New resting-state fMRI related studies at PubMed

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Decreased resting-state BOLD regional homogeneity and the intrinsic functional connectivity within dorsal striatum is associated with greater impulsivity in food-related decision-making and BMI change at 6-month follow up.

Fri, 05/04/2018 - 16:00

Decreased resting-state BOLD regional homogeneity and the intrinsic functional connectivity within dorsal striatum is associated with greater impulsivity in food-related decision-making and BMI change at 6-month follow up.

Appetite. 2018 Apr 30;:

Authors: Gao X, Liang Q, Wu G, She Y, Sui N, Chen H

Abstract
Increasing animal models as well as brain imaging studies among human suggest an association between substance-related impulsivity in decision-making and decreased function of dorsal striatum. However, the resting-state intrinsic functional organization of dorsal striatum underlying food-choice impulsivity remains unknown. To address this issue, we used resting-state functional MRI (rs-fMRI) to measure brain activity among adult females. Subjects underwent the food rating task, during which they rated each food item according to their subjective perception of its taste (from Dislike it very much to Like it very much), its long term effect on health (from very unhealthy to very healthy) and decision strength to eat it (from Strong no to Strong yes). Behaviorally, impulsivity in food-choice was indexed by the decision strength of the palatable high-calorie food rather than of the low-caloric food. Results on rs-fMRI showed that greater impulsivity in food-related decision-making was inversely correlated with spontaneous regional homogeneity in the dorsal striatum (dorsal caudate), as well as the resting-state functional connectivity (rs-FC) between the dorsal caudate seed and the rostral putamen. Furthermore, the caudate-putamen rs-FC inversely predicted BMI change at six-month follow-up. These findings may suggest the insensitivity to reward signals in dorsal caudate in decision-making coupled with an imbalance between goal-directed behaviors (modulated by dorsal caudate) and habitual actions (modulated by putamen) underlying impulsivity and future weight gain. In sum, these findings extend our understanding on the neural basis of food-related impulsivity, and provide evidence for the dorsal striatum as one of the landmarks in over eating and weight change.

PMID: 29723554 [PubMed - as supplied by publisher]

Functional Neuroimaging in Trigeminal Autonomic Cephalalgias.

Fri, 05/04/2018 - 16:00
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Functional Neuroimaging in Trigeminal Autonomic Cephalalgias.

Ann Indian Acad Neurol. 2018 Apr;21(Suppl 1):S51-S56

Authors: Obermann M, Holle D, Nagel S

Abstract
Functional neuroimaging was able to identify key structures for the pathophysiology of trigeminal autonomic cephalalgias (TACs) including cluster headache, paroxysmal hemicrania, and short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing or cranial autonomic features and hemicrania continua. The posterior hypothalamus was the structure most consistently depicted with functional imaging in different states of disease with and without pain. Network-oriented imaging techniques such as resting-state functional resonance imaging were able to show a broader involvement of human trigeminal pain processing in the underlying pathophysiological mechanisms of the different TACs, highlighting similarities between this distinct group of primary headache disorders, while also demonstrating the differences in brain activation across these disorders. The most important clinical assignment for neuroimaging research from the treating physician remains the objective and reliable distinction of each individual TAC syndrome from one another, to make the correct clinical diagnosis as the foundation for proper treatment. More research will be necessary to fulfill this unmet need.

PMID: 29720819 [PubMed]

Resting-state brain networks in patients with Parkinson's disease and impulse control disorders.

Fri, 05/04/2018 - 16:00
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Resting-state brain networks in patients with Parkinson's disease and impulse control disorders.

Cortex. 2017 09;94:63-72

Authors: Tessitore A, Santangelo G, De Micco R, Giordano A, Raimo S, Amboni M, Esposito F, Barone P, Tedeschi G, Vitale C

