New resting-state fMRI related studies at PubMed

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Interhemispheric disconnectivity in the sensorimotor network in bipolar disorder revealed by functional connectivity and diffusion tensor imaging analysis.

Thu, 07/20/2017 - 15:40
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Interhemispheric disconnectivity in the sensorimotor network in bipolar disorder revealed by functional connectivity and diffusion tensor imaging analysis.

Heliyon. 2017 Jun;3(6):e00335

Authors: Ishida T, Donishi T, Iwatani J, Yamada S, Takahashi S, Ukai S, Shinosaki K, Terada M, Kaneoke Y

Abstract
BACKGROUND: Little is known regarding interhemispheric functional connectivity (FC) abnormalities via the corpus callosum in subjects with bipolar disorder (BD), which might be a key pathophysiological basis of emotional processing alterations in BD.
METHODS: We performed tract-based spatial statistics (TBSS) using diffusion tensor imaging (DTI) in 24 healthy control (HC) and 22 BD subjects. Next, we analyzed the neural networks with independent component analysis (ICA) in 32HC and 25 BD subjects using resting-state functional magnetic resonance imaging.
RESULTS: In TBSS analysis, we found reduced fractional anisotropy (FA) in the corpus callosum of BD subjects. In ICA, functional within-connectivity was reduced in two clusters in the sensorimotor network (SMN) (right and left primary somatosensory areas) of BD subjects compared with HCs. FC between the two clusters and FA values in the corpus callosum of BD subjects was significantly correlated. Further, the functional within-connectivity was related to Young Mania Rating Scale (YMRS) total scores in the right premotor area in the SMN of BD subjects.
LIMITATIONS: Almost all of our BD subjects were taking several medications which could be a confounding factor.
CONCLUSIONS: Our findings suggest that interhemispheric FC dysfunction in the SMN is associated with the impaired nerve fibers in the corpus callosum, which could be one of pathophysiological bases of emotion processing dysregulation in BD patients.

PMID: 28721394 [PubMed]

Functional network integrity presages cognitive decline in preclinical Alzheimer disease.

Thu, 07/20/2017 - 15:40
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Functional network integrity presages cognitive decline in preclinical Alzheimer disease.

Neurology. 2017 Jul 04;89(1):29-37

Authors: Buckley RF, Schultz AP, Hedden T, Papp KV, Hanseeuw BJ, Marshall G, Sepulcre J, Smith EE, Rentz DM, Johnson KA, Sperling RA, Chhatwal JP

Abstract
OBJECTIVE: To examine the utility of resting-state functional connectivity MRI (rs-fcMRI) measurements of network integrity as a predictor of future cognitive decline in preclinical Alzheimer disease (AD).
METHODS: A total of 237 clinically normal older adults (aged 63-90 years, Clinical Dementia Rating 0) underwent baseline β-amyloid (Aβ) imaging with Pittsburgh compound B PET and structural and rs-fcMRI. We identified 7 networks for analysis, including 4 cognitive networks (default, salience, dorsal attention, and frontoparietal control) and 3 noncognitive networks (primary visual, extrastriate visual, motor). Using linear and curvilinear mixed models, we used baseline connectivity in these networks to predict longitudinal changes in preclinical Alzheimer cognitive composite (PACC) performance, both alone and interacting with Aβ burden. Median neuropsychological follow-up was 3 years.
RESULTS: Baseline connectivity in the default, salience, and control networks predicted longitudinal PACC decline, unlike connectivity in the dorsal attention and all noncognitive networks. Default, salience, and control network connectivity was also synergistic with Aβ burden in predicting decline, with combined higher Aβ and lower connectivity predicting the steepest curvilinear decline in PACC performance.
CONCLUSIONS: In clinically normal older adults, lower functional connectivity predicted more rapid decline in PACC scores over time, particularly when coupled with increased Aβ burden. Among examined networks, default, salience, and control networks were the strongest predictors of rate of change in PACC scores, with the inflection point of greatest decline beyond the fourth year of follow-up. These results suggest that rs-fcMRI may be a useful predictor of early, AD-related cognitive decline in clinical research settings.

PMID: 28592457 [PubMed - indexed for MEDLINE]

The Relationship between Structural and Functional Brain Changes and Altered Emotion and Cognition in Chronic Low Back Pain: A Systematic Review of MRI and fMRI Studies.

Thu, 07/20/2017 - 03:00
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The Relationship between Structural and Functional Brain Changes and Altered Emotion and Cognition in Chronic Low Back Pain: A Systematic Review of MRI and fMRI Studies.

