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"Switch-Off" of Respiratory Sinus Arrhythmia Can Occur in a Minority of Subjects During Functional Magnetic Resonance Imaging (fMRI).

Fri, 12/14/2018 - 01:41
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"Switch-Off" of Respiratory Sinus Arrhythmia Can Occur in a Minority of Subjects During Functional Magnetic Resonance Imaging (fMRI).

Front Physiol. 2018;9:1688

Authors: Rassler B, Schwerdtfeger A, Aigner CS, Pfurtscheller G

Abstract
A group of 23 healthy scanner naïve participants of a functional magnetic resonance imaging (fMRI) study with increased state anxiety exhibited 0.1 Hz oscillations in blood-oxygenation-level-dependent (BOLD) signals, heart rate (HR) beat-to-beat intervals (RRI) and respiration. The goal of the present paper is to explore slow oscillations in respiration and RRI and their phase-coupling by applying the dynamic "wave-by-wave" analysis. Five participants with either high or moderate levels of fMRI-related anxiety (age 23.8 ± 3.3y) were found with at least one bulk of consecutive breathing waves with a respiration rate between 6 to 9 breaths/min in a 5-min resting state. The following results were obtained: (i) Breathing oscillations with dominant frequencies at 0.1 Hz and 0.15 Hz displayed a 1:1 coupling with RRI. (ii) Inspiration time was significantly longer than expiration time. (iii) RRI minima (start of HR decrease) coincided with the early inspiration, and RRI maxima (start of HR increase) coincided with the late inspiration. (iv) RRI rhythm led over the respiratory rhythm. This phase-coupling pattern is quite contrary to typical respiratory sinus arrhythmia where HR increases during inspiration and decreases during expiration.

PMID: 30538642 [PubMed]

Disrupted Balance of Long- and Short-Range Functional Connectivity Density in Type 2 Diabetes Mellitus: A Resting-State fMRI Study.

Fri, 12/14/2018 - 01:41
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Disrupted Balance of Long- and Short-Range Functional Connectivity Density in Type 2 Diabetes Mellitus: A Resting-State fMRI Study.

Front Neurosci. 2018;12:875

Authors: Liu D, Chen L, Duan S, Yin X, Yang W, Shi Y, Zhang J, Wang J

Abstract
Previous studies have shown that type 2 diabetes mellitus (T2DM) can accelerate the rate of cognitive decline in patients. As an organ with high energy consumption, the brain network balances between lower energy consumption and higher information transmission efficiency. However, T2DM may modify the proportion of short- and long-range connections to adapt to the inadequate energy supply and to respond to various cognitive tasks under the energy pressure caused by homeostasis alterations in brain glucose metabolism. On the basis of the above theories, this study determined the abnormal functional connections of the brain in 32 T2DM patients compared with 32 healthy control (HC) subjects using long- and short-range functional connectivity density (FCD) analyses with resting-state fMRI data. The cognitive function level in these patients was also evaluated by neuropsychological tests. Moreover, the characteristics of abnormal FCD and their relationships with cognitive impairment were investigated in T2DM patients. Compared with the HC group, T2DM patients exhibited decreased long-range FCD in the left calcarine and left lingual gyrus and increased short-range FCD in the right angular gyrus and medial part of the left superior frontal gyrus (p < 0.05, Gaussian random-field theory corrected). In T2DM patients, the FCD z scores of the medial part of the left superior frontal gyrus were negatively correlated with the time cost in part B of the Trail Making Test (ρ = -0.422, p = 0.018). In addition, the FCD z scores of the right angular gyrus were negatively correlated with the long-term delayed recall scores of the Auditory Verbal Learning Test (ρ = -0.356, p = 0.049) and the forward scores of the Digital Span Test (ρ = -0.373, p = 0.039). T2DM patients exhibited aberrant long-range and short-range FCD patterns, which may suggest brain network reorganization at the expense of losing the integration of long-range FCD to adapt to the deficiency in energy supply. These changes may be associated with cognitive decline in T2DM patients.

PMID: 30538618 [PubMed]

Association between seizure freedom and default mode network reorganization in patients with unilateral temporal lobe epilepsy.

Fri, 12/14/2018 - 01:41
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Association between seizure freedom and default mode network reorganization in patients with unilateral temporal lobe epilepsy.