Abstract
INTRODUCTION: To investigate intrinsic neural networks connectivity changes in Parkinson's disease (PD) patients with and without impulse control disorders (ICD).
METHODS: Fifteen patients with PD with ICD (ICD+), 15 patients with PD without ICD (ICD-) and 24 age and sex-matched healthy controls (HC) were enrolled in the study. To identify patients with and without ICD and/or punding, we used the Minnesota Impulsive Disorders Interview (MIDI) and a clinical interview based on diagnostic criteria for each symptom. All patients underwent a detailed neuropsychological evaluation. Whole brain structural and functional imaging was performed on a 3T GE MR scanner. Statistical analysis of functional data was completed using BrainVoyager QX software. Voxel-based morphometry (VBM) was used to test whether between-group differences in resting-state connectivity were related to structural abnormalities.
RESULTS: The presence of ICD symptoms was associated with an increased connectivity within the salience and default-mode networks, as well as with a decreased connectivity within the central executive network (p < .05 corrected). ICD severity was correlated with both salience and default mode networks connectivity changes only in the ICD+ group. VBM analysis did not reveal any statistically significant differences in local grey matter volume between ICD+ and ICD- patients and between all patients and HC (p < .05. FWE).
CONCLUSIONS: The presence of a disrupted connectivity within the three core neurocognitive networks may be considered as a potential neural correlate of ICD presence in patients with PD. Our findings provide additional insights into the mechanisms underlying ICD in PD, confirming the crucial role of an abnormal prefrontal-limbic-striatal homeostasis in their development.

PMID: 28715675 [PubMed - indexed for MEDLINE]

Impulsive-antisocial psychopathic traits linked to increased volume and functional connectivity within prefrontal cortex.

Fri, 05/04/2018 - 16:00
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Impulsive-antisocial psychopathic traits linked to increased volume and functional connectivity within prefrontal cortex.

Soc Cogn Affect Neurosci. 2017 Jul 01;12(7):1169-1178

Authors: Korponay C, Pujara M, Deming P, Philippi C, Decety J, Kosson DS, Kiehl KA, Koenigs M

Abstract
Psychopathy is a personality disorder characterized by callous lack of empathy, impulsive antisocial behavior, and criminal recidivism. Studies of brain structure and function in psychopathy have frequently identified abnormalities in the prefrontal cortex. However, findings have not yet converged to yield a clear relationship between specific subregions of prefrontal cortex and particular psychopathic traits. We performed a multimodal neuroimaging study of prefrontal cortex volume and functional connectivity in psychopathy, using a sample of adult male prison inmates (N = 124). We conducted volumetric analyses in prefrontal subregions, and subsequently assessed resting-state functional connectivity in areas where volume was related to psychopathy severity. We found that overall psychopathy severity and Factor 2 scores (which index the impulsive/antisocial traits of psychopathy) were associated with larger prefrontal subregion volumes, particularly in the medial orbitofrontal cortex and dorsolateral prefrontal cortex. Furthermore, Factor 2 scores were also positively correlated with functional connectivity between several areas of the prefrontal cortex. The results were not attributable to age, race, IQ, substance use history, or brain volume. Collectively, these findings provide evidence for co-localized increases in prefrontal cortex volume and intra-prefrontal functional connectivity in relation to impulsive/antisocial psychopathic traits.

PMID: 28402565 [PubMed - indexed for MEDLINE]

The role of the default mode network in component processes underlying the wandering mind.

Fri, 05/04/2018 - 16:00
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The role of the default mode network in component processes underlying the wandering mind.

Soc Cogn Affect Neurosci. 2017 Jul 01;12(7):1047-1062

Authors: Poerio GL, Sormaz M, Wang HT, Margulies D, Jefferies E, Smallwood J

Abstract
Experiences such as mind-wandering illustrate that cognition is not always tethered to events in the here-and-now. Although converging evidence emphasises the default mode network (DMN) in mind-wandering, its precise contribution remains unclear. The DMN comprises cortical regions that are maximally distant from primary sensory and motor cortex, a topological location that may support the stimulus-independence of mind-wandering. The DMN is functionally heterogeneous, comprising regions engaged by memory, social cognition and planning; processes relevant to mind-wandering content. Our study examined the relationships between: (i) individual differences in resting-state DMN connectivity, (ii) performance on memory, social and planning tasks and (iii) variability in spontaneous thought, to investigate whether the DMN is critical to mind-wandering because it supports stimulus-independent cognition, memory retrieval, or both. Individual variation in task performance modulated the functional organization of the DMN: poor external engagement was linked to stronger coupling between medial and dorsal subsystems, while decoupling of the core from the cerebellum predicted reports of detailed memory retrieval. Both patterns predicted off-task future thoughts. Consistent with predictions from component process accounts of mind-wandering, our study suggests a 2-fold involvement of the DMN: (i) it supports experiences that are unrelated to the environment through strong coupling between its sub-systems; (ii) it allows memory representations to form the basis of conscious experience.