Clin J Pain. 2017 Jul 17;:

Authors: Ng SK, Urquhart DM, Fitzgerald PB, Cicuttini FM, Hussain SM, Fitzgibbon BM

Abstract
OBJECTIVES: Chronic low back pain (CLBP) is a major health issue, yet its underlying mechanisms remain unknown. Studies have demonstrated the importance of emotion and cognition in chronic pain, however, the relevant brain physiology in magnetic resonance imaging (MRI) studies are unclear in CLBP populations. Therefore, this review aimed to identify MRI brain changes and examine their potential relationship with emotional and cognitive processes in CLBP.
METHOD: A systematic search was conducted in 5 databases. Studies that recruited adult, chronic low back pain populations, and used brain MRI protocols were included.
RESULTS: Fifty-five studies met the inclusion criteria. Of the structural MRI studies, 10 of 15 studies found decreased gray matter and 7 of 8 studies found white matter changes in CLBP groups compared to controls. Fourteen resting-state functional MRI (fMRI) studies all reported differences between CLBP and control groups in the default mode network. Interestingly, only 3 of 10 fMRI studies observed significant differences during noxious stimulation between CLBP and control groups, while 13 of 16 studies observed significant brain activation differences in CLBP groups during various external tasks. Finally, there were 3 studies that observed a degree of recovery in functional connectivity following intervention.
DISCUSSION: The brain changes in CLBP groups were mainly observed in areas and networks important in emotion and cognition, rather than those typically associated with nociception. This supports the understanding that emotional and cognitive processes may be the core contributor to the CLBP experience, however, future studies need to explore these processes further.

PMID: 28719509 [PubMed - as supplied by publisher]

Chronic antiepileptic drug use and functional network efficiency: A functional magnetic resonance imaging study.

Thu, 07/20/2017 - 03:00
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Chronic antiepileptic drug use and functional network efficiency: A functional magnetic resonance imaging study.

World J Radiol. 2017 Jun 28;9(6):287-294

Authors: van Veenendaal TM, IJff DM, Aldenkamp AP, Lazeron RHC, Hofman PAM, de Louw AJA, Backes WH, Jansen JFA

Abstract
AIM: To increase our insight in the neuronal mechanisms underlying cognitive side-effects of antiepileptic drug (AED) treatment.
METHODS: The relation between functional magnetic resonance-acquired brain network measures, AED use, and cognitive function was investigated. Three groups of patients with epilepsy with a different risk profile for developing cognitive side effects were included: A "low risk" category (lamotrigine or levetiracetam, n = 16), an "intermediate risk" category (carbamazepine, oxcarbazepine, phenytoin, or valproate, n = 34) and a "high risk" category (topiramate, n = 5). Brain connectivity was assessed using resting state functional magnetic resonance imaging and graph theoretical network analysis. The Computerized Visual Searching Task was used to measure central information processing speed, a common cognitive side effect of AED treatment.
RESULTS: Central information processing speed was lower in patients taking AEDs from the intermediate and high risk categories, compared with patients from the low risk category. The effect of risk category on global efficiency was significant (P < 0.05, ANCOVA), with a significantly higher global efficiency for patient from the low category compared with the high risk category (P < 0.05, post-hoc test). Risk category had no significant effect on the clustering coefficient (ANCOVA, P > 0.2). Also no significant associations between information processing speed and global efficiency or the clustering coefficient (linear regression analysis, P > 0.15) were observed.
CONCLUSION: Only the four patients taking topiramate show aberrant network measures, suggesting that alterations in functional brain network organization may be only subtle and measureable in patients with more severe cognitive side effects.

PMID: 28717415 [PubMed]

Investigation of the Changes in the Power Distribution in Resting-State Brain Networks Associated with Pure Conduct Disorder.

Thu, 07/20/2017 - 03:00
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Investigation of the Changes in the Power Distribution in Resting-State Brain Networks Associated with Pure Conduct Disorder.

Sci Rep. 2017 Jul 17;7(1):5528

Authors: Zhang J, Zhou J, Lu F, Chen L, Huang Y, Chen H, Xiang Y, Yang G, Yuan Z

Abstract
Conduct disorder (CD) is a psychiatric disorder in children and adolescence. To investigate changes in the power distribution in brain networks between CD and typically developing (TD) groups, resting-state functional magnetic resonance imaging (rsfMRI) data of thirty-six subjects were first recorded, and then the data were preprocessed using DPARSF and SPM8. Meanwhile, the power of the blood oxygenation level-dependent (BOLD) signals of ninety brain regions was acquired using the integral of the Welch power spectral density (PSD). Additionally, the powers of the brain regions that reached significance (p < 0.05) were extracted using the bootstrap statistics, in which the standardized z-scores of the powers were used as a reference. The results of the analysis of the changes in power exhibited that there were significant power differences in some pairs of brain regions between the CD and TD groups, indicating a change in the power distribution. In addition, the results also suggest that the total power consumption of brain networks in CD patients is less than that observed in the TD group. Consequently, the study provided a paradigm for establishing quantifiable indicators via the power spectrum approach for the comparison and analysis of the BOLD signal power between CD patients and healthy controls.

PMID: 28717223 [PubMed - in process]

The structural basis of large-scale functional connectivity in the mouse.

