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Anosognosia in Alzheimer disease: Disconnection between memory and self networks.

Sat, 06/20/2015 - 14:00
Related Articles

Anosognosia in Alzheimer disease: Disconnection between memory and self networks.

Ann Neurol. 2015 Jun 18;

Authors: Perrotin A, Desgranges B, Landeau B, Mézenge F, La Joie R, Egret S, Pélerin A, de la Sayette V, Eustache F, Chételat G

Abstract
OBJECTIVE: Impaired awareness is a common symptom in many mental disorders including Alzheimer's disease (AD). This study aims at improving our understanding of the neural mechanisms underlying anosognosia of memory deficits in AD by combining measures of regional brain metabolism (resting-state FDG-PET) and intrinsic connectivity (resting-state fMRI).
METHODS: Twenty-three patients diagnosed with probable AD based on clinical and biomarker data, and thirty matched healthy control subjects were recruited in this study. An anosognosia index (difference between subjective and objective memory scores) was obtained in each participant. Resting-state FDG-PET for glucose metabolism measurement and resting-state fMRI for intrinsic connectivity measurement were also performed. AD and control groups were compared on behavioral data, and voxel-wise correlations between anosognosia and neuroimaging data were conducted within the AD group.
RESULTS: AD patients underestimated their memory deficits. Anosognosia in AD patients correlated with hypometabolism in orbitofrontal (OFC) and posterior cingulate (PCC) cortices. Using OFC and PCC as seed regions, intrinsic connectivity analyses in AD revealed a significant association between anosognosia and reduced intrinsic connectivity between these regions as well as with the medial temporal lobe.
INTERPRETATION: Anosognosia in AD is due not only to functional changes within cortical midline structures involved in self-referential processes (OFC, PCC), but also to disconnection between these regions as well as with the medial temporal lobe. These findings suggest that the lack of awareness of memory deficits in AD results from a disruption of the communication within, but also between, the self-related and the memory-related brain networks. This article is protected by copyright. All rights reserved.

PMID: 26085009 [PubMed - as supplied by publisher]

Default and Executive Network Coupling Supports Creative Idea Production.

Fri, 06/19/2015 - 16:00

Default and Executive Network Coupling Supports Creative Idea Production.

Sci Rep. 2015;5:10964

Authors: Beaty RE, Benedek M, Barry Kaufman S, Silvia PJ

Abstract
The role of attention in creative cognition remains controversial. Neuroimaging studies have reported activation of brain regions linked to both cognitive control and spontaneous imaginative processes, raising questions about how these regions interact to support creative thought. Using functional magnetic resonance imaging (fMRI), we explored this question by examining dynamic interactions between brain regions during a divergent thinking task. Multivariate pattern analysis revealed a distributed network associated with divergent thinking, including several core hubs of the default (posterior cingulate) and executive (dorsolateral prefrontal cortex) networks. The resting-state network affiliation of these regions was confirmed using data from an independent sample of participants. Graph theory analysis assessed global efficiency of the divergent thinking network, and network efficiency was found to increase as a function of individual differences in divergent thinking ability. Moreover, temporal connectivity analysis revealed increased coupling between default and salience network regions (bilateral insula) at the beginning of the task, followed by increased coupling between default and executive network regions at later stages. Such dynamic coupling suggests that divergent thinking involves cooperation between brain networks linked to cognitive control and spontaneous thought, which may reflect focused internal attention and the top-down control of spontaneous cognition during creative idea production.

PMID: 26084037 [PubMed - as supplied by publisher]

Reversal of functional changes in the brain associated with obstructive sleep apnoea following 6 months of CPAP.

Fri, 06/19/2015 - 16:00

Reversal of functional changes in the brain associated with obstructive sleep apnoea following 6 months of CPAP.

Neuroimage Clin. 2015;7:799-806

Authors: Fatouleh RH, Lundblad LC, Macey PM, McKenzie DK, Henderson LA, Macefield VG

