task. We found that older adults showed decreased functional connectivity within the medial prefrontal cortex, particularly between the ventromedial prefrontal cortex and the dorsal medial prefrontal cortex. Moreover, these changes in resting-state functional connectivity were associated with the individuals' risk-taking behavior, and mediated the influence of age on risk taking.

PMID: 28471240 [PubMed - indexed for MEDLINE]

Decreased resting-state interhemispheric functional connectivity correlated with neurocognitive deficits in drug-naive first-episode adolescent-onset schizophrenia.

Tue, 12/12/2017 - 14:00

Decreased resting-state interhemispheric functional connectivity correlated with neurocognitive deficits in drug-naive first-episode adolescent-onset schizophrenia.

Int J Neuropsychopharmacol. 2017 Nov 07;:

Authors: Liu Y, Zhang Y, Lv L, Hu F, Wu R, Zhao J, Guo W

Abstract
Background: Given that adolescence is a critical epoch in the onset of schizophrenia, studying aberrant brain changes in adolescent-onset schizophrenia (AOS), particularly in patients with drug-naive first-episode schizophrenia, is important to understand the biological mechanism of this disorder. Previous resting-state functional magnetic resonance imaging (fMRI) studies have shown abnormal functional connectivity in separate hemispheres in patients with adult-onset schizophrenia. Our aim to study AOS can provide clues for the early aetiology of schizophrenia.
Method: A total of 48 drug-naive first-episode AOS outpatients and 31 healthy controls underwent resting-state fMRI scans. Data were subjected to voxel-mirrored homotopic connectivity (VMHC) and support vector machine (SVM) analyses.
Results: Compared with the healthy controls, the AOS group showed significantly lower VMHC values in different brain regions, including the fusiform gyrus, superior temporal gyrus (STG)/insula, precentral gyrus, and precuneus. Decreased VMHC values in the STG/insula were significantly correlated with Trail-Making Test: Part A(TMT-A) performance (r = -0.437, p = 0.002). A combination of the VMHC values in the precentral gyrus and precuneus may be used to discriminate patients with AOS from controls with satisfactory classification results, which showed sensitivity of 100%, specificity of 87.09%, and accuracy of 94.93%.
Conclusion: Our findings highlight resting-state interhemispheric FC abnormalities within the sensorimotor network of patients with AOS and confirm the relationship between AOS and adult-onset schizophrenia. These findings suggest that reduced interhemispheric connectivity within the sensorimotor network has a pivotal role in the pathogenesis of schizophrenia.

PMID: 29228204 [PubMed - as supplied by publisher]

Structural abnormalities and altered regional brain activity in Multiple Sclerosis with Simple Spinal Cord Involvement.

Tue, 12/12/2017 - 14:00

Structural abnormalities and altered regional brain activity in Multiple Sclerosis with Simple Spinal Cord Involvement.

Br J Radiol. 2017 Dec 11;:20150777

Authors: Yin P, Liu Y, Xiong H, Han Y, Sah SK, Zeng C, Wang J, Li Y

Abstract
OBJECTIVE: To assess the changes of the structural and functional abnormalities in multiple sclerosis with simple spinal cord involvement (MS-SSCI) by using resting-state functional magnetic resonance imaging (RS-fMRI), voxel based morphology (VBM) and diffusion tensor tractography.
METHODS: The amplitude of low-frequency fluctuation (ALFF) of 22 patients with MS-SSCI and 22 healthy controls (HCs) matched for age, gender and education were compared by using RS-fMRI. We also compared the volume, fractional anisotropy (FA) and apparent diffusion coefficient (ADC) of the brain regions in baseline brain activity by using voxel-based morphology (VBM) and diffusion tensor imaging (DTI). The relationships between the expanded disability states scale (EDSS) scores, changed parameters of structure and function were further explored.
RESULTS: (1) Compared with HCs, the ALFF of the bilateral hippocampus and right middle temporal gyrus in MS-SSCI decreased significantly. However, patients exhibited increased ALFF in the left middle frontal gyrus, left posterior cingulate gyrus and right middle occipital gyrus ( two-sample t test, after AlphaSim correction, p < 0.01, voxel size > 40). The volume of right middle frontal gyrus reduced significantly(p < 0.01). The FA and ADC of right hippocampus, the FA of left hippocampus and right middle temporal gyrus were significantly different.(2) A significant correlation between EDSS scores and ALFF was noted only in the left posterior cingulate gyrus.
CONCLUSION: Our results detected structural and functional abnormalities in MS-SSCI and functional parameters were associated with clinical abnormalities. Multimodal imaging plays an important role in detecting structural and functional abnormalities in MS-SSCI. Advances in knowledge: This is the first time to apply RS-fMRI, VBM and diffusion tensor tractography to study the structural and functional abnormalities in MS-SSCI, and to explore its correlation with EDSS score.

