New resting-state fMRI related studies at PubMed

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Distinct resting-state functional connections associated with episodic and visuospatial memory in older adults.

Tue, 08/01/2017 - 23:20
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Distinct resting-state functional connections associated with episodic and visuospatial memory in older adults.

Neuroimage. 2017 Jul 26;159:122-130

Authors: Suri S, Topiwala A, Filippini N, Zsoldos E, Mahmood A, Sexton CE, Singh-Manoux A, Kivimäki M, Mackay CE, Smith S, Ebmeier KP

Abstract
Episodic and spatial memory are commonly impaired in ageing and Alzheimer's disease. Volumetric and task-based functional magnetic resonance imaging (fMRI) studies suggest a preferential involvement of the medial temporal lobe (MTL), particularly the hippocampus, in episodic and spatial memory processing. The present study examined how these two memory types were related in terms of their associated resting-state functional architecture. 3T multiband resting state fMRI scans from 497 participants (60-82 years old) of the cross-sectional Whitehall II Imaging sub-study were analysed using an unbiased, data-driven network-modelling technique (FSLNets). Factor analysis was performed on the cognitive battery; the Hopkins Verbal Learning test and Rey-Osterreith Complex Figure test factors were used to assess verbal and visuospatial memory respectively. We present a map of the macroscopic functional connectome for the Whitehall II Imaging sub-study, comprising 58 functionally distinct nodes clustered into five major resting-state networks. Within this map we identified distinct functional connections associated with verbal and visuospatial memory. Functional anticorrelation between the hippocampal formation and the frontal pole was significantly associated with better verbal memory in an age-dependent manner. In contrast, hippocampus-motor and parietal-motor functional connections were associated with visuospatial memory independently of age. These relationships were not driven by grey matter volume and were unique to the respective memory domain. Our findings provide new insights into current models of brain-behaviour interactions, and suggest that while both episodic and visuospatial memory engage MTL nodes of the default mode network, the two memory domains differ in terms of the associated functional connections between the MTL and other resting-state brain networks.

PMID: 28756237 [PubMed - as supplied by publisher]

Acute Affective Reactivity and Quality of Life in Older Adults with Amnestic Mild Cognitive Impairment: A Functional MRI Study.

Tue, 08/01/2017 - 23:20
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Acute Affective Reactivity and Quality of Life in Older Adults with Amnestic Mild Cognitive Impairment: A Functional MRI Study.

Am J Geriatr Psychiatry. 2017 Jun 27;:

Authors: Ren P, Heffner KL, Jacobs A, Lin F

Abstract
OBJECTIVES: Poor quality of life (QoL) is a major concern among older adults with amnestic mild cognitive impairment (MCI). Maladaptive affective regulation and its relevant frontal dysfunction that are often observed in older adults with MCI may provide an insight into the understanding of their QoL.
METHODS: In this case-controlled study, participants (MCI patients, N = 18; healthy comparisons [HC], N = 21) completed cognitive tasks, and underwent resting-state functional magnetic resonance imaging (rs-fMRI) immediately before and after the tasks. The amplitude of low-frequency fluctuations (ALFF) of rs-fMRI signals was calculated to examine the brain's spontaneous activity. The change in valence from the Self-Assessment Manikin indexed affective reactivity. QoL was assessed using Quality of Life-AD measure. Multiple mediator model was used to examine the mediating effect of frontal regions' ALFF reactivity between the affective reactivity and QoL.
RESULTS: The MCI group had significantly worse QoL and more negative affective reactivity than HC group. Less negative affective reactivity was significantly associated with better QoL in MCI not HC. ALFF in the anterior cingulate cortex, medial prefrontal cortex (MPFC), and superior frontal gyrus (SFG) increased significantly less after cognitive tasks in MCI than HC. For the entire sample, greater increases of ALFF in MPFC and SFG were significantly associated with better QoL, and SFG alone significantly mediated the association between affective reactivity and QoL.
CONCLUSIONS: Enhancing SFG activation, especially among those with MCI, may provide a therapeutic target for addressing the negative impact of maladaptive affective regulation on QoL.

PMID: 28755988 [PubMed - as supplied by publisher]

Ketamine changes the local resting-state functional properties of anesthetized-monkey brain.

Tue, 08/01/2017 - 23:20
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Ketamine changes the local resting-state functional properties of anesthetized-monkey brain.