Abstract
Obstructive sleep apnoea (OSA) is associated with an increase in the number of bursts of muscle sympathetic nerve activity (MSNA), leading to neurogenic hypertension. Continuous positive airway pressure (CPAP) is the most effective and widely used treatment for preventing collapse of the upper airway in OSA. In addition to improving sleep, CPAP decreases daytime MSNA towards control levels. It remains unknown how this restoration of MSNA occurs, in particular whether CPAP treatment results in a simple readjustment in activity of those brain regions responsible for the initial increase in MSNA or whether other brain regions are recruited to over-ride aberrant brain activity. By recording MSNA concurrently with functional Magnetic Resonance Imaging (fMRI), we aimed to assess brain activity associated with each individual subject's patterns of MSNA prior to and following 6 months of CPAP treatment. Spontaneous fluctuations in MSNA were recorded via tungsten microelectrodes inserted into the common peroneal nerve in 13 newly diagnosed patients with OSA before and after 6 months of treatment with CPAP and in 15 healthy control subjects while lying in a 3 T MRI scanner. Blood Oxygen Level Dependent (BOLD) contrast gradient echo, echo-planar images were continuously collected in a 4 s ON, 4 s OFF (200 volumes) sampling protocol. MSNA was significantly elevated in newly diagnosed OSA patients compared to control subjects (55 ± 4 vs 26 ± 2 bursts/min). Fluctuations in BOLD signal intensity in multiple regions covaried with the intensity of the concurrently recorded bursts of MSNA. There was a significant fall in MSNA after 6 months of CPAP (39 ± 2 bursts/min). The reduction in resting MSNA was coupled with significant falls in signal intensity in precuneus bilaterally, the left and right insula, right medial prefrontal cortex, right anterior cingulate cortex, right parahippocampus and the left and right retrosplenial cortices. These data support our contention that functional changes in these suprabulbar sites are, via projections to the brainstem, driving the augmented sympathetic outflow to the muscle vascular bed in untreated OSA.

PMID: 26082888 [PubMed - in process]

Network-specific cortico-thalamic dysconnection in schizophrenia revealed by intrinsic functional connectivity analyses.

Fri, 06/19/2015 - 16:00

Network-specific cortico-thalamic dysconnection in schizophrenia revealed by intrinsic functional connectivity analyses.

Schizophr Res. 2015 Jun 13;

Authors: Tu PC, Lee YC, Chen YS, Hsu JW, Li CT, Su TP

Abstract
BACKGROUND: Cortico-thalamic connections are thought to be abnormal in schizophrenia due to their important roles in sensory relay and higher cognitive control, both of which are affected by this devastating illness. This study tested the cortico-thalamic dysconnection hypothesis in schizophrenia and further explored cortico-thalamic network properties using functional connectivity MRI (fcMRI).
METHODS: Forty-eight participants with schizophrenia and 48 healthy controls underwent resting fMRI scans and clinical evaluations. Six a priori cortical regions of interests (ROIs) were used to derive the six networks: dorsal default mode network (dDMN), fronto-parietal network (FPN), cingulo-opercular network (CON), primary sensorimotor network (SM1), primary auditory network (A1) and primary visual network (V1). The cortico-thalamic connectivity for each network was calculated for each participant and then compared between groups.
RESULTS: A repeated measures analysis of variance (ANOVA) showed significant group×network interactions (F(5, 90)=9.5, P<0.001), which were driven by a significant increase in FC within the SM1 (t(94)=4.1, P<0.001) and A1 (t(94)=4.2, P<0.001) networks in schizophrenics, as well as a significant decrease within the CON (t(94)=-2.8, P=0.04). The cortico-thalamic dysconnection did not correlate with symptom severity, representing a state independent abnormality.
CONCLUSION: The network analysis indicates that cortico-thalamic dysconnection in schizophrenia involves multiple networks and shows network specific changes. The findings provide support for dysfunctional thalamus-related networks in schizophrenia and further elaborate their network properties.

PMID: 26081977 [PubMed - as supplied by publisher]

Layer-specific interhemispheric functional connectivity in the somatosensory cortex of rats: resting state electrophysiology and fMRI studies.

Thu, 06/18/2015 - 16:30

Layer-specific interhemispheric functional connectivity in the somatosensory cortex of rats: resting state electrophysiology and fMRI studies.

Brain Struct Funct. 2015 Jun 16;

Authors: Baek K, Shim WH, Jeong J, Radhakrishnan H, Rosen BR, Boas D, Franceschini M, Biswal BB, Kim YR

Abstract
The spontaneous cerebral hemodynamic fluctuations observed during the resting state have been frequently visualized using functional magnetic resonance imaging (rsfMRI). However, the neuronal populations and neuroelectric characteristics underlying the functional connectivity of cerebrohemodynamic activities are poorly understood. We investigated the characteristics of bi-hemispheric functional connectivity via electrophysiology and rsfMRI in the primary sensory cortex of rats anesthetized by α-chloralose. Unlike the evoked responses, the spontaneous electrophysiological activity was concentrated in the infragranular layers and could be classified into subtypes with distinctive current sources and sinks. Both neuroelectric and rsfMRI signals were interhemispherically correlated in a layer-specific manner, suggesting that there are independent neural inputs to infragranular and granular/supragranular layers. The majority of spontaneous electrophysiological activities were bilaterally paired with delays of up to ~50 ms between each pair. The variable interhemispheric delay implies the involvement of indirect, multi-neural pathways. Our findings demonstrated the diverse activity patterns of layer-specific electrophysiological substrates and suggest the recruitment of multiple, non-specific brain regions in construction of interhemispheric functional connectivity.

