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Intrinsic Functional Connectivity of the Central Nucleus of the Amygdala and Bed Nucleus of the Stria Terminalis.

Tue, 04/11/2017 - 10:55
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Intrinsic Functional Connectivity of the Central Nucleus of the Amygdala and Bed Nucleus of the Stria Terminalis.

Neuroimage. 2017 Apr 06;:

Authors: Gorka AX, Torrisi S, Shackman AJ, Grillon C, Ernst M

Abstract
The central nucleus of the amygdala (CeA) and bed nucleus of the stria terminalis (BNST), two nuclei within the central extended amygdala, function as critical relays within the distributed neural networks that coordinate sensory, emotional, and cognitive responses to threat. These structures have overlapping anatomical projections to downstream targets that initiate defensive responses. Despite these commonalities, researchers have also proposed a functional dissociation between the CeA and BNST, with the CeA promoting responses to discrete stimuli and the BNST promoting responses to diffuse threat. Intrinsic functional connectivity (iFC) provides a means to investigate the functional architecture of the brain, unbiased by task demands. Using ultra-high field neuroimaging (7-Tesla fMRI), which provides increased spatial resolution, this study compared the iFC networks of the CeA and BNST in 27 healthy individuals. Both structures were coupled with areas of the medial prefrontal cortex, hippocampus, thalamus, and periaqueductal gray matter. Compared to the BNST, the bilateral CeA was more strongly coupled with the insula and regions that support sensory processing, including thalamus and fusiform gyrus. In contrast, the bilateral BNST was more strongly coupled with regions involved in cognitive and motivational processes, including the dorsal paracingulate gyrus, posterior cingulate cortex, and striatum. Collectively, these findings suggest that responses to sensory stimulation are preferentially coordinated by the CeA and cognitive and motivational responses are preferentially coordinated by the BNST.

PMID: 28392491 [PubMed - as supplied by publisher]

Improved 7 Tesla resting-state fMRI connectivity measurements by cluster-based modeling of respiratory volume and heart rate effects.

Tue, 04/11/2017 - 10:55
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Improved 7 Tesla resting-state fMRI connectivity measurements by cluster-based modeling of respiratory volume and heart rate effects.

Neuroimage. 2017 Apr 06;:

Authors: Pinto J, Nunes S, Bianciardi M, Dias A, Silveira LM, Wald LL, Figueiredo P

Abstract
Several strategies have been proposed to model and remove physiological noise from resting-state fMRI (rs-fMRI) data, particularly at ultrahigh fields (7 T), including contributions from respiratory volume (RV) and heart rate (HR) signal fluctuations. Recent studies suggest that these contributions are highly variable across subjects and that physiological noise correction may thus benefit from optimization at the subject or even voxel level. Here, we systematically investigated the impact of the degree of spatial specificity (group, subject, newly proposed cluster, and voxel levels) on the optimization of RV and HR models. For each degree of spatial specificity, we measured the fMRI signal variance explained (VE) by each model, as well as the functional connectivity underlying three well-known resting-state networks (RSNs) obtained from the fMRI data after removal of RV+HR contributions. Whole-brain, high-resolution rs-fMRI data were acquired from twelve healthy volunteers at 7 T, while simultaneously recording their cardiac and respiratory signals. Although VE increased with spatial specificity up to the voxel level, the accuracy of functional connectivity measurements improved only up to the cluster level, and subsequently decreased at the voxel level. This suggests that voxelwise modeling over-fits to local fluctuations with no physiological meaning. In conclusion, our results indicate that 7 T rs-fMRI connectivity measurements improve if a cluster-based physiological noise correction approach is employed in order to take into account the individual spatial variability in the HR and RV contributions.

PMID: 28392488 [PubMed - as supplied by publisher]

Functional MRI Correlates of Resting-State Temporal Theta and Delta EEG Rhythms.

Tue, 04/11/2017 - 10:55
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Functional MRI Correlates of Resting-State Temporal Theta and Delta EEG Rhythms.

