New resting-state fMRI related studies at PubMed

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Abnormal Functional Connectivity of Anterior Cingulate Cortex in Patients With Primary Insomnia: A Resting-State Functional Magnetic Resonance Imaging Study.

Thu, 06/21/2018 - 11:00
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Abnormal Functional Connectivity of Anterior Cingulate Cortex in Patients With Primary Insomnia: A Resting-State Functional Magnetic Resonance Imaging Study.

Front Aging Neurosci. 2018;10:167

Authors: Yan CQ, Liu CZ, Wang X, Huo JW, Zhou P, Zhang S, Fu QN, Zhang J, Wang ZY, Liu QQ

Abstract
Background: Recently, there have been many reports about abnormalities regarding structural and functional brain connectivity of the patients with primary insomnia. However, the alterations in functional interaction between the left and right cerebral hemispheres have not been well understood. The resting-state fMRI approach, which reveals spontaneous neural fluctuations in blood-oxygen-level-dependent signals, offers a method to quantify functional interactions between the hemispheres directly. Methods: We compared interhemispheric functional connectivity (FC) between 26 patients with primary insomnia (48.85 ± 12.02 years) and 28 healthy controls (49.07 ± 11.81 years) using a voxel-mirrored homotopic connectivity (VMHC) method. The patients with primary insomnia and healthy controls were matched for age, gender, and education. Brain regions, which had significant differences in VMHC maps between the primary insomnia and healthy control groups, were defined as seed region of interests. A seed-based approach was further used to reveal significant differences of FC between the seeds and the whole contralateral hemisphere. Results: The patients with primary insomnia showed higher VMHC than healthy controls in the anterior cingulate cortex (ACC) bilaterally. The seed-based analyses demonstrated increased FC between the left ACC and right thalamus (and the right ACC and left orbitofrontal cortex) in patients with primary insomnia, revealing abnormal connectivity between the two cerebral hemispheres. The VMHC values in the ACC were positively correlated with the time to fall asleep and Self-Rating Depression Scale scores (SDS). Conclusions: The results demonstrate that there is abnormal interhemispheric resting-state FC in the brain regions of patients with primary insomnia, especially in the ACC. Our finding demonstrates valid evidence that the ACC is an area of interest in the neurobiology of primary insomnia.

PMID: 29922151 [PubMed]

Treatment response prediction and individualized identification of first-episode drug-naïve schizophrenia using brain functional connectivity.

Thu, 06/21/2018 - 11:00
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Treatment response prediction and individualized identification of first-episode drug-naïve schizophrenia using brain functional connectivity.

Mol Psychiatry. 2018 Jun 19;:

Authors: Cao B, Cho RY, Chen D, Xiu M, Wang L, Soares JC, Zhang XY

Abstract
Identifying biomarkers in schizophrenia during the first episode without the confounding effects of treatment has been challenging. Leveraging these biomarkers to establish diagnosis and make individualized predictions of future treatment responses to antipsychotics would be of great value, but there has been limited progress. In this study, by using machine learning algorithms and the functional connections of the superior temporal cortex, we successfully identified the first-episode drug-naive (FEDN) schizophrenia patients (accuracy 78.6%) and predict their responses to antipsychotic treatment (accuracy 82.5%) at an individual level. The functional connections (FC) were derived using the mutual information and the correlations, between the blood-oxygen-level dependent signals of the superior temporal cortex and other cortical regions acquired with the resting-state functional magnetic resonance imaging. We also found that the mutual information and correlation FC was informative in identifying individual FEDN schizophrenia and prediction of treatment response, respectively. The methods and findings in this paper could provide a critical step toward individualized identification and treatment response prediction in first-episode drug-naive schizophrenia, which could complement other biomarkers in the development of precision medicine approaches for this severe mental disorder.

PMID: 29921920 [PubMed - as supplied by publisher]

Test-retest reliability of cerebral blood flow in healthy individuals using arterial spin labeling: Findings from the EMBARC study.

Thu, 06/21/2018 - 11:00
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Test-retest reliability of cerebral blood flow in healthy individuals using arterial spin labeling: Findings from the EMBARC study.

Magn Reson Imaging. 2018 Jan;45:26-33

Authors: Almeida JRC, Greenberg T, Lu H, Chase HW, Fournier JC, Cooper CM, Deckersbach T, Adams P, Carmody T, Fava M, Kurian B, McGrath PJ, McInnis MG, Oquendo MA, Parsey R, Weissman M, Trivedi M, Phillips ML

