New resting-state fMRI related studies at PubMed

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Impaired prefrontal cortex-thalamus pathway in intractable temporal lobe epilepsy with aberrant executive control function: MRI evidence.

Sun, 02/17/2019 - 14:20
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Impaired prefrontal cortex-thalamus pathway in intractable temporal lobe epilepsy with aberrant executive control function: MRI evidence.

Clin Neurophysiol. 2019 Jan 18;130(4):484-490

Authors: Zhang C, Zhang H, Xu K, Yang H, Liu C, Yu T, Chen N, Li K

Abstract
OBJECTIVES: This study aimed to assess structural and functional connectivity alterations of the prefrontal cortex (PFC)-thalamus axis in individuals with unilateral intractable temporal lobe epilepsy (TLE) showing executive control function (ECF) impairment and to explore the potential mechanism.
METHODS: Thirty-eight individuals with intractable left TLE and twenty-nine healthy controls (HCs) were recruited for diffusion tensor imaging (DTI) and resting-state fMRI (rs-fMRI) scanning. According to the ECF state, patients were assigned to normal and impaired ECF groups. Functional connectivity (FC) and probabilistic diffusion tractography of the PFC- thalamus pathway were assessed. The general linear model (GLM) was employed for comparing fiber number (FN) and FC between groups. Pearson correlation analysis of FC, FN and ECF test scores was performed.
RESULTS: FC and FN of left DLPFC-thalamus pathway were significantly increased in the impaired ECF group compared with the normal ECF and HC groups. However, FC and FN were not correlated with ECF score.
CONCLUSIONS: These findings indicated increased connectivity between DLPFC and the ipsilateral thalamus might reflect nonfunctional nerve remodeling along the seizure pathway.
SIGNIFICANCE: The present findings suggest that the DLPFC-thalamus pathway may be an important structure for exploring the mechanisms of TLE with ECF dysfunction.

PMID: 30771725 [PubMed - as supplied by publisher]

Ultra-high field MRI reveals mood-related circuit disturbances in depression: a comparison between 3-Tesla and 7-Tesla.

Sun, 02/17/2019 - 14:20
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Ultra-high field MRI reveals mood-related circuit disturbances in depression: a comparison between 3-Tesla and 7-Tesla.

Transl Psychiatry. 2019 Feb 15;9(1):94

Authors: Morris LS, Kundu P, Costi S, Collins A, Schneider M, Verma G, Balchandani P, Murrough JW

Abstract
Ultra-high field 7-Tesla (7 T) MRI has the potential to advance our understanding of neuropsychiatric disorders, including major depressive disorder (MDD). To date, few studies have quantified the advantage of resting state functional MRI (fMRI) at 7 T compared to 3-Tesla (3 T). We conducted a series of experiments that demonstrate the improvement in temporal signal-to-noise ratio (TSNR) of a multi-echo multi-band fMRI protocol with ultra-high field 7 T MRI, compared to a similar protocol using 3 T MRI in healthy controls (HC). We also directly tested the enhancement in ultra-high field 7 T fMRI signal power by examining the ventral tegmental area (VTA), a small midbrain structure that is critical to the expected neuropathology of MDD but difficult to discern with standard 3 T MRI. We demonstrate up to 300% improvement in TSNR and resting state functional connectivity coefficients provided by ultra-high field 7 T fMRI compared to 3 T, indicating enhanced power for detection of functional neural architecture. A multi-echo based acquisition protocol and signal denoising pipeline afforded greater gain in signal power compared to classic acquisition and denoising pipelines. Furthermore, ultra-high field fMRI revealed mood-related neurocircuit disturbances in patients with MDD compared to HC, which were not detectable with 3 T fMRI. Ultra-high field 7 T fMRI may provide an effective tool for studying functional neural architecture relevant to MDD and other neuropsychiatric disorders.

PMID: 30770788 [PubMed - in process]

Functional asymmetry of thalamocortical networks in subjects at ultra-high risk for psychosis and first-episode schizophrenia.

Sun, 02/17/2019 - 14:20
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Functional asymmetry of thalamocortical networks in subjects at ultra-high risk for psychosis and first-episode schizophrenia.

Eur Neuropsychopharmacol. 2019 Feb 12;:

Authors: Zhu F, Liu Y, Liu F, Yang R, Li H, Chen J, Kennedy DN, Zhao J, Guo W

Abstract
Disrupted functional asymmetry has been implicated in schizophrenia. However, it remains unknown whether disrupted functional asymmetry originates from intra-hemispheric and/or inter-hemispheric functional connectivity (FC) in the patients, and whether it starts at very early stage of psychosis. Seventy-six patients with first-episode, drug-naive schizophrenia, 74 subjects at ultra-high risk for psychosis (UHR), and 71 healthy controls underwent resting-state functional magnetic resonance imaging. The 'Parameter of asymmetry' (PAS) metric was calculated and support vector machine (SVM) classification analysis was applied to analyze the data. Compared with healthy controls, patients exhibited decreased PAS in the left thalamus/pallidum, right hippocampus/parahippocampus, right inferior frontal gyrus/insula, right thalamus, and left inferior parietal lobule, and increased PAS in the left calcarine, right superior occipital gyrus/middle occipital gyrus, and right precentral gyrus/postcentral gyrus. By contrast, UHR subjects showed decreased PAS in the left thalamus relative to healthy controls. A negative correlation was observed between decreased PAS in the right hippocampus/parahippocampus and Brief Visuospatial Memory Test-Revised (BVMT-R) scores in the patients (r = -0.364, p = 0.002). Moreover, the PAS values in the left thalamus could discriminate the patients/UHR subjects from the controls with acceptable sensitivities (68.42%/81.08%). First-episode patients and UHR subjects shared decreased PAS in the left thalamus. This observed pattern of functional asymmetry highlights the involvement of the thalamus in the pathophysiology of psychosis and may also be applied as a very early marker for psychosis.