PMID: 26077581 [PubMed - as supplied by publisher]

Examining the resting-state vascular connectivity using fMRA in comparison with fMRI: a preliminary study.

Wed, 06/17/2015 - 11:00

Examining the resting-state vascular connectivity using fMRA in comparison with fMRI: a preliminary study.

Neuroreport. 2015 Jun 11;

Authors: Park CA, Kang CK, Kim YB, Cho ZH

Abstract
This study examined resting-state functional connectivity in the vascular system of the brain using functional magnetic resonance angiography (fMRA) with an ultra-high-field 7 T MRI. Four healthy individuals participated in the functional imaging study using fMRA and functional MRI (fMRI) for determination of vascular and blood oxygenation level-dependent (BOLD) connectivity, respectively. We calculated voxel-wise connectivity maps and measured the correlation coefficients of the region of interest (ROI)-wise connectivity in the resting-state human brain. Z-map in the posterior cingulate cortex showed more correlated voxels in fMRA than fMRI. There was little or weak interhemispheric vascular connectivity using fMRA in the lateral parietal cortex and the lateral temporal cortex. In contrast, both vascular and BOLD interhemispheric correlations in the precentral gyrus were strong. Correlation coefficients for ROI-wise connectivity analysis were statistically different between fMRA and fMRI in the left and right lateral parietal cortex and lateral temporal cortex (P=0.029). Unlike BOLD connectivity, vascular connectivity showed little interhemispheric correlation in the default mode network. These results could provide the vascular connectivity on the basis of arterial response that can only be obtained by fMRA with an ultra-high-field environment along with further studies. Therefore, this method could provide additional and supplementary information for investigating the vascular effect in patients with cerebrovascular disease.

PMID: 26076337 [PubMed - as supplied by publisher]

Enhanced repertoire of brain dynamical states during the psychedelic experience.

Wed, 06/17/2015 - 11:00
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Enhanced repertoire of brain dynamical states during the psychedelic experience.

Hum Brain Mapp. 2014 Nov;35(11):5442-56

Authors: Tagliazucchi E, Carhart-Harris R, Leech R, Nutt D, Chialvo DR

Abstract
The study of rapid changes in brain dynamics and functional connectivity (FC) is of increasing interest in neuroimaging. Brain states departing from normal waking consciousness are expected to be accompanied by alterations in the aforementioned dynamics. In particular, the psychedelic experience produced by psilocybin (a substance found in "magic mushrooms") is characterized by unconstrained cognition and profound alterations in the perception of time, space and selfhood. Considering the spontaneous and subjective manifestation of these effects, we hypothesize that neural correlates of the psychedelic experience can be found in the dynamics and variability of spontaneous brain activity fluctuations and connectivity, measurable with functional Magnetic Resonance Imaging (fMRI). Fifteen healthy subjects were scanned before, during and after intravenous infusion of psilocybin and an inert placebo. Blood-Oxygen Level Dependent (BOLD) temporal variability was assessed computing the variance and total spectral power, resulting in increased signal variability bilaterally in the hippocampi and anterior cingulate cortex. Changes in BOLD signal spectral behavior (including spectral scaling exponents) affected exclusively higher brain systems such as the default mode, executive control, and dorsal attention networks. A novel framework enabled us to track different connectivity states explored by the brain during rest. This approach revealed a wider repertoire of connectivity states post-psilocybin than during control conditions. Together, the present results provide a comprehensive account of the effects of psilocybin on dynamical behavior in the human brain at a macroscopic level and may have implications for our understanding of the unconstrained, hyper-associative quality of consciousness in the psychedelic state.

PMID: 24989126 [PubMed - indexed for MEDLINE]

Changes of gray matter volume and amplitude of low-frequency oscillations in amnestic MCI: An integrative multi-modal MRI study.

Wed, 06/17/2015 - 11:00
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Changes of gray matter volume and amplitude of low-frequency oscillations in amnestic MCI: An integrative multi-modal MRI study.