Epilepsy Behav. 2018 Dec 08;:

Authors: Ofer I, LeRose C, Mast H, LeVan P, Metternich B, Egger K, Urbach H, Schulze-Bonhage A, Wagner K

Abstract
RATIONALE: The spontaneous synchronized activity and intrinsic organization of the Default Mode Network (DMN) has been found to be altered because of epileptic activity of temporal lobe origin. Thus, the aim of the present study was to compare DMN's topological properties in patients with seizure-free (SF) and not seizure-free (NSF) temporal lobe epilepsy (TLE).
METHODS: Functional connectivity within the DMN was determined from an 8-minute resting state functional magnetic resonance imaging (fMRI) in 27 patients with TLE (12 SF, 15 NSF) and 15 healthy controls (HC). The DMN regions of interest were extracted according to the automated anatomical labeling (AAL) atlas. Network properties were assessed using standard graph-theoretical measures.
RESULTS: Analyses revealed, irrespectively of focus lateralization, borderline significance for longer paths (p = 0.049) and in trend reduced local efficiency within the DMN of SF when compared with that of NSF (p = 0.075). The SF and NSF patients did not differ in global network topology from HC (p > 0.05). At the nodal network level, the degree of central hubs was significantly reduced in SF when compared with that in NSF (0.002 ≤ p ≤ 0.080) and HC (0.001 ≤ p ≤ 0.066) while simultaneously, right anterior superior temporal gyrus revealed significantly higher degree in SF than in NSF (p = 0.005) and HC (p = 0.016).
CONCLUSION: Seizure freedom seems to be associated with hub redistributions that may underlie longer paths and (in trend) reduced local efficiency of the network. An associated slower system response might reduce the probability of a rapid spread of epileptic discharges over the whole network and may help to prevent hypersynchronous neuronal activity in brain networks that may result in epileptic seizures.

PMID: 30538081 [PubMed - as supplied by publisher]

Altered spontaneous brain activity in classical trigeminal neuralgia as determined by changes in regional homogeneity: a resting-state functional MRI study.

Thu, 12/13/2018 - 15:01
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Altered spontaneous brain activity in classical trigeminal neuralgia as determined by changes in regional homogeneity: a resting-state functional MRI study.

Pain Pract. 2018 Dec 11;:

Authors: Chu-Qing X, Liu WF, Qian-Hui X, Su T, Yong-Qiang S, Min YL, Yuan Q, Zhu PW, Kang-Cheng L, Jiang N, Ye L, Shao Y

Abstract
OBJECTIVE: Neuroimaging studies have reported that patients with pain-related conditions have altered neuronal activity and structural functions. The purpose of this study was to investigate whether classical trigeminal neuralgia (CTN) patients exhibit changes in corresponding neuronal activity via analysis of neuronal activity regional homogeneity (ReHo).
METHODS: A total of 28 patients presenting with sore eyes (12 men and 16 women) were matched with 28 healthy controls (12 men and 16 women). All participants underwent functional magnetic resonance imaging (fMRI). This ReHo method was used to assess the consistency of changes in neural activity in various brain regions. The receiver operating characteristic (ROC) curve was applied to differentiate ReHo values of CTN patients from healthy controls. Pearson's correlation analysis was applied to evaluate the correlation between ReHo values of different brain regions of CTN patients and clinical manifestations.
RESULTS: Compared with healthy controls, CTN patients were found to have increased ReHo values in the inferior cerebellum bilaterally, right inferior temporal gyrus, right middle occipital gyrus, right fusiform gyrus, right superior frontal gyrus, and right precentral gyrus. ROC curve analysis of each brain region revealed near-perfect accuracy regarding the area under the curve (AUC). However, no correlation between ReHo values and clinical manifestations in CTN patients was found.
CONCLUSIONS: CTN is associated with altered neuronal networks in different areas of the brain. ReHo values all possess different degrees of change, implying that CTN has a certain impact on cerebral function. This article is protected by copyright. All rights reserved.

PMID: 30536573 [PubMed - as supplied by publisher]

Multimodal magnetic resonance imaging investigation of basal forebrain damage and cognitive deficits in Parkinson's disease.

Thu, 12/13/2018 - 15:01
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Multimodal magnetic resonance imaging investigation of basal forebrain damage and cognitive deficits in Parkinson's disease.

Mov Disord. 2018 Dec 10;:

Authors: Gargouri F, Gallea C, Mongin M, Pyatigorskaya N, Valabregue R, Ewenczyk C, Sarazin M, Yahia-Cherif L, Vidailhet M, Lehéricy S

Abstract
BACKGROUND: Cognitive deficits in Parkinson's disease (PD) may result from damage in the cortex as well as in the dopaminergic, noradrenergic, and cholinergic inputs to the cortex. Cholinergic inputs to the cortex mainly originate from the basal forebrain and are clustered in several regions, called Ch1 to Ch4, that project to the hippocampus (Ch1-2), the olfactory bulb (Ch3), and the cortex and amygdala (Ch4).
OBJECTIVE: We investigated changes in basal forebrain and their role in cognitive deficits in PD.
METHODS: We studied 52 nondemented patients with PD (Hoehn & Yahr 1-2) and 25 age-matched healthy controls using diffusion and resting state functional MRI.
RESULTS: PD patients had a loss of structural integrity within the Ch1-2 and Ch3-4 nuclei of the basal forebrain as well as in the fornix. Tractography showed that the probability of anatomical connection was decreased in PD between Ch3-4 and the associative prefrontal cortex, occipital cortex, and peri-insular regions. There was a reduction in functional connectivity between Ch1-2 and the bilateral hippocampi and parahippocampal gyri, the left middle and superior temporal gyri, and the left fusiform gyrus and between Ch3-4 and the right inferior frontal gyrus and the right and left thalamus. In Ch1-2, loss of structural integrity and connectivity correlated with scores at the memory tests, whereas changes in Ch3-4 correlated with scores of global cognition and executive functions.
CONCLUSION: This study highlights the association between deficits of different cholinergic nuclei of the basal forebrain and the extent of cognitive impairments in nondemented PD patients. © 2018 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

PMID: 30536444 [PubMed - as supplied by publisher]

A SENtence Supramodal Areas AtlaS (SENSAAS) based on multiple task-induced activation mapping and graph analysis of intrinsic connectivity in 144 healthy right-handers.