J Clin Neurophysiol. 2017 Jan;34(1):69-76

Authors: Marawar RA, Yeh HJ, Carnabatu CJ, Stern JM

Abstract
PURPOSE: The EEG rhythms demonstrate changes in frequency and power with spontaneous changes in behavioral state that do not have well-understood metabolic correlates within the brain. To investigate this question and compare the temporal lobe theta and delta rhythms, resting-state functional MRI was obtained with simultaneous EEG.
METHODS: Simultaneous EEG-functional MRI was recorded from 14 healthy sleep-deprived subjects in awake and drowsy states. Scalp electrodes corresponding to bilateral temporal lobes were used to calculate delta and theta band power. The resulting time series was used as input in a general linear model, and the final power curves were convolved with the standard hemodynamic response function. Resulting images were thresholded at Z > 2.0.
RESULTS: Positive and negative correlations for unilateral theta and delta rhythms were present bilaterally in different structures and with differing correlation signs. Theta rhythm positive correlation was present in hindbrain, peri-opercular, and frontoparietal regions and subcortical gray structures, whereas negative correlation was present in parietooccipital cortex. Delta rhythm positive correlation was present in parietooccipital cortex, and negative correlation roughly resembled positive correlations for the theta rhythm.
CONCLUSIONS: Temporal lobe theta and delta rhythms are correlated with functional MRI signal in an almost mutually exclusive distribution. The different distributions indicate different corresponding networks. These normal findings supplement the understanding of theta and delta rhythm significance.

PMID: 27763967 [PubMed - indexed for MEDLINE]

Resting-state networks associated with cognitive processing show more age-related decline than those associated with emotional processing.

Mon, 04/10/2017 - 10:45
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Resting-state networks associated with cognitive processing show more age-related decline than those associated with emotional processing.

Neurobiol Aging. 2017 Mar 11;:

Authors: Nashiro K, Sakaki M, Braskie MN, Mather M

Abstract
Correlations in activity across disparate brain regions during rest reveal functional networks in the brain. Although previous studies largely agree that there is an age-related decline in the "default mode network," how age affects other resting-state networks, such as emotion-related networks, is still controversial. Here we used a dual-regression approach to investigate age-related alterations in resting-state networks. The results revealed age-related disruptions in functional connectivity in all 5 identified cognitive networks, namely the default mode network, cognitive-auditory, cognitive-speech (or speech-related somatosensory), and right and left frontoparietal networks, whereas such age effects were not observed in the 3 identified emotion networks. In addition, we observed age-related decline in functional connectivity in 3 visual and 3 motor/visuospatial networks. Older adults showed greater functional connectivity in regions outside 4 out of the 5 identified cognitive networks, consistent with the dedifferentiation effect previously observed in task-based functional magnetic resonance imaging studies. Both reduced within-network connectivity and increased out-of-network connectivity were correlated with poor cognitive performance, providing potential biomarkers for cognitive aging.

PMID: 28390824 [PubMed - as supplied by publisher]

Sources of disconnection in neurocognitive aging: cerebral white-matter integrity, resting-state functional connectivity, and white-matter hyperintensity volume.

Sun, 04/09/2017 - 10:25
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Sources of disconnection in neurocognitive aging: cerebral white-matter integrity, resting-state functional connectivity, and white-matter hyperintensity volume.

Neurobiol Aging. 2017 Mar 18;:

Authors: Madden DJ, Parks EL, Tallman CW, Boylan MA, Hoagey DA, Cocjin SB, Packard LE, Johnson MA, Chou YH, Potter GG, Chen NK, Siciliano RE, Monge ZA, Honig JA, Diaz MT

Abstract
Age-related decline in fluid cognition can be characterized as a disconnection among specific brain structures, leading to a decline in functional efficiency. The potential sources of disconnection, however, are unclear. We investigated imaging measures of cerebral white-matter integrity, resting-state functional connectivity, and white-matter hyperintensity volume as mediators of the relation between age and fluid cognition, in 145 healthy, community-dwelling adults 19-79 years of age. At a general level of analysis, with a single composite measure of fluid cognition and single measures of each of the 3 imaging modalities, age exhibited an independent influence on the cognitive and imaging measures, and the imaging variables did not mediate the age-cognition relation. At a more specific level of analysis, resting-state functional connectivity of sensorimotor networks was a significant mediator of the age-related decline in executive function. These findings suggest that different levels of analysis lead to different models of neurocognitive disconnection, and that resting-state functional connectivity, in particular, may contribute to age-related decline in executive function.