Acta Radiol. 2015 May;56(5):614-21

Authors: Zhao ZL, Fan FM, Lu J, Li HJ, Jia LF, Han Y, Li KC

Abstract
BACKGROUND: Numerous studies have reported that the amnestic-type mild cognitive impairment (aMCI) patients have impaired brain structural integrity and functional alterations separately.
PURPOSE: To investigate the changes of gray matter and amplitude of low-frequency oscillations in patients with aMCI by combining structural and functional magnetic resonance imaging (fMRI).
MATERIAL AND METHODS: Thirty-four patients with aMCI and 34 controls were recruited. We adopted optimized voxel-based morphometry to detect regions with gray matter volume (GMV) loss induced by aMCI. Then regional differences in amplitude of slow-4 band (0.027-0.073 Hz) oscillations among these regions between patients and healthy controls were examined. Both slow-4 amplitude of low-frequency fluctuations (ALFF) and slow-4 fractional ALFF (fALFF; the relative amplitude that resides in the low frequencies) were employed.
RESULTS: Patients with aMCI demonstrated significant GMV loss in the ventral medial prefrontal cortex (vMPFC), posterior cingulate cortex (PCC), bilateral hippocampus, right superior parietal gyrus, left insula and left middle temporal gyrus (P < 0.01). The patients exhibited significant decreases of slow-4 ALFF in the left hippocampus (P = 0.05) and PCC (P = 0.02), while the decreased slow-4 fALFF was detected in PCC (P = 0.01) and increased slow-4 fALFF in vMPFC (P = 0.03). In PCC, aMCI and controls exhibited significant different GMV-fALFF correlation (P < 0.05), with opposite correlation trend.
CONCLUSION: The correlates between anatomical deficits and functional alterations in aMCI suggest that anatomical and functional deficits are linked to each other. The differences of GMV-fALFF correlations demonstrated altered anatomical-functional relationship in aMCI.

PMID: 24792358 [PubMed - indexed for MEDLINE]

Cascades and cognitive state: focused attention incurs subcritical dynamics.

Wed, 06/17/2015 - 11:00
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Cascades and cognitive state: focused attention incurs subcritical dynamics.

J Neurosci. 2015 Mar 18;35(11):4626-34

Authors: Fagerholm ED, Lorenz R, Scott G, Dinov M, Hellyer PJ, Mirzaei N, Leeson C, Carmichael DW, Sharp DJ, Shew WL, Leech R

Abstract
The analysis of neuronal avalanches supports the hypothesis that the human cortex operates with critical neural dynamics. Here, we investigate the relationship between cascades of activity in electroencephalogram data, cognitive state, and reaction time in humans using a multimodal approach. We recruited 18 healthy volunteers for the acquisition of simultaneous electroencephalogram and functional magnetic resonance imaging during both rest and during a visuomotor cognitive task. We compared distributions of electroencephalogram-derived cascades to reference power laws for task and rest conditions. We then explored the large-scale spatial correspondence of these cascades in the simultaneously acquired functional magnetic resonance imaging data. Furthermore, we investigated whether individual variability in reaction times is associated with the amount of deviation from power law form. We found that while resting state cascades are associated with approximate power law form, the task state is associated with subcritical dynamics. Furthermore, we found that electroencephalogram cascades are related to blood oxygen level-dependent activation, predominantly in sensorimotor brain regions. Finally, we found that decreased reaction times during the task condition are associated with increased proximity to power law form of cascade distributions. These findings suggest that the resting state is associated with near-critical dynamics, in which a high dynamic range and a large repertoire of brain states may be advantageous. In contrast, a focused cognitive task induces subcritical dynamics, which is associated with a lower dynamic range, which in turn may reduce elements of interference affecting task performance.

PMID: 25788679 [PubMed - indexed for MEDLINE]

Test-Retest reliability of graph metrics of resting state MRI functional brain networks: a review.

Tue, 06/16/2015 - 12:30

Test-Retest reliability of graph metrics of resting state MRI functional brain networks: a review.