PMID: 28402561 [PubMed - indexed for MEDLINE]

Assessment of synchronous neural activities revealed by regional homogeneity in individuals with acute eye pain: a resting-state functional magnetic resonance imaging study.

Thu, 05/03/2018 - 14:40
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Assessment of synchronous neural activities revealed by regional homogeneity in individuals with acute eye pain: a resting-state functional magnetic resonance imaging study.

J Pain Res. 2018;11:843-850

Authors: Tang LY, Li HJ, Huang X, Bao J, Sethi Z, Ye L, Yuan Q, Zhu PW, Jiang N, Gao GP, Shao Y

Abstract
Objective: Previous neuroimaging studies have demonstrated that pain-related diseases are associated with brain function and anatomical abnormalities, whereas altered synchronous neural activity in acute eye pain (EP) patients has not been investigated. The purpose of this study was to explore whether or not synchronous neural activity changes were measured with the regional homogeneity (ReHo) method in acute EP patients.
Methods: A total of 20 patients (15 males and 5 females) with EP and 20 healthy controls (HCs) consisting of 15 and 5 age-, sex-, and education-matched males and females, respectively, underwent resting-state functional magnetic resonance imaging. The ReHo method was applied to assess synchronous neural activity changes.
Results: Compared with HCs, acute EP patients had significantly lower ReHo values in the left precentral/postcentral gyrus (Brodmann area [BA]3/4), right precentral/postcentral gyrus (BA3/4), and left middle frontal gyrus (BA6). In contrast, higher ReHo values in acute EP patients were observed in the left superior frontal gyrus (BA11), right inferior parietal lobule (BA39/40), and left precuneus (BA7). However, no relationship was found between the mean ReHo signal values of the different areas and clinical manifestations, which included both the duration and degree of pain in EP patients.
Conclusion: Our study highlighted that acute EP patients showed altered synchronous neural activities in many brain regions, including somatosensory regions. These findings might provide useful information for exploration of the neural mechanisms underlying acute EP.

PMID: 29719418 [PubMed]

Estimation of vocational aptitudes using functional brain networks.

Thu, 05/03/2018 - 14:40
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Estimation of vocational aptitudes using functional brain networks.

Hum Brain Mapp. 2018 May 01;:

Authors: Sung YW, Kawachi Y, Choi US, Kang D, Abe C, Otomo Y, Ogawa S

Abstract
The success of human life in modern society is highly dependent on occupation. Therefore, it is very important for people to identify and develop a career plan that best suits their aptitude. Traditional test batteries for vocational aptitudes are not oriented to measure developmental changes in job suitability because repeated measurements can introduce bias as the content of the test batteries is learned. In this study, we attempted to objectively assess vocational aptitudes by measuring functional brain networks and identified functional brain networks that intrinsically represented vocational aptitudes for 19 job divisions in a General Aptitude Test Battery. In addition, we derived classifiers based on these networks to predict the aptitudes of our test participants for each job division. Our results suggest that the measurement of brain function can indeed yield an objective evaluation of vocational aptitudes; this technique will enable a person to follow changes in one's job suitability with additional training or learning, paving a new way to advise people on career development.

PMID: 29717529 [PubMed - as supplied by publisher]

The salience network and human personality: Integrity of white matter tracts within anterior and posterior salience network relates to the self-directedness character trait.

Wed, 05/02/2018 - 13:40
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The salience network and human personality: Integrity of white matter tracts within anterior and posterior salience network relates to the self-directedness character trait.

Brain Res. 2018 Apr 28;:

Authors: Prillwitz C, Rüber T, Reuter M, Montag C, Weber B, Elger CE, Markett S

Abstract
A prevailing topic in personality neuroscience is the question how personality traits are reflected in the brain. Functional and structural networks have been examined by functional and structural magnetic resonance imaging, however, the structural correlates of functionally defined networks have not been investigated in a personality context. By using the Temperament and Character Inventory (TCI) and Diffusion Tensor Imaging (DTI), the present study assesses in a sample of 116 healthy participants how personality traits proposed in the framework of the biopsychosocial theory on personality relate to white matter pathways delineated by functional network imaging. We show that the character trait self-directedness relates to the overall microstructural integrity of white matter tracts constituting the salience network as indicated by DTI-derived measures. Self-directedness has been proposed as the executive control component of personality and describes the tendency to stay focused on the attainment of long-term goals. The present finding corroborates the view of the salience network as an executive control network that serves maintenance of rules and task-sets to guide ongoing behavior.