Thu, 07/20/2017 - 03:00
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The structural basis of large-scale functional connectivity in the mouse.

J Neurosci. 2017 Jul 17;:

Authors: Grandjean J, Zerbi V, Balsters J, Wenderoth N, Rudina M

Abstract
Translational neuroimaging requires approaches and techniques that can bridge between multiple different species and disease states. One candidate method, which offers insights into the brain's functional connectivity (FC), is resting state fMRI (rs-fMRI). In both humans and non-human primates, patterns of functional connectivity (often referred to as the functional connectome) have been related to the underlying structural connectivity (structural connectome). Given the recent rise in pre-clinical neuroimaging of mouse models it is an important question whether the mouse functional connectome conforms to the underlying structural connectivity. Here, we compared FC derived from rs-fMRI in female mice to the underlying monosynaptic structural connectome as provided by the Allen Brain Connectivity Atlas. We show that FC between inter-hemispheric homotopic cortical and hippocampal areas, as well as in cortical-striatal pathways, emerge primarily via monosynaptic structural connections. In particular, we demonstrate that the striatum can be segregated according to differential rs-fMRI connectivity patterns that mirror monosynaptic connectivity with isocortex. By contrast, for certain subcortical networks, FC emerges along polysynaptic pathways as shown for left and right striatum, which do not share direct anatomical connections, but high FC is putatively driven by a top-down cortical control. Finally, we show that FC involving cortico-thalamic pathways is limited, possibly confounded by the effect of anesthesia, small regional size and tracer injection volume. These findings provide a critical foundation for using rs-fMRI connectivity as a translational tool to study complex brain circuitry interactions and their pathology due to neurological or psychiatric diseases across species.SIGNIFICANCE STATEMENTA comprehensive understanding of how the anatomical architecture of the brain, often referred to as the "connectome", corresponds to its function is arguably one of the biggest challenges for understanding the brain and its pathologies. Here we use the mouse as a model for comparing functional connectivity derived from resting-state fMRI with gold standard structural connectivity measures based on tracer injections. In particular, we demonstrate high correspondence between functional connectivity measurements of cortico-cortico and cortico-striatal and their anatomical underpinnings. This work provides a critical foundation for studying the pathology of these circuits across mouse models and human patients.

PMID: 28716961 [PubMed - as supplied by publisher]

Functional parcellation using time courses of instantaneous connectivity.

Thu, 07/20/2017 - 03:00
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Functional parcellation using time courses of instantaneous connectivity.

Neuroimage. 2017 Jul 14;:

Authors: van Oort ESB, Mennes M, Navarro Schröder T, Kumar VJ, Zaragoza Jimenez NI, Grodd W, Doeller CF, Beckmann CF

Abstract
Functional neuroimaging studies have led to understanding the brain as a collection of spatially segregated functional networks. It is thought that each of these networks is in turn composed of a set of distinct sub-regions that together support each network's function. Considering the sub-regions to be an essential part of the brain's functional architecture, several strategies have been put forward that aim at identifying the functional sub-units of the brain by means of functional parcellations. Current parcellation strategies typically employ a bottom-up strategy, creating a parcellation by clustering smaller units. We propose a novel top-down parcellation strategy, using time courses of instantaneous connectivity to subdivide an initial region of interest into sub-regions. We use split-half reproducibility to choose the optimal number of sub-regions. We apply our Instantaneous Connectivity Parcellation (ICP) strategy on high-quality resting-state FMRI data, and demonstrate the ability to generate parcellations for thalamus, entorhinal cortex, motor cortex, and subcortex including brainstem and striatum. We evaluate the subdivisions against available cytoarchitecture maps to show that our parcellation strategy recovers biologically valid subdivisions that adhere to known cytoarchitectural features.

PMID: 28716715 [PubMed - as supplied by publisher]

Functional density and edge maps: Characterizing functional architecture in individuals and improving cross-subject registration.

Thu, 07/20/2017 - 03:00
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Functional density and edge maps: Characterizing functional architecture in individuals and improving cross-subject registration.

Neuroimage. 2017 Jul 14;:

Authors: Tong T, Aganj I, Ge T, Polimeni JR, Fischl B

Abstract
Population-level inferences and individual-level analyses are two important aspects in functional magnetic resonance imaging (fMRI) studies. Extracting reliable and informative features from fMRI data that capture biologically meaningful inter-subject variation is critical for aligning and comparing functional networks across subjects, and connecting the properties of functional brain organization with variations in behavior, cognition and genetics. In this study, we derive two new measures, which we term functional density map and edge map, and demonstrate their usefulness in characterizing the function of individual brains. Specifically, using data from the Human Connectome Project (HCP), we show that (1) both functional maps capture intrinsic properties of the functional connectivity pattern in individuals while exhibiting large variation across subjects; (2) functional maps derived from either resting-state or task-evoked fMRI can be used to accurately identify subjects from a population; and (3) cross-subject alignment using these functional maps considerably reduces functional variation and improves functional correspondence across subjects over state-of-the-art multimodal registration algorithms. Our results suggest that the proposed functional density and edge maps are promising features in characterizing the functional architecture in individuals and provide an alternative way to explore the functional variation across subjects.

