New resting-state fMRI related studies at PubMed

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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]

Dual-echo ASL contributes to decrypting the link between functional connectivity and cerebral blow flow.

Sat, 09/09/2017 - 14:00

Dual-echo ASL contributes to decrypting the link between functional connectivity and cerebral blow flow.

Hum Brain Mapp. 2017 Sep 08;:

Authors: Storti SF, Boscolo Galazzo I, Montemezzi S, Menegaz G, Pizzini FB

Abstract
Arterial spin labeling (ASL) MRI with a dual-echo readout module (DE-ASL) enables noninvasive simultaneous acquisition of cerebral blood flow (CBF)-weighted images and blood oxygenation level dependent (BOLD) contrast. Up to date, resting-state functional connectivity (FC) studies based on CBF fluctuations have been very limited, while the BOLD is still the method most frequently used. The purposes of this technical report were (i) to assess the potentiality of the DE-ASL sequence for the quantification of resting-state FC and brain organization, with respect to the conventional BOLD (cvBOLD) and (ii) to investigate the relationship between a series of complex network measures and the CBF information. Thirteen volunteers were scanned on a 3 T scanner acquiring a pseudocontinuous multislice DE-ASL sequence, from which the concomitant BOLD (ccBOLD) simultaneously to the ASL can be extracted. In the proposed comparison, the brain FC and graph-theoretical analysis were used for quantifying the connectivity strength between pairs of regions and for assessing the network model properties in all the sequences. The main finding was that the ccBOLD part of the DE-ASL sequence provided highly comparable connectivity results compared to cvBOLD. As expected, because of its different nature, ASL sequence showed different patterns of brain connectivity and graph indices compared to BOLD sequences. To conclude, the resting-state FC can be reliably detected using DE-ASL, simultaneously to CBF quantifications, whereas a single fMRI experiment precludes the quantitative measurement of BOLD signal changes. Hum Brain Mapp, 2017. © 2017 Wiley Periodicals, Inc.

PMID: 28885752 [PubMed - as supplied by publisher]

Static and Dynamic Measures of Human Brain Connectivity Predict Complementary Aspects of Human Cognitive Performance.

Sat, 09/09/2017 - 14:00

Static and Dynamic Measures of Human Brain Connectivity Predict Complementary Aspects of Human Cognitive Performance.

Front Hum Neurosci. 2017;11:420

Authors: Ramos-Nuñez AI, Fischer-Baum S, Martin RC, Yue Q, Ye F, Deem MW

Abstract
In cognitive network neuroscience, the connectivity and community structure of the brain network is related to measures of cognitive performance, like attention and memory. Research in this emerging discipline has largely focused on two measures of connectivity-modularity and flexibility-which, for the most part, have been examined in isolation. The current project investigates the relationship between these two measures of connectivity and how they make separable contribution to predicting individual differences in performance on cognitive tasks. Using resting state fMRI data from 52 young adults, we show that flexibility and modularity are highly negatively correlated. We use a Brodmann parcellation of the fMRI data and a sliding window approach for calculation of the flexibility. We also demonstrate that flexibility and modularity make unique contributions to explain task performance, with a clear result showing that modularity, not flexibility, predicts performance for simple tasks and that flexibility plays a greater role in predicting performance on complex tasks that require cognitive control and executive functioning. The theory and results presented here allow for stronger links between measures of brain network connectivity and cognitive processes.

PMID: 28883789 [PubMed]

Real-Time Motor Cortex Mapping for the Safe Resection of Glioma: An Intraoperative Resting-State fMRI Study.

Sat, 09/09/2017 - 14:00

Real-Time Motor Cortex Mapping for the Safe Resection of Glioma: An Intraoperative Resting-State fMRI Study.