J Neurosci Methods. 2015 Jun 10;

Authors: Andellini M, Cannatà V, Gazzellini S, Bernardi B, Napolitano A

Abstract
The employment of graph theory to analyze spontaneous fluctuations in resting state BOLD fMRI data has become a dominant theme in brain imaging studies and neuroscience. Analysis of resting state functional brain networks based on graph theory has proven to be a powerful tool to quantitatively characterize functional architecture of the brain and it has provided a new platform to explore the overall structure of local and global functional connectivity in the brain. Due to its increased use and possible expansion to clinical use, it is essential that the reliability of such a technique is very strongly assessed. In this review, we explore the outcome of recent studies in network reliability which apply graph theory to analyze connectome resting state networks. Therefore, we investigate which preprocessing steps may affect reproducibility the most. In order to investigate network reliability, we compared the test-retest (TRT) reliability of functional data of published neuroimaging studies with different preprocessing steps. In particular we tested influence of global signal regression, correlation metric choice, binary vs weighted link definition, frequency band selection and length of time series. Statistical analysis shows that only frequency band selection and length of time series seem to affect TRT reliability. Our results highlight the importance of the choice of the preprocessing steps to achieve more reproducible measurements.

PMID: 26072249 [PubMed - as supplied by publisher]

Reliance on functional resting-state network for stable task control predicts behavioral tendency for cooperation.

Mon, 06/15/2015 - 16:30
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Reliance on functional resting-state network for stable task control predicts behavioral tendency for cooperation.

Neuroimage. 2015 Jun 9;

Authors: Hahn T, Notebaert K, Anderl C, Reicherts P, Wieser M, Kopf J, Reif A, Fehl K, Semmann D, Windmann S

Abstract
Humans display individual variability in cooperative behaviour. While an ever-growing body of research has investigated the neural correlates of task-specific cooperation, the mechanisms by which situation-independent, stable differences in cooperation render behavior consistent across a wide range of situations remain elusive. Addressing this issue, we show that the individual tendency to behave in a prosocial or individualistic manner can be predicted from the functional resting-state connectome. More specifically, connections of the cinguloopercular network which supports goal-directed behavior encode cooperative tendency. Effects of virtual lesions to this network on the efficacy of information exchange throughout the brain corroborate our findings. These results shed light on the neural mechanisms underlying individualists' and prosocials' habitual social decisions by showing that reliance on the cinguloopercular task-control network predicts stable cooperative behavior. Based on this evidence, we provide a unifying framework for the interpretation of functional imaging and behavioral studies of cooperative behavior.

PMID: 26070266 [PubMed - as supplied by publisher]

Diagnosis of posttraumatic stress disorder (PTSD) based on correlations of prewhitened fMRI data: outcomes and areas involved.

Sun, 06/14/2015 - 18:00
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Diagnosis of posttraumatic stress disorder (PTSD) based on correlations of prewhitened fMRI data: outcomes and areas involved.

Exp Brain Res. 2015 Jun 13;

Authors: Christova P, James LM, Engdahl BE, Lewis SM, Georgopoulos AP

Abstract
Successful diagnosis of PTSD has been achieved using neural correlations from prewhitened magnetoencephalographic (MEG) time series (Georgopoulos et al. in J Neural Eng 7:16011, 2010. doi:10.1088/1741-2560/7/1/016011; James et al. 2015). Here, we show that highly successful classification of PTSD and control subjects can be obtained using neural correlations from prewhitened resting-state fMRI data. All but one PTSD (14/15; sensitivity = 93.3 %) and all but one control (20/21; specificity = 95.2 %) subjects were correctly classified using 15 out of 2701 possible correlations between 74 brain areas. In contrast, correlations of the same but non-prewhitened data yielded chance-level classifications. We conclude that, if properly processed, fMRI has the prospect of aiding significantly in PTSD diagnosis. Twenty-five brain areas were most prominently involved in correct subject classification, including areas from all cortical lobes and the left pallidum.

PMID: 26070898 [PubMed - as supplied by publisher]

Nodal approach reveals differential impact of lateralized focal epilepsies on hub reorganization.

Sun, 06/14/2015 - 18:00
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Nodal approach reveals differential impact of lateralized focal epilepsies on hub reorganization.

Neuroimage. 2015 Jun 9;

Authors: Ridley BG, Rousseau C, Wirsich J, Le Troter A, Soulier E, Confort-Gouny S, Bartolomei F, Ranjeva JP, Achard S, Guye M