Magn Reson Imaging. 2017 Jul 26;:

Authors: Rao JS, Liu Z, Zhao C, Wei RH, Zhao W, Tian PY, Zhou X, Yang ZY, Li XG

Abstract
OBJECTIVE: Ketamine is a well-known anesthetic. 'Recreational' use of ketamine always induces psychosis-like symptoms and cognitive impairments. The acute and chronic effects of ketamine on relevant brain circuits have been studied, but the effects of single-dose ketamine administration on the local resting-state functional properties of the brain remain unknown. In this study, we aimed to assess the effects of single-dose ketamine administration on the brain local intrinsic properties.
METHODS: We used resting-state functional magnetic resonance imaging (rs-fMRI) to explore the ketamine-induced alterations of brain intrinsic properties. Seven adult rhesus monkeys were imaged with rs-fMRI to examine the fractional amplitude of low-frequency fluctuation (fALFF) and regional homogeneity (ReHo) in the brain before and after ketamine injection. Paired comparisons were used to detect the significantly altered regions.
RESULTS: Results showed that the fALFF of the prefrontal cortex (p=0.046), caudate nucleus (left side, p=0.018; right side, p=0.025), and putamen (p=0.020) in post-injection stage significantly increased compared with those in pre-injection period. The ReHo of nucleus accumbens (p=0.049), caudate nucleus (p=0.037), and hippocampus (p=0.025) increased after ketamine injection, but that of prefrontal cortex decreased (p<0.05).
CONCLUSIONS: These findings demonstrated that single-dose ketamine administration can change the regional intensity and synchronism of brain activity, thereby providing evidence of ketamine-induced abnormal resting-state functional properties in primates. This evidence may help further elucidate the effects of ketamine on the cerebral resting status.

PMID: 28755862 [PubMed - as supplied by publisher]

Driving Human Motor Cortical Oscillations Leads to Behaviorally Relevant Changes in Local GABAA Inhibition: A tACS-TMS Study.

Tue, 08/01/2017 - 23:20
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Driving Human Motor Cortical Oscillations Leads to Behaviorally Relevant Changes in Local GABAA Inhibition: A tACS-TMS Study.

J Neurosci. 2017 Apr 26;37(17):4481-4492

Authors: Nowak M, Hinson E, van Ede F, Pogosyan A, Guerra A, Quinn A, Brown P, Stagg CJ

Abstract
Beta and gamma oscillations are the dominant oscillatory activity in the human motor cortex (M1). However, their physiological basis and precise functional significance remain poorly understood. Here, we used transcranial magnetic stimulation (TMS) to examine the physiological basis and behavioral relevance of driving beta and gamma oscillatory activity in the human M1 using transcranial alternating current stimulation (tACS). tACS was applied using a sham-controlled crossover design at individualized intensity for 20 min and TMS was performed at rest (before, during, and after tACS) and during movement preparation (before and after tACS). We demonstrated that driving gamma frequency oscillations using tACS led to a significant, duration-dependent decrease in local resting-state GABAA inhibition, as quantified by short interval intracortical inhibition. The magnitude of this effect was positively correlated with the magnitude of GABAA decrease during movement preparation, when gamma activity in motor circuitry is known to increase. In addition, gamma tACS-induced change in GABAA inhibition was closely related to performance in a motor learning task such that subjects who demonstrated a greater increase in GABAA inhibition also showed faster short-term learning. The findings presented here contribute to our understanding of the neurophysiological basis of motor rhythms and suggest that tACS may have similar physiological effects to endogenously driven local oscillatory activity. Moreover, the ability to modulate local interneuronal circuits by tACS in a behaviorally relevant manner provides a basis for tACS as a putative therapeutic intervention.SIGNIFICANCE STATEMENT Gamma oscillations have a vital role in motor control. Using a combined tACS-TMS approach, we demonstrate that driving gamma frequency oscillations modulates GABAA inhibition in the human motor cortex. Moreover, there is a clear relationship between the change in magnitude of GABAA inhibition induced by tACS and the magnitude of GABAA inhibition observed during task-related synchronization of oscillations in inhibitory interneuronal circuits, supporting the hypothesis that tACS engages endogenous oscillatory circuits. We also show that an individual's physiological response to tACS is closely related to their ability to learn a motor task. These findings contribute to our understanding of the neurophysiological basis of motor rhythms and their behavioral relevance and offer the possibility of developing tACS as a therapeutic tool.

PMID: 28348136 [PubMed - indexed for MEDLINE]

Maternal Systemic Interleukin-6 During Pregnancy Is Associated With Newborn Amygdala Phenotypes and Subsequent Behavior at 2 Years of Age.

Sun, 07/30/2017 - 14:40
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Maternal Systemic Interleukin-6 During Pregnancy Is Associated With Newborn Amygdala Phenotypes and Subsequent Behavior at 2 Years of Age.

