New resting-state fMRI related studies at PubMed

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ICN_Atlas: Automated description and quantification of functional MRI activation patterns in the framework of intrinsic connectivity networks.

Thu, 09/14/2017 - 13:40
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ICN_Atlas: Automated description and quantification of functional MRI activation patterns in the framework of intrinsic connectivity networks.

Neuroimage. 2017 Sep 09;:

Authors: Kozák LR, van Graan LA, Chaudhary UJ, Szabó Á, Lemieux L

Abstract
Generally, the interpretation of functional MRI (fMRI) activation maps continues to rely on assessing their relationship to anatomical structures, mostly in a qualitative and often subjective way. Recently, the existence of persistent and stable brain networks of functional nature has been revealed; in particular these so-called intrinsic connectivity networks (ICNs) appear to link patterns of resting state and task-related state connectivity. These networks provide an opportunity of functionally-derived description and interpretation of fMRI maps, that may be especially important in cases where the maps are predominantly task-unrelated, such as studies of spontaneous brain activity e.g. in the case of seizure-related fMRI maps in epilepsy patients or sleep states. Here we present a new toolbox (ICN_Atlas) aimed at facilitating the interpretation of fMRI data in the context of ICN. More specifically, the new methodology was designed to describe fMRI maps in function-oriented, objective and quantitative way using a set of 15 metrics conceived to quantify the degree of 'engagement' of ICNs for any given fMRI-derived statistical map of interest. We demonstrate that the proposed framework provides a highly reliable quantification of fMRI activation maps using a publicly available longitudinal (test-retest) resting-state fMRI dataset. The utility of the ICN_Atlas is also illustrated on a parametric task-modulation fMRI dataset, and on a dataset of a patient who had repeated seizures during resting-state fMRI, confirmed on simultaneously recorded EEG. The proposed ICN_Atlas framework will be made freely available for download at https://www.nitrc.org and at http://incatlas.com for researchers to use in their fMRI investigations.

PMID: 28899742 [PubMed - as supplied by publisher]

Anti-fragmentation of resting-state fMRI connectivity networks with node-wise thresholding.

Thu, 09/14/2017 - 13:40
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Anti-fragmentation of resting-state fMRI connectivity networks with node-wise thresholding.

Brain Connect. 2017 Sep 13;

Authors: Hayasaka S

Abstract
fMRI-based functional connectivity networks are often constructed by thresholding a correlation matrix of nodal time courses. In a typical thresholding approach known as hard thresholding, a single threshold is applied to the entire correlation matrix to identify edges representing super-threshold correlations. However, hard thresholding is known to produce a network with uneven allocation of edges, resulting in a fragmented network with a large number of disconnected nodes. It is suggested that an alternative network thresholding approach, node-wise thresholding, is able to overcome these problems. To examine this, various network characteristics were compared between networks constructed by hard thresholding and node-wise thresholding, with publicly available resting-state fMRI data from 123 healthy young subjects. It was found that networks constructed with hard thresholding included a large number of disconnected nodes, while such network fragmentation was not observed in networks formed with node-wise thresholding. Moreover, in hard thresholding networks, fragmentized modular organization was observed, characterized by a large number of small modules. On the other hand, such modular fragmentation was not observed in node-wise thresholding networks, producing modules that were robust at any threshold and highly consistent across subjects. These results indicate that node-wise thresholding may lead to less fragmented networks. Moreover, node-wise thresholding enables robust characterization of network properties without much influence by the selection of a threshold.

PMID: 28899207 [PubMed - as supplied by publisher]

Disrupted Brain Network Hubs in Subtype-Specific Parkinson's Disease.

Wed, 09/13/2017 - 12:20

Disrupted Brain Network Hubs in Subtype-Specific Parkinson's Disease.

Eur Neurol. 2017 Aug 25;78(3-4):200-209

Authors: Ma LY, Chen XD, He Y, Ma HZ, Feng T

Abstract
BACKGROUND/AIMS: The topological organization of brain functional networks is impaired in Parkinson's disease (PD). However, the altered patterns of functional network hubs in different subtypes of PD are not completely understood.
METHODS: 3T resting-state functional MRI and voxel-based graph-theory analysis were employed to systematically investigate the intrinsic functional connectivity patterns of whole-brain networks. We enrolled 31 patients with PD (12 tremor dominant [TD] and 19 with postural instability/gait difficulty [PIGD]) and 22 matched healthy controls. Whole-brain voxel-wise functional networks were constructed by measuring the temporal correlations of each pair of brain voxels. Functional connectivity strength was calculated to explore the brain network hubs.
RESULTS: We found that both the TD and PIGD subtypes had comprehensive disrupted regions. These mainly involved the basal ganglia, cerebellum, superior temporal gyrus, pre- and postcentral gyri, inferior frontal gyrus, middle temporal gyrus, lingual gyrus, insula, and parahippocampal gyrus. Furthermore, the PIGD subgroup had more disrupted hubs in the cerebellum than the TD subgroup. These disruptions of hub connectivity were not correlated with the HY stage or disease duration.
CONCLUSION: Our results emphasize the subtype-specific PD-related degeneration of brain hubs, providing novel insights into the pathophysiological mechanisms of connectivity dysfunction in different PD subgroups.