PMID: 28389085 [PubMed - as supplied by publisher]

BDNF-Dependent Effects on Amygdala-Cortical Circuitry and Depression Risk in Children and Youth.

Sat, 04/08/2017 - 10:05

BDNF-Dependent Effects on Amygdala-Cortical Circuitry and Depression Risk in Children and Youth.

Cereb Cortex. 2017 Apr 06;:1-11

Authors: Wheeler AL, Felsky D, Viviano JD, Stojanovski S, Ameis SH, Szatmari P, Lerch JP, Chakravarty MM, Voineskos AN

Abstract
The brain-derived neurotrophic factor (BDNF) is critical for brain development, and the functional BDNF Val66Met polymorphism is implicated in risk for mood disorders. The objective of this study was to determine how the Val66Met polymorphism influences amygdala-cortical connectivity during neurodevelopment and assess the relevance for mood disorders. Age- and sex-specific effects of the BDNF Val66Met polymorphism on amygdala-cortical connectivity were assessed by examining covariance of amygdala volumes with thickness throughout the cortex in a sample of Caucasian youths ages 8-22 that were part of the Philadelphia Neurodevelopmental Cohort (n = 339). Follow-up analyses assessed corresponding BDNF genotype effects on resting-state functional connectivity (n = 186) and the association between BDNF genotype and major depressive disorder (MDD) (n = 2749). In adolescents, amygdala-cortical covariance was significantly stronger in Met allele carriers compared with Val/Val homozygotes in amygdala-cortical networks implicated in depression; these differences were driven by females. In follow-up analyses, the Met allele was also associated with stronger resting-state functional connectivity in adolescents and increased likelihood of MDD in adolescent females. The BDNF Val66Met polymorphism may confer risk for mood disorders in females through effects on amygdala-cortical connectivity during adolescence, coinciding with a period in the lifespan when onset of depression often occurs, more commonly in females.

PMID: 28387866 [PubMed - as supplied by publisher]

GABA content within medial prefrontal cortex predicts the variability of fronto-limbic effective connectivity.

Sat, 04/08/2017 - 10:05
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GABA content within medial prefrontal cortex predicts the variability of fronto-limbic effective connectivity.

Brain Struct Funct. 2017 Apr 06;:

Authors: Delli Pizzi S, Chiacchieretta P, Mantini D, Bubbico G, Edden RA, Onofrj M, Ferretti A, Bonanni L

Abstract
The amygdala-medial prefrontal cortex (mPFC) circuit plays a key role in social behavior. The amygdala and mPFC are bidirectionally connected, functionally and anatomically, via the uncinate fasciculus. Recent evidence suggests that GABA-ergic neurotransmission within the mPFC could be central to the regulation of amygdala activity related to emotions and anxiety processing. However, the functional and neurochemical interactions within amygdala-mPFC circuits are unclear. In the current study, multimodal magnetic resonance imaging techniques were combined to investigate effective connectivity within the amygdala-mPFC network and its relationship with mPFC neurotransmission in 22 healthy subjects aged between 41 and 88 years. Effective connectivity in the amygdala-mPFC circuit was assessed on resting-state functional magnetic resonance imaging data using spectral dynamic causal modelling. State and trait anxiety were also assessed. The mPFC was shown to be the target of incoming outputs from the amygdalae and the source of exciting inputs to the limbic system. The amygdalae were reciprocally connected by excitatory projections. About half of the variance relating to the strength of top-down endogenous connection between right amygdala and mPFC was explained by mPFC GABA levels. State anxiety was correlated with the strength of the endogenous connections between right amygdala and mPFC. We suggest that mPFC GABA content predicts variability in the effective connectivity within the mPFC-amygdala circuit, providing new insights on emotional physiology and the underlying functional and neurochemical interactions.

PMID: 28386778 [PubMed - as supplied by publisher]

Concurrent tACS-fMRI reveals causal influence of power synchronized neural activity on resting state fMRI connectivity.