Biol Psychiatry. 2017 Jun 19;:

Authors: Graham AM, Rasmussen JM, Rudolph MD, Heim CM, Gilmore JH, Styner M, Potkin SG, Entringer S, Wadhwa PD, Fair DA, Buss C

Abstract
BACKGROUND: Maternal inflammation during pregnancy increases the risk for offspring psychiatric disorders and other adverse long-term health outcomes. The influence of inflammation on the developing fetal brain is hypothesized as one potential mechanism but has not been examined in humans.
METHODS: Participants were adult women (N = 86) who were recruited during early pregnancy and whose offspring were born after 34 weeks' gestation. A biological indicator of maternal inflammation (interleukin-6) that has been shown to influence fetal brain development in animal models was quantified serially in early, mid-, and late pregnancy. Structural and functional brain magnetic resonance imaging scans were acquired in neonates shortly after birth. Infants' amygdalae were individually segmented for measures of volume and as seeds for resting state functional connectivity. At 24 months of age, children completed a snack delay task to assess impulse control.
RESULTS: Higher average maternal interleukin-6 concentration during pregnancy was prospectively associated with larger right amygdala volume and stronger bilateral amygdala connectivity to brain regions involved in sensory processing and integration (fusiform, somatosensory cortex, and thalamus), salience detection (anterior insula), and learning and memory (caudate and parahippocampal gyrus). Larger newborn right amygdala volume and stronger left amygdala connectivity were in turn associated with lower impulse control at 24 months of age, and mediated the association between higher maternal interleukin-6 concentrations and lower impulse control.
CONCLUSIONS: These findings provide new evidence in humans linking maternal inflammation during pregnancy with newborn brain and emerging behavioral phenotypes relevant for psychiatric disorders. A better understanding of intrauterine conditions that influence offspring disease susceptibility is warranted to inform targeted early intervention and prevention efforts.

PMID: 28754515 [PubMed - as supplied by publisher]

Difference in the functional connectivity of the dorsolateral prefrontal cortex between smokers with nicotine dependence and individuals with internet gaming disorder.

Sat, 07/29/2017 - 13:20
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Difference in the functional connectivity of the dorsolateral prefrontal cortex between smokers with nicotine dependence and individuals with internet gaming disorder.

BMC Neurosci. 2017 Jul 27;18(1):54

Authors: Ge X, Sun Y, Han X, Wang Y, Ding W, Cao M, Du Y, Xu J, Zhou Y

Abstract
BACKGROUND: It has been reported that internet gaming disorder (IGD) and smokers with nicotine dependence (SND) share clinical characteristics, such as over-engagement despite negative consequences and cravings. This study is to investigate the alterations in the resting-state functional connectivity (rsFC) of the dorsolateral prefrontal cortex (DLPFC) observed in SND and IGD. In this study, 27 IGD, 29 SND, and 33 healthy controls (HC) underwent a resting-state functional magnetic resonance imaging (rs-fMRI) scan. DLPFC connectivity was determined in all participates by investigating the synchronized low-frequency fMRI signal fluctuations using a temporal seed-based correlation method.
RESULTS: Compared with the HC group, the IGD and SND groups showed decreased rsFC with DLPFC in the right insula and left inferior frontal gyrus with DLPFC. Compared with SND group, the IGD subjects exhibited increased rsFC in the left inferior temporal gyrus and right inferior orbital frontal gyrus and decreased rsFC in the right middle occipital gyrus, supramarginal gyrus, and cuneus with DLPFC.
CONCLUSION: Our results confirmed that SND and IGD share similar neural mechanisms related to craving and impulsive inhibitions. The significant difference in rsFC with DLPFC between the IGD and SND subjects may be attributed to the visual and auditory stimulation generated by long-term internet gaming.

PMID: 28750618 [PubMed - in process]

Primary Biliary Cholangitis Alters Functional Connections of the Brain's Deep Gray Matter.

Fri, 07/28/2017 - 12:00
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Primary Biliary Cholangitis Alters Functional Connections of the Brain's Deep Gray Matter.

Clin Transl Gastroenterol. 2017 Jul 27;8(7):e107

Authors: Mosher VAL, Swain MG, Pang JXQ, Kaplan GG, Sharkey KA, MacQueen GM, Goodyear BG

Abstract
OBJECTIVES: Fatigue, itch, depressed mood, and cognitive impairment significantly impact the quality of life of many patients with primary biliary cholangitis (PBC). Previous neuroimaging studies of non-hepatic diseases suggest that these symptoms are often associated with dysfunction of deep gray matter brain regions. We used resting-state functional magnetic resonance imaging (rsfMRI) to determine whether PBC patients exhibit altered functional connections of deep gray matter.
METHODS: Twenty female non-cirrhotic PBC patients and 21 age/gender-matched controls underwent rsfMRI. Resting-state functional connectivity (rsFC) of deep gray matter brain structures (putamen, thalamus, amygdala, hippocampus) was compared between groups. Fatigue, itch, mood, cognitive performance, and clinical response to ursodeoxycholic acid (UDCA) were assessed, and their association with rsFC was determined.
RESULTS: Relative to controls, PBC patients exhibited significantly increased rsFC between the putamen, thalamus, amygdala, and hippocampus, as well as with frontal and parietal regions. Reduced rsFC of the putamen and hippocampus with motor and sensory regions of the brain were also observed. Fatigue, itch, complete response to UDCA, and verbal working memory performance were also associated with altered rsFC of deep gray matter. These rsFC changes were independent of biochemical disease severity.
CONCLUSIONS: PBC patients have objective evidence of altered rsFC of the brain's deep gray matter that is in part linked to fatigue severity, itch, response to UDCA therapy, and cognitive performance. These results may guide future approaches to define how PBC leads to altered brain connectivity and provide insight into novel targets for treating PBC-associated brain dysfunction and behavioral symptoms.