PMID: 28898869 [PubMed - as supplied by publisher]

Distinct patterns of temporal and directional connectivity among intrinsic networks in the human brain.

Wed, 09/13/2017 - 12:20
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Distinct patterns of temporal and directional connectivity among intrinsic networks in the human brain.

J Neurosci. 2017 Sep 11;:

Authors: Shine JM, Kucyi A, Foster BL, Bickel S, Wang D, Liu H, Poldrack RA, Hsieh LT, Chun Hsiang J, Parvizi J

Abstract
To determine the spatiotemporal relationships among intrinsic networks of the human brain, we recruited seven neurosurgical patients (4 males; 3 females) who were implanted with intracranial depth electrodes. We first identified canonical resting state networks at the individual subject level using an iterative matching procedure on each subject's resting state fMRI data. We then introduced single electrical pulses to fMRI pre-identified nodes of the default (DN), frontoparietal (FPN) and salience networks (SN) while recording evoked responses in other recording sites within the same networks. We found bidirectional signal flow across the three networks, albeit with distinct patterns of evoked responses within different time windows. We used a data-driven clustering approach to show that stimulation of the FPN and SN evoked a rapid (<70 ms) response that was predominantly higher within the SN sites, whereas stimulation of the DN led to sustained responses in later time windows (85-200ms). Stimulations in the medial temporal lobe components of the DN evoked relatively late-effects (>130ms) in other nodes of the DN, as well as FPN and SN. Together, our results provide temporal information about the patterns of signal flow between intrinsic networks that provide insights into the spatiotemporal dynamics that are likely to constrain the architecture of the brain networks supporting human cognition and behavior.SIGNFICANCE STATEMENTDespite great progress in the functional neuroimaging of the human brain, we still don't know the precise set of rules that define the patterns of temporal organization between large-scale networks of the brain. In this study, we stimulated and then recorded electrical evoked potentials within and between three large-scale networks of the brain - the default (DN), frontoparietal (FPN) and salience networks (SN) - in 7 subjects undergoing invasive neurosurgery. Using a data-driven clustering approach, we observed distinct temporal and directional patterns between the three networks, with FPN and SN activity predominant in early windows, and DN stimulation affecting the network in later windows. These results provide important temporal information about the interactions between brain networks supporting human cognition and behavior.

PMID: 28893929 [PubMed - as supplied by publisher]

Resting state fMRI observations of baseline brain functional activities and connectivities in primary blepharospasm.

Wed, 09/13/2017 - 12:20
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Resting state fMRI observations of baseline brain functional activities and connectivities in primary blepharospasm.

Neurosci Lett. 2017 Sep 08;:

Authors: Ni MF, Huang XF, Miao YW, Liang ZH

Abstract
Primary blepharospasm (BPS) is a focal dystonia characterized by involuntary eyelid spasms and blinking. The pathophysiology of BPS remains unclear. Several functional and structural neuroimaging studies have demonstrated abnormalities of sensorimotor structures such as the sensorimotor cortex, the basal ganglia, the thalamus and the cerebellum in BPS patients. However, some of the results of these studies were inconsistent. In addition, the relationship between the motor and sensory structures in patients with BPS still needs to be investigated. Therefore, the purpose of this study was to investigate the abnormal alterations in both the intra-regional brain activities and inter-regional functional connectivities (FC) in patients with BPS using resting-state functional MRI(rs-fMRI) and to explore possible correlations between these rs-fMRI indices and clinical variables. The rs-fMRI images of the two groups of subjects (26 BPS patients and 26 healthy controls) were acquired using a 3.0T MRI scanner. The regional rs-fMRI indices, i.e., the fractional amplitude of the low-frequency fluctuation (fALFF) and the regional homogeneity (ReHo), were computed for all subjects. Then, two-sample t-tests were conducted to assess the significant differences between the two groups of subjects. To investigate the alterations in brain networks, cerebral regions with significant differences were used as regions of interest in the whole brain FC analysis. Compared to the control group, the BPS patients revealed significantly increased fALFF and ReHo values in the right caudate head. Significantly strengthened FC values were observed between the right caudate head and the left striatum and the right supplementary motor area in the BPS group. The fALFF and ReHo values in the right caudate head and the FC values between the right caudate head and the left striatum were positively correlated with the Jankovic Rating Scale sum score. In conclusion, this study indicated that BPS patients have both abnormal intra-regional spontaneous brain activities and inter-regional functional connectivities.