PMID: 29227148 [PubMed - as supplied by publisher]

Enhanced brain network activity in complex movement rhythms: a simultaneous fMRI-EEG study.

Tue, 12/12/2017 - 14:00

Enhanced brain network activity in complex movement rhythms: a simultaneous fMRI-EEG study.

Brain Connect. 2017 Dec 10;:

Authors: Adhikari BM, Epstein CM, Dhamala M

Abstract
Generating movement rhythms is known to involve a network of distributed brain regions associated with motor planning, control, execution, and perception of timing for the repertoire of motor actions. What brain areas are bound in the network and how the network activity is modulated by rhythmic complexity have not been completely explored. To contribute to answering these questions, we designed a study in which nine healthy participants performed simple to complex rhythmic finger movement tasks while undergoing simultaneous functional magnetic resonance imaging and electroencephalography (fMRI-EEG) recordings of their brain activity during the tasks and rest. From fMRI blood oxygenation-level dependent (BOLD) measurements, we found that the complexity of rhythms was associated with brain activations in the primary motor cortex (PMC), supplementary motor area (SMA), and cerebellum (Cb), and with network interactions from these cortical regions to the cerebellum. The spectral analysis of single-trial EEG source waveforms at the cortical regions further showed that there were bidirectional interactions between PMC and SMA, and the complexity of rhythms was associated with power spectra and Granger causality spectra in the beta (13-30 Hz) frequency band, not in the alpha (8-12 Hz) and gamma (30-58 Hz) bands. These results provide us new insights into the mechanisms for movement rhythm complexity.

PMID: 29226709 [PubMed - as supplied by publisher]

Retrospective correction of physiological noise: impact on sensitivity, specificity, and reproducibility of resting-state functional connectivity in a reading network model.

Tue, 12/12/2017 - 14:00

Retrospective correction of physiological noise: impact on sensitivity, specificity, and reproducibility of resting-state functional connectivity in a reading network model.

Brain Connect. 2017 Dec 10;:

Authors: Krishnamurthy V, Krishnamurthy LC, Schwam DM, Ealey A, Shin J, Greenberg D, Morris RD

Abstract
It is well accepted that physiological noise (PN) obscures the detection of neural fluctuations in resting-state functional connectivity (rsFC) MRI. However, a clear consensus for an optimal PN correction (PNC) methodology and how it can impact the rsFC signal characteristics is still lacking. In this study, we probe the impact of three PNC methods: RETROICOR: (Glover, et al. 2000), ANATICOR: (Jo, et al. 2010), and RVTMBPM: (Bianciardi, et al. 2009). Using a reading network model, we systematically explore the effects of PNC optimization on sensitivity, specificity, and reproducibility of rsFC signals. In terms of specificity, ANATICOR was found to be effective in removing local white matter (WM) fluctuations but also resulted in aggressive removal of expected cortical-to-subcortical functional connections. The ability of RETROICOR to remove PN was equivalent to removal of simulated random PN such that it artificially inflated the connection strength, thereby decreasing sensitivity. RVTMBPM maintained specificity and sensitivity by balanced removal of vasodilatory PN and local WM nuisance edges. Another aspect of this work was exploring the effects of PNC on identifying reading group differences. Most PNC methods accounted for between-subject PN variability resulting in reduced inter-session reproducibility. This effect facilitated the detection of the most consistent group differences. RVTMBPM was most effective in detecting significant group differences due to its inherent sensitivity to removing spatially structured and temporally repeating PN arising from dense vasculature. Finally, results suggest that combining all three PNC resulted in 'over-correction' by removing signal along with noise.

PMID: 29226700 [PubMed - as supplied by publisher]

Simultaneous Multi-slice Resting-state fMRI at 3 Tesla: Slice-Acceleration Related Biases in Physiological Effects.