AJNR Am J Neuroradiol. 2017 Sep 07;:

Authors: Qiu TM, Gong FY, Gong X, Wu JS, Lin CP, Biswal BB, Zhuang DX, Yao CJ, Zhang XL, Lu JF, Zhu FP, Mao Y, Zhou LF

Abstract
BACKGROUND AND PURPOSE: Resting-state functional MR imaging has been used for motor mapping in presurgical planning but never used intraoperatively. This study aimed to investigate the feasibility of applying intraoperative resting-state functional MR imaging for the safe resection of gliomas using real-time motor cortex mapping during an operation.
MATERIALS AND METHODS: Using interventional MR imaging, we conducted preoperative and intraoperative resting-state intrinsic functional connectivity analyses of the motor cortex in 30 patients with brain tumors. Factors that may influence intraoperative imaging quality, including anesthesia type (general or awake anesthesia) and tumor cavity (filled with normal saline or not), were studied to investigate image quality. Additionally, direct cortical stimulation was used to validate the accuracy of intraoperative resting-state fMRI in mapping the motor cortex.
RESULTS: Preoperative and intraoperative resting-state fMRI scans were acquired for all patients. Fourteen patients who successfully completed both sufficient intraoperative resting-state fMRI and direct cortical stimulation were used for further analysis of sensitivity and specificity. Compared with those subjected to direct cortical stimulation, the sensitivity and specificity of intraoperative resting-state fMRI in localizing the motor area were 61.7% and 93.7%, respectively. The image quality of intraoperative resting-state fMRI was better when the tumor cavity was filled with normal saline (P = .049). However, no significant difference between the anesthesia types was observed (P = .102).
CONCLUSIONS: This study demonstrates the feasibility of using intraoperative resting-state fMRI for real-time localization of functional areas during a neurologic operation. The findings suggest that using intraoperative resting-state fMRI can avoid the risk of intraoperative seizures due to direct cortical stimulation and may provide neurosurgeons with valuable information to facilitate the safe resection of gliomas.

PMID: 28882861 [PubMed - as supplied by publisher]

Cognition in patients with benign epilepsy with centrotemporal spikes: A study with long-term VEEG and RS-fMRI.

Sat, 09/09/2017 - 14:00

Cognition in patients with benign epilepsy with centrotemporal spikes: A study with long-term VEEG and RS-fMRI.

Epilepsy Behav. 2017 Sep 04;:

Authors: Yan X, Yu Q, Gao Y, Li L, Yu D, Chen Y, Yao X, Yang W, Chen Z, Yin J, An Y, Tan K

Abstract
OBJECTIVE: The purpose of this study was to investigate the relationship between alterations of functional brain network and cognition in patients with benign epilepsy with centrotemporal spikes (BECTS) as a function of spike-wave index (SWI) during slow wave sleep.
METHODS: Resting-state functional magnetic resonance imaging (RS-fMRI) data and Intelligence Quotient (IQ) were collected from two groups of patients with BECTS, including a SWI<50% group (5 cases) and a SWI≥50% group (7 cases). The SWI was calculated from the long-term video-electroencephalogram monitoring (one sleep cycle was included at least). The RS-fMRI data were analyzed by regional homogeneity (ReHo) method.
RESULTS: There were three main findings. Firstly, Full Intelligence Quotient (FIQ), Verbal Intelligence Quotient (VIQ), and Performance Intelligence Quotient (PIQ) of the SWI≥50% group were significantly lower than SWI<50% group (p<0.05). Secondly, there was a negative correlation between the FIQ, VIQ, PIQ, and SWI (p<0.05), and the FIQ, VIQ, and PIQ were not dependent on age, age of onset, disease course, years of education, and total number of seizures (p>0.05). Finally, compared with the SWI<50% group, the SWI≥50% group showed increased ReHo in the bilateral precentral gyrus, bilateral premotor area, bilateral subcortical structure, right temporal lobe, and bilateral insular lobe, while they showed decreased ReHo in the posterior cingulate cortex and posterior of right inferior temporal lobe.
CONCLUSIONS: The alterations of functional brain network caused by the frequent discharges during slow wave sleep could affect cognition in patients with BECTS.

PMID: 28882722 [PubMed - as supplied by publisher]

A network-level approach of cognitive flexibility impairment after surgery of a right temporo-parietal glioma.

Sat, 09/09/2017 - 14:00

A network-level approach of cognitive flexibility impairment after surgery of a right temporo-parietal glioma.