PMID: 29715443 [PubMed - as supplied by publisher]

Aberrant brain functional connectome in patients with obstructive sleep apnea.

Wed, 05/02/2018 - 13:40
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Aberrant brain functional connectome in patients with obstructive sleep apnea.

Neuropsychiatr Dis Treat. 2018;14:1059-1070

Authors: Chen LT, Fan XL, Li HJ, Ye CL, Yu HH, Xin HZ, Gong HH, Peng DC, Yan LP

Abstract
Objective: Obstructive sleep apnea (OSA) is accompanied by widespread abnormal spontaneous regional activity related to cognitive deficits. However, little is known about the topological properties of the functional brain connectome of patients with OSA. This study aimed to use the graph theory approaches to investigate the topological properties and functional connectivity (FC) of the functional connectome in patients with OSA, based on resting-state functional magnetic resonance imaging (rs-fMRI).
Methods: Forty-five male patients with newly diagnosed untreated severe OSA and 45 male good sleepers (GSs) underwent a polysomnography (PSG), clinical evaluations, and rs-fMRI scans. The automated anatomical labeling (AAL) atlas was used to construct the functional brain connectome. The topological organization and FC of brain functional networks in patients with OSA were characterized using graph theory methods and investigated the relationship between functional network topology and clinical variables.
Results: Both the patients with OSA and the GSs exhibited high-efficiency "small-world" network attributes. However, the patients with OSA exhibited decreased σ, γ, Eglob; increased Lp, λ; and abnormal nodal centralities in several default-mode network (DMN), salience network (SN), and central executive network (CEN) regions. However, the patients with OSA exhibited abnormal functional connections between the DMN, SN, and CEN. The disrupted FC was significantly positive correlations with the global network metrics γ and σ. The global network metrics were significantly correlated with the Epworth Sleepiness Scale (ESS) score, Montreal Cognitive Assessment (MoCA) score, and oxygen desaturation index.
Conclusion: The findings suggest that the functional connectome of patients with OSA exhibited disrupted functional integration and segregation, and functional disconnections of the DMN, SN, and CEN. The aberrant topological attributes may be associated with disrupted FC and cognitive functions. These topological abnormalities and disconnections might be potential biomarkers of cognitive impairments in patients with OSA.

PMID: 29713176 [PubMed]

Resting-state fMRI study of brain activation using low-intensity repetitive transcranial magnetic stimulation in rats.

Wed, 05/02/2018 - 13:40
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Resting-state fMRI study of brain activation using low-intensity repetitive transcranial magnetic stimulation in rats.

Sci Rep. 2018 Apr 30;8(1):6706

Authors: Seewoo BJ, Feindel KW, Etherington SJ, Rodger J

Abstract
Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive neuromodulation technique used to treat many neuropsychiatric conditions. However, the mechanisms underlying its mode of action are still unclear. This is the first rodent study using resting-state functional MRI (rs-fMRI) to examine low-intensity (LI) rTMS effects, in an effort to provide a direct means of comparison between rodent and human studies. Using anaesthetised Sprague-Dawley rats, rs-fMRI data were acquired before and after control or LI-rTMS at 1 Hz, 10 Hz, continuous theta burst stimulation (cTBS) or biomimetic high-frequency stimulation (BHFS). Independent component analysis revealed LI-rTMS-induced changes in the resting-state networks (RSN): (i) in the somatosensory cortex, the synchrony of resting activity decreased ipsilaterally following 10 Hz and bilaterally following 1 Hz stimulation and BHFS, and increased ipsilaterally following cTBS; (ii) the motor cortex showed bilateral changes following 1 Hz and 10 Hz stimulation, a contralateral decrease in synchrony following BHFS, and an ipsilateral increase following cTBS; and (iii) hippocampal synchrony decreased ipsilaterally following 10 Hz, and bilaterally following 1 Hz stimulation and BHFS. The present findings demonstrate that LI-rTMS modulates functional links within the rat RSN with frequency-specific outcomes, and the observed changes are similar to those described in humans following rTMS.

PMID: 29712947 [PubMed - in process]

Multi-task fused sparse learning for mild cognitive impairment identification.

Wed, 05/02/2018 - 13:40
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Multi-task fused sparse learning for mild cognitive impairment identification.