Abstract
INTRODUCTION: Previous investigations of test-retest reliability of cerebral blood flow (CBF) at rest measured with pseudo-continuous Arterial Spin Labeling (pCASL) demonstrated good reliability, but are limited by the use of similar scanner platforms. In the present study we examined test-retest reliability of CBF in regions implicated in emotion and the default mode network.
MATERIAL AND METHODS: We measured absolute and relative CBF at rest in thirty-one healthy subjects in two scan sessions, one week apart, at four different sites and three different scan platforms. We derived CBF from pCASL images with an automated algorithm and calculated intra-class correlation coefficients (ICCs) across sessions for regions of interest. In addition, we investigated site effects.
RESULTS: For both absolute and relative CBF measures, ICCs were good to excellent (i.e. >0.6) in most brain regions, with highest values observed for the subgenual anterior cingulate cortex and ventral striatum. A leave-one-site-out cross validation analysis did not show a significant effect for site on whole brain CBF and there was no proportional bias across sites. However, a significant site effect was present in the repeated measures ANOVA.
CONCLUSIONS: The high test-retest reliability of CBF measured with pCASL in a range of brain regions implicated in emotion and salience processing, emotion regulation, and the default mode network, which have been previously linked to depression symptomatology supports its use in studies that aim to identify neuroimaging biomarkers of treatment response.

PMID: 28888770 [PubMed - indexed for MEDLINE]

Pretherapeutic motor thalamus resting-state functional connectivity with visual areas predicts tremor arrest after thalamotomy for essential tremor: tracing the cerebello-thalamo-visuo-motor network.

Wed, 06/20/2018 - 16:20
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Pretherapeutic motor thalamus resting-state functional connectivity with visual areas predicts tremor arrest after thalamotomy for essential tremor: tracing the cerebello-thalamo-visuo-motor network.

World Neurosurg. 2018 Jun 16;:

Authors: Tuleasca C, Najdenovska E, Régis J, Witjas T, Girard N, Champoudry J, Faouzi M, Thiran JP, Cuadra MB, Levivier M, Van De Ville D

Abstract
BACKGROUND: Essential tremor (ET) is a common movement disorder. Resting state fMRI (rs-fMRI) is non-invasive neuroimaging method acquired in absence of task.
OBJECTIVE: Our study aims at correlating pretherapeutic ventro-lateral thalamus functional connectivity (FC) with clinical result 1 year after stereotactic radiosurgical thalamotomy (SRS-T) for drug-resistant ET. Data from 12 healthy controls was included.
METHODS: Resting-state was acquired for 17 consecutive (right handed) patients, before and after left unilateral SRS-T. Standard tremor scores were evaluated pretherapeutically and 1 year after SRS-T. Tremor network was investigated using region-of-interest (ROI), left ventro-lateral ventral (VLV) cluster, obtained from pretherapeutic diffusion MRI. Seed-based functional connectivity (FC) was obtained as correlations between the VLV's time courses and the one of every voxel. The seed-connectivity maps were obtained pretherapeutically and correlated across all patients with clinical outcome 1 year after SRS-T. One-year MR-signature volume was always located inside VLV and did not correlate with reported seed-FC measures (p>0.05).
RESULTS: We report statistically significant correlations between pretherapeutic seed-FC with clinical outcome for: 1). right visual association area (Brodmann area, BA 19) predicting 1 year activities of daily living (ADL) drop (punc=0.02); 2). left fusiform gyrus (BA 37) predicting 1 year head tremor score improvement (punc=0.04); 3). posterior cingulate (left BA 23, puncor=0.009), lateral temporal cortex (right BA 21, punc=0.02) predicting time to tremor arrest .
CONCLUSIONS: Our results suggest that pretherapeutic resting-state seed-FC of left VLV predicts tremor arrest after SRS-T for ET. Visual areas are identified as the main regions in this correlation.

PMID: 29920392 [PubMed - as supplied by publisher]

Consistent decreased activity in the putamen in Parkinson's disease: A meta-analysis and an independent validation of resting-state fMRI.

Wed, 06/20/2018 - 16:20
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Consistent decreased activity in the putamen in Parkinson's disease: A meta-analysis and an independent validation of resting-state fMRI.

Gigascience. 2018 Jun 18;:

Authors: Wang J, Zhang JR, Zang YF, Wu T

Abstract
Background: Resting-state functional magnetic resonance imaging (RS-fMRI) has frequently been used to investigate local spontaneous brain activity in Parkinson's disease (PD) in a whole-brain, voxel-wise manner. To quantitatively integrate these studies, we conducted a coordinate-based meta-analysis (CB meta-analysis), using the seed-based d mapping (SDM) method, on 15 studies that used amplitude of low frequency fluctuation (ALFF) and 11 studies that used regional homogeneity (ReHo). All these ALFF and ReHo studies have compared PD patients with healthy controls. We also performed a validation RS-fMRI study of ALFF and ReHo in a frequency-dependent manner for a novel dataset consisting of 49 PD and 49 healthy controls.
Findings: Decreased ALFF was found in the left putamen in PD by meta-analysis. This finding was replicated in our independent validation dataset in the 0.027 - 0.073 Hz band, but not in the conventional frequency band of 0.01 - 0.08 Hz.
Conclusions: Findings from the current study suggested that decreased ALFF in the putamen of PD is the most consistent finding. RS-fMRI is a promising technique for the precise localization of abnormal spontaneous activity in PD. However, more frequency-dependent studies using the same analytical methods are needed to replicate these results.