Sat, 04/08/2017 - 10:05
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Concurrent tACS-fMRI reveals causal influence of power synchronized neural activity on resting state fMRI connectivity.

J Neurosci. 2017 Apr 06;:

Authors: Bächinger M, Zerbi V, Moisa M, Polania R, Liu Q, Mantini D, Ruff C, Wenderoth N

Abstract
Resting state fMRI (rs-fMRI) is commonly used to study the brain's intrinsic neural coupling, which reveals specific spatiotemporal patterns in the form of resting state networks (RSN). It has been hypothesized that slow rs-fMRI oscillations (<0.1 Hz) are driven by underlying electrophysiological rhythms that typically occur at much faster timescales (>5 Hz); however, causal evidence for this relationship is currently lacking. Here we measured rs-fMRI in humans while applying transcranial alternating current stimulation (tACS) to entrain brain rhythms in left and right sensorimotor cortices.The two driving tACS signals were tailored to the individual's alpha rhythm (8-12 Hz) and fluctuated in amplitude according to a 1 Hz power envelope. We entrained the left versus right hemisphere in accordance to two different coupling modes where either alpha oscillations were synchronized between hemispheres (phase-synchronized tACS) or the slower oscillating power envelopes (power-synchronized tACS).Power-synchronized tACS significantly increased rs-fMRI connectivity within the stimulated RSN compared to phase-synchronized or no tACS. This effect outlasted the stimulation period and tended to be more effective in individuals who exhibited a naturally weak interhemispheric coupling. Using this novel approach, our data provide causal evidence that synchronized power fluctuations contribute to the formation of fMRI-based RSNs. Moreover, our findings demonstrate that the brain's intrinsic coupling at rest can be selectively modulated by choosing appropriate tACS signals, which could lead to new interventions for patients with altered rs-fMRI connectivity.SIGNIFICANCE STATEMENTResting state fMRI has become an important tool to estimate brain connectivity. However, relatively little is known about how slow hemodynamic oscillations measured with fMRI relate to electrophysiological processes.It was suggested that slowly fluctuating power envelopes of electrophysiological signals synchronize across brain areas and that the topography of this activity is spatially correlated to resting state networks derived from rs-fMRI. Here we take a novel approach to address this problem and establish a causal link between the power fluctuations of electrophysiological signals and rs-fMRI via a new neuromodulation paradigm, which exploits these power-synchronization mechanisms.These novel mechanistic insights bridge different scientific domains and are of broad interest to researchers in the fields of Medical Imaging, Neuroscience, Physiology and Psychology.

PMID: 28385876 [PubMed - as supplied by publisher]

Patterns of striatal functional connectivity differ in early and late onset Parkinson's disease.

Sat, 04/08/2017 - 10:05
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Patterns of striatal functional connectivity differ in early and late onset Parkinson's disease.

J Neurol. 2016 Oct;263(10):1993-2003

Authors: Hou Y, Yang J, Luo C, Ou R, Song W, Liu W, Gong Q, Shang H

Abstract
To map functional connectivity (FC) patterns of early onset Parkinson's disease (EOPD) and late onset PD (LOPD) in drug-naïve early stage. MRI was used to assess atrophy and resting-state FC focusing on striatal subregions of EOPD and LOPD in two subgroups of 18 patients matched for disease duration and severity, relative to age- and sex- matched healthy controls. Compared with controls, both PD subgroups showed FC alterations in cortico-striatal and cerebello-striatal loops but with different patterns in resting state. EOPD patients showed widespread increased FC between striatum and sensorimotor cortex, middle frontal gyrus, superior and inferior parietal lobules, superior and inferior temporal gyri, and cerebellum. While LOPD patients were evidenced with increased FC in cerebello-striatal circuit and decreased FC between orbitofrontal gyrus and striatum. In addition, Unified Parkinson's Disease Rating Scale part III scores were negatively correlated with the increased FC between the caudate nucleus and sensorimotor cortex (r = -0.571, p = 0.013) in EOPD patients, while negatively correlated with the increased FC between the putamen and cerebellum (r = -0.478, p = 0.045) in LOPD patients, suggesting that increased FC is here likely to reflect compensatory mechanism. FC changes in EOPD and LOPD share common features and have differences, which may suggest that the responses to defective basal ganglia are different between the two subtypes. Improved insights into the onset-related subtypes of PD and its disruptive FC pattern will be valuable for improving our understanding of the pathogenesis of the disease.