Thu, 12/13/2018 - 15:01
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A SENtence Supramodal Areas AtlaS (SENSAAS) based on multiple task-induced activation mapping and graph analysis of intrinsic connectivity in 144 healthy right-handers.

Brain Struct Funct. 2018 Dec 07;:

Authors: Labache L, Joliot M, Saracco J, Jobard G, Hesling I, Zago L, Mellet E, Petit L, Crivello F, Mazoyer B, Tzourio-Mazoyer N

Abstract
We herein propose an atlas of 32 sentence-related areas based on a 3-step method combining the analysis of activation and asymmetry during multiple language tasks with hierarchical clustering of resting-state connectivity and graph analyses. 144 healthy right-handers performed fMRI runs based on language production, reading and listening, both with sentences and lists of over-learned words. Sentence minus word-list BOLD contrast and left-minus-right BOLD asymmetry for each task were computed in pairs of homotopic regions of interest (hROIs) from the AICHA atlas. Thirty-two hROIs were identified that were conjointly activated and leftward asymmetrical in each of the three language contrasts. Analysis of resting-state temporal correlations of BOLD variations between these 32 hROIs allowed the segregation of a core network, SENT_CORE including 18 hROIs. Resting-state graph analysis applied to SENT_CORE hROIs revealed that the pars triangularis of the inferior frontal gyrus and the superior temporal sulcus were hubs based on their degree centrality (DC), betweenness, and participation values corresponding to epicentres of sentence processing. Positive correlations between DC and BOLD activation values for SENT_CORE hROIs were observed across individuals and across regions regardless of the task: the more a SENT_CORE area is connected at rest the stronger it is activated during sentence processing. DC measurements in SENT_CORE may thus be a valuable index for the evaluation of inter-individual variations in language areas functional activity in relation to anatomical or clinical patterns in large populations. SENSAAS (SENtence Supramodal Areas AtlaS), comprising the 32 supramodal sentence areas, including SENT_CORE network, can be downloaded at http://www.gin.cnrs.fr/en/tools/ .

PMID: 30535758 [PubMed - as supplied by publisher]

Oxytocin Modulates the Intrinsic Dynamics Between Attention-Related Large-Scale Networks.

Thu, 12/13/2018 - 15:01
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Oxytocin Modulates the Intrinsic Dynamics Between Attention-Related Large-Scale Networks.

Cereb Cortex. 2018 Dec 07;:

Authors: Xin F, Zhou F, Zhou X, Ma X, Geng Y, Zhao W, Yao S, Dong D, Biswal BB, Kendrick KM, Becker B

Abstract
Attention and salience processing have been linked to the intrinsic between- and within-network dynamics of large-scale networks engaged in internal (default network [DN]) and external attention allocation (dorsal attention network [DAN] and salience network [SN]). The central oxytocin (OXT) system appears ideally organized to modulate widely distributed neural systems and to regulate the switch between internal attention and salient stimuli in the environment. The current randomized placebo (PLC)-controlled between-subject pharmacological resting-state fMRI study in N = 187 (OXT, n = 94; PLC, n = 93; single-dose intranasal administration) healthy male and female participants employed an independent component analysis approach to determine the modulatory effects of OXT on the within- and between-network dynamics of the DAN–SN–DN triple network system. OXT increased the functional integration between subsystems within SN and DN and increased functional segregation of the DN with both attentional control networks (SN and DAN). Whereas no sex differences were observed, OXT effects on the DN–SN interaction were modulated by autistic traits. Together, the findings suggest that OXT may facilitate efficient attention allocation by modulating the intrinsic functional dynamics between DN components and large-scale networks involved in external attentional demands (SN and DAN).:

PMID: 30535355 [PubMed - as supplied by publisher]

Mouse optical imaging for understanding resting-state functional connectivity in human fMRI.

Thu, 12/13/2018 - 15:01
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Mouse optical imaging for understanding resting-state functional connectivity in human fMRI.