PMID: 29917066 [PubMed - as supplied by publisher]

Ghrelin reductions following bariatric surgery were associated with decreased resting state activity in the hippocampus.

Wed, 06/20/2018 - 16:20
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Ghrelin reductions following bariatric surgery were associated with decreased resting state activity in the hippocampus.

Int J Obes (Lond). 2018 Jun 18;:

Authors: Zhang Y, Ji G, Li G, Hu Y, Liu L, Jin Q, Meng Q, Zhao J, Yuan K, Liu J, von Deneen KM, Chen A, Cui G, Wang H, Zhao Q, Wu K, Tian J, Manza P, Tomasi D, Volkow ND, Nie Y, Wang GJ

Abstract
BACKGROUND/OBJECTIVE: Laparoscopic sleeve gastrectomy (LSG) is an effective bariatric surgery to treat obesity, and involves removal of the gastric fundus where ghrelin is mainly produced. Ghrelin stimulates appetite and regulates food intake through its effect on the hypothalamus and hippocampus (HIPP). While ghrelin's role on the hypothalamus has been explored, little is known about its role on HIPP. We tested the hypothesis that LSG-induced reductions in ghrelin levels would be associated with changes in HIPP activity.
SUBJECTS/METHODS: Brain activity was measured with amplitude of low-frequency fluctuations (ALFF) captured with resting-state functional magnetic resonance imaging (fMRI) in 30 obese participants, both before and after 1-month of LSG, and in 26 obese controls without surgery that were studied at baseline and 1-month later. A two-way analysis of variance (ANOVA) was performed to model the group and time effects on ALFF and resting-state functional connectivity.
RESULTS: One-month post-LSG there were significant decreases in appetite, body mass index (BMI), fasting plasma ghrelin and leptin levels, anxiety, and ALFF in HIPP and ALFF increases in posterior cingulate cortex (PCC, PFWE < 0.05). Decreases in HIPP ALFF correlated positively with decreases in fasting ghrelin and anxiety, and increases in PCC ALFF correlated positively with decreases in anxiety. Seed-voxel correlation analysis showed stronger connectivity between HIPP and insula, and between PCC and dorsolateral prefrontal cortex (DLPFC) post-LSG.
CONCLUSIONS: These findings suggest that ghrelin effects in HIPP modulate connectivity with the insula, which processes interoception and might be relevant to LSG-induced reductions in appetite/anxiety. Role of LSG in PCC and its enhanced connectivity with DLPFC in improving self-regulation following LSG requires further investigation.

PMID: 29915363 [PubMed - as supplied by publisher]

Multicenter Resting State Functional Connectivity in Prodromal and Dementia Stages of Alzheimer's Disease.

Wed, 06/20/2018 - 16:20
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Multicenter Resting State Functional Connectivity in Prodromal and Dementia Stages of Alzheimer's Disease.

J Alzheimers Dis. 2018 Jun 09;:

Authors: Teipel SJ, Metzger C, Brosseron F, Buerger K, Brueggen K, Catak C, Diesing D, Dobisch L, Fliebach K, Franke C, Heneka M, Kilimann I, Kofler B, Menne F, Peters O, Polcher A, Priller J, Schneider A, Spottke A, Spruth EJ, Thelen M, Thyrian RJ, Wagner M, Düzel E, Jessen F, Dyrba M, DELCODE study group

Abstract
BACKGROUND: Alterations of intrinsic networks from resting state fMRI (rs-fMRI) have been suggested as functional biomarkers of Alzheimer's disease (AD).
OBJECTIVE: To determine the diagnostic accuracy of multicenter rs-fMRI for prodromal and preclinical stages of AD.
METHODS: We determined rs-fMRI functional connectivity based on Pearson's correlation coefficients and amplitude of low-frequency fluctuation in people with subjective cognitive decline, people with mild cognitive impairment, and people with AD dementia compared with healthy controls. We used data of 247 participants of the prospective DELCODE study, a longitudinal multicenter observational study, imposing a unified fMRI acquisition protocol across sites. We determined cross-validated discrimination accuracy based on penalized logistic regression to account for multicollinearity of predictors.
RESULTS: Resting state functional connectivity reached significant cross-validated group discrimination only for the comparison of AD dementia cases with healthy controls, but not for the other diagnostic groups. AD dementia cases showed alterations in a large range of intrinsic resting state networks, including the default mode and salience networks, but also executive and language networks. When groups were stratified according to their CSF amyloid status that was available in a subset of cases, diagnostic accuracy was increased for amyloid positive mild cognitive impairment cases compared with amyloid negative controls, but still inferior to the accuracy of hippocampus volume.
CONCLUSION: Even when following a strictly harmonized data acquisition protocol and rigorous scan quality control, widely used connectivity measures of multicenter rs-fMRI do not reach levels of diagnostic accuracy sufficient for a useful biomarker in prodromal stages of AD.

PMID: 29914027 [PubMed - as supplied by publisher]

Neuroimaging of the human visceral pain system-A methodological review.

Wed, 06/20/2018 - 16:20
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Neuroimaging of the human visceral pain system-A methodological review.