PMID: 28749455 [PubMed]

Transcranial Electric Stimulation Can Impair Gains during Working Memory Training and Affects the Resting State Connectivity.

Fri, 07/28/2017 - 12:00
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Transcranial Electric Stimulation Can Impair Gains during Working Memory Training and Affects the Resting State Connectivity.

Front Hum Neurosci. 2017;11:364

Authors: Möller A, Nemmi F, Karlsson K, Klingberg T

Abstract
Transcranial electric stimulation (tES) is a promising technique that has been shown to improve working memory (WM) performance and enhance the effect of cognitive training. However, experimental set up and electrode placement are not always determined based on neurofunctional knowledge about WM, leading to inconsistent results. Additional research on the effects of tES grounded on neurofunctional evidence is therefore necessary. Sixty young, healthy, volunteers, assigned to six different groups, participated in 5 days of stimulation or sham treatment. Twenty-five of these subjects also participated in MRI acquisition. We performed three experiments: In the first one, we evaluated tES using either direct current stimulation (tDCS) with bilateral stimulation of the frontal or parietal lobe; in the second one, we used the same tDCS protocol with a different electrode placement (i.e., supraorbital cathode); in the third one, we used alternating currents (tACS) of 35 Hz, applied bilaterally to either the frontal or parietal lobes. The behavioral outcome measure was the WM capacity (i.e., number of remembered spatial position) during the 5 days of training. In a subsample of subjects we evaluated the neural effects of tDCS by measuring resting state connectivity with functional MRI, before and after the 5 days of tDCS and visuo-spatial WM training. We found a significant impairment of WM training-related gains associated with parietal tACS and frontal tDCS. Five days of tDCS stimulation was also associated with significant change in resting state connectivity revealed by multivariate pattern analysis. None of the stimulation paradigms resulted in improved WM performance or enhanced WM training gains. These results show that tES can have negative effects on cognitive plasticity and affect resting-state functional connectivity.

PMID: 28747878 [PubMed]

Combining Multiple Resting-State fMRI Features during Classification: Optimized Frameworks and Their Application to Nicotine Addiction.

Fri, 07/28/2017 - 12:00
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Combining Multiple Resting-State fMRI Features during Classification: Optimized Frameworks and Their Application to Nicotine Addiction.

Front Hum Neurosci. 2017;11:362

Authors: Ding X, Yang Y, Stein EA, Ross TJ

Abstract
Machine learning techniques have been applied to resting-state fMRI data to predict neurological or neuropsychiatric disease states. Existing studies have used either a single type of resting-state feature or a few feature types (<4) in the prediction model. However, resting-state data can be processed in many different ways, yielding different feature types containing complementary and/or novel information, leaving uncertain the most informative features to provide to the classifier. In this study, multiple resting-state features were calculated from two main analytical categories: local measures and network measures. Feature selection was adopted using an optimized grid-search approach selecting top ranked features from statistical tests. We then tested three optimized frameworks: feature combination, kernel combination, and classifier combination, all using the support vector machine as an elementary classifier, to combine these resting-state feature types. When applied to nicotine addiction, with a cohort size of 100 smokers and 100 non-smokers, via a 10-fold cross-validation procedure, the feature combination and the classifier combination achieved an accuracy of 75.5%, while the kernel combination achieved a 73.0% accuracy; all three combination frameworks improved classification performance compared to the single feature type based results (best accuracy 70.5%). This study not only reveals the discriminative power of resting-state data, but also demonstrates the efficiency of combining multiple features from one data phenotype to improve classification performance.

PMID: 28747877 [PubMed]

Hybrid High-order Functional Connectivity Networks Using Resting-state Functional MRI for Mild Cognitive Impairment Diagnosis.

Fri, 07/28/2017 - 12:00
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Hybrid High-order Functional Connectivity Networks Using Resting-state Functional MRI for Mild Cognitive Impairment Diagnosis.