PMID: 28716714 [PubMed - as supplied by publisher]

Selective Effects of Psychotherapy on Frontopolar Cortical Function in PTSD.

Thu, 07/20/2017 - 03:00
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Selective Effects of Psychotherapy on Frontopolar Cortical Function in PTSD.

Am J Psychiatry. 2017 Jul 18;:appiajp201716091073

Authors: Fonzo GA, Goodkind MS, Oathes DJ, Zaiko YV, Harvey M, Peng KK, Weiss ME, Thompson AL, Zack SE, Mills-Finnerty CE, Rosenberg BM, Edelstein R, Wright RN, Kole CA, Lindley SE, Arnow BA, Jo B, Gross JJ, Rothbaum BO, Etkin A

Abstract
OBJECTIVE: Exposure therapy is an effective treatment for posttraumatic stress disorder (PTSD), but a comprehensive, emotion-focused perspective on how psychotherapy affects brain function is lacking. The authors assessed changes in brain function after prolonged exposure therapy across three emotional reactivity and regulation paradigms.
METHOD: Individuals with PTSD underwent functional MRI (fMRI) at rest and while completing three tasks assessing emotional reactivity and regulation. Individuals were then randomly assigned to immediate prolonged exposure treatment (N=36) or a waiting list condition (N=30) and underwent a second scan approximately 4 weeks after the last treatment session or a comparable waiting period, respectively.
RESULTS: Treatment-specific changes were observed only during cognitive reappraisal of negative images. Psychotherapy increased lateral frontopolar cortex activity and connectivity with the ventromedial prefrontal cortex/ventral striatum. Greater increases in frontopolar activation were associated with improvement in hyperarousal symptoms and psychological well-being. The frontopolar cortex also displayed a greater variety of temporal resting-state signal pattern changes after treatment. Concurrent transcranial magnetic stimulation and fMRI in healthy participants demonstrated that the lateral frontopolar cortex exerts downstream influence on the ventromedial prefrontal cortex/ventral striatum.
CONCLUSIONS: Changes in frontopolar function during deliberate regulation of negative affect is one key mechanism of adaptive psychotherapeutic change in PTSD. Given that frontopolar connectivity with ventromedial regions during emotion regulation is enhanced by psychotherapy and that the frontopolar cortex exerts downstream influence on ventromedial regions in healthy individuals, these findings inform a novel conceptualization of how psychotherapy works, and they identify a promising target for stimulation-based therapeutics.

PMID: 28715907 [PubMed - as supplied by publisher]

Abdominal Pain, the Adolescent and Altered Brain Structure and Function.

Thu, 07/20/2017 - 03:00
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Abdominal Pain, the Adolescent and Altered Brain Structure and Function.

PLoS One. 2016;11(5):e0156545

Authors: Hubbard CS, Becerra L, Heinz N, Ludwick A, Rasooly T, Wu R, Johnson A, Schechter NL, Borsook D, Nurko S

Abstract
Irritable bowel syndrome (IBS) is a functional gastrointestinal (GI) disorder of unknown etiology. Although relatively common in children, how this condition affects brain structure and function in a pediatric population remains unclear. Here, we investigate brain changes in adolescents with IBS and healthy controls. Imaging was performed with a Siemens 3 Tesla Trio Tim MRI scanner equipped with a 32-channel head coil. A high-resolution T1-weighted anatomical scan was acquired followed by a T2-weighted functional scan. We used a surface-based morphometric approach along with a seed-based resting-state functional connectivity (RS-FC) analysis to determine if groups differed in cortical thickness and whether areas showing structural differences also showed abnormal RS-FC patterns. Patients completed the Abdominal Pain Index and the GI Module of the Pediatric Quality of Life Inventory to assess abdominal pain severity and impact of GI symptoms on health-related quality of life (HRQOL). Disease duration and pain intensity were also assessed. Pediatric IBS patients, relative to controls, showed cortical thickening in the posterior cingulate (PCC), whereas cortical thinning in posterior parietal and prefrontal areas were found, including the dorsolateral prefrontal cortex (DLPFC). In patients, abdominal pain severity was related to cortical thickening in the intra-abdominal area of the primary somatosensory cortex (SI), whereas HRQOL was associated with insular cortical thinning. Disease severity measures correlated with cortical thickness in bilateral DLPFC and orbitofrontal cortex. Patients also showed reduced anti-correlations between PCC and DLPFC compared to controls, a finding that may reflect aberrant connectivity between default mode and cognitive control networks. We are the first to demonstrate concomitant structural and functional brain changes associated with abdominal pain severity, HRQOL related to GI-specific symptoms, and disease-specific measures in adolescents with IBS. It is possible such changes will be responsive to therapeutic intervention and may be useful as potential markers of disease progression or reversal.