Scand J Pain. 2017 Dec 29;2(3):95-104

Authors: Frøkjær JB, Olesen SS, Graversen C, Andresen T, Lelic D, Drewes AM

Abstract
During the last decades there has been a tremendous development of non-invasive methods for assessment of brain activity following visceral pain. Improved methods for neurophysiological and brain imaging techniques have vastly increased our understanding of the central processing of gastrointestinal sensation and pain in both healthy volunteers as well as in patients suffering from gastrointestinal disorders. The techniques used are functional magnetic resonance imaging (fMRI), positron emission tomography (PET), electroencephalography (EEG)/evoked brain potentials (EPs), magnetoencephalography (MEG), single photon emission computed tomography (SPECT), and the multimodal combinations of these techniques. The use of these techniques has brought new insight into the complex brain processes underlying pain perception, including a number of subcortical and cortical regions, and paved new ways in our understanding of acute and chronic pain. The pathways are dynamic with a delicate balance between facilitatory and inhibitory pain mechanisms, and with modulation of the response to internal or external stressors with a high degree of plasticity. Hence, the ultimate goal in imaging of pain is to follow the stimulus response throughout the neuraxis. Brain activity measured by fMRI is based on subtracting regional changes in blood oxygenation during a resting condition from the signal during a stimulus condition, and has high spatial resolution but low temporal resolution. SPECT and PET are nuclear imaging techniques where radiolabeled molecules are injected with visualization of the distribution, density and activity of receptors in the brain allowing not only assessment of brain activity but also study of receptor sites. EEG is based on assessment of electrical activity in the brain, and recordings of the resting EEG and evoked potentials following an external stimulus are used to study normal visceral pain processing, alterations of pain processing in different patient groups and the effect of pharmacological intervention. EEG has high temporal resolution, but relative poor spatial resolution, which however to some extent can be overcome by applying inverse modelling algorithms and signal decomposition procedures. MEG is based on recording the magnetic fields produced by electrical currents in the brain, has high spatial resolution and is especially suitable for the study cortical activation. The treatment of chronic abdominal pain is often ineffective and dissapointing, which leads to search for optimized treatment achieved on the basis of a better understanding of underlying pain mechanisms. Application of the recent improvements in neuroimaging on the visceral pain system may likely in near future contribute substantially to our understanding of the functional and structural pathophysiology underlying chronic visceral pain disorders, and pave the road for optimized individual and mechanism based treatments. The purpose of this review is to give a state-of-the-art overview of these methods, with focus on EEG, and especially the advantages and limitations of the single methods in clinical gastrointestinal pain esearch including examples from relevant studies.

PMID: 29913746 [PubMed - in process]

Effect sizes of BOLD CVR, resting-state signal fluctuations and time delay measures for the assessment of hemodynamic impairment in carotid occlusion patients.

Tue, 06/19/2018 - 15:20

Effect sizes of BOLD CVR, resting-state signal fluctuations and time delay measures for the assessment of hemodynamic impairment in carotid occlusion patients.

Neuroimage. 2018 Jun 15;:

Authors: De Vis JB, Bhogal AA, Hendrikse J, Petersen ET, Siero JCW

Abstract
BACKGROUND AND PURPOSE: The BOLD signal amplitude as a response to a hypercapnia stimulus is commonly used to assess cerebrovascular reserve. Despite recent advances, the implementation remains cumbersome and alternative ways to assess hemodynamic impairment are desirable. Resting-state BOLD signal fluctuations (rsBOLD) have been proposed however data on its sensitivity and dependence on baseline venous cerebral blood volume (vCBV) is limited. The primary aim of this study was to compare the effect sizes of resting-state and hypercapnia induced BOLD signal changes in the detection of hemodynamic impairment. The second aim of the study was to assess the dependence of BOLD signal variability on vCBV.
MATERIALS AND METHODS: Fifteen patients with internal carotid artery occlusive disease and 15 matched healthy controls were included in this study. The BOLD signal was derived from a dual-echo gradient-echo echo-planar sequence during hypercapnia (HC) and hyperoxia (HO) gas modulations. BOLD (fractional) amplitude of low frequency fluctuations ((f)ALFF) was compared to HC-BOLD, BOLD response delays derived from time delay analysis and ΔBOLD in response to progressively increasing HC. Effect sizes (i.e. the standard mean difference between patients and controls) were calculated. HO-BOLD was used to estimate vCBV, and its contribution to the variability in rsBOLD signal was evaluated.
RESULTS: The effect sizes of ALFF and fALFF (0.61 and 0.72) were lower than the effect sizes related to hypercapnia-based hemodynamic assessment analysis; 1.62, 1.56 and 0.90 for HC-BOLD, BOLD response delays and ΔBOLD in response to progressively increasing HC. A moderate relation was found between (f)ALFF and HC-BOLD in controls (R2 of 0.61 and 0.42), but this relation decreased in patients (R2 of 0.33 and 0.15). (f)ALFF did not differ between patients and controls whereas HC-BOLD did (p < 0.005). The ΔBOLD response to progressively increasing HC was significantly different in between patients and controls for ΔEtCO2 values ≥ 2 mmHg (at +2  mmHg F(1, 18) = 5.85, p = 0.026). Up to 31% and 53% of the variance in the ALFF and HC-BOLD spatial distribution could be explained by HO-BOLD.
CONCLUSION: ALFF and fALFF demonstrated a moderate effect size to detect hemodynamic impairment whereas the effect size was large for methods employing a hypercapnia-based vascular stress stimulus. Based on our analysis of BOLD signal change as a response to a progressively increasing hypercapnia stimulus we can argue that a hypercapnia stimulus of at least 2 mmHg above baseline EtCO2 is necessary to evaluate hemodynamic impairment. We also demonstrated that a substantial amount of information imbedded in the rsBOLD and HC-BOLD was explained by HO-BOLD. HO-BOLD can serve as a proxy for vCBV and this thus indicates that one should be careful when adopting these techniques in disease cases with compromised CBV.