PMID: 28893588 [PubMed - as supplied by publisher]

Changes in resting-state brain networks after cognitive-behavioral therapy for chronic pain.

Wed, 09/13/2017 - 12:20
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Changes in resting-state brain networks after cognitive-behavioral therapy for chronic pain.

Psychol Med. 2017 Sep 12;:1-11

Authors: Yoshino A, Okamoto Y, Okada G, Takamura M, Ichikawa N, Shibasaki C, Yokoyama S, Doi M, Jinnin R, Yamashita H, Horikoshi M, Yamawaki S

Abstract
BACKGROUND: Cognitive-behavioral therapy (CBT) is thought to be useful for chronic pain, with the pathology of the latter being closely associated with cognitive-emotional components. However, there are few resting-state functional magnetic resonance imaging (R-fMRI) studies. We used the independent component analysis method to examine neural changes after CBT and to assess whether brain regions predict treatment response.
METHODS: We performed R-fMRI on a group of 29 chronic pain (somatoform pain disorder) patients and 30 age-matched healthy controls (T1). Patients were enrolled in a weekly 12-session group CBT (T2). We assessed selected regions of interest that exhibited differences in intrinsic connectivity network (ICN) connectivity strength between the patients and controls at T1, and compared T1 and T2. We also examined the correlations between treatment effects and rs-fMRI data.
RESULTS: Abnormal ICN connectivity of the orbitofrontal cortex (OFC) and inferior parietal lobule within the dorsal attention network (DAN) and of the paracentral lobule within the sensorimotor network in patients with chronic pain normalized after CBT. Higher ICN connectivity strength in the OFC indicated greater improvements in pain intensity. Furthermore, ICN connectivity strength in the dorsal posterior cingulate cortex (PCC) within the DAN at T1 was negatively correlated with CBT-related clinical improvements.
CONCLUSIONS: We conclude that the OFC is crucial for CBT-related improvement of pain intensity, and that the dorsal PCC activation at pretreatment also plays an important role in improvement of clinical symptoms via CBT.

PMID: 28893330 [PubMed - as supplied by publisher]

Depression in chronic ketamine users: Sex differences and neural bases.

Tue, 09/12/2017 - 11:00

Depression in chronic ketamine users: Sex differences and neural bases.

Psychiatry Res. 2017 Sep 05;269:1-8

Authors: Li CR, Zhang S, Hung CC, Chen CM, Duann JR, Lin CP, Lee TS

Abstract
Chronic ketamine use leads to cognitive and affective deficits including depression. Here, we examined sex differences and neural bases of depression in chronic ketamine users. Compared to non-drug using healthy controls (HC), ketamine-using females but not males showed increased depression score as assessed by the Center of Epidemiological Studies Depression Scale (CES-D). We evaluated resting state functional connectivity (rsFC) of the subgenual anterior cingulate cortex (sgACC), a prefrontal structure consistently implicated in the pathogenesis of depression. Compared to HC, ketamine users (KU) did not demonstrate significant changes in sgACC connectivities at a corrected threshold. However, in KU, a linear regression against CES-D score showed less sgACC connectivity to the orbitofrontal cortex (OFC) with increasing depression severity. Examined separately, male and female KU showed higher sgACC connectivity to bilateral superior temporal gyrus and dorsomedial prefrontal cortex (dmPFC), respectively, in correlation with depression. The linear correlation of sgACC-OFC and sgACC-dmPFC connectivity with depression was significantly different in slope between KU and HC. These findings highlighted changes in rsFC of the sgACC as associated with depression and sex differences in these changes in chronic ketamine users.

PMID: 28892733 [PubMed - as supplied by publisher]

Machine-learning Support to Individual Diagnosis of Mild Cognitive Impairment Using Multimodal MRI and Cognitive Assessments.

Tue, 09/12/2017 - 11:00

Machine-learning Support to Individual Diagnosis of Mild Cognitive Impairment Using Multimodal MRI and Cognitive Assessments.

