New resting-state fMRI related studies at PubMed

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How restful is it with all that noise? Comparison of Interleaved silent steady state (ISSS) and conventional imaging in resting-state fMRI.

Fri, 12/02/2016 - 23:05
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How restful is it with all that noise? Comparison of Interleaved silent steady state (ISSS) and conventional imaging in resting-state fMRI.

Neuroimage. 2016 Nov 27;:

Authors: Andoh J, Ferreira M, Leppert IR, Matsushita R, Pike B, Zatorre RJ

Abstract
Resting-state fMRI studies have become very important in cognitive neuroscience because they are able to identify BOLD fluctuations in brain circuits involved in motor, cognitive, or perceptual processes without the use of an explicit task. Such approaches have been fruitful when applied to various disordered populations, or to children or the elderly. However, insufficient attention has been paid to the consequences of the loud acoustic scanner noise associated with conventional fMRI acquisition, which could be an important confounding factor affecting auditory and/or cognitive networks in resting-state fMRI. Several approaches have been developed to mitigate the effects of acoustic noise on fMRI signals, including sparse sampling protocols and interleaved silent steady state (ISSS) acquisition methods, the latter being used only for task-based fMRI. Here, we developed an ISSS protocol for resting-state fMRI (rs-ISSS) consisting of rapid acquisition of a set of echo planar imaging volumes following each silent period, during which the steady state longitudinal magnetization was maintained with a train of relatively silent slice-selective excitation pulses. We evaluated the test-retest reliability of intensity and spatial extent of connectivity networks of fMRI BOLD signal across three different days for rs-ISSS and compared it with a standard resting-state fMRI (rs-STD). We also compared the strength and distribution of connectivity networks between rs-ISSS and rs-STD. We found that both rs-ISSS and rs-STD showed high reproducibility of fMRI signal across days. In addition, rs-ISSS showed a more robust pattern of functional connectivity within the somatosensory and motor networks, as well as an auditory network compared with rs-STD. An increased connectivity between the default mode network and the language network and with the anterior cingulate cortex (ACC) network was also found for rs-ISSS compared with rs-STD. Finally, region of interest analysis showed higher interhemispheric connectivity in Heschl's gyri in rs-ISSS compared with rs-STD, with lower variability across days. The present findings suggest that rs-ISSS may be advantageous for detecting network connectivity in a less noisy environment, and that resting-state studies carried out with standard scanning protocols should consider the potential effects of loud noise on the measured networks.

PMID: 27902936 [PubMed - as supplied by publisher]

Changes in functional connectivity of the brain associated with a history of sport concussion: A preliminary investigation.

Fri, 12/02/2016 - 23:05
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Changes in functional connectivity of the brain associated with a history of sport concussion: A preliminary investigation.

Brain Inj. 2016 Nov 30;:1-10

Authors: Churchill N, Hutchison MG, Leung G, Graham S, Schweizer TA

Abstract
OBJECTIVE: There is evidence of long-term clinical consequences associated with a history of sport concussion. However, there remains limited information about the underlying changes in brain function. The goal of this study was to identify brain regions where abnormal resting-state function is associated with chronic concussion, for athletes without persistent symptoms.
METHODS: Functional Magnetic Resonance Imaging (fMRI) was performed on a group of athletes with prior concussion (n = 22) and a group without documented injury (n = 21). Multivariate predictive modelling was used to localize reliable changes in brain connectivity that are associated with a history of concussion and with clinical factors, including number of prior concussions and recovery time from last injury.
RESULTS: No significant differences were found between athletes with and without a history of concussion, but functional connectivity was significantly associated with clinical history. The number of prior concussions was associated with most extensive connectivity changes, particularly for elements of the visual attention network and cerebellum.
CONCLUSION: The findings of this preliminary study indicate that functional brain abnormalities associated with chronic concussion may be significantly dependent on clinical history. In addition, elements of the visual and cerebellar systems may be most sensitive to the long-term effects of sport concussion.

PMID: 27901587 [PubMed - as supplied by publisher]

Functional brain mapping using specific sensory-circuit stimulation and a theoretical graph network analysis in mice with neuropathic allodynia.

Wed, 11/30/2016 - 16:25

Functional brain mapping using specific sensory-circuit stimulation and a theoretical graph network analysis in mice with neuropathic allodynia.