Abstract
The impact of the hemisphere affected by impairment in models of network disease is not fully understood. Among such models, focal epilepsies are characterized by recurrent seizures generated in epileptogenic areas also responsible for wider network dysfunction between seizures. Previous work focusing on functional connectivity within circumscribed networks suggests a divergence of network integrity and compensatory capacity between epilepsies as a function of the laterality of seizure onset. We evaluated the ability of complex network theory to reveal changes in focal epilepsy in global and nodal parameters using graph theoretical analysis of functional connectivity data obtained with resting-state fMRI. Graphs of functional connectivity networks were derived from 19 right and 13 left focal epilepsy patients and 15 controls. Topological metrics (degree, local efficiency, global efficiency and modularity) were computed for a whole-brain, atlas-defined network. We also calculated a hub disruption index for each graph metric, measuring the capacity of the brain network to demonstrate increased connectivity in some nodes for decreased connectivity in others. Our data demonstrate that the patient group as a whole is characterised by network-wide pattern of reorganization, even while global parameters fail to distinguish between groups. Furthermore, multiple metrics indicate that epilepsies with differently lateralized epileptic networks are asymmetric in their burden on functional brain networks; with left epilepsy patients being characterized by reduced efficiency and modularity, while in right epilepsy patients we provide the first evidence that functional brain networks are characterised by enhanced connectivity and efficiency at some nodes whereas reduced in others.

PMID: 26070261 [PubMed - as supplied by publisher]

Reduced Functional Connectivity of Default Mode and Set-Maintenance Networks in Ornithine Transcarbamylase Deficiency.

Sun, 06/14/2015 - 10:30

Reduced Functional Connectivity of Default Mode and Set-Maintenance Networks in Ornithine Transcarbamylase Deficiency.

PLoS One. 2015;10(6):e0129595

Authors: Pacheco-Colón I, Washington SD, Sprouse C, Helman G, Gropman AL, VanMeter JW

Abstract
BACKGROUND AND PURPOSE: Ornithine transcarbamylase deficiency (OTCD) is an X-chromosome linked urea cycle disorder (UCD) that causes hyperammonemic episodes leading to white matter injury and impairments in executive functioning, working memory, and motor planning. This study aims to investigate differences in functional connectivity of two resting-state networks-default mode and set-maintenance-between OTCD patients and healthy controls.
METHODS: Sixteen patients with partial OTCD and twenty-two control participants underwent a resting-state scan using 3T fMRI. Combining independent component analysis (ICA) and region-of-interest (ROI) analyses, we identified the nodes that comprised each network in each group, and assessed internodal connectivity.
RESULTS: Group comparisons revealed reduced functional connectivity in the default mode network (DMN) of OTCD patients, particularly between the anterior cingulate cortex/medial prefrontal cortex (ACC/mPFC) node and bilateral inferior parietal lobule (IPL), as well as between the ACC/mPFC node and the posterior cingulate cortex (PCC) node. Patients also showed reduced connectivity in the set-maintenance network, especially between right anterior insula/frontal operculum (aI/fO) node and bilateral superior frontal gyrus (SFG), as well as between the right aI/fO and ACC and between the ACC and right SFG.
CONCLUSION: Internodal functional connectivity in the DMN and set-maintenance network is reduced in patients with partial OTCD compared to controls, most likely due to hyperammonemia-related white matter damage. Because several of the affected areas are involved in executive functioning, it is postulated that this reduced connectivity is an underlying cause of the deficits OTCD patients display in this cognitive domain.

PMID: 26067829 [PubMed - as supplied by publisher]

Novelty seeking is related to individual risk preference and brain activation associated with risk prediction during decision making.

Sun, 06/14/2015 - 10:30

Novelty seeking is related to individual risk preference and brain activation associated with risk prediction during decision making.

Sci Rep. 2015;5:10534

Authors: Wang Y, Liu Y, Yang L, Gu F, Li X, Zha R, Wei Z, Pei Y, Zhang P, Zhou Y, Zhang X

Abstract
Novelty seeking (NS) is a personality trait reflecting excitement in response to novel stimuli. High NS is usually a predictor of risky behaviour such as drug abuse. However, the relationships between NS and risk-related cognitive processes, including individual risk preference and the brain activation associated with risk prediction, remain elusive. In this fMRI study, participants completed the Tridimensional Personality Questionnaire to measure NS and performed a probabilistic decision making task. Using a mathematical model, we estimated individual risk preference. Brain regions associated with risk prediction were determined via fMRI. The NS score showed a positive correlation with risk preference and a negative correlation with the activation elicited by risk prediction in the right posterior insula (r-PI), left anterior insula (l-AI), right striatum (r-striatum) and supplementary motor area (SMA). Within these brain regions, only the activation associated with risk prediction in the r-PI showed a correlation with NS after controlling for the effect of risk preference. Resting-state functional connectivity between the r-PI and r-striatum/l-AI was negatively correlated with NS. Our results suggest that high NS may be associated with less aversion to risk and that the r-PI plays an important role in relating risk prediction to NS.

PMID: 26065910 [PubMed - as supplied by publisher]

Associations between regional brain physiology and trait impulsivity, motor inhibition, and impaired control over drinking.