Neurochirurgie. 2017 Sep 04;:

Authors: Mandonnet E, Cerliani L, Siuda-Krzywicka K, Poisson I, Zhi N, Volle E, de Schotten MT

Abstract
OBJECTIVE: The right "non-dominant" temporo-parietal junction is usually not considered as a highly eloquent area. This contrasts with its mirrored left "dominant" counterpart, which is known as highly eloquent regarding language function. The question arises about which functions should be monitored when operating lesions of the right temporo-parietal junction under awake conditions.
METHODS: We report the case of a patient who underwent a surgical resection of a glioma located in the right temporo-parietal junction. Cognitive evaluations were performed preoperatively and 4 months after surgery, as well as resting state fMRI and diffusion-based tractography.
RESULTS: Long-term postoperative cognitive examination revealed an important deterioration of cognitive control abilities, especially regarding set-shifting abilities as measured by Trail making test part B. Based on pre- and postoperative resting state fMRI and diffusion-based tractography, we demonstrate that surgical resection massively impacted structural and functional connectivity of the right fronto-parieto-temporal network, a network that is classically involved in cognitive control, reasoning and working memory.
CONCLUSION: This case clearly illustrates how a white matter focal lesion can generate a neuropsychological deficit by remotely disconnecting distant cortical areas belonging to a functional network. Furthermore, our observation strongly supports the use of intraoperative cognitive control tests during surgery of the right temporo-parietal junction and promote the interest of pre and postoperative resting state functional connectivity to explore the potential mechanisms causing cognitive deficits.

PMID: 28882599 [PubMed - as supplied by publisher]

Associations between dynamic functional connectivity and age, metabolic risk, and cognitive performance.

Sat, 09/09/2017 - 14:00

Associations between dynamic functional connectivity and age, metabolic risk, and cognitive performance.

Neurobiol Aging. 2017 Aug 10;:

Authors: Viviano RP, Raz N, Yuan P, Damoiseaux JS

Abstract
Advanced age is associated with reduced within-network functional connectivity, particularly within the default mode network. Most studies to date have examined age differences in functional connectivity via static indices that are computed over the entire blood-oxygen-level dependent time series. Little is known about the effects of age on short-term temporal dynamics of functional connectivity. Here, we examined age differences in dynamic connectivity as well as associations between connectivity, metabolic risk, and cognitive performance in healthy adults (N = 168; age, 18-83 years). A sliding-window k-means clustering approach was used to assess dynamic connectivity from resting-state functional magnetic resonance imaging data. Three out of 8 dynamic connectivity profiles were associated with age. Furthermore, metabolic risk was associated with the relative amount of time allocated to 2 of these profiles. Finally, the relative amount of time allocated to a dynamic connectivity profile marked by heightened connectivity between default mode and medial temporal regions was positively associated with executive functions. Thus, dynamic connectivity analyses can enrich understanding of age-related differences beyond what is revealed by static analyses.

PMID: 28882422 [PubMed - as supplied by publisher]

The Default Mode Network as a Biomarker of Persistent Complaints After Mild Traumatic Brain Injury: A Longitudinal fMRI Study.

Sat, 09/09/2017 - 14:00

The Default Mode Network as a Biomarker of Persistent Complaints After Mild Traumatic Brain Injury: A Longitudinal fMRI Study.

J Neurotrauma. 2017 Sep 07;:

Authors: van der Horn HJ, Scheenen ME, de Koning ME, Liemburg EJ, Spikman JM, van der Naalt J

Abstract
The objective of this study was to examine longitudinal functional connectivity of resting-state networks in patients with and without complaints after uncomplicated mild traumatic brain injury (mTBI). Second, we aimed to determine the value of network connectivity in predicting persistent complaints, anxiety, depression and long-term outcome. Thirty mTBI patients with (≥ 3) posttraumatic complaints at two weeks post-injury, 19 without complaints, and 20 matched healthy controls were selected for this study. Resting-state fMRI was performed in patients at one month and three months post-injury, and once in healthy controls. Independent component analysis (ICA) was used to investigate the default mode, executive and salience networks. Persistent posttraumatic complaints, anxiety and depression were measured at three months post-injury and outcome was determined at one year post-injury. Within the group with complaints, higher functional connectivity between the anterior and posterior components of the default mode network at one month post-injury was associated with a higher number of complaints at three months post-injury (ρ=0.59, p=0.001). Minor longitudinal changes in functional connectivity were found for patients with and without complaints after mTBI, which were limited to connectivity within the precuneus component of the default mode network. No significant results were found for the executive and salience network. Current results suggest that the default mode network may serve as a biomarker of persistent complaints in patients with uncomplicated mTBI.