Sci Rep. 2016 Nov 29;6:37802

Authors: Komaki Y, Hikishima K, Shibata S, Konomi T, Seki F, Yamada M, Miyasaka N, Fujiyoshi K, Okano HJ, Nakamura M, Okano H

Abstract
Allodynia, a form of neuropathic pain, is defined as pain in response to a non-nociceptive stimulus. The brain regions responsible for pain, which are not normally activated, can be activated in allodynic mice by providing a suitable stimulus to Aβ-fibers, which transmit signals from tactile sensory fibers. Functional MRI (fMRI) can be used to objectively observe abnormal brain activation. In the present study, fMRI was conducted to investigate allodynia in mice; allodynia was generated by surgical injury at the L4 spinal nerve root, thus selectively stimulating sensory nerve fibers. In intact mice, only the primary somatosensory cortex (S1) was activated by stimulation of Aβ-fibers. Meanwhile, allodynic mice showed significantly higher BOLD signals in the anterior cingulate area (ACA) and thalamus. Using resting state fMRI, both degree and eigenvector centrality were significantly decreased in the contralateral S1, clustering coefficient and local efficiency were significantly increased in the ACA, and betweenness centrality was significantly higher in the ventral posterolateral nucleus of the thalamus. These results suggest that the observed abnormal BOLD activation is associated with defects in Aβ-fibers when Aβ-fibers in allodynic mice are selectively stimulated. The objective approach enabled by fMRI can improve our understanding of pathophysiological mechanisms and therapeutic efficacy.

PMID: 27898057 [PubMed - in process]

Abnormal coupling between DMN and delta and beta band EEG in psychotic patients.

Wed, 11/30/2016 - 16:25

Abnormal coupling between DMN and delta and beta band EEG in psychotic patients.

Brain Connect. 2016 Nov 29;

Authors: Baenninger A, Palzes VA, Roach BJ, Mathalon DH, Ford J, Koenig T

Abstract
Common-phase synchronization of neuronal oscillations is a mechanism by which distributed brain regions can be integrated into transiently stable networks. Based on the hypothesis that schizophrenia is characterized by deficits in functional integration within neuronal networks, this study aimed to explore whether psychotic patients exhibit differences in brain regions involved in integrative mechanisms. We report an EEG-informed fMRI analysis of eyes-open resting state data collected from patients and healthy controls at two study sites. Global field synchronization (GFS) was chosen as an EEG measure indicating common-phase synchronization across electrodes. Several brain clusters appeared to be coupled to GFS differently in patients and controls: Activation in brain areas belonging to the default mode network (DMN) were negatively associated to GFS delta (1 - 3.5Hz) and positively to GFS beta (13 - 30Hz) bands in patients, whereas controls showed an opposite pattern for both GFS frequency bands in those regions; activation in extrastriate visual cortex was inversely related to GFS alpha1 (8.5 - 10.5Hz) band in healthy controls, while patients had a tendency towards a positive relationship. Taken together, the GFS measure might be useful for detecting additional aspects of deficient functional network integration in psychosis.

PMID: 27897031 [PubMed - as supplied by publisher]

ADAPTIVE TESTING OF SNP-BRAIN FUNCTIONAL CONNECTIVITY ASSOCIATION VIA A MODULAR NETWORK ANALYSIS.

Wed, 11/30/2016 - 16:25

ADAPTIVE TESTING OF SNP-BRAIN FUNCTIONAL CONNECTIVITY ASSOCIATION VIA A MODULAR NETWORK ANALYSIS.

Pac Symp Biocomput. 2016;22:58-69

Authors: Gao C, Kim J, Pan W

Abstract
Due to its high dimensionality and high noise levels, analysis of a large brain functional network may not be powerful and easy to interpret; instead, decomposition of a large network into smaller subcomponents called modules may be more promising as suggested by some empirical evidence. For example, alteration of brain modularity is observed in patients suffering from various types of brain malfunctions. Although several methods exist for estimating brain functional networks, such as the sample correlation matrix or graphical lasso for a sparse precision matrix, it is still difficult to extract modules from such network estimates. Motivated by these considerations, we adapt a weighted gene co-expression network analysis (WGCNA) framework to resting-state fMRI (rs-fMRI) data to identify modular structures in brain functional networks. Modular structures are identified by using topological overlap matrix (TOM) elements in hierarchical clustering. We propose applying a new adaptive test built on the proportional odds model (POM) that can be applied to a high-dimensional setting, where the number of variables (p) can exceed the sample size (n) in addition to the usual p < n setting. We applied our proposed methods to the ADNI data to test for associations between a genetic variant and either the whole brain functional network or its various subcomponents using various connectivity measures. We uncovered several modules based on the control cohort, and some of them were marginally associated with the APOE4 variant and several other SNPs; however, due to the small sample size of the ADNI data, larger studies are needed.