Sci Rep. 2017 Jul 26;7(1):6530

Authors: Zhang Y, Zhang H, Chen X, Lee SW, Shen D

Abstract
Conventional functional connectivity (FC), referred to as low-order FC, estimates temporal correlation of the resting-state functional magnetic resonance imaging (rs-fMRI) time series between any pair of brain regions, simply ignoring the potentially high-level relationship among these brain regions. A high-order FC based on "correlation's correlation" has emerged as a new approach for abnormality detection of brain disease. However, separate construction of the low- and high-order FC networks overlooks information exchange between the two FC levels. Such a higher-level relationship could be more important for brain diseases study. In this paper, we propose a novel framework, namely "hybrid high-order FC networks" by exploiting the higher-level dynamic interaction among brain regions for early mild cognitive impairment (eMCI) diagnosis. For each sliding window-based rs-fMRI sub-series, we construct a whole-brain associated high-order network, by estimating the correlations between the topographical information of the high-order FC sub-network from one brain region and that of the low-order FC sub-network from another brain region. With multi-kernel learning, complementary features from multiple time-varying FC networks constructed at different levels are fused for eMCI classification. Compared with other state-of-the-art methods, the proposed framework achieves superior diagnosis accuracy, and hence could be promising for understanding pathological changes of brain connectome.

PMID: 28747782 [PubMed - in process]

Contextual connectivity: A framework for understanding the intrinsic dynamic architecture of large-scale functional brain networks.

Fri, 07/28/2017 - 12:00
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Contextual connectivity: A framework for understanding the intrinsic dynamic architecture of large-scale functional brain networks.

Sci Rep. 2017 Jul 26;7(1):6537

Authors: Ciric R, Nomi JS, Uddin LQ, Satpute AB

Abstract
Investigations of the human brain's connectomic architecture have produced two alternative models: one describes the brain's spatial structure in terms of static localized networks, and the other describes the brain's temporal structure in terms of dynamic whole-brain states. Here, we used tools from connectivity dynamics to develop a synthesis that bridges these models. Using resting fMRI data, we investigated the assumptions undergirding current models of the human connectome. Consistent with state-based models, our results suggest that static localized networks are superordinate approximations of underlying dynamic states. Furthermore, each of these localized, dynamic connectivity states is associated with global changes in the whole-brain functional connectome. By nesting localized dynamic connectivity states within their whole-brain contexts, we demonstrate the relative temporal independence of brain networks. Our assay for functional autonomy of coordinated neural systems is broadly applicable, and our findings provide evidence of structure in temporal state dynamics that complements the well-described static spatial organization of the brain.

PMID: 28747717 [PubMed - in process]

Resting-state brain connectivity changes in obese women after Roux-en-Y gastric bypass surgery: A longitudinal study.

Fri, 07/28/2017 - 12:00
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Resting-state brain connectivity changes in obese women after Roux-en-Y gastric bypass surgery: A longitudinal study.

Sci Rep. 2017 Jul 26;7(1):6616

Authors: Olivo G, Zhou W, Sundbom M, Zhukovsky C, Hogenkamp P, Nikontovic L, Stark J, Wiemerslage L, Larsson EM, Benedict C, Schiöth HB

Abstract
Bariatric surgery is an effective method to rapidly induce weight loss in severely obese people, however its impact on brain functional connectivity after longer periods of follow-up is yet to be assessed. We investigated changes in connectivity in 16 severely obese women one month before, one month after and one year after Roux-en-Y gastric bypass surgery (RYGB). 12 lean controls were also enrolled. Resting-state fMRI was acquired for all participants following an overnight fast and after a 260 kcal load. Connectivity between regions involved in food-related saliency attribution and reward-driven eating behavior was stronger in presurgery patients compared to controls, but progressively weakened after follow-up. At one year, changes in networks related to cognitive control over eating and bodily perception also occurred. Connectivity between regions involved in emotional control and social cognition had a temporary reduction early after treatment but had increased again after one year of follow-up. Furthermore, we could predict the BMI loss by presurgery connectivity in areas linked to emotional control and social interaction. RYGBP seems to reshape brain functional connectivity, early affecting cognitive control over eating, and these changes could be an important part of the therapeutic effect of bariatric surgery.

PMID: 28747648 [PubMed - in process]

Functional connectivity of the left DLPFC to striatum predicts treatment response of depression to TMS.

Fri, 07/28/2017 - 12:00
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Functional connectivity of the left DLPFC to striatum predicts treatment response of depression to TMS.

Brain Stimul. 2017 Jul 13;:

Authors: Avissar M, Powell F, Ilieva I, Respino M, Gunning FM, Liston C, Dubin MJ