Tue, 12/12/2017 - 14:00

Simultaneous Multi-slice Resting-state fMRI at 3 Tesla: Slice-Acceleration Related Biases in Physiological Effects.

Brain Connect. 2017 Dec 10;:

Authors: Golestani AM, Faraji-Dana Z, Kayvanrad MA, Setsompop K, Graham S, Chen JJ

Abstract
Simultaneous multi-slice echo-planar imaging (EPI) can enhance the spatiotemporal resolution of resting-state functional MRI (rs-fMRI) by encoding and simultaneously imaging "groups" of slices. However, phenomena including respiration, cardiac pulsatility, respiration volume per time (RVT) and cardiac-rate variation (CRV), referred to as "physiological processes", impact SMS-EPI rs-fMRI in a manner that has yet to be well characterized. In particular, physiological noise may incur aliasing and introduce spurious signals from one slice into another within the "slice-group" in rs-fMRI data, resulting in a deleterious effect on resting-state functional connectivity MRI (rs-fcMRI) maps. In the present work, we aimed to quantitatively compare the effects of physiological noise on regular EPI and SMS-EPI in terms of rs-fMRI data and resulting functional connectivity measurements. We compare SMS-EPI and regular EPI data acquired from 11 healthy young adults with matching parameters. The physiological-noise characteristics were compared between the two datasets through different combinations of physiological-regression steps. We observed that the physiological-noise characteristics differed between SMS-EPI and regular EPI, with cardiac pulsatility contributing more to noise in regular EPI data but low-frequency heart-rate variability contributing more to SMS EPI. Additionally, a significant slice-group bias was observed in the functional-connectivity density maps derived from SMS-EPI data. We conclude that making appropriate corrections for physiological noise is likely more important for SMS-EPI than for regular EPI acquisitions.

PMID: 29226689 [PubMed - as supplied by publisher]

Improving Functional MRI Registration Using Whole-Brain Functional Correlation Tensors.

Tue, 12/12/2017 - 14:00
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Improving Functional MRI Registration Using Whole-Brain Functional Correlation Tensors.

Med Image Comput Comput Assist Interv. 2017 Sep;10433:416-423

Authors: Zhou Y, Yap PT, Zhang H, Zhang L, Feng Q, Shen D

Abstract
Population studies of brain function with resting-state functional magnetic resonance imaging (rs-fMRI) largely rely on the accurate inter-subject registration of functional areas. This is typically achieved through registration of the corresponding T1-weighted MR images with more structural details. However, accumulating evidence has suggested that such strategy cannot well-align functional regions which are not necessarily confined by the anatomical boundaries defined by the T1-weighted MR images. To mitigate this problem, various registration algorithms based directly on rs-fMRI data have been developed, most of which have utilized functional connectivity (FC) as features for registration. However, most of the FC-based registration methods usually extract the functional features only from the thin and highly curved cortical grey matter (GM), posing a great challenge in accurately estimating the whole-brain deformation field. In this paper, we demonstrate that the additional useful functional features can be extracted from brain regions beyond the GM, particularly, white-matter (WM) based on rs-fMRI, for improving the overall functional registration. Specifically, we quantify the local anisotropic correlation patterns of the blood oxygenation level-dependent (BOLD) signals, modeled by functional correlation tensors (FCTs), in both GM and WM. Functional registration is then performed based on multiple components of the whole-brain FCTs using a multichannel Large Deformation Diffeomorphic Metric Mapping (mLDDMM) algorithm. Experimental results show that our proposed method achieves superior functional registration performance, compared with other conventional registration methods.

PMID: 29226283 [PubMed - in process]

Correlation between Traits of Emotion-Based Impulsivity and Intrinsic Default-Mode Network Activity.

Tue, 12/12/2017 - 14:00
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Correlation between Traits of Emotion-Based Impulsivity and Intrinsic Default-Mode Network Activity.

Neural Plast. 2017;2017:9297621

Authors: Zhao J, Tomasi D, Wiers CE, Shokri-Kojori E, Demiral ŞB, Zhang Y, Volkow ND, Wang GJ

Abstract
Negative urgency (NU) and positive urgency (PU) are implicated in several high-risk behaviors, such as eating disorders, substance use disorders, and nonsuicidal self-injury behavior. The current study aimed to explore the possible link between trait of urgency and brain activity at rest. We assessed the amplitude of low-frequency fluctuations (ALFF) of the resting-state functional magnetic resonance imaging (fMRI) signal in 85 healthy volunteers. Trait urgency measures were related to ALFF in the lateral orbitofrontal cortex, dorsolateral prefrontal cortex, ventral and dorsal medial frontal cortex, anterior cingulate, and posterior cingulate cortex/precuneus. In addition, trait urgency measures showed significant correlations with the functional connectivity of the posterior cingulate cortex/precuneus seed with the thalamus and midbrain region. These findings suggest an association between intrinsic brain activity and impulsive behaviors in healthy humans.