PMID: 27896962 [PubMed - in process]

Tradeoffs in pushing the spatial resolution of fMRI for the 7T Human Connectome Project.

Wed, 11/30/2016 - 16:25

Tradeoffs in pushing the spatial resolution of fMRI for the 7T Human Connectome Project.

Neuroimage. 2016 Nov 25;:

Authors: Thanh Vu A, Jamison K, Glasser MF, Smith SM, Coalson T, Moeller S, Auerbach EJ, Ugurbil K, Yacoub E

Abstract
Whole-brain functional magnetic resonance imaging (fMRI), in conjunction with multiband acceleration, has played an important role in mapping the functional connectivity throughout the entire brain with both high temporal and spatial resolution. Ultrahigh magnetic field strengths (7T and above) allow functional imaging with even higher functional contrast-to-noise ratios for improved spatial resolution and specificity compared to traditional field strengths (1.5T and 3T). High-resolution 7T fMRI, however, has primarily been constrained to smaller brain regions given the amount of time it takes to acquire the number of slices necessary for high resolution whole brain imaging. Here we evaluate a range of whole-brain high-resolution resting state fMRI protocols (0.9, 1.25, 1.5, 1.6 and 2 mm isotropic voxels) at 7T, obtained with both in-plane and slice acceleration parallel imaging techniques to maintain the temporal resolution and brain coverage typically acquired at 3T. Using the processing pipeline developed by the Human Connectome Project, we demonstrate that high resolution images acquired at 7T provide increased functional contrast to noise ratios with significantly less partial volume effects and more distinct spatial features, potentially allowing for robust individual subject parcellations and descriptions of fine-scaled patterns, such as visuotopic organization.

PMID: 27894889 [PubMed - as supplied by publisher]

Functional and Structural Signatures of the Anterior Insula are associated with Risk-taking Tendency of Analgesic Decision-making.

Tue, 11/29/2016 - 16:10

Functional and Structural Signatures of the Anterior Insula are associated with Risk-taking Tendency of Analgesic Decision-making.

Sci Rep. 2016 Nov 28;6:37816

Authors: Lin CS, Lin HH, Wu SY

Abstract
In a medical context, decision-making is associated with complicated assessment of gains, losses and uncertainty of outcomes. We here provide novel evidence about the brain mechanisms underlying decision-making of analgesic treatment. Thirty-six healthy participants were recruited and completed the Analgesic Decision-making Task (ADT), which quantified individual tendency of risk-taking (RPI), as the frequency of choosing a riskier option to relieve pain. All the participants received resting-state (rs) functional magnetic resonance imaging (MRI) and structural MRI. On rs-functional connectome, degree centrality (DC) of the bilateral anterior insula (aINS) was positively correlated with the RPI. The functional connectivity between the aINS, the nucleus accumbens and multiple brain regions, predominantly the medial frontal cortex, was positively correlated with the RPI. On structural signatures, the RPI was positively correlated with grey matter volume at the right aINS, and such an association was mediated by DC of the left aINS. Regression analyses revealed that both DC of the left aINS and participants' imagined pain relief, as the utility of pain reduction, could predict the individual RPI. The findings suggest that the functional and structural brain signature of the aINS is associated with the individual differences of risk-taking tendency in the context of analgesic decision-making.

PMID: 27892543 [PubMed - in process]

Environmental factors linked to depression vulnerability are associated with altered cerebellar resting-state synchronization.

Tue, 11/29/2016 - 16:10

Environmental factors linked to depression vulnerability are associated with altered cerebellar resting-state synchronization.