Abstract
BACKGROUND: Repetitive transcranial magnetic stimulation (TMS) is a non-invasive, safe, and efficacious treatment for depression. TMS has been shown to normalize abnormal functional connectivity of cortico-cortical circuits in depression and baseline functional connectivity of these circuits predicts treatment response. Less is known about the relationship between functional connectivity of frontostriatal circuits and treatment response.
OBJECTIVE/HYPOTHESIS: We investigated whether baseline functional connectivity of distinct frontostriatal circuits predicted response to TMS.
METHODS: Resting-state fMRI (rsfMRI) was acquired in 27 currently depressed subjects with treatment resistant depression and 27 healthy controls. Depressed subjects were treated with 5 weeks of daily TMS over the left dorsolateral prefrontal cortex (DLPFC). The functional connectivity between limbic, executive, rostral motor, and caudal motor regions of frontal cortex and their corresponding striatal targets were determined at baseline using an existing atlas based on diffusion tensor imaging. TMS treatment response was measured by percent reduction in the 24-item Hamilton Depression Rating Scale (HAMD24). In an exploratory analysis, correlations were determined between baseline functional connectivity and TMS treatment response.
RESULTS: Seven cortical clusters belonging to the executive and rostral motor frontostriatal projections had reduced functional connectivity in depression compared to healthy controls. No frontostriatal projections showed increased functional connectivity in depression (voxel-wise p < 0.01, family-wise α < 0.01). Only baseline functional connectivity between the left DLPFC and the striatum predicted TMS response. Higher baseline functional connectivity correlated with greater reductions in HAMD24 (Pearson's R = 0.58, p = 0.002).
CONCLUSION(S): In an exploratory analysis, higher functional connectivity between the left DLPFC and striatum predicted better treatment response. Our findings suggest that the antidepressant mechanism of action of TMS may require connectivity from cortex proximal to the stimulation site to the striatum.

PMID: 28747260 [PubMed - as supplied by publisher]

Graph Lasso-based test for evaluating functional brain connectivity in sickle cell disease.

Fri, 07/28/2017 - 12:00
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Graph Lasso-based test for evaluating functional brain connectivity in sickle cell disease.

Brain Connect. 2017 Jul 26;:

Authors: Coloigner J, Phlypo R, Coates TD, Lepore N, Wood JC

Abstract
Sickle cell disease (SCD) is a vascular disorder that is often associated with recurrent ischemia-reperfusion injury, anemia, vasculopathy and strokes. These cerebral injuries are associated with neurological dysfunction, limiting the full developing potential of the patient. However, recent large studies of SCD have demonstrated that cognitive impairment occurs even in the absence of brain abnormalities on conventional magnetic resonance imaging (MRI). These observations support an emerging consensus that brain injury in SCD is diffuse and that conventional neuroimaging often underestimates the extent of injury. In this paper, we postulated that alterations in the cerebral connectivity may constitute a sensitive biomarker of SCD severity. Using functional MRI, a connectivity study analyzing the SCD patients individually was performed. First, a robust learning scheme based on graphical lasso model and Fréchet mean was used for estimating a consistent descriptor of healthy brain connectivity. Then, we tested a statistical method that provides an individual index of similarity between this healthy connectivity model and each SCD patient's connectivity matrix. Our results demonstrated that the reference connectivity model was not appropriate to model connectivity for only 4 out of 27 patients. After controlling for the gender, two separate predictors of this individual similarity index were the anemia (p=0.02) and white matter hyperintensities (silent stroke) (p=0.03), so that patients with low hemoglobin level or with white matter hyperintensities have the least similarity to the reference connectivity model. Further studies are required to determine whether the resting state connectivity changes reflect pathological changes or compensatory responses to chronic anemia.

PMID: 28747064 [PubMed - as supplied by publisher]

Neural substrates of context- and person-dependent altruistic punishment.

Thu, 07/27/2017 - 11:00
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Neural substrates of context- and person-dependent altruistic punishment.

Hum Brain Mapp. 2017 Jul 26;:

Authors: Wang L, Lu X, Gu R, Zhu R, Xu R, Broster LS, Feng C

Abstract
Human altruistic behaviors are heterogeneous across both contexts and people, whereas the neural signatures underlying the heterogeneity remain to be elucidated. To address this issue, we examined the neural signatures underlying the context- and person-dependent altruistic punishment, conjoining event-related fMRI with both task-based and resting-state functional connectivity (RSFC). Acting as an impartial third party, participants decided how to punish norm violators either alone or in the presence of putative others. We found that the presence of others decreased altruistic punishment due to diffusion of responsibility. Those behavioral effects paralleled altered neural responses in the dorsal anterior cingulate cortex (dACC) and putamen. Further, we identified modulation of responsibility diffusion on task-based functional connectivity of dACC with the brain regions implicated in reward processing (i.e., posterior cingulate cortex and amygdala/orbital frontal cortex). Finally, the RSFC results revealed that (i) increased intrinsic connectivity strengths of the putamen with temporoparietal junction and dorsolateral PFC were associated with attenuated responsibility diffusion in altruistic punishment and (ii) increased putamen-dorsomedial PFC connectivity strengths were associated with reduced responsibility diffusion in self-reported responsibility. Taken together, our findings elucidate the context- and person-dependent altruistic behaviors as well as associated neural substrates and thus provide a potential neurocognitive mechanism of heterogeneous human altruistic behaviors. Hum Brain Mapp, 2017. © 2017 Wiley Periodicals, Inc.

PMID: 28744939 [PubMed - as supplied by publisher]

Multimodal Fingerprints of Resting State Networks as assessed by Simultaneous Trimodal MR-PET-EEG Imaging.

Thu, 07/27/2017 - 11:00
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Multimodal Fingerprints of Resting State Networks as assessed by Simultaneous Trimodal MR-PET-EEG Imaging.