Commun Integr Biol. 2018;11(4):e1528821

Authors: Matsui T, Murakami T, Ohki K

Abstract
Resting-state functional connectivity (FC), which measures the temporal correlation of spontaneous hemodynamic activity between distant brain areas, is a widely accepted method in functional magnetic resonance imaging (fMRI) to assess the connectome of healthy and diseased human brains. A common assumption underlying FC is that it reflects the temporal structure of large-scale neuronal activity that is converted into large-scale hemodynamic activity. However, direct observation of such relationship has been difficult. In this commentary, we describe our recent progress regarding this topic. Recently, transgenic mice that express a genetically encoded calcium indicator (GCaMP) in neocortical neurons are enabling the optical recording of neuronal activity in large-scale with high spatiotemporal resolution. Using these mice, we devised a method to simultaneously monitor neuronal and hemodynamic activity and addressed some key issues related to the neuronal basis of FC. We propose that many important questions about human resting-state fMRI can be answered using GCaMP expressing transgenic mice as a model system.

PMID: 30534348 [PubMed]

Differences in Neural Recovery From Acute Stress Between Cortisol Responders and Non-responders.

Thu, 12/13/2018 - 15:01
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Differences in Neural Recovery From Acute Stress Between Cortisol Responders and Non-responders.

Front Psychiatry. 2018;9:631

Authors: Dimitrov A, Demin K, Fehlner P, Walter H, Erk S, Veer IM

Abstract
Adaptive recovery from a stressor fosters resilience. So far, however, few studies have examined brain functional connectivity in the aftermath of stress, with inconsistent results reported. Focusing on the immediate recovery from psychosocial stress, the current study compared amygdala resting-state functional connectivity (RSFC) before and immediately after psychosocial stress between cortisol responders and non-responders. Differences between groups were expected for amygdala RSFC with regions involved in down-regulation of the physiological stress response, emotion regulation, and memory consolidation. Eighty-six healthy participants (36 males/50 females) underwent a social stress paradigm inside the MRI scanner. Before and immediately after stress, resting-state (RS) fMRI scans were acquired to determine amygdala RSFC. Next, changes in connectivity from pre- to post-stress were compared between cortisol responders and non-responders. Responders demonstrated a cortisol increase, higher negative affect, and decreased heart rate variability (HRV) in response to stress compared to non-responders. A significant Sex-by-Responder-by-Time interaction was found between the bilateral amygdala and posterior cingulate cortex (PCC) and precuneus (p < 0.05, corrected). As males were also more likely to show a cortisol increase to the stress task than females, follow-up analyses were conducted for both sexes separately. Whereas no difference was observed between female responders and non-responders, male non-responders showed an increase in FC after stress between the bilateral amygdala and the PCC and precuneus (p < 0.05, corrected). The increased coupling of the amygdala with the PCC/precuneus, a core component of the default mode network (DMN), might indicate an increased engagement of the amygdala within the DMN directly after stress in non-responders. Although this study was carried out in healthy participants, and the results likely reflect normal variations in the neural response to stress, understanding the mechanisms that underlie these variations could prove beneficial in revealing neural markers that promote resilience to stress-related disorders.

PMID: 30534092 [PubMed]

Aberrant Cerebral Activity in Early Postmenopausal Women: A Resting-State Functional Magnetic Resonance Imaging Study.

Thu, 12/13/2018 - 15:01
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Aberrant Cerebral Activity in Early Postmenopausal Women: A Resting-State Functional Magnetic Resonance Imaging Study.

Front Cell Neurosci. 2018;12:454

Authors: Zhang S, Hu J, Fan W, Liu B, Wen L, Wang G, Gong M, Yang C, Zhang D

Abstract
Background: Early postmenopausal women frequently suffer from cognitive impairments and emotional disorders, such as lack of attention, poor memory, deficits in executive function and depression. However, the underlying mechanisms of these impairments remain unclear. Method: Forty-three early postmenopausal women and forty-four age-matched premenopausal controls underwent serum sex hormone analysis, neuropsychological testing and resting-state functional magnetic resonance imaging (rs-fMRI). Degree centrality (DC) analysis was performed to confirm the peak points of the functionally abnormal brain areas as the centers of the seeds. Subsequently, the functional connectivity (FC) between these abnormal seeds and other voxels across the whole brain was calculated. Finally, the sex hormone levels, neuroimaging indices and neuropsychological data were combined to detect potential correlations. Results: Compared with the premenopausal controls, the early postmenopausal women exhibited significantly higher serum follicle-stimulating hormone (FSH) levels, more severe climacteric and depressive symptoms, worse sleep quality and more extensive cognitive impairments. Concurrently, the neuroimaging results showed elevated DC values in the left amygdala (AMYG.L), reduced DC values in the left middle occipital gyrus (MOG.L) and right middle occipital gyrus (MOG.R). When we used the AMYG.L as the seed point, FC with the left insula (INS.L), bilateral prefrontal cortex (PFC) and right superior frontal gyrus (SFG.R) was increased; these regions are related to depressive states, poor sleep quality and decreased executive function. When bilateral MOG were used as the seed points, FC with left inferior parietal gyrus (IPG.L), this area closely associated with impaired memory, was decreased. Conclusion: These results illuminated the regional and network-level brain dysfunction in early postmenopausal women, which might provide information on the underlying mechanisms of the different cognitive impairments and emotional alterations observed in this group.

PMID: 30534056 [PubMed]

Cognitive Deficit-Related Interhemispheric Asynchrony within the Medial Hub of the Default Mode Network Aids in Classifying the Hyperthyroid Patients.

