New resting-state fMRI related studies at PubMed

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Altered resting-state functional activity in isolated pontine infarction patients with pathological laughing and crying.

Wed, 07/26/2017 - 16:20
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Altered resting-state functional activity in isolated pontine infarction patients with pathological laughing and crying.

Oncotarget. 2017 Jul 17;:

Authors: Liu T, Li J, Huang S, Li C, Zhao Z, Wen G, Chen F

Abstract
We used resting-state functional magnetic resonance imaging to investigate the global spontaneous neural activity involved in pathological laughing and crying after stroke. Twelve pathological laughing and crying patients with isolated pontine infarction were included, along with 12 age- and gender-matched acute isolated pontine infarction patients without pathological laughing and crying, and 12 age- and gender-matched healthy controls. We examined both the amplitude of low-frequency fluctuation and the regional homogeneity in order to comprehensively evaluate the intrinsic activity in patients with post-stroke pathological laughing and crying. In the post-stroke pathological laughing and crying group, changes in these measures were observed mainly in components of the default mode network (medial prefrontal cortex/anterior cingulate cortex, middle temporal gyrus, inferior temporal gyrus, superior frontal gyrus, middle frontal gyrus and inferior parietal lobule), sensorimotor network (supplementary motor area, precentral gyrus and paracentral lobule), affective network (medial prefrontal cortex/anterior cingulate cortex, parahippocampal gyrus, middle temporal gyrus and inferior temporal gyrus) and cerebellar lobes (cerebellum posterior lobe). We therefore speculate that when disinhibition of the volitional system is lost, increased activation of the emotional system causes pathological laughing and crying.

PMID: 28740004 [PubMed - as supplied by publisher]

Insula-based networks in professional musicians: Evidence for increased functional connectivity during resting state fMRI.

Tue, 07/25/2017 - 15:00

Insula-based networks in professional musicians: Evidence for increased functional connectivity during resting state fMRI.

Hum Brain Mapp. 2017 Jul 24;:

Authors: Zamorano AM, Cifre I, Montoya P, Riquelme I, Kleber B

Abstract
Despite considerable research on experience-dependent neuroplasticity in professional musicians, detailed understanding of an involvement of the insula is only now beginning to emerge. We investigated the effects of musical training on intrinsic insula-based connectivity in professional classical musicians relative to nonmusicians using resting-state functional MRI. Following a tripartite scheme of insula subdivisions, coactivation profiles were analyzed for the posterior, ventral anterior, and dorsal anterior insula in both hemispheres. While whole-brain connectivity across all participants confirmed previously reported patterns, between-group comparisons revealed increased insular connectivity in musicians relative to nonmusicians. Coactivated regions encompassed constituents of large-scale networks involved in salience detection (e.g., anterior and middle cingulate cortex), affective processing (e.g., orbitofrontal cortex and temporal pole), and higher order cognition (e.g., dorsolateral prefrontal cortex and the temporoparietal junction), whereas no differences were found for the reversed group contrast. Importantly, these connectivity patterns were stronger in musicians who experienced more years of musical practice, including also sensorimotor regions involved in music performance (M1 hand area, S1, A1, and SMA). We conclude that musical training triggers significant reorganization in insula-based networks, potentially facilitating high-level cognitive and affective functions associated with the fast integration of multisensory information in the context of music performance. Hum Brain Mapp, 2017. © 2017 Wiley Periodicals, Inc.

PMID: 28737256 [PubMed - as supplied by publisher]

Impact of automated ICA-based denoising of fMRI data in acute stroke patients.

Tue, 07/25/2017 - 15:00
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Impact of automated ICA-based denoising of fMRI data in acute stroke patients.

Neuroimage Clin. 2017;16:23-31

Authors: Carone D, Licenik R, Suri S, Griffanti L, Filippini N, Kennedy J

Abstract
Different strategies have been developed using Independent Component Analysis (ICA) to automatically de-noise fMRI data, either focusing on removing only certain components (e.g. motion-ICA-AROMA, Pruim et al., 2015a) or using more complex classifiers to remove multiple types of noise components (e.g. FIX, Salimi-Khorshidi et al., 2014 Griffanti et al., 2014). However, denoising data obtained in an acute setting might prove challenging: the presence of multiple noise sources may not allow focused strategies to clean the data enough and the heterogeneity in the data may be so great to critically undermine complex approaches. The purpose of this study was to explore what automated ICA based approach would better cope with these limitations when cleaning fMRI data obtained from acute stroke patients. The performance of a focused classifier (ICA-AROMA) and a complex classifier (FIX) approaches were compared using data obtained from twenty consecutive acute lacunar stroke patients using metrics determining RSN identification, RSN reproducibility, changes in the BOLD variance, differences in the estimation of functional connectivity and loss of temporal degrees of freedom. The use of generic-trained FIX resulted in misclassification of components and significant loss of signal (< 80%), and was not explored further. Both ICA-AROMA and patient-trained FIX based denoising approaches resulted in significantly improved RSN reproducibility (p < 0.001), localized reduction in BOLD variance consistent with noise removal, and significant changes in functional connectivity (p < 0.001). Patient-trained FIX resulted in higher RSN identifiability (p < 0.001) and wider changes both in the BOLD variance and in functional connectivity compared to ICA-AROMA. The success of ICA-AROMA suggests that by focusing on selected components the full automation can deliver meaningful data for analysis even in population with multiple sources of noise. However, the time invested to train FIX with appropriate patient data proved valuable, particularly in improving the signal-to-noise ratio.