PMID: 29225975 [PubMed - in process]

High-Resolution CBV-fMRI Allows Mapping of Laminar Activity and Connectivity of Cortical Input and Output in Human M1.

Tue, 12/12/2017 - 14:00
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High-Resolution CBV-fMRI Allows Mapping of Laminar Activity and Connectivity of Cortical Input and Output in Human M1.

Neuron. 2017 Dec 06;:

Authors: Huber L, Handwerker DA, Jangraw DC, Chen G, Hall A, Stüber C, Gonzalez-Castillo J, Ivanov D, Marrett S, Guidi M, Goense J, Poser BA, Bandettini PA

Abstract
Layer-dependent fMRI allows measurements of information flow in cortical circuits, as afferent and efferent connections terminate in different cortical layers. However, it is unknown to what level human fMRI is specific and sensitive enough to reveal directional functional activity across layers. To answer this question, we developed acquisition and analysis methods for blood-oxygen-level-dependent (BOLD) and cerebral-blood-volume (CBV)-based laminar fMRI and used these to discriminate four different tasks in the human motor cortex (M1). In agreement with anatomical data from animal studies, we found evidence for somatosensory and premotor input in superficial layers of M1 and for cortico-spinal motor output in deep layers. Laminar resting-state fMRI showed directional functional connectivity of M1 with somatosensory and premotor areas. Our findings demonstrate that CBV-fMRI can be used to investigate cortical activity in humans with unprecedented detail, allowing investigations of information flow between brain regions and outperforming conventional BOLD results that are often buried under vascular biases.

PMID: 29224727 [PubMed - as supplied by publisher]

Intrinsic functional connectivity between amygdala and hippocampus during rest predicts enhanced memory under stress.

Tue, 12/12/2017 - 14:00
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Intrinsic functional connectivity between amygdala and hippocampus during rest predicts enhanced memory under stress.

Psychoneuroendocrinology. 2017 Jan;75:192-202

Authors: de Voogd LD, Klumpers F, Fernández G, Hermans EJ

Abstract
Declarative memories of stressful events are less prone to forgetting than mundane events. Animal research has demonstrated that such stress effects on consolidation of hippocampal-dependent memories require the amygdala. In humans, it has been shown that during learning, increased amygdala-hippocampal interactions are related to more efficient memory encoding. Animal models predict that following learning, amygdala-hippocampal interactions are instrumental to strengthening the consolidation of such declarative memories. Whether this is the case in humans is unknown and remains to be empirically verified. To test this, we analyzed data from a sample of 120 healthy male participants who performed an incidental encoding task and subsequently underwent resting-state functional MRI in a stressful and a neutral context. Stress was assessed by measures of salivary cortisol, blood pressure, heart rate, and subjective ratings. Memory was tested afterwards outside of the scanner. Our data show that memory was stronger in the stress context compared to the neutral context and that stress-induced cortisol responses were associated with this memory enhancement. Interestingly, amygdala-hippocampal connectivity during post-encoding awake rest regardless of context (stress or neutral) was associated with the enhanced memory performance under stress. Thus, our findings are in line with a role for intrinsic functional connectivity during rest between the amygdala and the hippocampus in the state effects of stress on strengthening memory.

PMID: 27837699 [PubMed - indexed for MEDLINE]

Circulating androgens correlate with resting-state MRI in transgender men.

Tue, 12/12/2017 - 14:00
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Circulating androgens correlate with resting-state MRI in transgender men.