Alzheimer Dis Assoc Disord. 2017 Sep 07;:

Authors: De Marco M, Beltrachini L, Biancardi A, Frangi AF, Venneri A

Abstract
BACKGROUND: Understanding whether the cognitive profile of a patient indicates mild cognitive impairment (MCI) or performance levels within normality is often a clinical challenge. The use of resting-state functional magnetic resonance imaging (RS-fMRI) and machine learning may represent valid aids in clinical settings for the identification of MCI patients.
METHODS: Machine-learning models were computed to test the classificatory accuracy of cognitive, volumetric [structural magnetic resonance imaging (sMRI)] and blood oxygen level dependent-connectivity (extracted from RS-fMRI) features, in single-modality and mixed classifiers.
RESULTS: The best and most significant classifier was the RS-fMRI+Cognitive mixed classifier (94% accuracy), whereas the worst performing was the sMRI classifier (∼80%). The mixed global (sMRI+RS-fMRI+Cognitive) had a slightly lower accuracy (∼90%), although not statistically different from the mixed RS-fMRI+Cognitive classifier. The most important cognitive features were indices of declarative memory and semantic processing. The crucial volumetric feature was the hippocampus. The RS-fMRI features selected by the algorithms were heavily based on the connectivity of mediotemporal, left temporal, and other neocortical regions.
CONCLUSION: Feature selection was profoundly driven by statistical independence. Some features showed no between-group differences, or showed a trend in either direction. This indicates that clinically relevant brain alterations typical of MCI might be subtle and not inferable from group analysis.

PMID: 28891818 [PubMed - as supplied by publisher]

Comparison of separation performance of independent component analysis algorithms for fMRI data.

Tue, 09/12/2017 - 11:00

Comparison of separation performance of independent component analysis algorithms for fMRI data.

J Integr Neurosci. 2017;16(2):157-175

Authors: Sariya YK, Anand RS

Abstract
Independent component analysis, a data-driven analysis method, has found significant applications in task-based as well as resting state fMRI studies. There are numbers of independent component analysis algorithms available, but only a few of them have been used frequently so far for fMRI images. With a view that algorithms that are overlooked may outperform the most opted, a comparative study is taken up in this paper to analyze their abilities for the purpose of synthesis of fMRI images. In this paper, ten independent component algorithms: Fast ICA, INFOMAX, SIMBEC, JADE, ERICA, EVD, RADICAL, ICA-EBM, ERBM, and COMBI are compared. Their separation abilities are adjudged on both, synthetic and real fMRI images. Performance to decompose synthetic fMRI images is being monitored on the basis of spatial correlation coefficients, time elapsed to extract independent components and the visual appearance of independent components. Ranking of their performances on task-based real fMRI images are based on the closeness of time courses of identified independent components with model time course and the closeness of spatial maps of components with spatial templates while their competencies for resting state fMRI data are analyzed by examining how distinctly they decompose the data into the most consistent resting state networks. Sum of mutual information between all the permutations of decomposed components of resting state fMRI data are also calculated.

PMID: 28891507 [PubMed - in process]

Association between resting-state brain network topological organization and creative ability: evidence from a multiple linear regression model.

Tue, 09/12/2017 - 11:00
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Association between resting-state brain network topological organization and creative ability: evidence from a multiple linear regression model.

Biol Psychol. 2017 Sep 07;:

Authors: Jiao B, Zhang D, Liang A, Liang B, Wang Z, Li J, Cai Y, Gao M, Gao Z, Chang S, Huang R, Liu M

Abstract
Previous studies have indicated a tight linkage between resting-state functional connectivity of the human brain and creative ability. This study aimed to further investigate the association between the topological organization of resting-state brain networks and creativity. Therefore, we acquired resting-state fMRI data from 22 high-creativity participants and 22 low-creativity participants (as determined by their Torrance Tests of Creative Thinking scores). We then constructed functional brain networks for each participant and assessed group differences in network topological properties before exploring the relationships between respective network topological properties and creative ability. We identified an optimized organization of intrinsic brain networks in both groups. However, compared with low-creativity participants, high-creativity participants exhibited increased global efficiency and substantially decreased path length, suggesting increased efficiency of information transmission across brain networks in creative individuals. Using a multiple linear regression model, we further demonstrated that regional functional integration properties (i.e., the betweenness centrality and global efficiency) of brain networks, particularly the default mode network (DMN) and sensorimotor network (SMN), significantly predicted the individual differences in creative ability. Furthermore, the associations between network regional properties and creative performance were creativity-level dependent, where the difference in the resource control component may be important in explaining individual difference in creative performance. These findings provide novel insights into the neural substrate of creativity and may facilitate objective identification of creative ability.

PMID: 28890001 [PubMed - as supplied by publisher]

A Multimodal Imaging- and Stimulation-based Method of Evaluating Connectivity-related Brain Excitability in Patients with Epilepsy.

Tue, 09/12/2017 - 11:00
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A Multimodal Imaging- and Stimulation-based Method of Evaluating Connectivity-related Brain Excitability in Patients with Epilepsy.