Sci Rep. 2016 Nov 28;6:37384

Authors: Córdova-Palomera A, Tornador C, Falcón C, Bargalló N, Brambilla P, Crespo-Facorro B, Deco G, Fañanás L

Abstract
Hosting nearly eighty percent of all human neurons, the cerebellum is functionally connected to large regions of the brain. Accumulating data suggest that some cerebellar resting-state alterations may constitute a key candidate mechanism for depressive psychopathology. While there is some evidence linking cerebellar function and depression, two topics remain largely unexplored. First, the genetic or environmental roots of this putative association have not been elicited. Secondly, while different mathematical representations of resting-state fMRI patterns can embed diverse information of relevance for health and disease, many of them have not been studied in detail regarding the cerebellum and depression. Here, high-resolution fMRI scans were examined to estimate functional connectivity patterns across twenty-six cerebellar regions in a sample of 48 identical twins (24 pairs) informative for depression liability. A network-based statistic approach was employed to analyze cerebellar functional networks built using three methods: the conventional approach of filtered BOLD fMRI time-series, and two analytic components of this oscillatory activity (amplitude envelope and instantaneous phase). The findings indicate that some environmental factors may lead to depression vulnerability through alterations of the neural oscillatory activity of the cerebellum during resting-state. These effects may be observed particularly when exploring the amplitude envelope of fMRI oscillations.

PMID: 27892484 [PubMed - in process]

Pain Perception Can Be Modulated by Mindfulness Training: A Resting-State fMRI Study.

Tue, 11/29/2016 - 16:10

Pain Perception Can Be Modulated by Mindfulness Training: A Resting-State fMRI Study.

Front Hum Neurosci. 2016;10:570

Authors: Su IW, Wu FW, Liang KC, Cheng KY, Hsieh ST, Sun WZ, Chou TL

Abstract
The multi-dimensional nature of pain renders difficult a holistic understanding of it. The conceptual framework of pain is said to be cognitive-evaluative, in addition to being sensory-discriminative and affective-motivational. To compare participants' brain-behavior response before and after a 6-week mindfulness-based stress reduction training course on mindfulness in relation to pain modulation, three questionnaires (the Dallas Pain Questionnaire, Short Form McGill Pain Questionnaire-SFMPQ, and Kentucky Inventory of Mindfulness) as well as resting-state functional magnetic resonance imaging were administered to participants, divided into a pain-afflicted group (N = 18) and a control group (N = 16). Our results showed that the pain-afflicted group experienced significantly less pain after the mindfulness treatment than before, as measured by the SFMPQ. In conjunction, an increased connection from the anterior insular cortex (AIC) to the dorsal anterior midcingulate cortex (daMCC) was observed in the post-training pain-afflicted group and a significant correlation was found between AIC-daMCC connectivity and SFMPQ scores. The results suggest that mindfulness training can modulate the brain network dynamics underlying the subjective experience of pain.

PMID: 27891085 [PubMed - in process]

Can Mouse Imaging Studies Bring Order to Autism Connectivity Chaos?

Tue, 11/29/2016 - 16:10

Can Mouse Imaging Studies Bring Order to Autism Connectivity Chaos?

Front Neurosci. 2016;10:484

Authors: Liska A, Gozzi A

Abstract
Functional Magnetic Resonance Imaging (fMRI) has consistently highlighted impaired or aberrant functional connectivity across brain regions of autism spectrum disorder (ASD) patients. However, the manifestation and neural substrates of these alterations are highly heterogeneous and often conflicting. Moreover, their neurobiological underpinnings and etiopathological significance remain largely unknown. A deeper understanding of the complex pathophysiological cascade leading to aberrant connectivity in ASD can greatly benefit from the use of model organisms where individual pathophysiological or phenotypic components of ASD can be recreated and investigated via approaches that are either off limits or confounded by clinical heterogeneity. Despite some obvious limitations in reliably modeling the full phenotypic spectrum of a complex developmental disorder like ASD, mouse models have played a central role in advancing our basic mechanistic and molecular understanding of this syndrome. Recent progress in mouse brain connectivity mapping via resting-state fMRI (rsfMRI) offers the opportunity to generate and test mechanistic hypotheses about the elusive origin and significance of connectional aberrations observed in autism. Here we discuss recent progress toward this goal, and illustrate initial examples of how the approach can be employed to establish causal links between ASD-related mutations, developmental processes, and brain connectional architecture. As the spectrum of genetic and pathophysiological components of ASD modeled in the mouse is rapidly expanding, the use of rsfMRI can advance our mechanistic understanding of the origin and significance of the connectional alterations associated with autism, and their heterogeneous expression across patient cohorts.

PMID: 27891068 [PubMed - in process]

Interaction of language, auditory and memory brain networks in auditory verbal hallucinations.