PMID: 28882089 [PubMed - as supplied by publisher]

Remodeling of Sensorimotor Brain Connectivity in Gpr88 deficient mice.

Sat, 09/09/2017 - 14:00

Remodeling of Sensorimotor Brain Connectivity in Gpr88 deficient mice.

Brain Connect. 2017 Sep 07;:

Authors: Arefin T, Mechling AE, Meirsman CA, Bienert T, Huebner NS, Lee HL, Ben Hamida S, Ehrlich A, Roquet D, Hennig J, von Elverfeldt D, Kieffer BL, Harsan LA

Abstract
Recent studies have demonstrated that orchestrated gene activity and expression supports synchronous activity of brain networks. However, there is a paucity of information on the consequences of single gene function on overall brain functional organization and connectivity, and how this translates at behavioral level. Here we combined mouse mutagenesis with functional and structural magnetic resonance imaging (MRI) to determine whether targeted inactivation of a single gene would modify whole brain connectivity in live animals. The targeted gene encodes GPR88, an orphan G protein-coupled receptor enriched in the striatum and previously linked to behavioral traits relevant to neuropsychiatric disorders. Connectivity analysis of GPR88 deficient mice revealed extensive remodeling of intra-cortical and cortico-subcortical networks. Most prominent modifications were observed at the level of retrosplenial cortex connectivity, central to the default mode network (DMN) whose alteration is considered a hallmark of many psychiatric conditions. Next, somatosensory and motor cortical networks were most affected. These modifications directly relate to sensorimotor gating deficiency reported in mutant animals, and also likely underlie their hyperactivity phenotype. Finally we identified alterations within hippocampal and dorsal striatum functional connectivity, most relevant to a specific learning deficit that we previously reported in Gpr88-/- animals. Also, amygdala connectivity with cortex and striatum was weakened, perhaps underlying the "risk-taking" behavior of these animals. This is the first evidence demonstrating that GPR88 activity shapes the mouse brain functional and structural connectome. The concordance between connectivity alterations and behavior deficits observed in Gpr88 deficient mice, suggest a role for GPR88 in brain communication.

PMID: 28882062 [PubMed - as supplied by publisher]

Altered right anterior insular connectivity and loss of associated functions in adolescent chronic fatigue syndrome.

Fri, 09/08/2017 - 13:00

Altered right anterior insular connectivity and loss of associated functions in adolescent chronic fatigue syndrome.

PLoS One. 2017;12(9):e0184325

Authors: Wortinger LA, Glenne Øie M, Endestad T, Bruun Wyller V

Abstract
Impairments in cognition, pain intolerance, and physical inactivity characterize adolescent chronic fatigue syndrome (CFS), yet little is known about its neurobiology. The right dorsal anterior insular (dAI) connectivity of the salience network provides a motivational context to stimuli. In this study, we examined regional functional connectivity (FC) patterns of the right dAI in adolescent CFS patients and healthy participants. Eighteen adolescent patients with CFS and 18 aged-matched healthy adolescent control participants underwent resting-state functional magnetic resonance imaging. The right dAI region of interest was examined in a seed-to-voxel resting-state FC analysis using SPM and CONN toolbox. Relative to healthy adolescents, CFS patients demonstrated reduced FC of the right dAI to the right posterior parietal cortex (PPC) node of the central executive network. The decreased FC of the right dAI-PPC might indicate impaired cognitive control development in adolescent CFS. Immature FC of the right dAI-PPC in patients also lacked associations with three known functional domains: cognition, pain and physical activity, which were observed in the healthy group. These results suggest a distinct biological signature of adolescent CFS and might represent a fundamental role of the dAI in motivated behavior.