PMID: 27394147 [PubMed - indexed for MEDLINE]

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

Fri, 04/07/2017 - 15:50
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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 - in process]

Human Genomic Signatures of Brain Oscillations During Memory Encoding.

Fri, 04/07/2017 - 15:50
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Human Genomic Signatures of Brain Oscillations During Memory Encoding.

Cereb Cortex. 2017 Apr 05;:1-16

Authors: Berto S, Wang GZ, Germi J, Lega BC, Konopka G

Abstract
Memory encoding is an essential step for all learning. However, the genetic and molecular mechanisms underlying human memory encoding remain poorly understood, and how this molecular framework permits the emergence of specific patterns of brain oscillations observed during mnemonic processing is unknown. Here, we directly compare intracranial electroencephalography recordings from the neocortex in individuals performing an episodic memory task with human gene expression from the same areas. We identify genes correlated with oscillatory memory effects across 6 frequency bands. These genes are enriched for autism-related genes and have preferential expression in neurons, in particular genes encoding synaptic proteins and ion channels, supporting the idea that the genes regulating voltage gradients are involved in the modulation of oscillatory patterns during successful memory encoding across brain areas. Memory-related genes are distinct from those correlated with other forms of cognitive processing and resting state fMRI. These data are the first to identify correlations between gene expression and active human brain states as well as provide a molecular window into memory encoding oscillations in the human brain.

PMID: 28383644 [PubMed - as supplied by publisher]

High transition frequencies of dynamic functional connectivity states in the creative brain.

Fri, 04/07/2017 - 15:50
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High transition frequencies of dynamic functional connectivity states in the creative brain.

Sci Rep. 2017 Apr 06;7:46072

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

Abstract
Creativity is thought to require the flexible reconfiguration of multiple brain regions that interact in transient and complex communication patterns. In contrast to prior emphases on searching for specific regions or networks associated with creative performance, we focused on exploring the association between the reconfiguration of dynamic functional connectivity states and creative ability. We hypothesized that a high frequency of dynamic functional connectivity state transitions will be associated with creative ability. To test this hypothesis, we recruited a high-creative group (HCG) and a low-creative group (LCG) of participants and collected resting-state fMRI (R-fMRI) data and Torrance Tests of Creative Thinking (TTCT) scores from each participant. By combining an independent component analysis with a dynamic network analysis approach, we discovered the HCG had more frequent transitions between dynamic functional connectivity (dFC) states than the LCG. Moreover, a confirmatory analysis using multiplication of temporal derivatives also indicated that there were more frequent dFC state transitions in the HCG. Taken together, these results provided empirical evidence for a linkage between the flexible reconfiguration of dynamic functional connectivity states and creative ability. These findings have the potential to provide new insights into the neural basis of creativity.

PMID: 28383052 [PubMed - in process]

Association between serotonin denervation and resting-state functional connectivity in mild cognitive impairment.

Thu, 04/06/2017 - 21:35
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Association between serotonin denervation and resting-state functional connectivity in mild cognitive impairment.

Hum Brain Mapp. 2017 Apr 05;:

Authors: Barrett FS, Workman CI, Sair HI, Savonenko AV, Kraut MA, Sodums DJ, Joo JJ, Nassery N, Marano CM, Munro CA, Brandt J, Zhou Y, Wong DF, Smith GS