PMID: 28736698 [PubMed - in process]

Mind-Body Practice Changes Fractional Amplitude of Low Frequency Fluctuations in Intrinsic Control Networks.

Tue, 07/25/2017 - 15:00
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Mind-Body Practice Changes Fractional Amplitude of Low Frequency Fluctuations in Intrinsic Control Networks.

Front Psychol. 2017;8:1049

Authors: Wei GX, Gong ZQ, Yang Z, Zuo XN

Abstract
Cognitive control impairment is a typical symptom largely reported in populations with neurological disorders. Previous studies have provided evidence about the changes in cognitive control induced by mind-body training. However, the neural correlates underlying the effect of extensive mind-body practice on cognitive control remain largely unknown. Using resting-state functional magnetic resonance imaging, we characterized dynamic fluctuations in large-scale intrinsic connectivity networks associated with mind-body practice, and examined their differences between healthy controls and Tai Chi Chuan (TCC) practitioners. Compared with a control group, the TCC group revealed significantly decreased fractional Amplitude of Low Frequency Fluctuations (fALFF) in the bilateral frontoparietal network, default mode network and dorsal prefrontal-angular gyri network. Furthermore, we detected a significant association between mind-body practice experience and fALFF in the default mode network, as well as an association between cognitive control performance and fALFF of the frontoparietal network. This provides the first evidence of large-scale functional connectivity in brain networks associated with mind-body practice, shedding light on the neural network changes that accompany intensive mind-body training. It also highlights the functionally plastic role of the frontoparietal network in the context of the "immune system" of mental health recently developed in relation to flexible hub theory.

PMID: 28736535 [PubMed]

Weaker Functional Connectivity Strength in Patients with Type 2 Diabetes Mellitus.

Tue, 07/25/2017 - 15:00
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Weaker Functional Connectivity Strength in Patients with Type 2 Diabetes Mellitus.

Front Neurosci. 2017;11:390

Authors: Liu L, Li W, Zhang Y, Qin W, Lu S, Zhang Q

Abstract
Type 2 diabetes mellitus (T2DM) is related to cognitive impairments and increased risk for dementia. Neuroimaging studies have demonstrated T2DM-related brain structural and functional changes which are partly associated to the cognitive decline. However, few studies focused on the early neuroimaging findingsin T2DM patients. In this study, a data-driven whole-brain resting state functional connectivity strength (rsFCS) methodwas used to evaluate resting functional changes in 53 T2DM patients compared with 55 matched healthy controls (HCs), and to detect the associations between the rsFCSchanges and cognitive functions in T2DM patients. The T2DM patients exhibited weaker long-range rsFCS in the right insula and weaker short-range rsFCS in the right supramarginalgyrus (SG) compared with the HCs. Additionally, seed-based functional connectivity (FC) analysis revealed weaker FC between the right insula and the bilateral superior parietal lobule (SPL), and between the right SG and the bilateral supplementary motor area (SMA)/right SPL in T2DM patientscompared with the HCs. In T2DM patients, negative correlation was found between the long-range rsFCS in the right insula and HbA1c levels; and the FC between the right SG and the bilateral SMA negatively correlated with TMT-A scores. Our results indicated that the rsFCS alteration occurredbefore obvious cognitive deficits in T2DM patients, which might be helpful for understanding the neuromechanism of cognitive declines in T2DM patients.

PMID: 28736516 [PubMed]

Resting state functional connectivity correlates of emotional awareness.

Tue, 07/25/2017 - 15:00
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Resting state functional connectivity correlates of emotional awareness.