Technol Health Care. 2018 Apr 14;:

Authors: Yang P, Lei B, Ni D, Chen S, Wang T

Abstract
BACKGROUND: Brain functional connectivity network (BFCN) has been widely applied to identify biomarkers for the brain function understanding and brain diseases analysis.
OBJECTIVE: Building a biologically meaningful brain network is a crucial work in these applications. For this task, sparse learning has been widely applied for the network construction. If multiple time-point data is added to the brain imaging application, the disease progression pattern in the longitudinal analysis can be better revealed.
METHODS: A novel longitudinal analysis for MCI classification is devised based on resting-state functional magnetic resonating imaging (rs-fMRI). Specifically, this paper proposes a novel multi-task learning method to integrate fused penalty by regularization. In addition, a novel objective function is developed for fused sparse learning via smoothness constraint.
RESULTS: The proposed method achieves the best classification performance with an accuracy of 95.74% for baseline and 93.64% for year 1 data.
CONCLUSIONS: The experimental results show that our proposed method achieves quite promising classification performance.

PMID: 29710750 [PubMed - as supplied by publisher]

Simultaneous resting-state FDG-PET/fMRI in Alzheimer Disease: Relationship between glucose metabolism and intrinsic activity.

Wed, 05/02/2018 - 13:40
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Simultaneous resting-state FDG-PET/fMRI in Alzheimer Disease: Relationship between glucose metabolism and intrinsic activity.

Neuroimage. 2018 Apr 27;:

Authors: Marchitelli R, Aiello M, Cachia A, Quarantelli M, Cavaliere C, Postiglione A, Tedeschi G, Montella P, Milan G, Salvatore M, Salvatore E, Baron JC, Pappatà S

Abstract
Simultaneously evaluating resting-state brain glucose metabolism and intrinsic functional activity has potential to impact the clinical neurosciences of Alzheimer Disease (AD). Indeed, integrating such combined information obtained in the same physiological setting may clarify how impairments in neuroenergetic and neuronal function interact and contribute to the mechanisms underlying AD. The present study used this multimodality approach to investigate, by means of a hybrid PET/MR scanner, the coupling between glucose consumption and intrinsic functional activity in 23 patients with AD-related cognitive impairment ranging from amnestic mild cognitive impairment (MCI) to mild-moderate AD (aMCI/AD), in comparison with a group of 23 healthy elderly controls. Between-group (Controls > Patients) comparisons were conducted on data from both imaging modalities using voxelwise 2-sample t-tests, corrected for partial-volume effects, head motion, age, gender and multiple tests. FDG-PET/fMRI relationships were assessed within and across subjects using Spearman partial correlations for three different resting-state fMRI (rs-fMRI) metrics sensitive to AD: fractional amplitude of low frequency fluctuations (fALFF) and regional homogeneity (ReHo) of rs-fMRI BOLD signal along with group independent component analysis with dual regression (gICA-DR). FDG and rs-fMRI metrics distinguished aMCI/AD from controls according to spatial patterns analogous to those found in stand-alone studies. Within-subject correlations were comparable across the three rs-fMRI metrics. Correlations were overall high in healthy controls (ρ = 0.80 ± 0.04), but showed a significant 17% reduction (p < 0.05) in aMCI/AD patients (ρ = 0.67 ± 0.05). Positive across-subject correlations were overall moderate (ρ = 0.33 ± 0.07) and consistent across rs-fMRI metrics. These were confined around AD-target posterior regions for metrics of functional connectivity (ReHo and gICA-DR). In contrast, FDG/fALFF correlations were distributed in the frontal gyrus, thalami and caudate nuclei. Taken together, these results support the presence of bioenergetic coupling between glucose utilization and rapid transmission of neural information in healthy ageing, which is substantially reduced in aMCI/AD, suggesting that abnormal glucose utilization is in some way linked to communication breakdown among brain regions impacted by the underlying pathological process.

PMID: 29709628 [PubMed - as supplied by publisher]

Dynamic functional connectivity markers of objective trait mindfulness.

Wed, 05/02/2018 - 13:40
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Dynamic functional connectivity markers of objective trait mindfulness.