Tue, 11/29/2016 - 16:10

Interaction of language, auditory and memory brain networks in auditory verbal hallucinations.

Prog Neurobiol. 2016 Nov 24;:

Authors: Ćurčić-Blake B, Ford J, Hubl D, Orlov ND, Sommer IE, Waters F, Allen P, Jardri R, Woodruff PW, Olivier D, Mulert C, Woodward TS, Aleman A

Abstract
Auditory verbal hallucinations (AVH) occur in psychotic disorders, but also as a symptom of other conditions and even in healthy people. Several current theories on the origin of AVH converge, with neuroimaging studies suggesting that the language, auditory and memory/limbic networks are of particular relevance. However, reconciliation of these theories with experimental evidence is missing. We review 50 studies investigating functional (EEG and fMRI) and anatomic (diffusion tensor imaging) connectivity in these networks, and explore the evidence supporting abnormal connectivity in these networks associated with AVH. We distinguish between functional connectivity during an actual hallucination experience (symptom capture) and functional connectivity during either the resting state or a task comparing individuals who hallucinate with those who do not (symptom association studies). Symptom capture studies clearly reveal a pattern of increased coupling among the auditory, language and striatal regions. Anatomical and symptom association functional studies suggest that the interhemispheric connectivity between posterior auditory regions may depend on the phase of illness, with increases in non-psychotic individuals and first episode patients and decreases in chronic patients. Leading hypotheses involving concepts as unstable memories, source monitoring, top-down attention, and hybrid models of hallucinations are supported in part by the published connectivity data, although several caveats and inconsistencies remain. Specifically, possible changes in fronto-temporal connectivity are still under debate. Precise hypotheses concerning the directionality of connections deduced from current theoretical approaches should be tested using experimental approaches that allow for discrimination of competing hypotheses.

PMID: 27890810 [PubMed - as supplied by publisher]

Functional coupling between frontoparietal and occipitotemporal pathways during action and perception.

Tue, 11/29/2016 - 16:10

Functional coupling between frontoparietal and occipitotemporal pathways during action and perception.

Cortex. 2016 Nov 9;:

Authors: Hutchison RM, Gallivan JP

Abstract
Several lines of evidence point to areas in the occipitotemporal pathway as being critical in the processes of visual perception and object recognition. Much less appreciated, however, is the role that this pathway plays in object-related processing for the purposes of visually guided action. Here, using functional MRI (fMRI) and functional connectivity (FC) measures, we examined interactions between areas in frontoparietal cortex (FPC) involved in grasping, reaching, eye movements, and tool use and areas in occipitotemporal cortex (OTC) involved in object-, face-, scene-, body-, tool-, and motion-related processing, both during the performance of sensorimotor and visual-perceptual tasks, as well as during passive fixation (resting-state). Cluster analysis of regional time course data identified correspondence in the patterns of FPC and OTC connectivity during the visual-perceptual tasks and rest that both tended to segregate regions along traditional dorsal/ventral pathway boundaries. During the sensorimotor tasks, however, we observed a notable separation in functional coupling between ventral-medial and ventral-lateral regions of OTC, with several of the latter areas often being clustered together with sensorimotor-defined areas in parietal cortex. These findings indicate that the functional coupling of ventral-lateral OTC areas to dorsal parietal and ventral-medial structures is flexible and task-dependent, and suggests that regions in lateral occipital cortex, in particular, may play an important role in mediating interactions between the dorsal and ventral pathways during tasks involving sensorimotor control.

PMID: 27890325 [PubMed - as supplied by publisher]

Functional Connectivity Analysis of Brain Default Mode Networks Using Hamiltonian Path.

Tue, 11/29/2016 - 16:10

Functional Connectivity Analysis of Brain Default Mode Networks Using Hamiltonian Path.

CNS Neurol Disord Drug Targets. 2016 Nov 24;

Authors: Jiao Z, Ma K, Wang H, Zou L, Xiang J

Abstract
The aim of this study is to introduce Hamiltonian path to analyze functional connectivity of brain default mode networks (DMNs). Firstly, the brain DMNs in resting state are constructed with the employment of functional Magnetic Resonance Imaging (fMRI) data. Then, the Dijkstra algorithm is used to calculate the shortest path length of the node which represents each brain region, and the Hamiltonian path of the default network is solved through the improved adaptive ant colony algorithm. Finally, complex network analysis methods are introduced to discuss the node and network properties of brain functional connectivity in both normal subjects and stroke patients. The experimental result demonstrated that there are some significant differences in the properties of the DMNs between stroke patients and normal subjects, especially the length of Hamiltonian path. It also verifies the effectiveness on studying the functional connectivity of the brain DMNs by applying the proposed method of Hamiltonian path.