Neuroimage. 2017 Jul 20;:

Authors: Smith R, Alkozei A, Bao J, Smith C, Lane RD, Killgore WDS

Abstract
Multiple neuroimaging studies have now linked emotional awareness (EA), as measured by the Levels of Emotional Awareness Scale (LEAS), with activation in regions of neural networks associated with both conceptualization (i.e., default mode network [DMN] regions) and interoception (i.e., salience network [SN] regions) - consistent with the definition of EA as one's ability to appropriately recognize, conceptualize, and articulate the emotions of self and other in fine-grained, differentiated ways. However, no study has yet tested the hypothesis that greater LEAS scores are associated with greater resting state functional connectivity (FC) within these networks. Twenty-six adults (13 female) underwent resting state functional magnetic resonance imaging, and also completed the LEAS. Using pre-defined functional ROIs from the DMN and SN, we observed that LEAS scores were significantly positively correlated with FC between several regions of both of these networks, even when controlling for differences in general intelligence (IQ). These results suggest that higher EA may be associated with more efficient information exchange between brain regions involved in both interoception- and conceptualization-based processing, which could plausibly contribute to more differentiated bodily feelings and more fine-grained conceptualization of those feelings.

PMID: 28736312 [PubMed - as supplied by publisher]

Disrupted relationship between "resting state" connectivity and task-evoked activity during social perception in schizophrenia.

Tue, 07/25/2017 - 15:00
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Disrupted relationship between "resting state" connectivity and task-evoked activity during social perception in schizophrenia.

Schizophr Res. 2017 Jul 20;:

Authors: Ebisch SJH, Gallese V, Salone A, Martinotti G, di Iorio G, Mantini D, Perrucci MG, Romani GL, Di Giannantonio M, Northoff G

Abstract
Schizophrenia has been described as a self-disorder, whereas social deficits are key features of the illness. Changes in "resting state" activity of brain networks involved in self-related processing have been consistently reported in schizophrenia, but their meaning for social perception deficits remains poorly understood. Here, we applied a novel approach investigating the relationship between task-evoked neural activity during social perception and functional organization of self-related brain networks during a "resting state". "Resting state" functional MRI was combined with task-related functional MRI using a social perception experiment. Twenty-one healthy control participants (HC) and 21 out-patients with a diagnosis of schizophrenia (SCH) were included. There were no significant differences concerning age, IQ, education and gender between the groups. Results showed reduced "resting state" functional connectivity between ventromedial prefrontal cortex and dorsal posterior cingulate cortex in SCH, compared to HC. During social perception, neural activity in dorsal posterior cingulate cortex and behavioral data indicated impaired congruence coding of social stimuli in SCH. Task-evoked activity during social perception in dorsal posterior cingulate cortex co-varied with dorsal posterior cingulate cortex-ventromedial prefrontal cortex functional connectivity during a "resting state" in HC, but not in SCH. Task-evoked activity also correlated with negative symptoms in SCH. These preliminary findings, showing disrupted prediction of social perception measures by "resting state" functioning of self-related brain networks in schizophrenia, provide important insight in the hypothesized link between self and social deficits. They also shed light on the meaning of "resting state" changes for tasks such as social perception.

PMID: 28735643 [PubMed - as supplied by publisher]

Risk and resilience brain networks in treatment-resistant schizophrenia.

Tue, 07/25/2017 - 15:00
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Risk and resilience brain networks in treatment-resistant schizophrenia.

Schizophr Res. 2017 Jul 20;:

Authors: Ganella EP, Seguin C, Bartholomeusz CF, Whittle S, Bousman C, Wannan CMJ, Di Biase MA, Phassouliotis C, Everall I, Pantelis C, Zalesky A

Abstract
BACKGROUND: Genes, molecules and neural circuits that are associated with, or confer risk to developing schizophrenia have been studied and mapped. It is hypothesized that certain neural systems may counterbalance familial risk of schizophrenia, and thus confer resilience to developing the disorder. This study sought to identify resting-state functional brain connectivity (rs-FC) representing putative risk or resilience endophenotypes in schizophrenia.
METHODS: Resting-state functional magnetic resonance imaging (rs-fMRI) was performed in 42 individuals with treatment resistant schizophrenia (TRS), 16 unaffected first-degree family members (UFM) and 42 healthy controls. Whole-brain rs-FC networks were mapped for each individual and analysed graph theoretically to identify network markers associated with schizophrenia risk or resilience.
RESULTS: The ~900 functional connections showing between-group differences were operationalized as conferring: i) resilience, ii) risk, or iii) precipitating risk and/or illness effects. Approximately 95% of connections belonged to the latter two categories, with substantially fewer connections associated with resilience. Schizophrenia risk primarily involved reduced frontal and occipital rs-FC, with patients showing additional reduced frontal and temporal rs-FC. Functional brain networks were characterized by greater local efficiency in UFM, compared to TRS and controls.
CONCLUSIONS: TRS and UFM share frontal and occipital rs-FC deficits, representing a 'risk' endophenotype. Additional reductions in frontal and temporal rs-FC appear to be associated with risk that precipitates psychosis in vulnerable individuals, or may be due to other illness-related effects, such as medication. Functional brain networks are more topologically resilient in UFM compared to TRS, which may protect UFM from psychosis onset despite familial liability.