Sun, 06/14/2015 - 10:30

Associations between regional brain physiology and trait impulsivity, motor inhibition, and impaired control over drinking.

Psychiatry Res. 2015 May 7;

Authors: Weafer J, Dzemidzic M, Eiler Ii W, Oberlin BG, Wang Y, Kareken DA

Abstract
Trait impulsivity and poor inhibitory control are well-established risk factors for alcohol misuse, yet little is known about the associated neurobiological endophenotypes. Here we examined correlations among brain physiology and self-reported trait impulsive behavior, impaired control over drinking, and a behavioral measure of response inhibition. A sample of healthy drinkers (n=117) completed a pulsed arterial spin labeling (PASL) scan to quantify resting regional cerebral blood flow (rCBF), as well as measures of self-reported impulsivity (Eysenck I7 Impulsivity scale) and impaired control over drinking. A subset of subjects (n=40) performed a stop signal task during blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging to assess brain regions involved in response inhibition. Eysenck I7 scores were inversely related to blood flow in the right precentral gyrus. Significant BOLD activation during response inhibition occurred in an overlapping right frontal motor/premotor region. Moreover, impaired control over drinking was associated with reduced BOLD response in the same region. These findings suggest that impulsive personality and impaired control over drinking are associated with brain physiology in areas implicated in response inhibition. This is consistent with the idea that difficulty controlling behavior is due in part to impairment in motor restraint systems.

PMID: 26065376 [PubMed - as supplied by publisher]

Insulin Resistance-Associated Interhemispheric Functional Connectivity Alterations in T2DM: A Resting-State fMRI Study.

Sun, 06/14/2015 - 10:30
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Insulin Resistance-Associated Interhemispheric Functional Connectivity Alterations in T2DM: A Resting-State fMRI Study.

Biomed Res Int. 2015;2015:719076

Authors: Xia W, Wang S, Spaeth AM, Rao H, Wang P, Yang Y, Huang R, Cai R, Sun H

Abstract
We aim to investigate whether decreased interhemispheric functional connectivity exists in patients with type 2 diabetes mellitus (T2DM) by using resting-state functional magnetic resonance imaging (rs-fMRI). In addition, we sought to determine whether interhemispheric functional connectivity deficits associated with cognition and insulin resistance (IR) among T2DM patients. We compared the interhemispheric resting state functional connectivity of 32 T2DM patients and 30 healthy controls using rs-fMRI. Partial correlation coefficients were used to detect the relationship between rs-fMRI information and cognitive or clinical data. Compared with healthy controls, T2DM patients showed bidirectional alteration of functional connectivity in several brain regions. Functional connectivity values in the middle temporal gyrus (MTG) and in the superior frontal gyrus were inversely correlated with Trail Making Test-B score of patients. Notably, insulin resistance (log homeostasis model assessment-IR) negatively correlated with functional connectivity in the MTG of patients. In conclusion, T2DM patients exhibit abnormal interhemispheric functional connectivity in several default mode network regions, particularly in the MTG, and such alteration is associated with IR. Alterations in interhemispheric functional connectivity might contribute to cognitive dysfunction in T2DM patients.

PMID: 26064945 [PubMed - in process]

The Effects of Acupuncture at Real or Sham Acupoints on the Intrinsic Brain Activity in Mild Cognitive Impairment Patients.

Sun, 06/14/2015 - 10:30
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The Effects of Acupuncture at Real or Sham Acupoints on the Intrinsic Brain Activity in Mild Cognitive Impairment Patients.

Evid Based Complement Alternat Med. 2015;2015:529675

Authors: Jia B, Liu Z, Min B, Wang Z, Zhou A, Li Y, Qiao H, Jia J

Abstract
Accumulating neuroimaging studies in humans have shown that acupuncture can modulate a widely distributed brain network in mild cognitive impairment (MCI) and Alzheimer's disease (AD) patients. Acupuncture at different acupoints could exert different modulatory effects on the brain network. However, whether acupuncture at real or sham acupoints can produce different effects on the brain network in MCI or AD patients remains unclear. Using resting-state fMRI, we reported that acupuncture at Taixi (KI3) induced amplitude of low-frequency fluctuation (ALFF) change of different brain regions in MCI patients from those shown in the healthy controls. In MCI patients, acupuncture at KI3 increased or decreased ALFF in the different regions from those activated by acupuncture in the healthy controls. Acupuncture at the sham acupoint in MCI patients activated the different brain regions from those in healthy controls. Therefore, we concluded that acupuncture displays more significant effect on neuronal activities of the above brain regions in MCI patients than that in healthy controls. Acupuncture at KI3 exhibits different effects on the neuronal activities of the brain regions from acupuncture at sham acupoint, although the difference is only shown at several regions due to the close distance between the above points.