PMID: 29913284 [PubMed - as supplied by publisher]

Anterior Cingulate Glutamate and GABA Associations on Functional Connectivity in Schizophrenia.

Tue, 06/19/2018 - 15:20

Anterior Cingulate Glutamate and GABA Associations on Functional Connectivity in Schizophrenia.

Schizophr Bull. 2018 Jun 15;:

Authors: Shukla DK, Wijtenburg SA, Chen H, Chiappelli JJ, Kochunov P, Hong LE, Rowland LM

Abstract
Background: The underlying neurobiological mechanism for abnormal functional connectivity in schizophrenia (SCZ) remains unknown. This project investigated whether glutamate and GABA, 2 metabolites that contribute to excitatory and inhibitory functions, may influence functional connectivity in SCZ.
Methods: Resting-state functional magnetic resonance imaging and proton magnetic resonance spectroscopy were acquired from 58 SCZ patients and 61 healthy controls (HC). Seed-based connectivity maps were extracted between the anterior cingulate cortex (ACC) spectroscopic voxel and all other brain voxels. Magnetic resonance spectroscopy (MRS) spectra were processed to quantify glutamate and GABA levels. Regression analysis was performed to describe relationships between functional connectivity and glutamate and GABA levels.
Results: Reduced ACC functional connectivity in SCZ was found in regions associated with several neural networks including the default mode network (DMN) compared to HC. In the HC, positive correlations were found between glutamate and both ACC-right inferior frontal gyrus functional connectivity and ACC-bilateral superior temporal gyrus functional connectivity. A negative correlation between GABA and ACC-left posterior cingulate functional connectivity was also observed in HC. These same relationships were not statistically significant in SCZ.
Conclusions: The present investigation is one of the first studies to examine links between functional connectivity and glutamate and GABA levels in SCZ. Results indicate that glutamate and GABA play an important role in the functional connectivity modulation in the healthy brain. The absence of glutamate and GABA correlations in areas where SCZ showed significantly reduced functional connectivity may suggest that this chemical-functional relationship is disrupted in SCZ.

PMID: 29912445 [PubMed - as supplied by publisher]

Fluid and flexible minds: Intelligence reflects synchrony in the brain's intrinsic network architecture.

Tue, 06/19/2018 - 15:20

Fluid and flexible minds: Intelligence reflects synchrony in the brain's intrinsic network architecture.

Netw Neurosci. 2017;1(2):192-207

Authors: Ferguson MA, Anderson JS, Spreng RN

Abstract
Human intelligence has been conceptualized as a complex system of dissociable cognitive processes, yet studies investigating the neural basis of intelligence have typically emphasized the contributions of discrete brain regions or, more recently, of specific networks of functionally connected regions. Here we take a broader, systems perspective in order to investigate whether intelligence is an emergent property of synchrony within the brain's intrinsic network architecture. Using a large sample of resting-state fMRI and cognitive data (n = 830), we report that the synchrony of functional interactions within and across distributed brain networks reliably predicts fluid and flexible intellectual functioning. By adopting a whole-brain, systems-level approach, we were able to reliably predict individual differences in human intelligence by characterizing features of the brain's intrinsic network architecture. These findings hold promise for the eventual development of neural markers to predict changes in intellectual function that are associated with neurodevelopment, normal aging, and brain disease.

PMID: 29911673 [PubMed]

Visibility graphs for fMRI data: Multiplex temporal graphs and their modulations across resting-state networks.

Tue, 06/19/2018 - 15:20

Visibility graphs for fMRI data: Multiplex temporal graphs and their modulations across resting-state networks.