Abstract
Resting-state functional connectivity alterations have been demonstrated in Alzheimer's disease (AD) and mild cognitive impairment (MCI) before the observation of AD neuropathology, but mechanisms driving these changes are not well understood. Serotonin neurodegeneration has been observed in MCI and AD and is associated with cognitive deficits and neuropsychiatric symptoms, but the role of the serotonin system in relation to brain network dysfunction has not been a major focus of investigation. The current study investigated the relationship between serotonin transporter availability (SERT; measured using positron emission tomography) and brain network functional connectivity (measured using resting-state functional MRI) in 20 participants with MCI and 21 healthy controls. Two SERT regions of interest were selected for the analysis: the Dorsal Raphe Nuclei (DRN) and the precuneus which represent the cell bodies of origin and a cortical target of projections of the serotonin system, respectively. Both regions show decreased SERT in MCI compared to controls and are the site of early AD pathology. Average resting-state functional connectivity did not differ between MCI and controls. Decreased SERT in DRN was associated with lower hippocampal resting-state connectivity in MCI participants compared to controls. Decreased SERT in the right precuneus was also associated with lower resting-state connectivity of the retrosplenial cortex to the dorsal lateral prefrontal cortex and higher resting-state connectivity of the retrosplenial cortex to the posterior cingulate and in patients with MCI but not in controls. These results suggest that a serotonergic mechanism may underlie changes in brain functional connectivity in MCI. Hum Brain Mapp, 2017. © 2017 Wiley Periodicals, Inc.

PMID: 28379618 [PubMed - as supplied by publisher]

Latent and Abnormal Functional Connectivity Circuits in Autism Spectrum Disorder.

Thu, 04/06/2017 - 21:35
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Latent and Abnormal Functional Connectivity Circuits in Autism Spectrum Disorder.

Front Neurosci. 2017;11:125

Authors: Chen S, Xing Y, Kang J

Abstract
Autism spectrum disorder (ASD) is associated with disrupted brain networks. Neuroimaging techniques provide noninvasive methods of investigating abnormal connectivity patterns in ASD. In the present study, we compare functional connectivity networks in people with ASD with those in typical controls, using neuroimaging data from the Autism Brain Imaging Data Exchange (ABIDE) project. Specifically, we focus on the characteristics of intrinsic functional connectivity based on data collected by resting-state functional magnetic resonance imaging (rs-fMRI). Our aim was to identify disrupted brain connectivity patterns across all networks, instead of in individual edges, by using advanced statistical methods. Unlike many brain connectome studies, in which networks are prespecified before the edge connectivity in each network is compared between clinical groups, we detected the latent differentially expressed networks automatically. Our network-level analysis identified abnormal connectome networks that (i) included a high proportion of edges that were differentially expressed between people with ASD and typical controls; and (ii) showed highly-organized graph topology. These findings provide new insight into the study of the underlying neuropsychiatric mechanism of ASD.

PMID: 28377688 [PubMed - in process]

Short- and long-range functional connectivity density alterations in adolescents with pure conduct disorder at resting-state.

Thu, 04/06/2017 - 21:35
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Short- and long-range functional connectivity density alterations in adolescents with pure conduct disorder at resting-state.

Neuroscience. 2017 Apr 01;:

Authors: Lu FM, Zhou JS, Wang XP, Xiang YT, Yuan Z

Abstract
Conduct disorder (CD) is a developmental disorder defined by a repetitive and persistent display of antisocial and aggressive behaviors that violates the rights of others or basic social rules. Recently, resting-state functional magnetic resonance imaging (rsfMRI) has been widely adopted to investigate the altered intrinsic neural activities and the disrupted endogenous brain connectivity of CD. In this study, functional connectivity density (FCD) mapping, a newly developed ultrafast voxel-wise method based on rsfMRI, was applied for the first time to examine the changes in the brain functional connectivity in CD at the voxel level. We assessed the differences in FCD between eighteen male adolescents with CD and eighteen typically-developing (TD) individuals. Then, the identified brain regions in which CD patients and healthy controls exhibited significant difference in FCD were extracted to calculate the correlations between measures of FCD values and clinical data. We discovered that compared to healthy controls, CD patients showed increased short-range FCD in the default-mode network including the bilateral posterior cingulate cortex (PCC) and the bilateral precuneus (PCUN). More importantly, increased short-range FCD values in the bilateral PCC, the bilateral PCUN, and increased long-range FCD values in the left MCC showed significant correlations with the impulsivity. Overall, these results suggested that the FCD abnormalities in CD patients occurred in brain regions known to be involved in cognition, emotion and visual perception.

PMID: 28377176 [PubMed - as supplied by publisher]

Effect of smoking on resting-state functional connectivity in smokers: An fMRI study.

Wed, 04/05/2017 - 14:40

Effect of smoking on resting-state functional connectivity in smokers: An fMRI study.