Thu, 12/13/2018 - 15:01
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Cognitive Deficit-Related Interhemispheric Asynchrony within the Medial Hub of the Default Mode Network Aids in Classifying the Hyperthyroid Patients.

Neural Plast. 2018;2018:9023604

Authors: Zhi M, Hou Z, Zhang Y, Yue Y, Li L, Yuan Y

Abstract
Background and Purpose: Recent studies suggest that abnormal structure and function in the brain network were related to cognitive and emotional impairment in hyperthyroid patients (HPs). The association between altered voxel-mirrored homotopic connectivity (VMHC) and neuropsychological impairment in HPs remains unclear. This study is aimed at investigating the association between the disrupted functional coordination and psychological dysfunction in hyperthyroidism.
Method: Thirty-three hyperthyroid patients and thirty-three matched healthy controls (HCs) were recruited, and they received resting-state functional magnetic resonance imaging (fMRI) scans and neuropsychological evaluation. The VMHC value was computed to reveal the functional coordination between homotopic regions in both groups. The neurobehavioral relevancy method was employed to explore the relationship between the altered VMHC and emotional, cognition measures. Further receiver operating characteristic (ROC) curve analysis was adopted to examine the power of changed regional VMHC in classifying the patients with hyperthyroidism.
Results: Compared with the HCs, the HPs exhibited significantly declined VMHC values in the bilateral medial frontal gyrus (MeFG). The interhemispheric asynchrony in the MeFG was positively correlated with Z scores of episodic memory. The ROC analysis further determined that abnormal VMHC in the MeFG could efficiently distinguish the HPs from the HCs (area under the curve (AUC) = 0.808, P < 0.001).
Conclusion: The altered interhemispheric coordination in the hub of the default mode network may implicated in the modulation of episodic memory in HPs patients and the distinct feature of the interhemispheric asynchrony may be treated as a potential target for the early recognition and intervention for the HPs with cognitive impairments.
Clinical Trial Registration: This is a study of the neurological basis for dysfunction of mood and cognition in hyperthyroid patients: a resting-state fMRI study (registration number: ChiCTR-OOC-16008607).

PMID: 30532774 [PubMed - in process]

Dynamic Functional Connectivity and Symptoms of Parkinson's Disease: A Resting-State fMRI Study.

Thu, 12/13/2018 - 15:01
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Dynamic Functional Connectivity and Symptoms of Parkinson's Disease: A Resting-State fMRI Study.

Front Aging Neurosci. 2018;10:388

Authors: Engels G, Vlaar A, McCoy B, Scherder E, Douw L

Abstract
Research has shown that dynamic functional connectivity (dFC) in Parkinson's disease (PD) is associated with better attention performance and with motor symptom severity. In the current study, we aimed to investigate dFC of both the default mode network (DMN) and the frontoparietal network (FPN) as neural correlates of cognitive functioning in patients with PD. Additionally, we investigated pain and motor problems as symptoms of PD in relation to dFC. Twenty-four PD patients and 27 healthy controls participated in this study. Memory and executive functioning were assessed with neuropsychological tests. Pain was assessed with the Numeric Rating Scale (NRS); motor symptom severity was assessed with the Unified Parkinson's Disease Rating Scale (UPDRS). All subjects underwent resting-state functional magnetic resonance imaging (fMRI), from which dFC was defined by calculating the variability of functional connectivity over a number of sliding windows within each scan. dFC of both the DMN and FPN with the rest of the brain was calculated. Patients performed worse on tests of visuospatial memory, verbal memory and working memory. No difference existed between groups regarding dFC of the DMN nor the FPN with the rest of the brain. A positive correlation existed between dFC of the DMN and visuospatial memory. Our results suggest that dynamics during the resting state are a neural correlate of visuospatial memory in PD patients. Furthermore, we suggest that brain dynamics of the DMN, as measured with dFC, could be a phenomenon specifically linked to cognitive functioning in PD, but not to other symptoms.

PMID: 30532703 [PubMed]

Abnormal Topology of the Structural Connectome in the Limbic Cortico-Basal-Ganglia Circuit and Default-Mode Network Among Primary Insomnia Patients.

Thu, 12/13/2018 - 15:01
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Abnormal Topology of the Structural Connectome in the Limbic Cortico-Basal-Ganglia Circuit and Default-Mode Network Among Primary Insomnia Patients.