Netw Neurosci. 2017 Oct 01;1(3):208-221

Authors: Sannino S, Stramaglia S, Lacasa L, Marinazzo D

Abstract
Visibility algorithms are a family of methods that map time series into graphs, such that the tools of graph theory and network science can be used for the characterization of time series. This approach has proved a convenient tool, and visibility graphs have found applications across several disciplines. Recently, an approach has been proposed to extend this framework to multivariate time series, allowing a novel way to describe collective dynamics. Here we test their application to fMRI time series, following two main motivations, namely that (a) this approach allows vs to simultaneously capture and process relevant aspects of both local and global dynamics in an easy and intuitive way, and (b) this provides a suggestive bridge between time series and network theory that nicely fits the consolidating field of network neuroscience. Our application to a large open dataset reveals differences in the similarities of temporal networks (and thus in correlated dynamics) across resting-state networks, and gives indications that some differences in brain activity connected to psychiatric disorders could be picked up by this approach.

PMID: 29911672 [PubMed]

From static to temporal network theory: Applications to functional brain connectivity.

Tue, 06/19/2018 - 15:20

From static to temporal network theory: Applications to functional brain connectivity.

Netw Neurosci. 2017;1(2):69-99

Authors: Thompson WH, Brantefors P, Fransson P

Abstract
Network neuroscience has become an established paradigm to tackle questions related to the functional and structural connectome of the brain. Recently, interest has been growing in examining the temporal dynamics of the brain's network activity. Although different approaches to capturing fluctuations in brain connectivity have been proposed, there have been few attempts to quantify these fluctuations using temporal network theory. This theory is an extension of network theory that has been successfully applied to the modeling of dynamic processes in economics, social sciences, and engineering article but it has not been adopted to a great extent within network neuroscience. The objective of this article is twofold: (i) to present a detailed description of the central tenets of temporal network theory and describe its measures, and; (ii) to apply these measures to a resting-state fMRI dataset to illustrate their utility. Furthermore, we discuss the interpretation of temporal network theory in the context of the dynamic functional brain connectome. All the temporal network measures and plotting functions described in this article are freely available as the Python package Teneto.

PMID: 29911669 [PubMed]

Neural correlates of executive functions in patients with obesity.

Tue, 06/19/2018 - 15:20
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Neural correlates of executive functions in patients with obesity.

PeerJ. 2018;6:e5002

Authors: Ho MC, Chen VC, Chao SH, Fang CT, Liu YC, Weng JC

Abstract
Obesity is one of the most challenging problems in human health and is recognized as an important risk factor for many chronic diseases. It remains unclear how the neural systems (e.g., the mesolimbic "reward" and the prefrontal "control" neural systems) are correlated with patients' executive function (EF), conceptualized as the integration of "cool" EF and "hot" EF. "Cool" EF refers to relatively abstract, non-affective operations such as inhibitory control and mental flexibility. "Hot" EF refers to motivationally significant affective operations such as affective decision-making. We tried to find the correlation between structural and functional neuroimaging indices and EF in obese patients. The study population comprised seventeen patients with obesity (seven males and 10 females, BMI = 37.99 ± 5.40, age = 31.82 ± 8.75 year-old) preparing to undergo bariatric surgery. We used noninvasive diffusion tensor imaging, generalized q-sampling imaging, and resting-state functional magnetic resonance imaging to examine the neural correlations between structural and functional neuroimaging indices and EF performances in patients with obesity. We reported that many brain areas are correlated to the patients' EF performances. More interestingly, some correlations may implicate the possible associations of EF and the incentive motivational effects of food. The neural correlation between the left precuneus and middle occipital gyrus and inhibitory control may suggest that patients with a better ability to detect appetitive food may have worse inhibitory control. Also, the neural correlation between the superior frontal blade and affective decision-making may suggest that patients' affective decision-making may be associated with the incentive motivational effects of food. Our results provide evidence suggesting neural correlates of EF in patients with obesity.

PMID: 29910989 [PubMed]

More than just statics: temporal dynamics of intrinsic brain activity predicts the suicidal ideation in depressed patients.

Tue, 06/19/2018 - 15:20
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More than just statics: temporal dynamics of intrinsic brain activity predicts the suicidal ideation in depressed patients.

Psychol Med. 2018 Jun 18;:1-9

Authors: Li J, Duan X, Cui Q, Chen H, Liao W

Abstract
BACKGROUND: Major depressive disorder (MDD) is associated with high risk of suicide. Conventional neuroimaging works showed abnormalities of static brain activity and connectivity in MDD with suicidal ideation (SI). However, little is known regarding alterations of brain dynamics. More broadly, it remains unclear whether temporal dynamics of the brain activity could predict the prognosis of SI.
METHODS: We included MDD patients (n = 48) with and without SI and age-, gender-, and education-matched healthy controls (n = 30) who underwent resting-state functional magnetic resonance imaging. We first assessed dynamic amplitude of low-frequency fluctuation (dALFF) - a proxy for intrinsic brain activity (iBA) - using sliding-window analysis. Furthermore, the temporal variability (dynamics) of iBA was quantified as the variance of dALFF over time. In addition, the prediction of the severity of SI from temporal variability was conducted using a general linear model.
RESULTS: Compared with MDD without SI, the SI group showed decreased brain dynamics (less temporal variability) in the dorsal anterior cingulate cortex, the left orbital frontal cortex, the left inferior temporal gyrus, and the left hippocampus. Importantly, these temporal variabilities could be used to predict the severity of SI (r = 0.43, p = 0.03), whereas static ALFF could not in the current data set.
CONCLUSIONS: These findings suggest that alterations of temporal variability in regions involved in executive and emotional processing are associated with SI in MDD patients. This novel predictive model using the dynamics of iBA could be useful in developing neuromarkers for clinical applications.