PMID: 27244227 [PubMed - indexed for MEDLINE]

Age-Related Decline in the Variation of Dynamic Functional Connectivity: A Resting State Analysis.

Tue, 07/18/2017 - 13:00
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Age-Related Decline in the Variation of Dynamic Functional Connectivity: A Resting State Analysis.

Front Aging Neurosci. 2017;9:203

Authors: Chen Y, Wang W, Zhao X, Sha M, Liu Y, Zhang X, Ma J, Ni H, Ming D

Abstract
Normal aging is typically characterized by abnormal resting-state functional connectivity (FC), including decreasing connectivity within networks and increasing connectivity between networks, under the assumption that the FC over the scan time was stationary. In fact, the resting-state FC has been shown in recent years to vary over time even within minutes, thus showing the great potential of intrinsic interactions and organization of the brain. In this article, we assumed that the dynamic FC consisted of an intrinsic dynamic balance in the resting brain and was altered with increasing age. Two groups of individuals (N = 36, ages 20-25 for the young group; N = 32, ages 60-85 for the senior group) were recruited from the public data of the Nathan Kline Institute. Phase randomization was first used to examine the reliability of the dynamic FC. Next, the variation in the dynamic FC and the energy ratio of the dynamic FC fluctuations within a higher frequency band were calculated and further checked for differences between groups by non-parametric permutation tests. The results robustly showed modularization of the dynamic FC variation, which declined with aging; moreover, the FC variation of the inter-network connections, which mainly consisted of the frontal-parietal network-associated and occipital-associated connections, decreased. In addition, a higher energy ratio in the higher FC fluctuation frequency band was observed in the senior group, which indicated the frequency interactions in the FC fluctuations. These results highly supported the basis of abnormality and compensation in the aging brain and might provide new insights into both aging and relevant compensatory mechanisms.

PMID: 28713261 [PubMed]

59-year-old female with breathlessness.

Tue, 07/18/2017 - 13:00
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59-year-old female with breathlessness.

Heart. 2016 Oct 15;102(20):1654

Authors: Scatteia A, De Garate E, Bucciarelli-Ducci C

Abstract
CLINICAL INTRODUCTION: A 59-year-old female underwent an electrocardiogram (ECG) and echocardiographic screening. Her brother died at quite a young age of kidney failure. Resting ECG showed borderline voltage criteria for left ventricular hypertrophy (LVH), with marked widespread T-wave inversion. Echocardiogram was normal, but in consideration of exertional breathlessness and abnormal baseline ECG, she underwent a coronary angiogram, which showed unobstructed coronaries. She was then referred to have a cardiac MR (CMR) for further characterisation. CMR images were acquired with a 1.5 T scanner and the imaging protocol included Steady-State Free Precession (SSFP) cine images (Figure 1A) as well as late gadolinium enhancement (LGE) images in the long-axis and short-axis planes covering the whole left ventricle (Figure 1B). In addition, native and postcontrast T1 mapping (Modified Look-Locker (MOLLI)) images were acquired for further tissue characterisation (Figure 1C and D, respectively).
QUESTION: What is the most likely diagnosis based on CMR findings? Anderson-Fabry's disease (AFD)Cardiac amyloidosisGenotype (+), phenotype (-) hypertrophic cardiomyopathy (HCM)Myocardial iron overloadNormal heart.

PMID: 27333905 [PubMed - indexed for MEDLINE]

Determinants of resting cerebral blood flow in sickle cell disease.

Tue, 07/18/2017 - 13:00
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Determinants of resting cerebral blood flow in sickle cell disease.

Am J Hematol. 2016 Sep;91(9):912-7

Authors: Bush AM, Borzage MT, Choi S, Václavů L, Tamrazi B, Nederveen AJ, Coates TD, Wood JC

Abstract
Stroke is common in children with sickle cell disease and results from an imbalance in oxygen supply and demand. Cerebral blood flow (CBF) is increased in patients with sickle cell disease to compensate for their anemia, but adequacy of their oxygen delivery has not been systematically demonstrated. This study examined the physiological determinants of CBF in 37 patients with sickle cell disease, 38 ethnicity matched control subjects and 16 patients with anemia of non-sickle origin. Cerebral blood flow was measured using phase contrast MRI of the carotid and vertebral arteries. CBF increased inversely to oxygen content (r(2)  = 0.69, P < 0.0001). Brain oxygen delivery, the product of CBF and oxygen content, was normal in all groups. Brain composition, specifically the relative amounts of grey and white matter, was the next strongest CBF predictor, presumably by influencing cerebral metabolic rate. Grey matter/white matter ratio and CBF declined monotonically until the age of 25 in all subjects, consistent with known maturational changes in brain composition. Further CBF reductions were observed with age in subjects older than 35 years of age, likely reflecting microvascular aging. On multivariate regression, CBF was independent of disease state, hemoglobin S, hemoglobin F, reticulocyte count and cell free hemoglobin, suggesting that it is regulated similarly in patients and control subjects. In conclusion, sickle cell disease patients had sufficient oxygen delivery at rest, but accomplish this only by marked increases in their resting CBF, potentially limiting their ability to further augment flow in response to stress. Am. J. Hematol. 91:912-917, 2016. © 2016 Wiley Periodicals, Inc.