PMID: 28735641 [PubMed - as supplied by publisher]

Left Anterior Temporal Lobe and Bilateral Anterior Cingulate Cortex Are Semantic Hub Regions: Evidence from Behavior-Nodal Degree Mapping in Brain-Damaged Patients.

Tue, 07/25/2017 - 15:00
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Left Anterior Temporal Lobe and Bilateral Anterior Cingulate Cortex Are Semantic Hub Regions: Evidence from Behavior-Nodal Degree Mapping in Brain-Damaged Patients.

J Neurosci. 2017 Jan 04;37(1):141-151

Authors: Zhao Y, Song L, Ding J, Lin N, Wang Q, Du X, Sun R, Han Z

Abstract
The organizational principles of semantic memory in the human brain are still controversial. Although studies have shown that the semantic system contains hub regions that bind information from different sensorimotoric modalities to form concepts, it is unknown whether there are hub regions other than the anterior temporal lobe (ATL). Meanwhile, previous studies have rarely used network measurements to explore the hubs or correlated network indexes with semantic performance, although the most direct supportive evidence of hubs should come from the network perspective. To fill this gap, we correlated the brain-network index with semantic performance in 86 brain-damaged patients. We especially selected the nodal degree measure that reflects how well a node is connected in the network. The measure was calculated as the total number of connections of a given node with other nodes in the resting-state functional MRI network. Semantic ability was measured using the performance of both general and modality-specific (object form, color, motion, sound, manipulation, and function) semantic tasks. We found that the left ATL and the bilateral anterior cingulate cortex could be semantic hubs because the reduced nodal degree values of these regions could effectively predict the deficits in both general and modality-specific semantic performance. Moreover, the effects remained when the analyses were performed only in the patients who did not have lesions in these regions. The two hub regions might support semantic representations and executive control processes, respectively. These data provide empirical evidence for the distributed-plus-hub theory of semantic memory from the network perspective.
SIGNIFICANCE STATEMENT: Although the distributed-plus-hub organization of semantic memory has been proposed for several years, it remains unclear which hubs other than the anterior temporal lobe are included in the semantic system. Here, we identified such hubs from an innovative network perspective. The voxelwise nodal degree values were correlated with the performance of general and modality-specific semantic tasks in 86 patients with brain damage. We observed that the left anterior temporal lobe and bilateral anterior cingulate cortex could be semantic hubs because their decreased nodal degree values were significantly correlated with the severity of the deficit in semantic performance. The two hub regions might contribute to semantic representational and control processes, respectively. These findings offer new evidence for the distributed-plus-hub theory.

PMID: 28053037 [PubMed - indexed for MEDLINE]

Reduced haemodynamic coupling and exercise are associated with vascular stiffening in pulmonary arterial hypertension.

Tue, 07/25/2017 - 15:00
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Reduced haemodynamic coupling and exercise are associated with vascular stiffening in pulmonary arterial hypertension.

Heart. 2017 Mar;103(6):421-427

Authors: Bellofiore A, Dinges E, Naeije R, Mkrdichian H, Beussink-Nelson L, Bailey M, Cuttica MJ, Sweis R, Runo JR, Keevil JG, Francois CJ, Shah SJ, Chesler NC

Abstract
OBJECTIVE: Inadequate right ventricular (RV) and pulmonary arterial (PA) functional responses to exercise are important yet poorly understood features of pulmonary arterial hypertension (PAH). This study combined invasive catheterisation with echocardiography to assess RV afterload, RV function and ventricular-vascular coupling in subjects with PAH.
METHODS: Twenty-six subjects with PAH were prospectively recruited to undergo right heart catheterisation and Doppler echocardiography at rest and during incremental exercise, and cardiac MRI at rest. Measurements at rest included basic haemodynamics, RV function and coupling efficiency (η). Measurements during incremental exercise included pulmonary vascular resistance (Z0), characteristic impedance (ZC, a measure of proximal PA stiffness) and proximal and distal PA compliance (CPA).
RESULTS: In patients with PAH, the proximal PAs were significantly stiffer at maximum exercise (ZC =2.31±0.38 vs 1.33±0.15 WU×m(2) at rest; p=0.003) and PA compliance was decreased (CPA=0.88±0.10 vs 1.32±0.17 mL/mm Hg/m(2) at rest; p=0.0002). Z0 did not change with exercise. As a result, the resistance-compliance (RC) time decreased with exercise (0.67±0.05 vs 1.00±0.07 s at rest; p<10(-6)). When patients were grouped according to resting coupling efficiency, those with poorer η exhibited stiffer proximal PAs at rest, a lower maximum exercise level, and more limited CPA reduction at maximum exercise.
CONCLUSIONS: In PAH, exercise causes proximal and distal PA stiffening, which combined with preserved Z0 results in decreased RC time with exercise. Stiff PAs at rest may also contribute to poor haemodynamic coupling, reflecting reduced pulmonary vascular reserve that contributes to limit the maximum exercise level tolerated.