Psychoneuroendocrinology. 2016 Nov;73:91-98

Authors: Mueller SC, Wierckx K, Jackson K, T'Sjoen G

Abstract
Despite mounting evidence regarding the underlying neurobiology in transgender persons, information regarding resting-state activity, particularly after hormonal treatment, is lacking. The present study examined differences between transgender persons on long-term cross-sex hormone therapy and comparisons on two measures of local functional connectivity, intensity of spontaneous resting-state activity (low frequency fluctuations, LFF) and local synchronization of specific brain areas (regional homogeneity, ReHo). Nineteen transgender women (TW, male-to-female), 19 transgender men (TM, female-to-male), 21 non-transgender men (NTM) and 20 non-transgender women (NTW) underwent a resting-state MRI scan. The results showed differences between transgender persons and non-transgender comparisons on both LFF and ReHo measures in the frontal cortex, medial temporal lobe, and cerebellum. More interestingly, circulating androgens correlated for TM in the cerebellum and regions of the frontal cortex, an effect that was associated with treatment duration in the cerebellum. By comparison, no associations were found for TW with estrogens. These data provide first evidence for a potential masculinization of local functional connectivity in hormonally-treated transgender men.

PMID: 27479654 [PubMed - indexed for MEDLINE]

Task-based and resting-state fMRI reveal compensatory network changes following damage to left inferior frontal gyrus.

Mon, 12/11/2017 - 13:00

Task-based and resting-state fMRI reveal compensatory network changes following damage to left inferior frontal gyrus.

Cortex. 2017 Oct 17;99:150-165

Authors: Hallam GP, Thompson HE, Hymers M, Millman RE, Rodd JM, Lambon Ralph MA, Smallwood J, Jefferies E

Abstract
Damage to left inferior prefrontal cortex in stroke aphasia is associated with semantic deficits reflecting poor control over conceptual retrieval, as opposed to loss of knowledge. However, little is known about how functional recruitment within the semantic network changes in patients with executive-semantic deficits. The current study acquired functional magnetic resonance imaging (fMRI) data from 14 patients with semantic aphasia, who had difficulty with flexible semantic retrieval following left prefrontal damage, and 16 healthy age-matched controls, allowing us to examine activation and connectivity in the semantic network. We examined neural activity while participants listened to spoken sentences that varied in their levels of lexical ambiguity and during rest. We found group differences in two regions thought to be good candidates for functional compensation: ventral anterior temporal lobe (vATL), which is strongly implicated in comprehension, and posterior middle temporal gyrus (pMTG), which is hypothesized to work together with left inferior prefrontal cortex to support controlled aspects of semantic retrieval. The patients recruited both of these sites more than controls in response to meaningful sentences. Subsequent analysis identified that, in control participants, the recruitment of pMTG to ambiguous sentences was inversely related to functional coupling between pMTG and anterior superior temporal gyrus (aSTG) at rest, while the patients showed the opposite pattern. Moreover, stronger connectivity between pMTG and aSTG in patients was associated with better performance on a test of verbal semantic association, suggesting that this temporal lobe connection supports comprehension in the face of damage to left inferior prefrontal cortex. These results characterize network changes in patients with executive-semantic deficits and converge with studies of healthy participants in providing evidence for a distributed system underpinning semantic control that includes pMTG in addition to left inferior prefrontal cortex.

PMID: 29223933 [PubMed - as supplied by publisher]

Network analysis reveals disrupted functional brain circuitry in drug-naive social anxiety disorder.

Mon, 12/11/2017 - 13:00

Network analysis reveals disrupted functional brain circuitry in drug-naive social anxiety disorder.

Neuroimage. 2017 Dec 06;:

Authors: Yang X, Liu J, Meng Y, Xia M, Cui Z, Wu X, Hu X, Zhang W, Gong G, Gong Q, Sweeney JA, He Y

Abstract
Social anxiety disorder (SAD) is a common and disabling condition characterized by excessive fear and avoidance of public scrutiny. Neuroimaging studies have suggested that the emotional and behavior deficits in SAD are associated with abnormalities in regional brain function and functional connectivity. However, little is known about whether intrinsic functional brain networks in patients with SAD are topologically disrupted. Here, we collected resting-state fMRI data from 33 drug-naive patients with SAD and 32 healthy controls (HC), constructed functional networks with 34 predefined regions based on previous meta-analytic research with task-based fMRI in SAD, and performed network-based statistic and graph-theory analyses. The network-based statistic analysis revealed a single connected abnormal circuitry including the frontolimbic circuit (termed the "fear circuit", including the dorsolateral prefrontal cortex, ventral medial prefrontal cortex and insula) and posterior cingulate/occipital areas supporting perceptual processing. In this single altered network, patients with SAD had higher functional connectivity than HC. At the global level, graph-theory analysis revealed that the patients exhibited a lower normalized characteristic path length than HC, which suggests a disorder-related shift of network topology toward randomized configurations. SAD-related deficits in nodal degree, efficiency and participation coefficient were detected in the parahippocampal gyrus, posterior cingulate cortex, dorsolateral prefrontal cortex, insula and the calcarine sulcus. Aspects of abnormal connectivity were associated with anxiety symptoms. These findings highlight the aberrant topological organization of functional brain network organization in SAD, which provides insights into the neural mechanisms underlying excessive fear and avoidance of social interactions in patients with debilitating social anxiety.