Front Neurosci. 2018;12:860

Authors: Wu Y, Liu M, Zeng S, Ma X, Yan J, Lin C, Xu G, Li G, Yin Y, Fu S, Hua K, Li C, Wang T, Li C, Jiang G

Abstract
Purpose: Primary insomnia (PI) is the second most common mental disorder. However, the topologic alterations in structural brain connectome in patients with PI remain largely unknown. Methods: A total of 44 PI patients and 46 age-, gender-, and education level matched healthy control (HC) participants were recruited in this study. Diffusion tensor imaging (DTI) and resting state MRI were used to construct structural connectome for each participant, and the network parameters were employed by non-parametric permutations to evaluate the significant differences between the two groups. Relationships between abnormal network metrics and clinical characteristics, including the disease duration, the Pittsburgh Sleep Quality Index (PSQI), the Insomnia Severity Index (ISI), the Self-Rating Anxiety Scale (SAS), and the Self-Rating Depression Scale (SDS), were investigated with Spearman's correlation analysis in PI patients. Results: PI patients demonstrated small-world architecture with lower global (P = 0.005) and local (P = 0.035) efficiencies compared with the HC group. The unique hub nodal properties in PI patients were mainly in the right limbic cortico-basal-ganglia circuit. Five disrupted subnetworks in PI patients were observed in the limbic cortico-basal-ganglia circuit and left default-mode networks (DMN) (P < 0.05, NBS corrected). Moreover, most unique hub nodal properties in the right limbic cortico-basal-ganglia circuit were significantly correlated with disease duration, and clinical characteristics (SAS, SDS, ISI scores) in PI processing. Conclusion: These findings suggested the abnormal anatomical network architecture may be closely linked to clinical characteristics in PI. The study provided novel insights into the neural substrates underlying symptoms and neurophysiologic mechanisms of PI.

PMID: 30532688 [PubMed]

Intrinsic functional boundaries of lateral frontal cortex in the common marmoset monkey.

Thu, 12/13/2018 - 15:01
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Intrinsic functional boundaries of lateral frontal cortex in the common marmoset monkey.

J Neurosci. 2018 Dec 10;:

Authors: Schaeffer DJ, Gilbert KM, Gati JS, Menon RS, Everling S

Abstract
The common marmoset (Callithrix jacchus) is a small New World primate species that has been recently targeted as a potentially powerful preclinical model of human prefrontal cortex dysfunction. Although the structural boundaries of frontal cortex were described in marmosets at the start of the 20th century (Brodmann, 1909) and refined more recently (e.g., Paxinos et al., 2012), the broad functional boundaries of marmoset frontal cortex have yet to be established. In this study, we sought to functionally derive boundaries of marmoset lateral frontal cortex (LFC) using ultra-high field (9.4 T) resting state functional magnetic resonance imaging (RS-fMRI). We collected RS-fMRI in seven (4 females, 3 males) lightly anesthetized marmosets and employed a data-driven hierarchical clustering approach to derive subdivisions of LFC based on intrinsic functional connectivity. We then conducted seed-based analyses to assess the functional connectivity between these clusters and the rest of the brain. The results demonstrated seven distinct functional clusters within LFC. The functional connectivity patterns of these clusters with the rest of the brain were also found to be distinct and organized along a rostro-caudal gradient, consonant to that found in humans and macaques. Overall, these results support the view that marmosets are a promising preclinical modelling species for studying LFC dysfunction related to neuropsychiatric or neurodegenerative human brain diseases.SIGNIFICANCE STATEMENTThe common marmoset is a New World primate that has garnered recent attention as a powerful complement to canonical Old World primate (e.g., macaques) and rodent models (e.g., rats, mice) for preclinical modelling of the human brain in healthy and diseased states. A critical step in the development of marmosets for such models is to characterize functional network topologies of frontal cortex in healthy, normally functioning marmosets -- i.e., how these circuitries are functionally divided, and how those topologies compare to human circuitry. To our knowledge, this is the first study to demonstrate functional boundaries of LFC and the corresponding network topologies in marmoset monkeys.

PMID: 30530862 [PubMed - as supplied by publisher]

Changes in endogenous dopamine induced by methylphenidate predict functional connectivity in non-human primates.

Thu, 12/13/2018 - 15:01
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Changes in endogenous dopamine induced by methylphenidate predict functional connectivity in non-human primates.

J Neurosci. 2018 Dec 10;:

Authors: Birn RM, Converse AK, Rajala AZ, Alexander AL, Block WF, McMillan AB, Christian BT, Filla CN, Murali D, Hurley SA, Jenison RL, Populin LC

Abstract
Dopamine (DA) levels in the striatum are increased by many therapeutic drugs, such as methylphenidate (MPH), which also alters behavioral and cognitive functions thought to be controlled by the prefrontal cortex (PFC) dose-dependently. We linked DA changes and functional connectivity (FC) using simultaneous [18F]fallypride PET and resting state functional magnetic resonance imaging (fMRI) in awake male rhesus monkeys after oral administration of various doses of MPH. We found a negative correlation between [18F]fallypride nondisplaceable binding potential (BPND) and MPH dose in the head of the caudate (hCd), demonstrating increased extracellular DA resulting from MPH administration. This decrease in BPND was negatively correlated with FC between hCd and PFC. Subsequent voxel-wise analyses revealed negative correlations with FC between the hCd and the dorsolateral PFC, hippocampus, and precuneus. These results, showing that MPH-induced changes in DA levels in hCd predict resting state FC, shed light on a mechanism by which changes in striatal DA could influence function in the PFC.SIGNIFICANCE STATEMENTDopamine transmission is thought to play an essential role in shaping large scale-neural networks that underlie cognitive functions. It is the target of therapeutic drugs such as methylphenidate (Ritalin), which blocks the dopamine transporter, thereby increasing extracellular dopamine levels. Methylphenidate is used extensively to treat ADHD, even though its effects on cognitive functions and their underlying neural mechanisms are not well understood. To date, little is known about the link between changes in dopamine levels and changes in functional brain organization. Using simultaneous PET/MR imaging we show that methylphenidate-induced changes in endogenous dopamine levels in the head of the caudate predict changes in resting state functional connectivity between this structure and the prefrontal cortex, precuneus, and hippocampus.