PMID: 27566296 [PubMed - indexed for MEDLINE]

Affected Anatomical Rich Club and Structural-Functional Coupling in Young Offspring of Schizophrenia and Bipolar Disorder Patients.

Mon, 07/24/2017 - 13:40
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Affected Anatomical Rich Club and Structural-Functional Coupling in Young Offspring of Schizophrenia and Bipolar Disorder Patients.

Biol Psychiatry. 2017 Jun 21;:

Authors: Collin G, Scholtens LH, Kahn RS, Hillegers MHJ, van den Heuvel MP

Abstract
BACKGROUND: Emerging evidence suggests disruptions in the wiring organization of the brain's network in schizophrenia (SZ) and bipolar disorder (BD). As the importance of genetic predisposition has been firmly established in these illnesses, children (offspring) of patients constitute an at-risk population. This study examines connectome organization in children at familial high risk for psychosis.
METHODS: Diffusion-weighted magnetic resonance imaging scans were collected from 127 nonpsychotic offspring 8 to 18 years of age (average age = 13.5 years) of a parent diagnosed with SZ (SZ offspring; n = 28) or BD (BD offspring; N = 60) and community control subjects (n = 39). Resting-state functional magnetic resonance imaging scans were available for 82 subjects. Anatomical and functional brain networks were reconstructed and examined using graph theoretical analysis.
RESULTS: SZ offspring were found to show connectivity deficits of the brain's central rich club (RC) system relative to both control subjects and BD offspring. The disruption in anatomical RC connectivity in SZ offspring was associated with increased modularity of the functional connectome. In addition, increased coupling between structural and functional connectivity of long-distance connections was observed in both SZ offspring and BD offspring.
CONCLUSIONS: This study shows lower levels of anatomical RC connectivity in nonpsychotic young offspring of SZ patients. This finding suggests that the brain's anatomical RC system is affected in at-risk youths, reflecting a connectome signature of familial risk for psychotic illness. Moreover, finding no RC deficits in offspring of BD patients suggest a differential effect of genetic predisposition for SZ versus BD on the developmental formation of the connectome.

PMID: 28734460 [PubMed - as supplied by publisher]

Localized reductions in resting-state functional connectivity in children with prenatal alcohol exposure.

Mon, 07/24/2017 - 07:20
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Localized reductions in resting-state functional connectivity in children with prenatal alcohol exposure.

Hum Brain Mapp. 2017 Jul 22;:

Authors: Fan J, Taylor PA, Jacobson SW, Molteno CD, Gohel S, Biswal BB, Jacobson JL, Meintjes EM

Abstract
Fetal alcohol spectrum disorders (FASD) are characterized by impairment in cognitive function that may or may not be accompanied by craniofacial anomalies, microcephaly, and/or growth retardation. Resting-state functional MRI (rs-fMRI), which examines the low-frequency component of the blood oxygen level dependent (BOLD) signal in the absence of an explicit task, provides an efficient and powerful mechanism for studying functional brain networks even in low-functioning and young subjects. Studies using independent component analysis (ICA) have identified a set of resting-state networks (RSNs) that have been linked to distinct domains of cognitive and perceptual function, which are believed to reflect the intrinsic functional architecture of the brain. This study is the first to examine resting-state functional connectivity within these RSNs in FASD. Rs-fMRI scans were performed on 38 children with FASD (19 with either full fetal alcohol syndrome (FAS) or partial FAS (PFAS), 19 nonsyndromal heavily exposed (HE)), and 19 controls, mean age 11.3 ± 0.9 years, from the Cape Town Longitudinal Cohort. Nine resting-state networks were generated by ICA. Voxelwise group comparison between a combined FAS/PFAS group and controls revealed localized dose-dependent functional connectivity reductions in five regions in separate networks: anterior default mode, salience, ventral and dorsal attention, and R executive control. The former three also showed lower connectivity in the HE group. Gray matter connectivity deficits in four of the five networks appear to be related to deficits in white matter tracts that provide intra-RSN connections. Hum Brain Mapp, 2017. © 2017 Wiley Periodicals, Inc.

PMID: 28734059 [PubMed - as supplied by publisher]

Long-term intensive gymnastic training induced changes in intra- and inter-network functional connectivity: an independent component analysis.

Mon, 07/24/2017 - 07:20
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Long-term intensive gymnastic training induced changes in intra- and inter-network functional connectivity: an independent component analysis.