Respirology. 2017 Apr 04;:

Authors: Zhou S, Xiao D, Peng P, Wang SK, Liu Z, Qin HY, Li SS, Wang C

Abstract
BACKGROUND AND OBJECTIVE: Smoking is a leading cause of death in the world. Aberrant brain function has been repeatedly linked to tobacco smoking. However, little is known about insula-based resting-state functional connectivity (rsFC) in non-deprived tobacco-dependent smokers. This study characterized the correlation between insula-based rsFC and tobacco dependence severity in non-deprived smokers.
METHODS: A total of 37 male smokers and 37 age-matched male non-smokers completed resting-state functional MRI (fMRI) scans. The insula-based rsFC differences between smokers and controls were investigated and the correlation between insula-based rsFC and FTND (Fagerström Test for Nicotine Dependence) scores were then assessed.
RESULTS: Compared with controls, smokers showed significantly lower rsFC between orbitofrontal cortex, superior frontal gyrus, temporal lobe and insula. The rsFC between orbitofrontal cortex, temporal lobe, inferior parietal cortex, occipital lobe and insula was positively correlated with FTND. However, the rsFC between anterior cingulate cortex and insula was negatively correlated with FTND.
CONCLUSION: Our findings suggest differences in brain functional connectivity between smokers and non-smokers. This study sheds new insights into the neural mechanisms of tobacco dependence.

PMID: 28374936 [PubMed - as supplied by publisher]

Restructuring Reward Mechanisms in Nicotine Addiction: A Pilot fMRI Study of Mindfulness-Oriented Recovery Enhancement for Cigarette Smokers.

Wed, 04/05/2017 - 14:40
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Restructuring Reward Mechanisms in Nicotine Addiction: A Pilot fMRI Study of Mindfulness-Oriented Recovery Enhancement for Cigarette Smokers.

Evid Based Complement Alternat Med. 2017;2017:7018014

Authors: Froeliger B, Mathew AR, McConnell PA, Eichberg C, Saladin ME, Carpenter MJ, Garland EL

Abstract
The primary goal of this pilot feasibility study was to examine the effects of Mindfulness-Oriented Recovery Enhancement (MORE), a behavioral treatment grounded in dual-process models derived from cognitive science, on frontostriatal reward processes among cigarette smokers. Healthy adult (N = 13; mean (SD) age 49 ± 12.2) smokers provided informed consent to participate in a 10-week study testing MORE versus a comparison group (CG). All participants underwent two fMRI scans: pre-tx and after 8-weeks of MORE. Emotion regulation (ER), smoking cue reactivity (CR), and resting-state functional connectivity (rsFC) were assessed at each fMRI visit; smoking and mood were assessed throughout. As compared to the CG, MORE significantly reduced smoking (d = 2.06) and increased positive affect (d = 2.02). MORE participants evidenced decreased CR-BOLD response in ventral striatum (VS; d = 1.57) and ventral prefrontal cortex (vPFC; d = 1.7) and increased positive ER-BOLD in VS (dVS = 2.13) and vPFC (dvmPFC = 2.66). Importantly, ER was correlated with smoking reduction (r's = .68 to .91) and increased positive affect (r's = .52 to .61). These findings provide preliminary evidence that MORE may facilitate the restructuring of reward processes and play a role in treating the pathophysiology of nicotine addiction.

PMID: 28373890 [PubMed - in process]

Can brain state be manipulated to emphasize individual differences in functional connectivity?

Wed, 04/05/2017 - 14:40
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Can brain state be manipulated to emphasize individual differences in functional connectivity?

Neuroimage. 2017 Mar 31;:

Authors: Finn ES, Scheinost D, Finn DM, Shen X, Papademetris X, Constable RT

Abstract
While neuroimaging studies typically collapse data from many subjects, brain functional organization varies between individuals, and characterizing this variability is crucial for relating brain activity to behavioral phenotypes. Rest has become the default state for probing individual differences, chiefly because it is easy to acquire and a supposed neutral backdrop. However, the assumption that rest is the optimal condition for individual differences research is largely untested. In fact, other brain states may afford a better ratio of within- to between-subject variability, facilitating biomarker discovery. Depending on the trait or behavior under study, certain tasks may bring out meaningful idiosyncrasies across subjects, essentially enhancing the individual signal in networks of interest beyond what can be measured at rest. Here, we review theoretical considerations and existing work on how brain state influences individual differences in functional connectivity, present some preliminary analyses of within- and between-subject variability across conditions using data from the Human Connectome Project, and outline questions for future study.