PMID: 29223742 [PubMed - as supplied by publisher]

Assessing age-dependent multi-task functional co-activation changes using measures of task-potency.

Mon, 12/11/2017 - 13:00

Assessing age-dependent multi-task functional co-activation changes using measures of task-potency.

Dev Cogn Neurosci. 2017 Dec 05;:

Authors: Chauvin RJ, Mennes M, Buitelaar JK, Beckmann CF

Abstract
It is being hypothesised that the developing adolescent brain is increasingly enlisting long-range connectivity, allowing improved communication between spatially distant brain regions. The developmental trajectories of such maturational changes remain elusive. Here, we aim to study how the brain engages in multiple tasks (working memory, reward processing, and inhibition) at the network-level and evaluate how effects of age across these tasks are related to each other. We characterise how the brain departs from its functional baseline architecture towards task-induced functional connectivity modulations using a novel measure called task potency, allowing direct comparison between tasks by defining sensitivity to one or multiple tasks. By applying this method in a sample of healthy participants (N=218) aged 8-30 years, we demonstrate maturational changes in task-dependent functional co-activation over and above baseline connectivity maturation. Our results provide evidence for task-specific maturational windows with different cognitive systems probed by different tasks displaying specific age-range dependencies of strongest developmental change. Our results highlight the use of task potency for modelling developmental trajectories and the impact of differential maturation across tasks. This enables better characterisation of cognitive processes disrupted in neurodevelopmental disorders and may explain the increased level of heterogeneity observed in adolescent population studies.

PMID: 29223425 [PubMed - as supplied by publisher]

Effective network of deep brain stimulation of subthalamic nucleus with bimodal positron emission tomography/functional magnetic resonance imaging in Parkinson's disease.

Sun, 12/10/2017 - 11:40
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Effective network of deep brain stimulation of subthalamic nucleus with bimodal positron emission tomography/functional magnetic resonance imaging in Parkinson's disease.

CNS Neurosci Ther. 2017 Dec 08;:

Authors: Chen HM, Sha ZQ, Ma HZ, He Y, Feng T

Abstract
AIMS: Deep brain stimulation of the subthalamic nucleus (STN-DBS) has become an effective treatment strategy for patients with Parkinson's disease. However, the biological mechanism underlying DBS treatment remains poorly understood.
METHOD: In this study, we investigated how STN-DBS modulated the brain network using a bimodal positron emission tomography (PET)/functional magnetic resonance imaging (fMRI) dataset. We first performed an activation likelihood estimation meta-analysis of 13 PET/SPECT studies concerning STN-DBS effects on resting-state brain activity in Parkinson's disease. Additionally, using a functional connectivity analysis in resting-state fMRI, we investigated whether these STN-DBS-affected regions were functionally connected to constitute an effective network.
RESULTS: The results revealed that STN-DBS reduced brain activity in the right thalamus, bilateral caudal supplementary area, and the left primary motor cortex, and it increased brain activity in the left thalamus during rest. Second, these STN-DBS-affected areas were functionally connected within an STN-DBS effective network.
CONCLUSION: Deep brain stimulation of the subthalamic nucleus (STN-DBS) may deactivate the motor cortex as a remote and network effect, affecting the target and the neighboring subcortical areas. These areas may constitute an effective network of STN-DBS modulation. Our results shed light on the mechanisms of STN-DBS treatment from a network perspective and highlight the potential therapeutic benefits of targeted network modulation.

PMID: 29222835 [PubMed - as supplied by publisher]

Task-related effective connectivity reveals that the cortical rich club gates cortex-wide communication.

Sun, 12/10/2017 - 11:40
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Task-related effective connectivity reveals that the cortical rich club gates cortex-wide communication.