Brain Struct Funct. 2017 Jul 21;:

Authors: Huang H, Wang J, Seger C, Lu M, Deng F, Wu X, He Y, Niu C, Wang J, Huang R

Abstract
Long-term intensive gymnastic training can induce brain structural and functional reorganization. Previous studies have identified structural and functional network differences between world class gymnasts (WCGs) and non-athletes at the whole-brain level. However, it is still unclear how interactions within and between functional networks are affected by long-term intensive gymnastic training. We examined both intra- and inter-network functional connectivity of gymnasts relative to non-athletes using resting-state fMRI (R-fMRI). R-fMRI data were acquired from 13 WCGs and 14 non-athlete controls. Group-independent component analysis (ICA) was adopted to decompose the R-fMRI data into spatial independent components and associated time courses. An automatic component identification method was used to identify components of interest associated with resting-state networks (RSNs). We identified nine RSNs, the basal ganglia network (BG), sensorimotor network (SMN), cerebellum (CB), anterior and posterior default mode networks (aDMN/pDMN), left and right fronto-parietal networks (lFPN/rFPN), primary visual network (PVN), and extrastriate visual network (EVN). Statistical analyses revealed that the intra-network functional connectivity was significantly decreased within the BG, aDMN, lFPN, and rFPN, but increased within the EVN in the WCGs compared to the controls. In addition, the WCGs showed uniformly decreased inter-network functional connectivity between SMN and BG, CB, and PVN, BG and PVN, and pDMN and rFPN compared to the controls. We interpret this generally weaker intra- and inter-network functional connectivity in WCGs during the resting state as a result of greater efficiency in the WCGs' brain associated with long-term motor skill training.

PMID: 28733834 [PubMed - as supplied by publisher]

Left Frontal Hub Connectivity during Memory Performance Supports Reserve in Aging and Mild Cognitive Impairment.

Sat, 07/22/2017 - 11:20

Left Frontal Hub Connectivity during Memory Performance Supports Reserve in Aging and Mild Cognitive Impairment.

J Alzheimers Dis. 2017 Jul 17;:

Authors: Franzmeier N, Hartmann JC, Taylor AN, Araque Caballero MA, Simon-Vermot L, Buerger K, Kambeitz-Ilankovic LM, Ertl-Wagner B, Mueller C, Catak C, Janowitz D, Stahl R, Dichgans M, Duering M, Ewers M

Abstract
Reserve in aging and Alzheimer's disease (AD) is defined as maintaining cognition at a relatively high level in the presence of neurodegeneration, an ability often associated with higher education among other life factors. Recent evidence suggests that higher resting-state functional connectivity within the frontoparietal control network, specifically the left frontal cortex (LFC) hub, contributes to higher reserve. Following up these previous resting-state fMRI findings, we probed memory-task related functional connectivity of the LFC hub as a neural substrate of reserve. In elderly controls (CN, n = 37) and patients with mild cognitive impairment (MCI, n = 17), we assessed global connectivity of the LFC hub during successful face-name association learning, using generalized psychophysiological interaction analyses. Reserve was quantified as residualized memory performance, accounted for gender and proxies of neurodegeneration (age, hippocampus atrophy, and APOE genotype). We found that greater education was associated with higher LFC-connectivity in both CN and MCI during successful memory. Furthermore, higher LFC-connectivity predicted higher residualized memory (i.e., reserve). These results suggest that higher LFC-connectivity contributes to reserve in both healthy and pathological aging.

PMID: 28731448 [PubMed - as supplied by publisher]

Shared atypical default mode and salience network functional connectivity between autism and schizophrenia.

Sat, 07/22/2017 - 11:20
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Shared atypical default mode and salience network functional connectivity between autism and schizophrenia.

Autism Res. 2017 Jul 21;:

Authors: Chen H, Uddin LQ, Duan X, Zheng J, Long Z, Zhang Y, Guo X, Zhang Y, Zhao J, Chen H

Abstract
Schizophrenia and autism spectrum disorder (ASD) are two prevalent neurodevelopmental disorders sharing some similar genetic basis and clinical features. The extent to which they share common neural substrates remains unclear. Resting-state fMRI data were collected from 35 drug-naïve adolescent participants with first-episode schizophrenia (15.6 ± 1.8 years old) and 31 healthy controls (15.4 ± 1.6 years old). Data from 22 participants with ASD (13.1 ± 3.1 years old) and 21 healthy controls (12.9 ± 2.9 years old) were downloaded from the Autism Brain Imaging Data Exchange. Resting-state functional networks were constructed using predefined regions of interest. Multivariate pattern analysis combined with multi-task regression feature selection methods were conducted in two datasets separately. Classification between individuals with disorders and controls was achieved with high accuracy (schizophrenia dataset: accuracy = 83%; ASD dataset: accuracy = 80%). Shared atypical brain connections contributing to classification were mostly present in the default mode network (DMN) and salience network (SN). These functional connections were further related to severity of social deficits in ASD (p = 0.002). Distinct atypical connections were also more related to the DMN and SN, but showed different atypical connectivity patterns between the two disorders. These results suggest some common neural mechanisms contributing to schizophrenia and ASD, and may aid in understanding the pathology of these two neurodevelopmental disorders. Autism Res 2017. © 2017 International Society for Autism Research, Wiley Periodicals, Inc.