PMID: 29909788 [PubMed - as supplied by publisher]

Altered Functional Connectivity in Sickle Cell Disease Exists at Rest and During Acute Pain Challenge.

Tue, 06/19/2018 - 15:20
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Altered Functional Connectivity in Sickle Cell Disease Exists at Rest and During Acute Pain Challenge.

Clin J Pain. 2017 Dec;33(12):1060-1070

Authors: Zempsky WT, Stevens MC, Santanelli JP, Gaynor AM, Khadka S

Abstract
OBJECTIVES: Sickle cell disease (SCD) is a chronic pain disorder in which abnormally shaped red blood cells obstruct microcirculation causing ischemia and pain. The lack of SCD responsiveness to analgesics has led many to propose that nociceptive neural systems engaged when detecting pain become sensitized, resulting in an enhancement of pain response.
METHODS: Individuals with SCD and non-SCD controls were exposed to a painful stimuli of varying intensity using a pressure algometer and underwent several neuroimaging tasks.
RESULTS: This study identified and characterized the neural correlates of possible central sensitization in SCD. We found functional connectivity abnormalities in individuals with SCD in the brain's somatosensory network, salience network, and default mode network during both an unstructured resting state and paradigm involving acute pain challenge.
DISCUSSION: There was evidence for both increased and decreased connectivity which is consistent with findings in other chronic pain disorders. Preliminary evidence was found that subcortical brain regions might contribute to neurodevelopmental abnormalities in chronic pain. The results support a model in which SCD pain sensitization involves abnormally low functional integration of brain regions that make use of nociceptive information to plan movements, and hyperconnectivity of various frontal and parietal lobe regions that direct attention to or represent higher-order abstractions within circuits involved with either nocioceptive processing or detection of abnormally salient environmental stimuli.

PMID: 28272117 [PubMed - indexed for MEDLINE]

Intrinsic functional neurocircuitry associated with treatment response to transdiagnostic CBT in bipolar disorder with anxiety.

Mon, 06/18/2018 - 14:20
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Intrinsic functional neurocircuitry associated with treatment response to transdiagnostic CBT in bipolar disorder with anxiety.

J Affect Disord. 2018 Jun 02;238:383-391

Authors: Ellard KK, Gosai AG, Bernstein EE, Kaur N, Sylvia LG, Camprodon JA, Dougherty DD, Nierenberg AA, Deckersbach T

Abstract
BACKGROUND: Anxiety in bipolar disorder (BD) exacerbates emotion dysregulation and reduces treatment response. We recently conducted a pilot trial of transdiagnostic CBT to target anxiety and emotion dysregulation in BD adjunctive to pharmacotherapy. Reductions in depression and anxiety symptoms were significantly predicted by baseline levels of neuroticism and perceived affective control, as well as changes over time in emotion regulation skills. The present study investigates mechanism of treatment response by examining the relationship between baseline emotion regulation-related neural circuitry and trial outcomes.
METHODS: Nineteen patients completed baseline resting state fMRI scans prior to treatment randomization. Functional connectivity between the anterior insula (AI) and regions in the salience network (SN), default mode network (DMN), and executive control network (ECN) were examined as predictors of baseline and treatment-related changes in emotion regulation.
RESULTS: Greater improvements in emotion regulation were predicted by weaker right dorsal AI - right ventrolateral prefrontal cortex (VLPFC; SN) and stronger bilateral dorsal AI - bilateral amygdala functional connectivity. Baseline neuroticism was negatively correlated with right dorsal AI- inferior parietal lobule (ECN) functional connectivity, and baseline deficits in perceived affective control were positively associated with ventral AI - bilateral dACC (SN) connectivity.
LIMITATIONS: Small sample limits interpretability of treatment-specific effects.
CONCLUSION: Baseline functional connectivity of emotion-regulation related neural circuitry significantly predicted change in emotion regulation-related dimensions associated with anxiety and depression symptom reduction. Future studies are needed to determine if employing methods such as neuromodulation to rehabilitate relevant neural circuitry may improve ultimate treatment outcomes of transdiagnostic CBT for BD and anxiety.

PMID: 29909301 [PubMed - as supplied by publisher]

Age-related differences in striatal, medial temporal, and frontal involvement during value-based decision processing.

Mon, 06/18/2018 - 14:20
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Age-related differences in striatal, medial temporal, and frontal involvement during value-based decision processing.