Sci Rep. 2017 Jul 25;7(1):6452

Authors: Shah NJ, Arrubla J, Rajkumar R, Farrher E, Mauler J, Kops ER, Tellmann L, Scheins J, Boers F, Dammers J, Sripad P, Lerche C, Langen KJ, Herzog H, Neuner I

Abstract
Simultaneous MR-PET-EEG (magnetic resonance imaging - positron emission tomography - electroencephalography), a new tool for the investigation of neuronal networks in the human brain, is presented here for the first time. It enables the assessment of molecular metabolic information with high spatial and temporal resolution in a given brain simultaneously. Here, we characterize the brain's default mode network (DMN) in healthy male subjects using multimodal fingerprinting by quantifying energy metabolism via 2- [(18)F]fluoro-2-desoxy-D-glucose PET (FDG-PET), the inhibition - excitation balance of neuronal activation via magnetic resonance spectroscopy (MRS), its functional connectivity via fMRI and its electrophysiological signature via EEG. The trimodal approach reveals a complementary fingerprint. Neuronal activation within the DMN as assessed with fMRI is positively correlated with the mean standard uptake value of FDG. Electrical source localization of EEG signals shows a significant difference between the dorsal DMN and sensorimotor network in the frequency range of δ, θ, α and β-1, but not with β-2 and β-3. In addition to basic neuroscience questions addressing neurovascular-metabolic coupling, this new methodology lays the foundation for individual physiological and pathological fingerprints for a wide research field addressing healthy aging, gender effects, plasticity and different psychiatric and neurological diseases.

PMID: 28743861 [PubMed - in process]

Brain structural and functional dissociated patterns in schizophrenia.

Thu, 07/27/2017 - 11:00
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Brain structural and functional dissociated patterns in schizophrenia.

BMC Psychiatry. 2017 Jan 31;17(1):45

Authors: Zhuo C, Zhu J, Wang C, Qu H, Ma X, Tian H, Liu M, Qin W

Abstract
BACKGROUND: Although previous studies found that aberrations in gray matter volume (GMV) and global functional connectivity density (gFCD) are important characteristics of schizophrenia, to the best of our knowledge no study to date has investigated the associations between the spatial distribution patterns of GMV and gFCD alterations. We investigated pattern changes in gFCD and GMV among patients with schizophrenia and their associated spatial distributions.
METHODS: Ninety-five patients with schizophrenia and 93 matched healthy controls underwent structural and resting-state functional MRI scanning to assess gFCD and GMV.
RESULTS: We found that gFCD increased in the subcortical regions (caudate, pallidum, putamen, and thalami) and limbic system (left hippocampus and parahippocampus), and decreased in the posterior parieto-occipito-temporal cortices (postcentral gyri, occipital cortex, temporo-occipital conjunction, and inferior parietal lobule), in patients with schizophrenia. By contrast, we found decreased GMV in brain regions including the frontal, parietal, temporal, occipital, cingulate cortices, and the insular, striatum, thalamus in these patients. Increased gFCD primarily occurred in subcortical regions including the basal ganglia and some regions of the limbic system. Decreased gFCD appeared primarily in the cortical regions. There were no statistically significant correlations between changes in gFCD and GMV, and their spatial distribution patterns, in different regions.
CONCLUSIONS: Our findings indicate that gFCD and GMV are both perturbed in multiple brain regions in schizophrenia. gFCD and GMV consistently decreased in the cortical regions, with the exception of the Supplementary Motor Area (SMA). However, in the sub-cortical regions, the alterations of gFCD and GMV showed the opposite pattern, with increased gFCD and decreased GMV simultaneously observed in these regions. Overall, our findings suggest that structural and functional alterations appear to contribute independently to the neurobiology of schizophrenia.

PMID: 28143464 [PubMed - indexed for MEDLINE]

Altered connectivity within and between the default mode, central executive, and salience networks in obsessive-compulsive disorder.

Wed, 07/26/2017 - 16:20

Altered connectivity within and between the default mode, central executive, and salience networks in obsessive-compulsive disorder.

J Affect Disord. 2017 Jul 20;223:106-114

Authors: Fan J, Zhong M, Gan J, Liu W, Niu C, Liao H, Zhang H, Yi J, Chan RCK, Tan C, Zhu X