PMID: 27890008 [PubMed - as supplied by publisher]

Electroconvulsive Therapy-Induced Brain Structural and Functional Changes in Major Depressive Disorders: A Longitudinal Study.

Sun, 11/27/2016 - 15:40

Electroconvulsive Therapy-Induced Brain Structural and Functional Changes in Major Depressive Disorders: A Longitudinal Study.

Med Sci Monit. 2016 Nov 26;22:4577-4586

Authors: Qiu H, Li X, Zhao W, Du L, Huang P, Fu Y, Qiu T, Xie P, Meng H, Luo Q

Abstract
BACKGROUND This study aimed to study the brain structural and functional changes after 8 courses of electroconvulsive therapy (ECT) on patients with major depressive disorder (MDD). MATERIAL AND METHODS MRI scans were performed on 12 depressive patients before and after 8 courses of ECT and compared with those of 15 normal controls. Data were analyzed by voxel-based morphometry (VBM) using SPM8 software. Functional MRI (fMRI) and regional homogeneity (ReHo) analyses were used to assess the functional changes after ECT. RESULTS Grey matter volumes were smaller in the right cingulate gyrus of depressive patients before ECT compared with normal controls. After false discovery rate (FDR) correction, post-ECT grey matter volumes were increased in bilateral amygdala and hippocampus compared with pre-ECT. Resting-state ReHo maps showed significant differences in brain activity pre- and post-ECT. Compared with healthy controls, MDD patients treated with 8 courses of ECT showed higher ReHo values in the bilateral frontal lobe, bilateral parietal lobe, and right caudate nucleus. Decreased ReHo values were observed in the right medial temporal gyrus, right superior temporal gyrus, right cingulate gyrus, and left anterior cerebellar lobe. CONCLUSIONS Results suggested that there were both structural and functional differences between the brains of MDD patients and healthy controls. After ECT, both structural and functional changes occurred, but without complete recovery to normal. ECT may display effects through regulating other brain regions to compensate for the original defects.

PMID: 27888657 [PubMed - in process]

Cerebrovascular reactivity mapping without gas challenges.

Sun, 11/27/2016 - 15:40

Cerebrovascular reactivity mapping without gas challenges.

Neuroimage. 2016 Nov 22;:

Authors: Liu P, Li Y, Pinho M, Park DC, Welch BG, Lu H

Abstract
Cerebrovascular reactivity (CVR), the ability of cerebral vessels to dilate or constrict, has been shown to provide valuable information in the diagnosis and treatment evaluation of patients with various cerebrovascular conditions. CVR mapping is typically performed using hypercapnic gas inhalation as a vasoactive challenge while collecting BOLD images, but the inherent need of gas inhalation and the associated apparatus setup present a practical obstacle in applying it in routine clinical use. Therefore, we aimed to develop a new method to map CVR using resting-state BOLD data without the need of gas inhalation. This approach exploits the natural variation in respiration and measures its influence on BOLD MRI signal. In this work, we first identified a surrogate of the arterial CO2 fluctuation during spontaneous breathing from the global BOLD signal. Second, we tested the feasibility and reproducibility of the proposed approach to use the above-mentioned surrogate as a regressor to estimate voxel-wise CVR. Third, we validated the "resting-state CVR map" with a conventional CVR map obtained with hypercapnic gas inhalation in healthy volunteers. Finally, we tested the utility of this new approach in detecting abnormal CVR in a group of patients with Moyamoya disease, and again validated the results using the conventional gas inhalation method. Our results showed that global BOLD signal fluctuation in the frequency range of 0.02-0.04Hz contains the most prominent contribution from natural variation in arterial CO2. The CVR map calculated using this signal as a regressor is reproducible across runs (ICC=0.91±0.06), and manifests a strong spatial correlation with results measured with a conventional hypercapnia-based method in healthy subjects (r=0.88, p<0.001). We also found that resting-state CVR was able to identify vasodilatory deficit in patients with steno-occlusive disease, the spatial pattern of which matches that obtained using the conventional gas method (r=0.71±0.18). These results suggest that CVR obtained with resting-state BOLD may be a useful alternative in detecting vascular deficits in clinical applications when gas challenge is not feasible.