PMID: 27263497 [PubMed - indexed for MEDLINE]

Motor-symptom laterality affects acquisition in Parkinson's disease: A cognitive and functional magnetic resonance imaging study.

Mon, 07/17/2017 - 11:40

Motor-symptom laterality affects acquisition in Parkinson's disease: A cognitive and functional magnetic resonance imaging study.

Mov Disord. 2017 Jul;32(7):1047-1055

Authors: Huang P, Tan YY, Liu DQ, Herzallah MM, Lapidow E, Wang Y, Zang YF, Gluck MA, Chen SD

Abstract
BACKGROUND AND OBJECTIVES: Asymmetric onset of motor symptoms in PD can affect cognitive function. We examined whether motor-symptom laterality could affect feedback-based associative learning and explored its underlying neural mechanism by functional magnetic resonance imaging in PD patients.
METHODS: We recruited 63 early-stage medication-naïve PD patients (29 left-onset medication-naïve patients, 34 right-onset medication-naïve patients) and 38 matched normal controls. Subjects completed an acquired equivalence task (including acquisition, retention, and generalization) and resting-state functional magnetic resonance imaging scans. Learning accuracy and response time in each phase of the task were recorded for behavioral measures. Regional homogeneity was used to analyze resting-state functional magnetic resonance imaging data, with regional homogeneity lateralization to evaluate hemispheric functional asymmetry in the striatum.
RESULTS: Left-onset patients made significantly more errors in acquisition (feedback-based associative learning) than right-onset patients and normal controls, whereas right-onset patients performed as well as normal controls. There was no significant difference among these three groups in the accuracy of either retention or generalization phase. The three groups did not show significant differences in response time. In the left-onset group, there was an inverse relationship between acquisition errors and regional homogeneity in the right dorsal rostral putamen. There were no significant regional homogeneity changes in either the left or the right dorsal rostral putamen in right-onset patients when compared to controls.
CONCLUSIONS: Motor-symptom laterality could affect feedback-based associative learning in PD, with left-onset medication-naïve patients being selectively impaired. Dysfunction in the right dorsal rostral putamen may underlie the observed deficit in associative learning in patients with left-sided onset.© 2016 International Parkinson and Movement Disorder Society.

PMID: 28712121 [PubMed - in process]

Resisting Sleep Pressure: Impact on Resting State Functional Network Connectivity.

Mon, 07/17/2017 - 11:40

Resisting Sleep Pressure: Impact on Resting State Functional Network Connectivity.

Brain Topogr. 2017 Jul 15;:

Authors: Tüshaus L, Balsters JH, Schläpfer A, Brandeis D, O'Gorman Tuura R, Achermann P

Abstract
In today's 24/7 society, sleep restriction is a common phenomenon which leads to increased levels of sleep pressure in daily life. However, the magnitude and extent of impairment of brain functioning due to increased sleep pressure is still not completely understood. Resting state network (RSN) analyses have become increasingly popular because they allow us to investigate brain activity patterns in the absence of a specific task and to identify changes under different levels of vigilance (e.g. due to increased sleep pressure). RSNs are commonly derived from BOLD fMRI signals but studies progressively also employ cerebral blood flow (CBF) signals. To investigate the impact of sleep pressure on RSNs, we examined RSNs of participants under high (19 h awake) and normal (10 h awake) sleep pressure with three imaging modalities (arterial spin labeling, BOLD, pseudo BOLD) while providing confirmation of vigilance states in most conditions. We demonstrated that CBF and pseudo BOLD signals (measured with arterial spin labeling) are suited to derive independent component analysis based RSNs. The spatial map differences of these RSNs were rather small, suggesting a strong biological substrate underlying these networks. Interestingly, increased sleep pressure, namely longer time awake, specifically changed the functional network connectivity (FNC) between RSNs. In summary, all FNCs of the default mode network with any other network or component showed increasing effects as a function of increased 'time awake'. All other FNCs became more anti-correlated with increased 'time awake'. The sensorimotor networks were the only ones who showed a within network change of FNC, namely decreased connectivity as function of 'time awake'. These specific changes of FNC could reflect both compensatory mechanisms aiming to fight sleep as well as a first reduction of consciousness while becoming drowsy. We think that the specific changes observed in functional network connectivity could imply an impairment of information transfer between the affected RSNs.

PMID: 28712063 [PubMed - as supplied by publisher]

Onset age of L2 acquisition influences language network in early and late Cantonese-Mandarin bilinguals.