PMID: 28373122 [PubMed - as supplied by publisher]

Higher serum cholesterol is associated with intensified age-related neural network decoupling and cognitive decline in early- to mid-life.

Tue, 04/04/2017 - 13:20
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Higher serum cholesterol is associated with intensified age-related neural network decoupling and cognitive decline in early- to mid-life.

Hum Brain Mapp. 2017 Mar 31;:

Authors: Spielberg JM, Sadeh N, Leritz EC, McGlinchey RE, Milberg WP, Hayes JP, Salat DH

Abstract
Mounting evidence indicates that serum cholesterol and other risk factors for cardiovascular disease intensify normative trajectories of age-related cognitive decline. However, the neural mechanisms by which this occurs remain largely unknown. To understand the impact of cholesterol on brain networks, we applied graph theory to resting-state fMRI in a large sample of early- to mid-life Veterans (N = 206, Meanage  = 32). A network emerged (centered on the banks of the superior temporal sulcus) that evidenced age-related decoupling (i.e., decreased network connectivity with age), but only in participants with clinically-elevated total cholesterol (≥180 mg/dL). Crucially, decoupling in this network corresponded to greater day-to-day disability and mediated age-related declines in psychomotor speed. Finally, examination of network organization revealed a pattern of age-related dedifferentiation for the banks of the superior temporal sulcus, again present only with higher cholesterol. More specifically, age was related to decreasing within-module communication (indexed by Within-Module Degree Z-Score) and increasing between-module communication (indexed by Participation Coefficient), but only in participants with clinically-elevated cholesterol. Follow-up analyses indicated that all findings were driven by low-density lipoprotein (LDL) levels, rather than high-density lipoprotein (HDL) or triglycerides, which is interesting as LDL levels have been linked to increased risk for cardiovascular disease, whereas HDL levels appear inversely related to such disease. These findings provide novel insight into the deleterious effects of cholesterol on brain health and suggest that cholesterol accelerates the impact of age on neural trajectories by disrupting connectivity in circuits implicated in integrative processes and behavioral control. Hum Brain Mapp, 2017. © 2017 Wiley Periodicals, Inc.

PMID: 28370780 [PubMed - as supplied by publisher]

Tired and misconnected: A breakdown of brain modularity following sleep deprivation.

Tue, 04/04/2017 - 13:20
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Tired and misconnected: A breakdown of brain modularity following sleep deprivation.

Hum Brain Mapp. 2017 Apr 03;:

Authors: Ben Simon E, Maron-Katz A, Lahav N, Shamir R, Hendler T

Abstract
Sleep deprivation (SD) critically affects a range of cognitive and affective functions, typically assessed during task performance. Whether such impairments stem from changes to the brain's intrinsic functional connectivity remain largely unknown. To examine this hypothesis, we applied graph theoretical analysis on resting-state fMRI data derived from 18 healthy participants, acquired during both sleep-rested and sleep-deprived states. We hypothesized that parameters indicative of graph connectivity, such as modularity, will be impaired by sleep deprivation and that these changes will correlate with behavioral outcomes elicited by sleep loss. As expected, our findings point to a profound reduction in network modularity without sleep, evident in the limbic, default-mode, salience and executive modules. These changes were further associated with behavioral impairments elicited by SD: a decrease in salience module density was associated with worse task performance, an increase in limbic module density was predictive of stronger amygdala activation in a subsequent emotional-distraction task and a shift in frontal hub lateralization (from left to right) was associated with increased negative mood. Altogether, these results portray a loss of functional segregation within the brain and a shift towards a more random-like network without sleep, already detected in the spontaneous activity of the sleep-deprived brain. Hum Brain Mapp, 2017. © 2017 Wiley Periodicals, Inc.

PMID: 28370703 [PubMed - as supplied by publisher]

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