PMID: 30530859 [PubMed - as supplied by publisher]

Resting amygdala connectivity and basal sympathetic tone as markers of chronic hypervigilance.

Thu, 12/13/2018 - 15:01
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Resting amygdala connectivity and basal sympathetic tone as markers of chronic hypervigilance.

Psychoneuroendocrinology. 2018 Nov 26;102:68-78

Authors: Kleshchova O, Rieder JK, Grinband J, Weierich MR

Abstract
BACKGROUND: Chronic hypervigilance, a state of sustained alertness and hyperarousal in the absence of threat, has been shown to predict poorer clinical outcomes post-trauma. An exaggerated and persistent amygdala alerting response to affective information has been proposed as a reactivity-based, and thus indirect, marker of hypervigilance. However, because chronic hypervigilance is a persistent rather than reactive state, it should be directly observable under resting-state conditions without the need for exposure to affectively charged stimuli.
OBJECTIVE: We tested resting amygdala connectivity and basal sympathetic and hypothalamic-pituitary-adrenal axis activity as direct neural and neuroendocrine markers of chronic hypervigilance.
PARTICIPANTS: 24 trauma-exposed women (age M = 22.9, SD = 5.5) and 20 no-trauma controls (age M = 21.1, SD = 3.2).
MEASURES: Amygdala connectivity was measured using functional magnetic resonance imaging at rest and during viewing of novel and familiar affective scenes. Elevated amygdala connectivity during the viewing of novel scenes (exaggerated alerting response) and familiar scenes (persistent alerting response) was used as a reactivity-based index of hypervigilance. Resting amygdala connectivity and basal salivary alpha-amylase (sAA) and cortisol were tested as neural and neuroendocrine markers of hypervigilance, respectively.
RESULTS: Compared to no-trauma controls, trauma-exposed women showed greater connectivity between the left amygdala and the ventral anterior cingulate cortex (vACC) both during affective processing and at rest. Exaggerated neural novelty response was associated with greater resting left amygdala-vACC connectivity and higher basal sAA, but not cortisol.
CONCLUSIONS: Greater synchronization of threat-detection circuitry in the absence of threat and basal sympathetic tone might serve as complementary resting-state markers of the cognitive and physiological components of chronic hypervigilance, respectively.

PMID: 30529716 [PubMed - as supplied by publisher]

Nutrient biomarker patterns, cognitive function, and fMRI measures of network efficiency in the aging brain.

Thu, 12/13/2018 - 15:01
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Nutrient biomarker patterns, cognitive function, and fMRI measures of network efficiency in the aging brain.

Neuroimage. 2018 Dec 07;:

Authors: Zwilling CE, Talukdar T, Zamroziewicz MK, Barbey AK

Abstract
A central aim of research in the psychological and brain sciences is to establish therapeutic interventions to promote healthy brain aging. Accumulating evidence indicates that diet and the many bioactive substances present in food are reasonable interventions to examine for dementia prevention. However, interdisciplinary research that applies methods from nutritional epidemiology and network neuroscience to investigate the role of nutrition in shaping functional brain network efficiency remains to be conducted. The present study therefore sought to combine methods across disciplines, applying nutrient biomarker pattern (NBP) analysis to capture the effects of plasma nutrients in combination and to examine their collective influence on measures of functional brain network efficiency (small-world propensity). We examined the contribution of NBPs to multiple indices of cognition and brain health in non-demented elders (n = 116), investigating performance on measures of general intelligence, executive function, and memory, and resting-state fMRI measures of brain network efficiency within seven intrinsic connectivity networks. Statistical moderation investigated whether nutrient biomarker patterns influenced network efficiency and cognitive outcomes. The results revealed five NBPs that were associated with enhanced cognitive performance, including biomarker patterns high in plasma: (1) ω-3 and ω-6 polyunsaturated fatty acids (PUFAs), (2) lycopene, (3) ω-3 PUFAs, (4) carotenoids, and (5) vitamins B (riboflavin, folate, B12) and D. Furthermore, three NBPs were associated with enhanced functional brain network efficiency, including biomarker patterns high in plasma: (1) ω-6 PUFAs, (2) ω-3 PUFAs, and (3) carotene. Finally, ω-3 PUFAs moderated the fronto-parietal network and general intelligence, while ω-6 PUFAs and lycopene moderated the dorsal attention network and executive function. In sum, NBPs account for a significant proportion of variance in measures of cognitive performance and functional brain network efficiency. The results motivate a multidisciplinary approach that applies methods from nutritional epidemiology (nutrient biomarker pattern analysis) and cognitive neuroscience (functional brain network efficiency) to characterize the impact of nutrition on human health, aging, and disease.