PMID: 28880891 [PubMed - in process]

Hemodynamic variability in soldiers with trauma: Implications for functional MRI connectivity studies.

Fri, 09/08/2017 - 13:00
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Hemodynamic variability in soldiers with trauma: Implications for functional MRI connectivity studies.

Neuroimage Clin. 2017;16:409-417

Authors: Rangaprakash D, Dretsch MN, Yan W, Katz JS, Denney TS, Deshpande G

Abstract
Functional MRI (fMRI) is an indirect measure of neural activity as a result of the convolution of the hemodynamic response function (HRF) and latent (unmeasured) neural activity. Recent studies have shown variability of HRF across brain regions (intra-subject spatial variability) and between subjects (inter-subject variability). Ignoring this HRF variability during data analysis could impair the reliability of such fMRI results. Using whole-brain resting-state fMRI (rs-fMRI), we employed hemodynamic deconvolution to estimate voxel-wise HRF. Studying the impact of mental disorders on HRF variability, we identified HRF aberrations in soldiers (N = 87) with posttraumatic stress disorder (PTSD) and mild-traumatic brain injury (mTBI) compared to combat controls. Certain subcortical and default-mode regions were found to have significant HRF aberrations in the clinical groups. These brain regions have been previously associated with neurochemical alterations in PTSD, which are known to impact the shape of the HRF. We followed-up these findings with seed-based functional connectivity (FC) analysis using regions-of-interest (ROIs) whose HRFs differed between the groups. We found that part of the connectivity group differences reported from traditional FC analysis (no deconvolution) were attributable to HRF variability. These findings raise the question of the degree of reliability of findings from conventional rs-fMRI studies (especially in psychiatric populations like PTSD and mTBI), which are corrupted by HRF variability. We also report and discus, for the first time, voxel-level HRF alterations in PTSD and mTBI. To the best of our knowledge, this is the first study to report evidence for the impact of HRF variability on connectivity group differences. Our work has implications for rs-fMRI connectivity studies. We encourage researchers to incorporate hemodynamic deconvolution during pre-processing to minimize the impact of HRF variability.

PMID: 28879082 [PubMed - in process]

Structural, Functional, and Metabolic Brain Markers Differentiate Collision versus Contact and Non-Contact Athletes.

Fri, 09/08/2017 - 13:00
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Structural, Functional, and Metabolic Brain Markers Differentiate Collision versus Contact and Non-Contact Athletes.

Front Neurol. 2017;8:390

Authors: Churchill NW, Hutchison MG, Di Battista AP, Graham SJ, Schweizer TA

Abstract
There is growing concern about how participation in contact sports affects the brain. Retrospective evidence suggests that contact sports are associated with long-term negative health outcomes. However, much of the research to date has focused on former athletes with significant health problems. Less is known about the health of current athletes in contact and collision sports who have not reported significant medical issues. In this cross-sectional study, advanced magnetic resonance imaging (MRI) was used to evaluate multiple aspects of brain physiology in three groups of athletes participating in non-contact sports (N = 20), contact sports (N = 22), and collision sports (N = 23). Diffusion tensor imaging was used to assess white matter microstructure based on measures of fractional anisotropy (FA) and mean diffusivity (MD); resting-state functional MRI was used to evaluate global functional connectivity; single-voxel spectroscopy was used to compare ratios of neural metabolites, including N-acetyl aspartate (NAA), creatine (Cr), choline, and myo-inositol. Multivariate analysis revealed structural, functional, and metabolic measures that reliably differentiated between sport groups. The collision group had significantly elevated FA and reduced MD in white matter, compared to both contact and non-contact groups. In contrast, the collision group showed significant reductions in functional connectivity and the NAA/Cr metabolite ratio, relative to only the non-contact group, while the contact group overlapped with both non-contact and collision groups. For brain regions associated with contact sport participation, athletes with a history of concussion also showed greater alterations in FA and functional connectivity, indicating a potential cumulative effect of both contact exposure and concussion history on brain physiology. These findings indicate persistent differences in brain physiology for athletes participating in contact and collision sports, which should be considered in future studies of concussion and subconcussive impacts.