J Vis Exp. 2016 Nov 13;(117):

Authors: Shafi MM, Whitfield-Gabrieli S, Chu CJ, Pascual-Leone A, Chang BS

Abstract
Resting-state functional connectivity MRI (rs-fcMRI) is a technique that identifies connectivity between different brain regions based on correlations over time in the blood-oxygenation level dependent signal. rs-fcMRI has been applied extensively to identify abnormalities in brain connectivity in different neurologic and psychiatric diseases. However, the relationship among rs-fcMRI connectivity abnormalities, brain electrophysiology and disease state is unknown, in part because the causal significance of alterations in functional connectivity in disease pathophysiology has not been established. Transcranial Magnetic Stimulation (TMS) is a technique that uses electromagnetic induction to noninvasively produce focal changes in cortical activity. When combined with electroencephalography (EEG), TMS can be used to assess the brain's response to external perturbations. Here we provide a protocol for combining rs-fcMRI, TMS and EEG to assess the physiologic significance of alterations in functional connectivity in patients with neuropsychiatric disease. We provide representative results from a previously published study in which rs-fcMRI was used to identify regions with abnormal connectivity in patients with epilepsy due to a malformation of cortical development, periventricular nodular heterotopia (PNH). Stimulation in patients with epilepsy resulted in abnormal TMS-evoked EEG activity relative to stimulation of the same sites in matched healthy control patients, with an abnormal increase in the late component of the TMS-evoked potential, consistent with cortical hyperexcitability. This abnormality was specific to regions with abnormal resting-state functional connectivity. Electrical source analysis in a subject with previously recorded seizures demonstrated that the origin of the abnormal TMS-evoked activity co-localized with the seizure-onset zone, suggesting the presence of an epileptogenic circuit. These results demonstrate how rs-fcMRI, TMS and EEG can be utilized together to identify and understand the physiological significance of abnormal brain connectivity in human diseases.

PMID: 27911366 [PubMed - indexed for MEDLINE]

Mobilization of Medial and Lateral Frontal-Striatal Circuits in Cocaine Users and Controls: An Interleaved TMS/BOLD Functional Connectivity Study.

Tue, 09/12/2017 - 11:00
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Mobilization of Medial and Lateral Frontal-Striatal Circuits in Cocaine Users and Controls: An Interleaved TMS/BOLD Functional Connectivity Study.

Neuropsychopharmacology. 2016 Dec;41(13):3032-3041

Authors: Hanlon CA, Dowdle LT, Moss H, Canterberry M, George MS

Abstract
The integrity of frontal-striatal circuits is an area of great interest in substance dependence literature, particularly as the field begins to develop neural circuit-specific brain stimulation treatments for these individuals. Prior research indicates that frontal-striatal connectivity is disrupted in chronic cocaine users in a baseline (resting) state. It is unclear, however, if this is also true when these circuits are mobilized by an external source. In this study, we measured the functional and structural integrity of frontal-striatal circuitry involved in limbic arousal and executive control in 36 individuals-18 cocaine-dependent individuals with a history of failed quit attempts and 18 age-matched controls. This was achieved by applying a transcranial magnetic stimulation to the medial prefrontal cortex (Brodmann area 10) and the dorsolateral prefrontal cortex (lateral Brodmann 9) while participants rested in the MRI scanner (TMS/BOLD imaging). Relative to the controls, cocaine users had a lower ventral striatal BOLD response to MPFC stimulation. The dorsal striatal BOLD response to DLPFC stimulation however was not significantly different between the groups. Among controls, DLPFC stimulation led to a reciprocal attenuation of MPFC activity (BA 10), but this pattern did not exist in cocaine users. No relationship was found between regional diffusion metrics and functional activity. Considered together these data suggest that, when engaged, cocaine users can mobilize their executive control system similar to controls, but that the 'set point' for mobilizing their limbic arousal system has been elevated-an interpretation consistent with opponent process theories of addiction.

PMID: 27374278 [PubMed - indexed for MEDLINE]

A flexible graphical model for multi-modal parcellation of the cortex.

Mon, 09/11/2017 - 16:00

A flexible graphical model for multi-modal parcellation of the cortex.