PMID: 30529508 [PubMed - as supplied by publisher]

Linked MRI signatures of the brain's acute and persistent response to concussion in female varsity rugby players.

Thu, 12/13/2018 - 15:01
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Linked MRI signatures of the brain's acute and persistent response to concussion in female varsity rugby players.

Neuroimage Clin. 2018 Dec 03;:

Authors: Manning KY, Llera A, Dekaban GA, Bartha R, Barreira C, Brown A, Fischer L, Jevremovic T, Blackney K, Doherty TJ, Fraser DD, Holmes J, Beckmann CF, Menon RS

Abstract
Acute brain changes are expected after concussion, yet there is growing evidence of persistent abnormalities well beyond clinical recovery and clearance to return to play. Multiparametric MRI is a powerful approach to non-invasively study structure-function relationships in the brain, however it remains challenging to interpret the complex and heterogeneous cascade of brain changes that manifest after concussion. Emerging conjunctive, data-driven analysis approaches like linked independent component analysis can integrate structural and functional imaging data to produce linked components that describe the shared inter-subject variance across images. These linked components not only offer the potential of a more comprehensive understanding of the underlying neurobiology of concussion, but can also provide reliable information at the level of an individual athlete. In this study, we analyzed resting-state functional MRI (rs-fMRI) and diffusion tensor imaging (DTI) within a cohort of female varsity rugby players (n = 52) through the in- and off-season, including concussed athletes (n = 21) who were studied longitudinally at three days, three months and six months after a diagnosed concussion. Linked components representing co-varying white matter microstructure and functional network connectivity characterized (a) the brain's acute response to concussion and (b) persistent alterations beyond clinical recovery. Furthermore, we demonstrate that these long-term brain changes related to specific aspects of a concussion history and allowed us to monitor individual athletes before and longitudinally after a diagnosed concussion.

PMID: 30528959 [PubMed - as supplied by publisher]

The effect of transcutaneous auricular vagus nerve stimulation on treatment-resistant depression monitored by resting-state fMRI and MRS: The first case report.

Thu, 12/13/2018 - 15:01
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The effect of transcutaneous auricular vagus nerve stimulation on treatment-resistant depression monitored by resting-state fMRI and MRS: The first case report.

Brain Stimul. 2018 Nov 27;:

Authors: Li XJ, Wang L, Wang HX, Zhang L, Zhang GL, Rong PJ, Fang JL

PMID: 30528347 [PubMed - as supplied by publisher]

Juvenile myoclonic epilepsy has hyper dynamic functional connectivity in the dorsolateral frontal cortex.

Thu, 12/13/2018 - 15:01
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Juvenile myoclonic epilepsy has hyper dynamic functional connectivity in the dorsolateral frontal cortex.

Neuroimage Clin. 2018 Nov 19;:

Authors: Wang Y, Berglund IS, Uppman M, Li TQ

Abstract
PURPOSE: Characterize the static and dynamic functional connectivity for subjects with juvenile myoclonic epilepsy (JME) using a quantitative data-driven analysis approach.
METHODS: Whole-brain resting-state functional MRI data were acquired on a 3 T whole-body clinical MRI scanner from 18 subjects clinically diagnosed with JME and 25 healthy control subjects. 2-min sliding-window approach was incorporated in the quantitative data-driven data analysis framework to assess both the dynamic and static functional connectivity in the resting brains. Two-sample t-tests were performed voxel-wise to detect the differences in functional connectivity metrics based on connectivity strength and density.
RESULTS: The static functional connectivity metrics based on quantitative data-driven analysis of the entire 10-min acquisition window of resting-state functional MRI data revealed significantly enhanced functional connectivity in JME patients in bilateral dorsolateral prefrontal cortex, dorsal striatum, precentral and middle temporal gyri. The dynamic functional connectivity metrics derived by incorporating a 2-min sliding window into quantitative data-driven analysis demonstrated significant hyper dynamic functional connectivity in the dorsolateral prefrontal cortex, middle temporal gyrus and dorsal striatum. Connectivity strength metrics (both static and dynamic) can detect more extensive functional connectivity abnormalities in the resting-state functional networks (RFNs) and depict also larger overlap between static and dynamic functional connectivity results.
CONCLUSION: Incorporating a 2-min sliding window into quantitative data-driven analysis of resting-state functional MRI data can reveal additional information on the temporally fluctuating RFNs of the human brain, which indicate that RFNs involving dorsolateral prefrontal cortex have temporal varying hyper dynamic characteristics in JME patients. Assessing dynamic along with static functional connectivity may provide further insights into the abnormal function connectivity underlying the pathological brain functioning in JME.

PMID: 30527355 [PubMed - as supplied by publisher]