Abstract
BACKGROUND: Default mode network (DMN), central executive network (CEN) and salience network (SN) are the three most important intrinsic networks of the human brain. Recent studies emphasized the importance of the "triple-network model" which illustrated the interactions within and between DMN, CEN and SN in the pathophysiology of psychiatric disorders. However, previous studies of obsessive-compulsive disorder (OCD) just explored the altered connectivity within these networks while neglected the coupling between them. Hence, the present study was designed to fill this research gap.
METHODS: Resting-state functional magnetic resonance imaging (fMRI) data from 35 OCD patients and 32 healthy controls (HCs) were acquired. Independent component analysis (ICA) was used to extract sub-networks of the DMN, CEN, and SN. Functional connectivity (FC) values within and between these networks were measured.
RESULTS: OCD patients had increased FC within several DMN, CEN, and SN subsystems. In addition, OCD patients demonstrated aberrant functional interactions between the SN and anterior DMN (aDMN) as well as between the SN and the dorsal CEN (dCEN), and the interaction between the SN and dCEN significantly correlated with trait anxiety level in the OCD group.
LIMITATION: Lack of the assessments of cognitive functions is the main limitation of the present study.
CONCLUSIONS: Not only impaired coupling within the brain core intrinsic large-scale networks, but also coupling between large-scale neurocognitive networks, which reflect the difficulties in switching between task-negative and task-positive processing modes are involved in the neurobiological mechanism of OCD.

PMID: 28743059 [PubMed - as supplied by publisher]

Multimodal characterization of gray matter alterations in neuromyelitis optica.

Wed, 07/26/2017 - 16:20
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Multimodal characterization of gray matter alterations in neuromyelitis optica.

Mult Scler. 2017 Jul 01;:1352458517721053

Authors: Liu Y, Jiang X, Butzkueven H, Duan Y, Huang J, Ren Z, Dong H, Shi FD, Barkhof F, Li K, Wang J

Abstract
OBJECTIVE: To investigate structural and functional alterations of gray matter (GM) and examine their clinical relevance in neuromyelitis optica (NMO) using multimodal magnetic resonance imaging (MRI) techniques.
METHODS: A total of 35 NMO and 36 healthy controls (HC) were recruited in this study. Cortical lesions were investigated by double inversion recovery technique. Five voxel-wise MRI measurements were obtained for each participant in the GM including gray matter volume (GMV), fractional anisotropy (FA), mean diffusivity (MD), amplitude of low-frequency fluctuation (ALFF), and weighted functional connectivity strength (wFCS). Between-group differences, cross-modality relationships, and MRI-clinical correlations were examined.
RESULTS: No cortical lesions were found in NMO. Compared to HC, NMO patients exhibited significantly decreased GMV in deep GM and cortical regions involving visual function and cognition. Diffusion GM abnormalities were widespread in the patients. Decreased ALFF and wFCS were observed in the patients in sensorimotor, visual, cognition, and cerebellar sites. GM structural alterations were correlated with cognitive but not physical disability scores of the patients.
CONCLUSION: Despite the lack of focal cortical lesions, patients with NMO exhibit both structural and functional alterations of GM in cerebrum and cerebellum that predominantly involve deep GM, visual, motor, and cognitive regions. GM alterations are associated with cognitive impairment but not physical disability.

PMID: 28741987 [PubMed - as supplied by publisher]

Reduced Ventral Tegmental Area-Hippocampal Connectivity in Children and Adolescents Exposed to Early Threat.

Wed, 07/26/2017 - 16:20
Related Articles

Reduced Ventral Tegmental Area-Hippocampal Connectivity in Children and Adolescents Exposed to Early Threat.

Biol Psychiatry Cogn Neurosci Neuroimaging. 2017 Mar;2(2):130-137

Authors: Marusak HA, Hatfield JRB, Thomason ME, Rabinak CA

Abstract
BACKGROUND: Preclinical data suggest that early life stress has detrimental effects on the brain's dopaminergic system, particularly the mesocorticolimbic pathway. Altered dopamine function is thought to contribute to the development of stress-related pathologies; yet, little is known about the impact of early stress on dopamine systems during childhood and adolescence, when stress-related disorders frequently emerge. Here, we evaluate the impact of early threat exposure (violence, abuse) on functional connectivity of putative dopaminergic midbrain regions, the ventral tegmental area (VTA) and substantia nigra (SN), giving rise to mesocorticolimbic and nigrostriatal pathways, respectively.
METHODS: Resting-state functional magnetic resonance imaging scans were completed in 43 trauma-exposed and 43 matched comparison youth (ages 7-17). Functional connectivity of the VTA and SN were compared between groups.
RESULTS: The trauma group demonstrated lower functional connectivity between the VTA and hippocampus. No group differences in SN connectivity were observed. Across all participants, there were age-related decreases in connectivity of both VTA and SN with the hippocampus, suggesting that age-related attenuations in VTA-hippocampal circuitry may be exacerbated in trauma-exposed youth. Higher levels of anxiety symptomology were associated with reduced SN-nucleus accumbens connectivity.
CONCLUSIONS: Prior research suggests that VTA-hippocampal circuitry is critical for the gating of new information into long-term memory. Lower connectivity in this circuitry suggests a novel mechanism that may serve to adaptively prevent the overwriting of a previously stored trauma memory, but at the same time contribute to the broad range of cognitive and emotional difficulties linked to early stress exposure.

PMID: 28740870 [PubMed]

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