Neuroimage. 2017 Sep 06;:

Authors: Parisot S, Glocker B, Ktena SI, Arslan S, Schirmer MD, Rueckert D

Abstract
Advances in neuroimaging have provided a tremendous amount of in-vivo information on the brain's organisation. Its anatomy and cortical organisation can be investigated from the point of view of several imaging modalities, many of which have been studied for mapping functionally specialised cortical areas. There is strong evidence that a single modality is not sufficient to fully identify the brain's cortical organisation. Combining multiple modalities in the same parcellation task has the potential to provide more accurate and robust subdivisions of the cortex. Nonetheless, existing brain parcellation methods are typically developed and tested on single modalities using a specific type of information. In this paper, we propose Graph-based Multi-modal Parcellation (GraMPa), an iterative framework designed to handle the large variety of available input modalities to tackle the multi-modal parcellation task. At each iteration, we compute a set of parcellations from different modalities and fuse them based on their local reliabilities. The fused parcellation is used to initialise the next iteration, forcing the parcellations to converge towards a set of mutually informed modality specific parcellations, where correspondences are established. We explore two different multi-modal configurations for group-wise parcellation using resting-state fMRI, diffusion MRI tractography, myelin maps and task fMRI. Quantitative and qualitative results on the Human Connectome Project database show that integrating multi-modal information yields a stronger agreement with well established atlases and more robust connectivity networks that provide a better representation of the population.

PMID: 28889005 [PubMed - as supplied by publisher]

Quantitative vascular neuroimaging of the rat brain using superparamagnetic nanoparticles: New insights on vascular organization and brain function.

Mon, 09/11/2017 - 16:00

Quantitative vascular neuroimaging of the rat brain using superparamagnetic nanoparticles: New insights on vascular organization and brain function.

Neuroimage. 2017 Sep 06;:

Authors: Gharagouzloo CA, Timms L, Qiao J, Fang Z, Nneji J, Pandya A, Kulkarni P, van de Ven AL, Ferris C, Sridhar S

Abstract
A method called Quantitative Ultra-Short Time-to-Echo Contrast Enhanced (QUTE-CE) Magnetic Resonance Imaging (MRI) which utilizes superparamagnetic iron oxide nanoparticles (SPIONs) as a contrast agent to yield positive contrast angiograms with high clarity and definition is applied to the whole live rat brain. QUTE-CE MRI intensity data are particularly well suited for measuring quantitative cerebral blood volume (qCBV). A global map of qCBV in the awake resting-state with unprecedented detail was created via application of a 3D MRI rat brain atlas with 173 segmented and annotated brain areas. From this map we identified two distributed, integrated neural circuits showing the highest capillary densities in the brain. One is the neural circuitry involved with the primary senses of smell, hearing and vision and the other is the neural circuitry of memory. Under isoflurane anesthesia, these same circuits showed significant decreases in qCBV suggesting a role in consciousness. Neural circuits in the brainstem associated with the reticular activating system and the maintenance of respiration, body temperature and cardiovascular function showed an increase in qCBV with anesthesia. During awake CO2 challenge, 84 regions showed significant increases relative to an awake baseline state. This CO2 response provides a measure of cerebral vascular reactivity and regional perfusion reserve with the highest response measured in the somatosensory cortex. These results demonstrate the utility of QUTE-CE MRI for qCBV analysis and offer a new perspective on brain function and vascular organization.

PMID: 28889004 [PubMed - as supplied by publisher]

Attentional control underlies the perceptual load effect: evidence from voxel-wise degree centrality and resting-state functional connectivity.

Mon, 09/11/2017 - 16:00

Attentional control underlies the perceptual load effect: evidence from voxel-wise degree centrality and resting-state functional connectivity.

Neuroscience. 2017 Sep 06;:

Authors: Yin S, Liu L, Tan J, Ding C, Yao D, Chen A

Abstract
The fact that interference from peripheral distracting information can be reduced in high perceptual load tasks has been widely demonstrated in previous research. The modulation from the perceptual load is known as perceptual load effect (PLE). Previous fMRI studies on perceptual load have reported the brain areas implicated in attentional control. To date, the contribution of attentional control to PLE and the relationship between the organization of functional connectivity and PLE are still poorly understood. In the present study, we used resting-state functional magnetic resonance imaging (fMRI) to explore the association between the voxel-wise degree centrality (DC) and PLE in an individual differences design and further investigated the potential resting-state functional connectivity (RSFC) contributing to individual's PLE. DC-PLE correlation analysis revealed that PLE was positively associated with the right middle temporal visual area (MT)-one of dorsal attention network (DAN) nodes. Furthermore, the right MT functionally connected to the conventional dorsal attention network (DAN) and the RSFCs between right MT and DAN nodes were also positively associated with individual difference in PLE. The results suggest an important role of attentional control in perceptual load tasks and provide novel insights into the understanding of the neural correlates underlying PLE.

PMID: 28888953 [PubMed - as supplied by publisher]

Test-retest reliability of cerebral blood flow in healthy individuals using arterial spin labeling: Findings from the EMBARC study.

Mon, 09/11/2017 - 16:00

Test-retest reliability of cerebral blood flow in healthy individuals using arterial spin labeling: Findings from the EMBARC study.