PMID: 28878729 [PubMed]

Changes in Resting-State Cerebral Activity in Patients with Hyperthyroidism: A Short-Term Follow-Up Functional MR Imaging Study.

Fri, 09/08/2017 - 13:00
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Changes in Resting-State Cerebral Activity in Patients with Hyperthyroidism: A Short-Term Follow-Up Functional MR Imaging Study.

Sci Rep. 2017 Sep 06;7(1):10627

Authors: Liu B, Ran Q, Liu D, Zhang S, Zhang D

Abstract
To investigate the brain functional abnormality of hyperthyroid patients before and after treatment for one month using resting-state functional magnetic resonance imaging (rs-fMRI). Amplitude of low-frequency fluctuation (ALFF) and seed-based functional connectivity (FC) analysis were performed in 27 new-onset untreated hyperthyroid patients relative to 30 healthy controls. In addition, follow-up data were available for 19 patients treated with methimazole for one month. Compared with healthy controls, patients exhibited lower ALFF in the right posterior cingulate cortex (PCC); increased FC in the bilateral anterior insula (AI), bilateral posterior insula (PI) and left anterior lobe of the cerebellum (ALC); and decreased FC in the bilateral lateral prefrontal cortex (LPFC), the right medial temporal gyrus (MTG) and the bilateral PCC. Compared with the hyperthyroid status, patients with improved thyroid function showed increased FC in the right LPFC and right dorsolateral prefrontal cortex (DLPFC). Subsequently, Pearson's correlation analyses were performed between abnormal ALFF, FC, neuropsychological assessment and serum free triiodothyronine (FT3) levels. The results indicated that the alterations in regional and network-level brain functions, which might underlie different psychiatric complications were dynamic and interactional processes in hyperthyroidism. Moreover, the improvement in regional brain FC was correlated with the efficacy of anti-thyroid medication.

PMID: 28878279 [PubMed - in process]

Amplitude of low-frequency fluctuations in first-episode, drug-naïve depressive patients: A 5-year retrospective study.

Fri, 09/08/2017 - 13:00
Related Articles

Amplitude of low-frequency fluctuations in first-episode, drug-naïve depressive patients: A 5-year retrospective study.

PLoS One. 2017;12(4):e0174564

Authors: Zhang K, Liu Z, Cao X, Yang C, Xu Y, Xu T, Xu C, Yang Z

Abstract
Despite different treatments and courses of illness, depressive symptoms appear similar in bipolar disorder (BD) and major depressive disorder (MDD), causing BD with an onset of depressive episode being frequently misdiagnosed as MDD, and leading to inappropriate treatment and poor clinical outcomes. Therefore, there is an urgent need to explore underlying neural basis to distinguish BD from MDD. The medical records of 80 first-episode, drug-naïve depressive patients with an initial diagnosis of MDD and illness duration of at least 5 years were reviewed retrospectively for this study. Fourteen bipolar depressed patients with a diagnosis conversion from MDD to BD, 14 patients with diagnosis of MDD, and 14 healthy subjects demographically matched with the BD group, were selected to participate in the study. Firstly, we examined whether there were differences among the three groups in whole brain fALFF during resting state. Secondly, clusters showing group differences in fALFF in any two groups were chosen as regions of interest (ROI) and then correlation between clinical features and fALFF values of ROIs were calculated. The BD group showed increased fALFF in bilateral putamen relative to both the MDD group and controls, while the MDD group exhibited decreased fALFF in left superior frontal gyrus (SFG) relative to both the BD group and controls (p < 0.05, corrected). Positive correlations between abnormality in the putamen and symptom severity were observed (significant for the MDD group, p = 0.043; marginally significant for the BD group, p = 0.060/0.076). These results implicate that abnormalities of key regions in the striatum and prefrontal areas may be trait markers for BD and MDD.

PMID: 28384269 [PubMed - indexed for MEDLINE]

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