Neuroimage. 2018 Apr 27;:

Authors: Lim J, Teng J, Patanaik A, Tandi J, Massar SAA

Abstract
While mindfulness is commonly viewed as a skill to be cultivated through practice, untrained individuals can also vary widely in dispositional mindfulness. Prior research has identified static neural connectivity correlates of this trait. Here, we use dynamic functional connectivity (DFC) analysis of resting-state fMRI to study time-varying connectivity patterns associated with naturally varying and objectively measured trait mindfulness. Participants were selected from the top and bottom tertiles of performers on a breath-counting task to form high trait mindfulness (HTM; N = 21) and low trait mindfulness (LTM; N = 18) groups. DFC analysis of resting state fMRI data revealed that the HTM group spent significantly more time in a brain state associated with task-readiness - a state characterized by high within-network connectivity and greater anti-correlations between task-positive networks and the default-mode network (DMN). The HTM group transitioned between brain states more frequently, but the dwell time in each episode of the task-ready state was equivalent between groups. These results persisted even after controlling for vigilance. Across individuals, certain connectivity metrics were weakly correlated with self-reported mindfulness as measured by the Five Facet Mindfulness Questionnaire, though these did not survive multiple comparisons correction. In the static connectivity maps, HTM individuals had greater within-network connectivity in the DMN and the salience network, and greater anti-correlations between the DMN and task-positive networks. In sum, DFC features robustly distinguish HTM and LTM individuals, and may be useful biological markers for the measurement of dispositional mindfulness.

PMID: 29709625 [PubMed - as supplied by publisher]

Resting-state network connectivity and metastability predict clinical symptoms in schizophrenia.

Wed, 05/02/2018 - 13:40
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Resting-state network connectivity and metastability predict clinical symptoms in schizophrenia.

Schizophr Res. 2018 Apr 27;:

Authors: Lee WH, Doucet GE, Leibu E, Frangou S

Abstract
BACKGROUND: The functional architecture of resting-state networks (RSNs) is defined by their connectivity and metastability. Disrupted RSN connectivity has been amply demonstrated in schizophrenia while the role of metastability remains poorly defined. Here, we undertake a comprehensive characterisation of RSN organization in schizophrenia and test its contribution to the clinical profile of this disorder.
METHODS: We extracted RSNs representing the default mode (DMN), central executive (CEN), salience (SAL), language (LAN), sensorimotor (SMN), auditory (AN) and visual (VN) networks from resting-state functional magnetic resonance imaging data obtained from patients with schizophrenia (n = 85) and healthy individuals (n = 48). For each network, we computed its functional cohesiveness and integration and used the Kuramoto order parameter to compute metastability. We used stepwise multiple regression analyses to test these RSN features as predictors of symptom severity in patients.
RESULTS: RSN features respectively explained 14%, 17%, 12% and 5% of the variance in positive, negative, anxious/depressive and agitation/disorganization symptoms. Lower functional integration between the DMN, CEN and SMN primarily contributed to positive symptoms. The functional properties of the SAL network were key predictors of all other symptom dimensions; specifically, lower cohesiveness of the SAL, lower integration of this network with the LAN and higher integration with the CEN respectively contributed to negative, anxious/depressive and disorganization symptoms. Increased SAL metastability was associated with negative symptoms.
CONCLUSIONS: These results confirm the primacy of the SAL network for schizophrenia and demonstrate that abnormalities in RSN connectivity and metastability are significant predictors of schizophrenia-related psychopathology.

PMID: 29709491 [PubMed - as supplied by publisher]

Temporal Evolution of Brain Functional Connectivity Metrics: Could 7 Min of Rest be Enough?

Wed, 05/02/2018 - 13:40
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Temporal Evolution of Brain Functional Connectivity Metrics: Could 7 Min of Rest be Enough?

Cereb Cortex. 2017 Aug 01;27(8):4153-4165

Authors: Tomasi DG, Shokri-Kojori E, Volkow ND

Abstract
Unaccounted temporal dynamics of resting-state functional connectivity (FC) metrics challenges their potential as biomarkers for clinical applications in neuroscience. Here we studied the scan time required to reach stable values for various FC metrics including seed-voxel correlations and spatial independent component analyses (sICA), and for the local functional connectivity density (lFCD), a graph theory metric. By increasing the number of time points included in the analysis, we assessed the effects of scan time on convergence of accuracy, sensitivity, specificity, reproducibility, and reliability of these FC metrics. The necessary scan time to attenuate the effects of the temporal dynamics by 80% varied across connectivity metrics and was shorter for lFCD (7 min) than for FC (11 min) or for sICA (10 min). Findings suggest that the scan time required to achieve stable FC is metric-dependent, with lFCD being the most resilient metric to the effects of temporal dynamics. Thus, the lFCD metric could be particularly useful for pediatric and patient populations who may not tolerate long scans.