Hum Brain Mapp. 2017 Dec 08;:

Authors: Senden M, Reuter N, van den Heuvel MP, Goebel R, Deco G, Gilson M

Abstract
Higher cognition may require the globally coordinated integration of specialized brain regions into functional networks. A collection of structural cortical hubs-referred to as the rich club-has been hypothesized to support task-specific functional integration. In the present paper, we use a whole-cortex model to estimate directed interactions between 68 cortical regions from functional magnetic resonance imaging activity for four different tasks (reflecting different cognitive domains) and resting state. We analyze the state-dependent input and output effective connectivity (EC) of the structural rich club and relate these to whole-cortex dynamics and network reconfigurations. We find that the cortical rich club exhibits an increase in outgoing EC during task performance as compared with rest while incoming connectivity remains constant. Increased outgoing connectivity targets a sparse set of peripheral regions with specific regions strongly overlapping between tasks. At the same time, community detection analyses reveal massive reorganizations of interactions among peripheral regions, including those serving as target of increased rich club output. This suggests that while peripheral regions may play a role in several tasks, their concrete interplay might nonetheless be task-specific. Furthermore, we observe that whole-cortex dynamics are faster during task as compared with rest. The decoupling effects usually accompanying faster dynamics appear to be counteracted by the increased rich club outgoing EC. Together our findings speak to a gating mechanism of the rich club that supports fast-paced information exchange among relevant peripheral regions in a task-specific and goal-directed fashion, while constantly listening to the whole network.

PMID: 29222818 [PubMed - as supplied by publisher]

Shyness and Trajectories of Functional Network Connectivity Over Early Adolescence.

Sun, 12/10/2017 - 11:40
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Shyness and Trajectories of Functional Network Connectivity Over Early Adolescence.

Child Dev. 2017 Dec 08;:

Authors: Sylvester CM, Whalen DJ, Belden AC, Sanchez SL, Luby JL, Barch DM

Abstract
High shyness during early adolescence is associated with impaired peer relationships and risk for psychiatric disorders. Little is known, however, about the relation between shyness and trajectories of brain development over early adolescence. The current study longitudinally examined trajectories of resting-state functional connectivity (rs-fc) within four brain networks in 147 adolescents. Subjects underwent functional magnetic resonance imaging at three different time points, at average ages 10.5 (range = 7.8-13.0), 11.7 (range = 9.3-14.1), and 12.9 years (range = 10.1-15.2). Multilevel linear modeling indicated that high shyness was associated with a less steep negative slope of default mode network (DMN) rs-fc over early adolescence relative to low shyness. Less steep decreases in DMN rs-fc may relate to increased self-focus in adolescents with high shyness.

PMID: 29222816 [PubMed - as supplied by publisher]

Altered resting state functional connectivity in early course schizophrenia.

Sat, 12/09/2017 - 16:40

Altered resting state functional connectivity in early course schizophrenia.

Psychiatry Res. 2017 Nov 22;271:17-23

Authors: Sharma A, Kumar A, Singh S, Bhatia T, Beniwal RP, Khushu S, Prasad KM, Deshpande SN

Abstract
Impaired connectivity is proposed to underlie pathophysiology of schizophrenia. Existing studies on functional connectivity show inconsistent results. We examined functional connectivity in a clinically homogenous sample of 34 early course schizophrenia patients compared with/to 19 healthy controls using resting state functional magnetic resonance imaging (rsfMRI). Mean duration of illness for schizophrenia patients was 4 ± 1.78 years. Following a comprehensive clinical assessment, rsfMRI data were acquired using a 3.0 T magnetic resonance imaging scanner, and analyzed using FSL version 5.01 software (FMRIB's Software Library, www.fmrib.ox.ac.uk/fsl). Compared to healthy controls, schizophrenia patients had significantly decreased functional connectivity in the left fronto-parietal network, lateral and medial visual network, motor network, default mode network and auditory network. Our data suggests significant functional hypoconnectivity in selected brain networks in early schizophrenia patients compared to controls. It is likely that the observed functional hypoconnectivity may be associated with features of schizophrenia other than those examined in this study. It is possible that hypoconnectivity is necessary but not sufficient to the clinical manifestation of schizophrenia. The examination of functional connectivity as a biomarker should be extended to a wider array of disease phenotypes to better understand its significance.

PMID: 29220695 [PubMed - as supplied by publisher]

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