Magn Reson Imaging. 2017 Sep 06;:

Authors: Almeida JRC, Greenberg T, Lu H, Chase HW, Fournier J, Cooper CM, Deckersbach T, Adams P, Carmody T, Fava M, Kurian B, McGrath PJ, McInnis M, Oquendo MA, Parsey R, Weissman M, Trivedi M, Phillips ML

Abstract
INTRODUCTION: Previous investigations of test-retest reliability of cerebral blood flow (CBF) at rest measured with pseudo-continuous Arterial Spin Labeling (pCASL) demonstrated good reliability, but are limited by the use of similar scanner platforms. In the present study we examined test-retest reliability of CBF in regions implicated in emotion and the default mode network.
MATERIAL AND METHODS: We measured absolute and relative CBF at rest in thirty-one healthy subjects in two scan sessions, one week apart, at four different sites and three different scan platforms. We derived CBF from pCASL images with an automated algorithm and calculated intra-class correlation coefficients (ICCs) across sessions for regions of interest. In addition, we investigated site effects.
RESULTS: For both absolute and relative CBF measures, ICCs were good to excellent (i.e. >0.6) in most brain regions, with highest values observed for the subgenual anterior cingulate cortex and ventral striatum. A leave-one-site-out cross validation analysis did not show a significant effect for site on whole brain CBF and there was no proportional bias across sites. However, a significant site effect was present in the repeated measures ANOVA.
CONCLUSIONS: The high test-retest reliability of CBF measured with pCASL in a range of brain regions implicated in emotion and salience processing, emotion regulation, and the default mode network, which have been previously linked to depression symptomatology supports its use in studies that aim to identify neuroimaging biomarkers of treatment response.

PMID: 28888770 [PubMed - as supplied by publisher]

Inter-vender and test-retest reliabilities of resting-state functional magnetic resonance imaging: Implications for multi-center imaging studies.

Mon, 09/11/2017 - 16:00

Inter-vender and test-retest reliabilities of resting-state functional magnetic resonance imaging: Implications for multi-center imaging studies.

Magn Reson Imaging. 2017 Sep 06;:

Authors: An HS, Moon WJ, Ryu JK, Park JY, Yun WS, Choi JW, Jahng GH, Park JY

Abstract
This prospective multi-center study aimed to evaluate the inter-vendor and test-retest reliabilities of resting-state functional magnetic resonance imaging (RS-fMRI) by assessing the temporal signal-to-noise ratio (tSNR) and functional connectivity. Study included 10 healthy subjects and each subject was scanned using three 3T MR scanners (GE Signa HDxt, Siemens Skyra, and Philips Achieva) in two sessions. The tSNR was calculated from the time course data. Inter-vendor and test-retest reliabilities were assessed with intra-class correlation coefficients (ICCs) derived from variant component analysis. Independent component analysis was performed to identify the connectivity of the default-mode network (DMN). In result, the tSNR for the DMN was not significantly different among the GE, Philips, and Siemens scanners (P=0.638). In terms of vendor differences, the inter-vendor reliability was good (ICC=0.774). Regarding the test-retest reliability, the GE scanner showed excellent correlation (ICC=0.961), while the Philips (ICC=0.671) and Siemens (ICC=0.726) scanners showed relatively good correlation. The DMN pattern of the subjects between the two sessions for each scanner and between three scanners showed the identical patterns of functional connectivity. The inter-vendor and test-retest reliabilities of RS-fMRI using different 3T MR scanners are good. Thus, we suggest that RS-fMRI could be used in multicenter imaging studies as a reliable imaging marker.

PMID: 28888769 [PubMed - as supplied by publisher]

Mindfulness and dynamic functional neural connectivity in children and adolescents.

Sun, 09/10/2017 - 15:00
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Mindfulness and dynamic functional neural connectivity in children and adolescents.

Behav Brain Res. 2017 Sep 05;:

Authors: Marusak HA, Elrahal F, Peters CA, Kundu P, Lombardo MV, Calhoun VD, Goldberg EK, Cohen C, Taub JW, Rabinak CA

Abstract
BACKGROUND: Interventions that promote mindfulness consistently show salutary effects on cognition and emotional wellbeing in adults, and more recently, in children and adolescents. However, we lack understanding of the neurobiological mechanisms underlying mindfulness in youth that should allow for more judicious application of these interventions in clinical and educational settings.
METHODS: Using multi-echo multi-band fMRI, we examined dynamic (i.e., time-varying) and conventional static resting-state connectivity between core neurocognitive networks (i.e., salience/emotion, default mode, central executive) in 42 children and adolescents (ages 6-17).
RESULTS: We found that trait mindfulness in youth relates to dynamic but not static resting-state connectivity. Specifically, more mindful youth transitioned more between brain states over the course of the scan, spent overall less time in a certain connectivity state, and showed a state-specific reduction in connectivity between salience/emotion and central executive networks. The number of state transitions mediated the link between higher mindfulness and lower anxiety, providing new insights into potential neural mechanisms underlying benefits of mindfulness on psychological health in youth.
CONCLUSIONS: Our results provide new evidence that mindfulness in youth relates to functional neural dynamics and interactions between neurocognitive networks, over time.