PMID: 28730732 [PubMed - as supplied by publisher]

Functional connectivity and cognitive impairment in migraine with and without aura.

Sat, 07/22/2017 - 11:20
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Functional connectivity and cognitive impairment in migraine with and without aura.

J Headache Pain. 2017 Dec;18(1):72

Authors: Lo Buono V, Bonanno L, Corallo F, Pisani LR, Lo Presti R, Grugno R, Di Lorenzo G, Bramanti P, Marino S

Abstract
BACKGROUND: Several fMRI studies in migraine assessed resting state functional connectivity in different networks suggesting that this neurological condition was associated with brain functional alteration. The aim of present study was to explore the association between cognitive functions and cerebral functional connectivity, in default mode network, in migraine patients without and with aura, during interictal episodic attack.
METHODS: Twenty-eight migraine patients (14 without and 14 with aura) and 14 matched normal controls, were consecutively recruited. A battery of standardized neuropsychological test was administered to evaluate cognitive functions and all subjects underwent a resting state with high field fMRI examination.
RESULTS: Migraine patients did not show abnormalities in neuropsychological evaluation, while, we found a specific alteration in cortical network, if we compared migraine with and without aura. We observed, in migraine with aura, an increased connectivity in left angular gyrus, left supramarginal gyrus, right precentral gyrus, right postcentral gyrus, right insular cortex.
CONCLUSION: Our findings showed in migraine patients an alteration in functional connectivity architecture. We think that our results could be useful to better understand migraine pathogenesis.

PMID: 28730563 [PubMed - in process]

Abnormal resting state effective connectivity within the default mode network in major depressive disorder: A spectral dynamic causal modeling study.

Sat, 07/22/2017 - 11:20
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Abnormal resting state effective connectivity within the default mode network in major depressive disorder: A spectral dynamic causal modeling study.

Brain Behav. 2017 Jul;7(7):e00732

Authors: Li L, Li B, Bai Y, Liu W, Wang H, Leung HC, Tian P, Zhang L, Guo F, Cui LB, Yin H, Lu H, Tan Q

Abstract
INTRODUCTION: Understanding the neural basis underlying major depressive disorder (MDD) is essential for the diagnosis and treatment of this mental disorder. Aberrant activation and functional connectivity of the default mode network (DMN) have been consistently found in patients with MDD. It is not known whether effective connectivity within the DMN is altered in MDD.
OBJECTS: The primary object of this study is to investigate the effective connectivity within the DMN during resting state in MDD patients before and after eight weeks of antidepressant treatment.
METHODS: We defined four regions of the DMN (medial frontal cortex, posterior cingulate cortex, left parietal cortex, and right parietal cortex) for each participant using a group independent component analysis. The coupling parameters reflecting the causal interactions among the DMN regions were estimated using spectral dynamic causal modeling (DCM).
RESULTS: Twenty-seven MDD patients and 27 healthy controls were included in the statistical analysis. Our results showed declined influences from the left parietal cortex to other DMN regions in the pre-treatment patients as compared with healthy controls. After eight weeks of treatment, the influence from the right parietal cortex to the posterior cingulate cortex significantly decreased.
CONCLUSION: These findings suggest that the reduced excitatory causal influence of the left parietal cortex is the key alteration of the DMN in patients with MDD, and the disrupted causal influences that parietal cortex exerts on the posterior cingulate cortex is responsive to antidepressant treatment.

PMID: 28729938 [PubMed - in process]

Coherence of BOLD signal and electrical activity in the human brain during deep sevoflurane anesthesia.

Sat, 07/22/2017 - 11:20
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Coherence of BOLD signal and electrical activity in the human brain during deep sevoflurane anesthesia.

Brain Behav. 2017 Jul;7(7):e00679

Authors: Golkowski D, Ranft A, Kiel T, Riedl V, Kohl P, Rohrer G, Pientka J, Berger S, Preibisch C, Zimmer C, Mashour GA, Schneider G, Kochs EF, Ilg R, Jordan D