PMID: 27522070 [PubMed - indexed for MEDLINE]

Resting-State Functional Connectivity Predicts Cognitive Impairment Related to Alzheimer's Disease.

Tue, 05/01/2018 - 18:40
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Resting-State Functional Connectivity Predicts Cognitive Impairment Related to Alzheimer's Disease.

Front Aging Neurosci. 2018;10:94

Authors: Lin Q, Rosenberg MD, Yoo K, Hsu TW, O'Connell TP, Chun MM

Abstract
Resting-state functional connectivity (rs-FC) is a promising neuromarker for cognitive decline in aging population, based on its ability to reveal functional differences associated with cognitive impairment across individuals, and because rs-fMRI may be less taxing for participants than task-based fMRI or neuropsychological tests. Here, we employ an approach that uses rs-FC to predict the Alzheimer's Disease Assessment Scale (11 items; ADAS11) scores, which measure overall cognitive functioning, in novel individuals. We applied this technique, connectome-based predictive modeling, to a heterogeneous sample of 59 subjects from the Alzheimer's Disease Neuroimaging Initiative, including normal aging, mild cognitive impairment, and AD subjects. First, we built linear regression models to predict ADAS11 scores from rs-FC measured with Pearson's r correlation. The positive network model tested with leave-one-out cross validation (LOOCV) significantly predicted individual differences in cognitive function from rs-FC. In a second analysis, we considered other functional connectivity features, accordance and discordance, which disentangle the correlation and anticorrelation components of activity timecourses between brain areas. Using partial least square regression and LOOCV, we again built models to successfully predict ADAS11 scores in novel individuals. Our study provides promising evidence that rs-FC can reveal cognitive impairment in an aging population, although more development is needed for clinical application.

PMID: 29706883 [PubMed]

The neural markers of MRI to differentiate depression and panic disorder.

Tue, 05/01/2018 - 18:40
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The neural markers of MRI to differentiate depression and panic disorder.

Prog Neuropsychopharmacol Biol Psychiatry. 2018 Apr 26;:

Authors: Lai CH

Abstract
Depression and panic disorder (PD) share the common pathophysiology from the perspectives of neurotransmitters. The relatively high comorbidity between depression and PD contributes to the substantial obstacles to differentiate from depression and PD, especially for the brain pathophysiology. There are significant differences in the diagnostic criteria between depression and PD. However, the paradox of similar pathophysiology and different diagnostic criteria in these two disorders were still the issues needing to be addressed. Therefore the clarification of potential difference in the field of neuroscience and pathophysiology between depression and PD can help the clinicians and scientists to understand more comprehensively about significant differences between depression and PD. The researchers should be curious about the underlying difference of pathophysiology beneath the significant distinction of clinical symptoms. In this review article, I tried to find some evidences for the differences between depression and PD, especially for neural markers revealed by magnetic resonance imaging (MRI). The distinctions of structural and functional alterations in depression and PD are reviewed. From the structural perspectives, PD seems to have less severe gray matter alterations in frontal and temporal lobes than depression. The study of white matter microintegrity reveals more widespread alterations in fronto-limbic circuit of depression patients than PD patients, such as the uncinate fasciculus and anterior thalamic radiation. PD might have a more restrictive pattern of structural alterations when compared to depression. For the functional perspectives, the core site of depression pathophysiology is the anterior subnetwork of resting-state network, such as anterior cingulate cortex, which is not significantly altered in PD. A possibly emerging pattern of fronto-limbic distinction between depression and PD has been revealed by these explorative reports. The future trend for machine learning and pattern recognition might confirm the differentiation pattern between depression and PD based on the explorative results.

PMID: 29705713 [PubMed - as supplied by publisher]

Altered thalamo-cortical resting state functional connectivity in smokers.

Tue, 05/01/2018 - 18:40
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Altered thalamo-cortical resting state functional connectivity in smokers.