PMID: 27888058 [PubMed - as supplied by publisher]

Olanzapine modulation of long- and short-range functional connectivity in the resting brain in a sample of patients with schizophrenia.

Sun, 11/27/2016 - 15:40

Olanzapine modulation of long- and short-range functional connectivity in the resting brain in a sample of patients with schizophrenia.

Eur Neuropsychopharmacol. 2016 Nov 22;:

Authors: Guo W, Liu F, Chen J, Wu R, Li L, Zhang Z, Zhao J

Abstract
Treatment effects of antipsychotic drugs on cerebral function are seldom examined. Exploring functional connectivity (FC) in drug-free schizophrenia patients before and after antipsychotic treatment can improve the understanding of antipsychotic drug mechanisms. A total of 17 drug-free patients with recurrent schizophrenia and 24 healthy controls underwent resting-state functional magnetic resonance imaging scans. Long- and short-range FC strengths (FCS) were calculated for each participant. Compared with the controls, the patients at baseline exhibited increased long-range positive FCS (lpFCS) in the bilateral inferior parietal lobule (IPL) and decreased lpFCS in the brain regions of the default-mode network (DMN) regions and sensorimotor circuits of the brain. By contrast, increased short-range positive FCS was observed in the right IPL of the patients at baseline compared with the controls. After treatment with olanzapine, increased FC in the DMN and sensorimotor circuits of the brain was noted, whereas decreased FC was observed in the left superior temporal gyrus (STG). Moreover, the alterations of the FCS values and the reductions in symptom severity among the patients after treatment were correlated. The present study provides evidence that olanzapine normalizes the abnormalities of long- and short-range FCs in schizophrenia. FC reductions in the right IPL may be associated with early treatment response, whereas those in the left STG may be related to poor treatment outcome.

PMID: 27887859 [PubMed - as supplied by publisher]

Structural and Functional Connectivity of Default Mode Network underlying the Cognitive Impairment in Late-onset Depression.

Sat, 11/26/2016 - 15:20

Structural and Functional Connectivity of Default Mode Network underlying the Cognitive Impairment in Late-onset Depression.

Sci Rep. 2016 Nov 25;6:37617

Authors: Yin Y, He X, Xu M, Hou Z, Song X, Sui Y, Liu Z, Jiang W, Yue Y, Zhang Y, Liu Y, Yuan Y

Abstract
To identify the association between the functional and structural changes of default mode network (DMN) underlying the cognitive impairment in Late-onset depression (LOD), 32 LOD patients and 39 normal controls were recruited and underwent resting-state fMRI, DTI scans, and cognitive assessments. Seed-based correlation analysis was conducted to explore the functional connectivity (FC) of the DMN. Deterministic tractography between FC-impaired regions was performed to examine the structural connectivity (SC). Partial correlation analyses were employed to evaluate the cognitive association of those altered FC and SC. Compared with controls, LOD patients showed decreased FC between DMN and the cingulo-opercular network (CON), as well as the thalamus. Decreased FA and increased RD of these fiber tracts connecting DMN with CON were found in LOD patient. The DMN-CON FC and the FA, RD of the fiber tracts were both significantly correlated with the cognitive performance. Therefore, the cognitive impairment in LOD might be associated with the decreased FC between the DMN and the CON, which probably resulted from the demyelination of the white matter.

PMID: 27886212 [PubMed - in process]

Abnormal connectivity in the sensorimotor network predicts attention deficits in traumatic brain injury.

Sat, 11/26/2016 - 15:20

Abnormal connectivity in the sensorimotor network predicts attention deficits in traumatic brain injury.

Exp Brain Res. 2016 Nov 24;