Mon, 07/17/2017 - 11:40

Onset age of L2 acquisition influences language network in early and late Cantonese-Mandarin bilinguals.

Brain Lang. 2017 Jul 13;174:16-28

Authors: Liu X, Tu L, Wang J, Jiang B, Gao W, Pan X, Li M, Zhong M, Zhu Z, Niu M, Li Y, Zhao L, Chen X, Liu C, Lu Z, Huang R

Abstract
Early second language (L2) experience influences the neural organization of L2 in neuro-plastic terms. Previous studies tried to reveal these plastic effects of age of second language acquisition (AoA-L2) and proficiency-level in L2 (PL-L2) on the neural basis of language processing in bilinguals. Although different activation patterns have been observed during language processing in early and late bilinguals by task-fMRI, few studies reported the effect of AoA-L2 and high PL-L2 on language network at resting state. In this study, we acquired resting-state fMRI (R-fMRI) data from 10 Cantonese (L1)-Mandarin (L2) early bilinguals (acquired L2: 3years old) and 11 late bilinguals (acquired L2: 6years old), and analyzed their topological properties of language networks after controlling the language daily exposure and usage as well as PL in L1 and L2. We found that early bilinguals had significantly a higher clustering coefficient, global and local efficiency, but significantly lower characteristic path length compared to late bilinguals. Modular analysis indicated that compared to late bilinguals, early bilinguals showed significantly stronger intra-modular functional connectivity in the semantic and phonetic modules, stronger inter-modular functional connectivity between the semantic and phonetic modules as well as between the phonetic and syntactic modules. Differences in global and local parameters may reflect different patterns of neuro-plasticity respectively for early and late bilinguals. These results suggested that different L2 experience influences topological properties of language network, even if late bilinguals achieve high PL-L2. Our findings may provide a new perspective of neural mechanisms related to early and late bilinguals.

PMID: 28711720 [PubMed - as supplied by publisher]

Interactions of the salience network and its subsystems with the default-mode and the central-executive networks in normal aging and mild cognitive impairment.

Sat, 07/15/2017 - 15:20

Interactions of the salience network and its subsystems with the default-mode and the central-executive networks in normal aging and mild cognitive impairment.

Brain Connect. 2017 Jul 14;:

Authors: Chand G, Wu J, Hajjar I, Qiu D

Abstract
Previous functional MRI (fMRI) investigations suggest that the intrinsically organized large-scale networks and the interaction between them might be crucial for cognitive activities. A triple network model, which consists of the default-mode network, salience network, and central-executive network, has been recently employed to understand the connectivity patterns of the cognitively normal brains versus the brains with disorders. This model suggests that the salience network dynamically controls the default-mode and central-executive networks in healthy young individuals. However, the patterns of interactions have remained largely unknown in healthy aging or those with cognitive decline. Here, we assess the patterns of interactions between the three networks using dynamical causal modeling in resting state fMRI data and compare them between subjects with normal cognition and mild cognitive impairment (MCI). In healthy elderly subjects, our analysis showed that the salience network, especially its dorsal sub-network, modulates the interaction between the default-mode network and the central-executive network (Mann-Whitney U test; p<0.05), which was consistent with the pattern of interaction reported in young adults. In contrast, this pattern of modulation by salience network was disrupted in MCI (Mann-Whitney U test; p<0.05). Further, the degree of disruption in salience network control correlated significantly with lower overall cognitive performance measured by Montreal Cognitive Assessment (Pearson's correlation = 0.295; p<0.05). This study suggests that a disruption of the salience network control, especially the dorsal salience network, over other networks provides a neuronal basis for cognitive decline and may be a candidate neuroimaging biomarker of cognitive impairment.

PMID: 28707959 [PubMed - as supplied by publisher]

Altered dynamic functional connectivity in the default mode network in patients with cirrhosis and minimal hepatic encephalopathy.

Sat, 07/15/2017 - 15:20

Altered dynamic functional connectivity in the default mode network in patients with cirrhosis and minimal hepatic encephalopathy.

Neuroradiology. 2017 Jul 13;:

Authors: Chen HJ, Lin HL, Chen QF, Liu PF

Abstract
PURPOSE: Abnormal brain intrinsic functional connectivity (FC) has been documented in minimal hepatic encephalopathy (MHE) by static connectivity analysis. However, changes in dynamic FC (dFC) remain unknown. We aimed to identify altered dFC within the default mode network (DMN) associated with MHE.
METHODS: Resting-state functional MRI data were acquired from 20 cirrhotic patients with MHE and 24 healthy controls. DMN seed regions were defined using seed-based FC analysis (centered on the posterior cingulate cortex (PCC)). Dynamic FC architecture was calculated using a sliding time-window method. K-means clustering (number of clusters = 2-4) was applied to estimate FC states.
RESULTS: When the number of clusters was 2, MHE patients presented weaker connectivity strengths compared with controls in states 1 and 2. In state 1, decreased FC strength was found between the PCC/precuneus (PCUN) and right medial temporal lobe (MTL)/bilateral lateral temporal cortex (LTC); left inferior parietal lobule (IPL) and right MTL/left LTC; right IPL and right MTL/bilateral LTC; right MTL and right LTC; and medial prefrontal cortex (MPFC) and right MTL/bilateral LTC. In state 2, reduced FC strength was observed between the PCC/PCUN and bilateral MTL/bilateral LTC; left IPL and left MTL/bilateral LTC/MPFC; and left LTC and right LTC. Altered connectivities from state 1 were correlated with patient cognitive performance. Similar findings were observed when the number of clusters was set to 3 or 4.
CONCLUSION: Aberrant dynamic DMN connectivity is an additional characteristic of MHE. Dynamic connectivity analysis offers a novel paradigm for understanding MHE-related mechanisms.

PMID: 28707166 [PubMed - as supplied by publisher]

Common and distinct dysfunctional patterns contribute to triple network model in schizophrenia and depression: A preliminary study.

Sat, 07/15/2017 - 15:20

Common and distinct dysfunctional patterns contribute to triple network model in schizophrenia and depression: A preliminary study.

Prog Neuropsychopharmacol Biol Psychiatry. 2017 Jul 10;:

Authors: Jiang Y, Duan M, Chen X, Chang X, He H, Li Y, Luo C, Yao D

Abstract
BACKGROUND: Schizophrenia (SCH) and depression (DEP) are prevalent psychiatric disorders and share common and distinguished elements in their pathophysiology. A triple network model composed of the default mode network (DMN), salience network (SN) and central executive network (CEN) may represent a major abnormality across several psychiatric disorders including SCH and DEP. However, common and distinct dysfunctional patterns between SCH and DEP across three core networks remain unclear.
METHOD: Resting-state functional magnetic resonance imaging (fMRI) was obtained in 20 patients with SCH, 20 patients with DEP and 20 healthy controls (HC). Both functional connectivity (FC) and Granger causal connectivity across DMN, SN and CEN were evaluated to uncover common and distinct dysfunctional patterns between SCH and DEP.
RESULTS: Two patient groups showed identical abnormal causal connectivity between key nodes of DMN and SN, as well as opposing aberrant FC of DMN-CEN and SN-CEN. Compared with HC, the FC between CEN and DMN was increased in SCH while decreased in DEP. Conversely, DEP showed enhanced FC between CEN and SN, whereas SCH showed decreased FC.
LIMITATIONS: The sample size was relatively small, and all participants were taking medication.
CONCLUSIONS: Our results identified common patterns including dysconnectivity between DMN and SN, which may contribute to shared cognitive and affective impairment in DEP and SCH. Moreover, opposing dysconnectivity patterns of DMN-CEN may be associated with different self-referential processing abnormalities. These opposing dysconnectivity patterns may indicate an unbalanced recruitment between SN and CEN. Therefore, this study provides dysconnectivity patterns to advance the understanding of the triple network model with regard to psychiatric disorders.

PMID: 28705767 [PubMed - as supplied by publisher]

Functional Connectivity Within and Between Intrinsic Networks Correlates with Trait Mind Wandering.

Sat, 07/15/2017 - 15:20

Functional Connectivity Within and Between Intrinsic Networks Correlates with Trait Mind Wandering.

Neuropsychologia. 2017 Jul 10;:

Authors: Godwin CA, Hunter MA, Bezdek MA, Lieberman G, Elkin-Frankston S, Romero VL, Witkiewitz K, Clark VP, Schumacher EH

Abstract
Individual differences across a variety of cognitive processes are functionally associated with individual differences in intrinsic networks such as the default mode network (DMN). Furthermore, the extent to which these networks correlate or anticorrelate has been associated with performance in a variety of circumstances. Despite the established role of the DMN in mind wandering processes, little research has investigated how large-scale brain networks at rest relate to mind wandering tendencies outside the laboratory. Here we examine the extent to which the DMN, along with the dorsal attention network (DAN) and frontoparietal control network (FPCN) correlate with the tendency to mind wander in daily life. Participants completed the Mind Wandering Questionnaire and a 5-minute resting state fMRI scan. In addition, participants completed measures of executive function, fluid intelligence, and creativity. We observed significant positive correlations between trait mind wandering and 1) increased DMN connectivity at rest and 2) increased connectivity between the DMN and FPCN at rest. Lastly, we found significant positive correlations between trait mind wandering and fluid intelligence (Ravens) and creativity (Remote Associates Task). We interpret these findings within the context of current theories of mind wandering and executive function and discuss the possibility that certain instances of mind wandering may not be inherently harmful. Due to the controversial nature of global signal regression (GSReg) in functional connectivity analyses, we performed our analyses with and without GSReg and contrast the results from each set of analyses.

PMID: 28705691 [PubMed - as supplied by publisher]

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