Neurosci Lett. 2017 Jul 13;653:120-125

Authors: Wang C, Bai J, Wang C, von Deneen KM, Yuan K, Cheng J

Abstract
The thalamus has widespread connections with the prefrontal cortex (PFC) and modulates communication between the striatum and PFC, which is crucial to the neural mechanisms of smoking. However, relatively few studies focused on the thalamic resting state functional connectivity (RSFC) patterns and their association with smoking behaviors in smokers. 24 young male smokers and 24 non-smokers were enrolled in our study. Fagerström Test for Nicotine Dependence (FTND) was used to assess the nicotine dependence level. The bilateral thalamic RSFC patterns were compared between smokers and non-smokers. The relationship between neuroimaging findings and smoking behaviors (FTND and pack-years) were also investigated in smokers. Relative to nonsmokers, smokers showed reduced RSFC strength between the left thalamus and several brain regions, i.e. the right dorsolateral prefrontal cortex (dlPFC), the anterior cingulate cortex (ACC) and the bilateral caudate. In addition, the right thalamus showed reduced RSFC with the right dlPFC as well as the bilateral insula in smokers. Therefore, the findings in the current study revealed the reduced RSFC of the thalamus with the dlPFC, the ACC, the insula and the caudate in smokers, which provided new insights into the roles of the thalamus in nicotine addiction from a function integration perspective.

PMID: 28536051 [PubMed - indexed for MEDLINE]

Contribution of systemic vascular effects to fMRI activity in white matter.

Mon, 04/30/2018 - 17:20
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Contribution of systemic vascular effects to fMRI activity in white matter.

Neuroimage. 2018 Apr 25;:

Authors: Özbay PS, Chang C, Picchioni D, Mandelkow H, Moehlman TM, Chappel-Farley MG, van Gelderen P, de Zwart JA, Duyn JH

Abstract
To investigate a potential contribution of systemic physiology to recently reported BOLD fMRI signals in white matter, we compared photo-plethysmography (PPG) and whole-brain fMRI signals recorded simultaneously during long resting-state scans from an overnight sleep study. We found that intermittent drops in the amplitude of the PPG signal exhibited strong and widespread correlations with the fMRI signal, both in white matter (WM) and in gray matter (GM). The WM signal pattern resembled that seen in previous resting-state fMRI studies and closely tracked the location of medullary veins. Its temporal cross-correlation with the PPG amplitude was bipolar, with an early negative value. In GM, the correlation was consistently positive. Consistent with previous studies comparing physiological signals with fMRI, these findings point to a systemic vascular contribution to WM fMRI signals. The PPG drops are interpreted as systemic vasoconstrictive events, possibly related to intermittent increases in sympathetic tone related to fluctuations in arousal state. The counter-intuitive polarity of the WM signal is explained by long blood transit times in the medullary vasculature of WM, which cause blood oxygenation loss and a substantial timing mismatch between blood volume and blood oxygenation effects. A similar mechanism may explain previous findings of negative WM signals around large draining veins during both task- and resting-state fMRI.

PMID: 29704614 [PubMed - as supplied by publisher]

Dynamic functional connectivity and its behavioral correlates beyond vigilance.

Mon, 04/30/2018 - 17:20
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Dynamic functional connectivity and its behavioral correlates beyond vigilance.

Neuroimage. 2018 Apr 25;:

Authors: Patanaik A, Tandi J, Ong JL, Wang C, Zhou J, Chee MWL

Abstract
Fluctuations in resting-state functional connectivity and global signal have been found to correspond with vigilance fluctuations, but their associations with other behavioral measures are unclear. We evaluated 52 healthy adolescents after a week of adequate sleep followed by five nights of sleep restriction to unmask inter-individual differences in cognition and mood. Resting state scans obtained at baseline only, analyzed using sliding window analysis, consistently yielded two polar dynamic functional connectivity states (DCSs) corresponding to previously reported 'low arousal' and 'high arousal' states. We found that the relative temporal preponderance of two dynamic connectivity states (DCS) in well-rested participants, indexed by a median split of participants, based on the relative time spent in these DCS, revealed highly significant group differences in vigilance at baseline and its decline following multiple nights of sleep restriction. Group differences in processing speed and working memory following manipulation but not at baseline suggest utility of DCS in predicting cognitive vulnerabilities unmasked by a stressor like sleep restriction. DCS temporal predominance was uninformative about mood and sleepiness speaking to specificity in its behavioral predictions. Global signal fluctuation provided information confined to vigilance. This appears to be related to head motion, which increases during periods of low arousal.

PMID: 29704612 [PubMed - as supplied by publisher]

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