Authors: Shumskaya E, van Gerven MA, Norris DG, Vos PE, Kessels RP

Abstract
The aim of this study was to explore modifications of functional connectivity in multiple resting-state networks (RSNs) after moderate to severe traumatic brain injury (TBI) and evaluate the relationship between functional connectivity patterns and cognitive abnormalities. Forty-three moderate/severe TBI patients and 34 healthy controls (HC) underwent resting-state fMRI. Group ICA was applied to identify RSNs. Between-subject analysis was performed using dual regression. Multiple linear regressions were used to investigate the relationship between abnormal connectivity strength and neuropsychological outcome. Forty (93%) TBI patients showed moderate disability, while 2 (5%) and 1 (2%) upper severe disability and low good recovery, respectively. TBI patients performed worse than HC on the domains attention and language. We found increased connectivity in sensorimotor, visual, default mode (DMN), executive, and cerebellar RSNs after TBI. We demonstrated an effect of connectivity in the sensorimotor RSN on attention (p < 10(-3)) and a trend towards a significant effect of the DMN connectivity on attention (p = 0.058). A group-by-network interaction on attention was found in the sensorimotor network (p = 0.002). In TBI, attention was positively related to abnormal connectivity within the sensorimotor RSN, while in HC this relation was negative. Our results show altered patterns of functional connectivity after TBI. Attention impairments in TBI were associated with increased connectivity in the sensorimotor network. Further research is needed to test whether attention in TBI patients is directly affected by changes in functional connectivity in the sensorimotor network or whether the effect is actually driven by changes in the DMN.

PMID: 27885406 [PubMed - as supplied by publisher]

Neural markers of loss aversion in resting-state brain activity.

Sat, 11/26/2016 - 15:20

Neural markers of loss aversion in resting-state brain activity.

Neuroimage. 2016 Nov 21;:

Authors: Canessa N, Crespi C, Baud-Bovy G, Dodich A, Falini A, Antonellis G, Cappa SF

Abstract
Neural responses in striatal, limbic and somatosensory brain regions track individual differences in loss aversion, i.e. the higher sensitivity to potential losses compared with equivalent gains in decision-making under risk. The engagement of structures involved in the processing of aversive stimuli and experiences raises a further question, i.e. whether the tendency to avoid losses rather than acquire gains represents a transient fearful overreaction elicited by choice-related information, or rather a stable component of one's own preference function, reflecting a specific pattern of neural activity. We tested the latter hypothesis by assessing in 57 healthy human subjects whether the relationship between behavioral and neural loss aversion holds at rest, i.e. when the BOLD signal is collected during 5minutes of cross-fixation in the absence of an explicit task. Within the resting-state networks highlighted by a spatial group Independent Component Analysis (gICA), we found a significant correlation between strength of activity and behavioral loss aversion in the left ventral striatum and right posterior insula/supramarginal gyrus, i.e. the very same regions displaying a pattern of neural loss aversion during explicit choices. Cross-study analyses confirmed that this correlation holds when voxels identified by gICA are used as regions of interest in task-related activity and vice versa. These results suggest that the individual degree of (neural) loss aversion represents a stable dimension of decision-making, which reflects in specific metrics of intrinsic brain activity at rest possibly modulating cortical excitability at choice.

PMID: 27884798 [PubMed - as supplied by publisher]

Disrupted functional connectivity affects resting state based language lateralization.

Fri, 11/25/2016 - 15:00

Disrupted functional connectivity affects resting state based language lateralization.

Neuroimage Clin. 2016;12:910-927

Authors: Teghipco A, Hussain A, Tivarus ME

Abstract
Pre-operative assessment of language localization and lateralization is critical to preserving brain function after lesion or epileptogenic tissue resection. Task fMRI (t-fMRI) has been extensively and reliably used to this end, but resting state fMRI (rs-fMRI) is emerging as an alternative pre-operative brain mapping method that is independent of a patient's ability to comply with a task. We sought to evaluate if language lateralization obtained from rs-fMRI can replace standard assessment using t-fMRI. In a group of 43 patients scheduled for pre-operative fMRI brain mapping and 17 healthy controls, we found that existing methods of determining rs-fMRI lateralization by considering interhemispheric and intrahemispheric functional connectivity are inadequate compared to t-fMRI when applied to the language network. We determined that this was attributable to widespread but nuanced disturbances in the functional connectivity of the language network in patients. We found changes in interhemispheric and intrahemispheric functional connectivity that were dependent on lesion location, and particularly impacted patients with lesions in the left temporal lobe. We then tested whether a simpler measure of functional connectivity to the language network has a better relation to t-fMRI based language lateralization. Remarkably, we found that functional connectivity between the language network and the frontal pole, and superior frontal gyrus, as well as the supramarginal gyrus, significantly correlated to task based language lateralization indices in both patients and healthy controls. These findings are consistent with prior work with epilepsy patients, and provide a framework for evaluating language lateralization at rest.

PMID: 27882297 [PubMed - in process]

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