PMID: 26064166 [PubMed]

Connectivity pattern differences bilaterally in the cerebellum posterior lobe in healthy subjects after normal sleep and sleep deprivation: a resting-state functional MRI study.

Sun, 06/14/2015 - 10:30
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Connectivity pattern differences bilaterally in the cerebellum posterior lobe in healthy subjects after normal sleep and sleep deprivation: a resting-state functional MRI study.

Neuropsychiatr Dis Treat. 2015;11:1279-89

Authors: Liu X, Yan Z, Wang T, Yang X, Feng F, Fan L, Jiang J

Abstract
OBJECTIVE: The aim of this study was to use functional magnetic resonance imaging (fMRI) technique to explore the resting-state functional connectivity (rsFC) differences of the bilaterial cerebellum posterior lobe (CPL) after normal sleep (NS) and after sleep deprivation (SD).
METHODS: A total of 16 healthy subjects (eight males, eight females) underwent an fMRI scan twice at random: once following NS and the other following 24 hours' SD, with an interval of 1 month between the two scans. The fMRI scanning included resting state and acupuncture stimulation. The special activated regions located during the acupuncture stimulation were selected as regions of interest for rsFC analysis.
RESULTS: Bilateral CPLs were positively activated by acupuncture stimulation. In the NS group, the left CPL showed rsFC with the bilateral CPL, bilateral frontal lobe (BFL), left precuneus and right inferior parietal lobule, while the right CPL showed rsFC with the bilateral temporal lobe, right cerebellum anterior lobe, right CPL, left frontal lobe, left anterior cingulate, right posterior cingulate, and bilateral inferior parietal lobule. In the SD group, the left CPL showed rsFC with the left posterior cingulate gyrus bilateral CPL, left precuneus, left precentral gyrus, BFL, and the left parietal lobe, while the right CPL showed rsFC with bilateral cerebellum anterior lobe, bilateral CPL, left frontal lobe and left temporal lobe. Compared with the NS group, the left CPL had increased rsFC in the SD group with the right inferior frontal gyrus, right fusiform gyrus, right cingulate gyrus, right thalamus, and bilateral precuneus, and decreased rsFC with the BFL, while the right CPL had increased rsFC with the left superior frontal gyrus and decreased rsFC with the left precentral gyrus, right superior temporal gyrus, and the BFL.
CONCLUSION: Bilateral CPL are possibly involved in acupuncture stimulation in different manners, and the right CPL showed more rsFC impairment.

PMID: 26064046 [PubMed]

Computational Modeling of Resting-State Activity Demonstrates Markers of Normalcy in Children with Prenatal or Perinatal Stroke.

Sun, 06/14/2015 - 10:30
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Computational Modeling of Resting-State Activity Demonstrates Markers of Normalcy in Children with Prenatal or Perinatal Stroke.

J Neurosci. 2015 Jun 10;35(23):8914-24

Authors: Adhikari MH, Raja Beharelle A, Griffa A, Hagmann P, Solodkin A, McIntosh AR, Small SL, Deco G

Abstract
Children who sustain a prenatal or perinatal brain injury in the form of a stroke develop remarkably normal cognitive functions in certain areas, with a particular strength in language skills. A dominant explanation for this is that brain regions from the contralesional hemisphere "take over" their functions, whereas the damaged areas and other ipsilesional regions play much less of a role. However, it is difficult to tease apart whether changes in neural activity after early brain injury are due to damage caused by the lesion or by processes related to postinjury reorganization. We sought to differentiate between these two causes by investigating the functional connectivity (FC) of brain areas during the resting state in human children with early brain injury using a computational model. We simulated a large-scale network consisting of realistic models of local brain areas coupled through anatomical connectivity information of healthy and injured participants. We then compared the resulting simulated FC values of healthy and injured participants with the empirical ones. We found that the empirical connectivity values, especially of the damaged areas, correlated better with simulated values of a healthy brain than those of an injured brain. This result indicates that the structural damage caused by an early brain injury is unlikely to have an adverse and sustained impact on the functional connections, albeit during the resting state, of damaged areas. Therefore, these areas could continue to play a role in the development of near-normal function in certain domains such as language in these children.

PMID: 26063923 [PubMed - in process]