Abstract
INTRODUCTION: Changes in neural activity induce changes in functional magnetic resonance (fMRI) blood oxygenation level dependent (BOLD) signal. Commonly, increases in BOLD signal are ascribed to cellular excitation.
OBJECTIVE: The relationship between electrical activity and BOLD signal in the human brain was probed on the basis of burst suppression EEG. This condition includes two distinct states of high and low electrical activity.
METHODS: Resting-state simultaneous EEG and BOLD measurements were acquired during deep sevoflurane anesthesia with burst suppression EEG in nineteen healthy volunteers. Afterwards, fMRI volumes were assigned to one of the two states (burst or suppression) as defined by the EEG.
RESULTS: In the frontal, parietal and temporal lobes as well as in the basal ganglia, BOLD signal increased after burst onset in the EEG and decreased after onset of EEG suppression. In contrast, BOLD signal in the occipital lobe was anticorrelated to electrical activity. This finding was obtained consistently in a general linear model and in raw data.
CONCLUSIONS: In human brains exhibiting burst suppression EEG induced by sevoflurane, the positive correlation between BOLD signal and electrical brain activity could be confirmed in most gray matter. The exceptional behavior of the occipital lobe with an anticorrelation of BOLD signal and electrical activity might be due to specific neurovascular coupling mechanisms that are pronounced in the deeply anesthetized brain.

PMID: 28729926 [PubMed - in process]

Investigating Focal Connectivity Deficits in Alzheimer's Disease Using Directional Brain Networks Derived from Resting-State fMRI.

Sat, 07/22/2017 - 11:20
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Investigating Focal Connectivity Deficits in Alzheimer's Disease Using Directional Brain Networks Derived from Resting-State fMRI.

Front Aging Neurosci. 2017;9:211

Authors: Zhao S, Rangaprakash D, Venkataraman A, Liang P, Deshpande G

Abstract
Connectivity analysis of resting-state fMRI has been widely used to identify biomarkers of Alzheimer's disease (AD) based on brain network aberrations. However, it is not straightforward to interpret such connectivity results since our understanding of brain functioning relies on regional properties (activations and morphometric changes) more than connections. Further, from an interventional standpoint, it is easier to modulate the activity of regions (using brain stimulation, neurofeedback, etc.) rather than connections. Therefore, we employed a novel approach for identifying focal directed connectivity deficits in AD compared to healthy controls. In brief, we present a model of directed connectivity (using Granger causality) that characterizes the coupling among different regions in healthy controls and Alzheimer's disease. We then characterized group differences using a (between-subject) generative model of pathology, which generates latent connectivity variables that best explain the (within-subject) directed connectivity. Crucially, our generative model at the second (between-subject) level explains connectivity in terms of local or regionally specific abnormalities. This allows one to explain disconnections among multiple regions in terms of regionally specific pathology; thereby offering a target for therapeutic intervention. Two foci were identified, locus coeruleus in the brain stem and right orbitofrontal cortex. Corresponding disrupted connectivity network associated with the foci showed that the brainstem is the critical focus of disruption in AD. We further partitioned the aberrant connectomic network into four unique sub-networks, which likely leads to symptoms commonly observed in AD. Our findings suggest that fMRI studies of AD, which have been largely cortico-centric, could in future investigate the role of brain stem in AD.

PMID: 28729831 [PubMed]

Resting-State Fluctuations of EEG Sensorimotor Rhythm Reflect BOLD Activities in the Pericentral Areas: A Simultaneous EEG-fMRI Study.

Sat, 07/22/2017 - 11:20
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Resting-State Fluctuations of EEG Sensorimotor Rhythm Reflect BOLD Activities in the Pericentral Areas: A Simultaneous EEG-fMRI Study.

Front Hum Neurosci. 2017;11:356

Authors: Tsuchimoto S, Shibusawa S, Mizuguchi N, Kato K, Ebata H, Liu M, Hanakawa T, Ushiba J

Abstract
Blockade of the scalp electroencephalographic (EEG) sensorimotor rhythm (SMR) is a well-known phenomenon following attempted or executed motor functions. Such a frequency-specific power attenuation of the SMR occurs in the alpha and beta frequency bands and is spatially registered at primary somatosensory and motor cortices. Here, we hypothesized that resting-state fluctuations of the SMR in the alpha and beta frequency bands also covary with resting-state sensorimotor cortical activity, without involving task-related neural dynamics. The present study employed functional magnetic resonance imaging (fMRI) to investigate the neural regions whose activities were correlated with the simultaneously recorded SMR power fluctuations. The SMR power fluctuations were convolved with a canonical hemodynamic response function and correlated with blood-oxygen-level dependent (BOLD) signals obtained from the entire brain. Our findings show that the alpha and beta power components of the SMR correlate with activities of the pericentral area. Furthermore, brain regions with correlations between BOLD signals and the alpha-band SMR fluctuations were located posterior to those with correlations between BOLD signals and the beta-band SMR. These results are consistent with those of event-related studies of SMR modulation induced by sensory input or motor output. Our findings may help to understand the role of the sensorimotor cortex activity in contributing to the amplitude modulation of SMR during the resting state. This knowledge may be applied to the diagnosis of pathological conditions in the pericentral areas or the refinement of brain-computer interfaces using SMR in the future.

PMID: 28729830 [PubMed]

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