Neurobiol Aging. 2018 May 21;69:185-198

Authors: Su YS, Chen JT, Tang YJ, Yuan SY, McCarrey AC, Goh JOS

Abstract
Appropriate neural representation of value and application of decision strategies are necessary to make optimal investment choices in real life. Normative human aging alters neural selectivity and control processing in brain regions implicated in value-based decision processing including striatal, medial temporal, and frontal areas. However, the specific neural mechanisms of how these age-related functional brain changes modulate value processing in older adults remain unclear. Here, young and older adults performed a lottery-choice functional magnetic resonance imaging experiment in which probabilities of winning different magnitudes of points constituted expected values of stakes. Increasing probability of winning modulated striatal responses in young adults, but modulated medial temporal and ventromedial prefrontal areas instead in older adults. Older adults additionally engaged higher responses in dorso-medio-lateral prefrontal cortices to more unfavorable stakes. Such extrastriatal involvement mediated age-related increase in risk-taking decisions. Furthermore, lower resting-state functional connectivity between lateral prefrontal and striatal areas also predicted lottery-choice task risk-taking that was mediated by higher functional connectivity between prefrontal and medial temporal areas during the task, with this mediation relationship being stronger in older than younger adults. Overall, we report evidence of a systemic neural mechanistic change in processing of probability in mixed-lottery values with age that increases risk-taking of unfavorable stakes in older adults. Moreover, individual differences in age-related effects on baseline frontostriatal communication may be a central determinant of such subsequent age differences in value-based decision neural processing and resulting behaviors.

PMID: 29909176 [PubMed - as supplied by publisher]

Resting-state brain activity changes associated with tardive dyskinesia in patients with schizophrenia: fractional amplitude of low-frequency fluctuation decreased in the occipital lobe.

Mon, 06/18/2018 - 14:20
Related Articles

Resting-state brain activity changes associated with tardive dyskinesia in patients with schizophrenia: fractional amplitude of low-frequency fluctuation decreased in the occipital lobe.

Neuroscience. 2018 Jun 14;:

Authors: Zhang P, Li Y, Fan F, Li CR, Luo X, Yang F, Yao Y, Tan Y

Abstract
We explored resting-state brain activity and its potential links to clinical parameters in schizophrenic patients with tardive dyskinesia (TD) using fractional amplitude of low frequency fluctuations(fALFF). Resting-state functional magnetic resonance imaging data were acquired from 32 schizophrenic patients with TD (TD group), 31 without TD (NTD group), and 32 healthy controls (HC group). Clinical parameters including psychopathological symptoms, severity of TD, and cognitive function were assessed using the Positive and Negative Syndrome Scale, Abnormal Involuntary Movement Scale (AIMS), and Repeatable Battery for the Assessment of Neuropsychological Status, respectively. Pearson correlation analyses were performed to determine the relationship between the regions with altered fALFF values and clinical parameters in TD patients. The TD group showed decreased fALFF in the left middle occipital gyrus (MOG) and the right calcarine sulcus (CAL) compared to the HC group, and decreased fALFF in the left cuneus compared to the NTD group. In the TD group, fALFF values in the left MOG and the right CAL were correlated separately with the delayed memory score (r = 0.44, p = 0.027; r = 0.43, p = 0.028, respectively). The AIMS total score was negatively correlated to the visuospatial/constructional score (r = -0.53, p = 0.005).Our findings suggested that resting-state brain activity changes were associated with TD in schizophrenic patients. There was an association between the decreased brain activity in the occipital lobe and the delayed memory cognition impairment in this population.

PMID: 29909076 [PubMed - as supplied by publisher]

Scale invariant rearrangement of resting state networks in the human brain under sustained stimulation.

Mon, 06/18/2018 - 14:20
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Scale invariant rearrangement of resting state networks in the human brain under sustained stimulation.

Neuroimage. 2018 Jun 14;:

Authors: Tommasin S, Mascali D, Moraschi M, Gili T, Assan IE, Fratini M, DiNuzzo M, Wise RG, Mangia S, Macaluso E, Giove F

Abstract
Brain activity at rest is characterized by widely distributed and spatially specific patterns of synchronized low-frequency blood-oxygenation level-dependent (BOLD) fluctuations, which correspond to physiologically relevant brain networks. This network behaviour is known to persist also during task execution, yet the details underlying task-associated modulations of within- and between-network connectivity are largely unknown. In this study we exploited a multi-parametric and multi-scale approach to investigate how low-frequency fluctuations adapt to a sustained n-back working memory task. We found that the transition from the resting state to the task state involves a behaviourally relevant and scale-invariant modulation of synchronization patterns within both task-positive and default mode networks. Specifically, decreases of connectivity within networks are accompanied by increases of connectivity between networks. In spite of large and widespread changes of connectivity strength, the overall topology of brain networks is remarkably preserved. We show that these findings are strongly influenced by connectivity at rest, suggesting that the absolute change of connectivity (i.e., disregarding the baseline) may be not the most suitable metric to study dynamic modulations of functional connectivity. Our results indicate that a task can evoke scale-invariant, distributed changes of BOLD fluctuations, further confirming that low frequency BOLD oscillations show a specialized response and are tightly bound to task-evoked activation.

PMID: 29908935 [PubMed - as supplied by publisher]

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