PMID: 28887198 [PubMed - as supplied by publisher]

Network Mechanisms of Clinical Response to Transcranial Magnetic Stimulation in Posttraumatic Stress Disorder and Major Depressive Disorder.

Sun, 09/10/2017 - 15:00
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Network Mechanisms of Clinical Response to Transcranial Magnetic Stimulation in Posttraumatic Stress Disorder and Major Depressive Disorder.

Biol Psychiatry. 2017 Aug 08;:

Authors: Philip NS, Barredo J, van 't Wout-Frank M, Tyrka AR, Price LH, Carpenter LL

Abstract
BACKGROUND: Repetitive transcranial magnetic stimulation (TMS) therapy can modulate pathological neural network functional connectivity in major depressive disorder (MDD). Posttraumatic stress disorder is often comorbid with MDD, and symptoms of both disorders can be alleviated with TMS therapy. This is the first study to evaluate TMS-associated changes in connectivity in patients with comorbid posttraumatic stress disorder and MDD.
METHODS: Resting-state functional connectivity magnetic resonance imaging was acquired before and after TMS therapy in 33 adult outpatients in a prospective open trial. TMS at 5 Hz was delivered, in up to 40 daily sessions, to the left dorsolateral prefrontal cortex. Analyses used a priori seeds relevant to TMS, posttraumatic stress disorder, or MDD (subgenual anterior cingulate cortex [sgACC], left dorsolateral prefrontal cortex, hippocampus, and basolateral amygdala) to identify imaging predictors of response and to evaluate clinically relevant changes in connectivity after TMS, followed by leave-one-out cross-validation. Imaging results were explored using data-driven multivoxel pattern activation.
RESULTS: More negative pretreatment connectivity between the sgACC and the default mode network predicted clinical improvement, as did more positive amygdala-to-ventromedial prefrontal cortex connectivity. After TMS, symptom reduction was associated with reduced connectivity between the sgACC and the default mode network, left dorsolateral prefrontal cortex, and insula, and reduced connectivity between the hippocampus and the salience network. Multivoxel pattern activation confirmed seed-based predictors and correlates of treatment outcomes.
CONCLUSIONS: These results highlight the central role of the sgACC, default mode network, and salience network as predictors of TMS response and suggest their involvement in mechanisms of action. Furthermore, this work indicates that there may be network-based biomarkers of clinical response relevant to these commonly comorbid disorders.

PMID: 28886760 [PubMed - as supplied by publisher]

Functional connectivity of the hippocampus to the thalamocortical circuitry in an animal model of absence seizures.

Sat, 09/09/2017 - 14:00

Functional connectivity of the hippocampus to the thalamocortical circuitry in an animal model of absence seizures.

Epilepsy Res. 2017 Aug 24;137:19-24

Authors: Mousavi SR, Arcaro JA, Leung LS, Tenney JR, Mirsattari SM

Abstract
OBJECTIVE: Using the gamma-butyrolactone (GBL) rat model of absence seizures, this study investigated the functional connectivity of the hippocampus, thalamus and cerebral cortex before and during absence seizures.
METHODS: Functional connectivity between the hippocampus, thalamus and sensory and motor cortecies, were examined by the temporal correlations of the resting state blood-oxygen-level-dependent (BOLD) signal. Functional connectivity between these regions was calculated at baseline, 5min after saline injection, and at 5, 20 and 52min after GBL injection. This time interval spans the onset of behaviours including chewing and staring spells associated with GBL-induced absence seizures, along with the onset and suppression of spike-and-wave discharges (SWDs).
RESULTS: Overall there was an increase in functional connectivity across most regions. The functional connectivity generally decreased over time and it returned to baseline 52min post-GBL injection. Functional connectivity of the thalamus to the sensory and motor cortecies increased during absence seizure. The results revealed enhanced connectivity of the left dorsal hippocampus and the thalamus shortly after GBL injection, which coincided with the appearance of SWDs in this rat model.
SIGNIFICANCE: Increased functional connectivity between the hippocampus and the thalamus suggests that the hippocampus participates in the GBL model of absence seizures. Involvement of the hippocampus during absence seizure has implications for studies into the mechanisms in cognitive impairments in patients with absence epilepsy.

PMID: 28886474 [PubMed - as supplied by publisher]

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