PMID: 30770234 [PubMed - as supplied by publisher]

Integration and segregation of functional segmented anterior and posterior hippocampal networks in memory performance.

Sat, 02/16/2019 - 13:20
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Integration and segregation of functional segmented anterior and posterior hippocampal networks in memory performance.

Behav Brain Res. 2019 Feb 12;:

Authors: Xu J, Zhang M

Abstract
PURPOSE: To determine the association between functional connectivity (FC) of functional-segmented anterior and posterior portions of the hippocampus and performance on verbal and visual memory tests in a young, healthy population.
METHODS: We recruited 100 healthy participants in the age of 19-29. Resting state fMRI data were acquired and voxel-wise correlation analysis was performed to functionally divide the hippocampus. We investigated the inter-hemispheric hippocampal-cortical functional connectivity after the participants took the assessment of episodic memory using verbal (California Verbal Learning Test II, CVLT-II) and visual subtests (Rey-Osterrieth Complex Figure, ROCF). The partial correlations were used to identify the association between the intra-hemispheric hippocampal-cortical mean resting correlation and memory performance.
RESULTS: The results showed that the anterior and posterior hippocampal networks involved differently in verbal and visual memory. Intra-hemispheric FC between left posterior hippocampus and posterior parahippocampal gyrus (PPHG) was positively correlated with CVLT-II Trail 2 Immediate Free Recall (r = 0.223, p = 0.029). Intra-hemispheric FC between left posterior hippocampus and posterior cingulate (PCC) was negatively correlated with ROCF Immediate Recall (r=-0.217 p = 0.034). Intra-hemispheric FC between left anterior hippocampus and temporal pole (TP) negatively correlated with ROCF Delayed Recall (r=-0.228, p = 0.025). Split half resampling procedure results showed some repeatability in our subjects.
CONCLUSION: The present results demonstrated that, the anterior hippocampus was specifically involved in the visual memory processing, whereas the posterior hippocampus contributed to both the verbal and visual memories, which may have implications for a functionally synergetic and dissociable role of the hippocampus in different kinds of memory.

PMID: 30768997 [PubMed - as supplied by publisher]

Sertraline Effects on Striatal Resting-State Functional Connectivity in Youth With OCD: A Pilot Study.

Sat, 02/16/2019 - 13:20
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Sertraline Effects on Striatal Resting-State Functional Connectivity in Youth With OCD: A Pilot Study.

J Am Acad Child Adolesc Psychiatry. 2018 Oct 30;:

Authors: Bernstein GA, Cullen KR, Harris EC, Conelea CA, Zagoloff AD, Carstedt PA, Lee SS, Mueller BA

Abstract
OBJECTIVE: Foundational knowledge on neural circuitry underlying pediatric obsessive-compulsive disorder (OCD) and how it changes during standard treatment is needed to provide the basis for conceptualization and development of novel, targeted treatments. This study explored the effects of sertraline, a selective serotonin reuptake inhibitor, on resting-state functional connectivity (RSFC) in cortico-striatal-thalamic-cortical circuits in pediatric OCD.
METHOD: Medication-free youths with OCD (n=14) and healthy controls (n=14) were examined at baseline and 12 weeks with resting-state fMRI. Between scan sessions, participants with OCD received 12 weeks of sertraline. For each scan, we conducted seed-based whole-brain RSFC analyses with 6 striatal seeds. Analysis of variance (ANOVA) examined the interaction between group and time on striatal connectivity, including cluster-based thresholding to correct for multiple tests. Connectivity changes within circuits identified in group analyses were correlated with clinical change.
RESULTS: Two significant group x time effects in the OCD group showed increased striatal connectivity from baseline to 12 weeks compared with controls. Circuits demonstrating this pattern included right putamen with left frontal cortex/insula and left putamen with left frontal cortex and pre- and post-central cortices. Increase in connectivity in left putamen circuit was significantly correlated with clinical improvement on Children's Yale-Brown Obsessive-Compulsive Scale (r = -0.58, p = .03).
CONCLUSION: Sertraline appears to affect specific striatal-based circuits in pediatric OCD, and in part, these changes may account for clinical improvement. Future work is needed to confirm these preliminary findings, which would facilitate identification of circuit-based targets for novel treatment development.

PMID: 30768407 [PubMed - as supplied by publisher]

Association Between Age and Familial Risk for Alcoholism on Functional Connectivity in Adolescence.

Sat, 02/16/2019 - 13:20
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Association Between Age and Familial Risk for Alcoholism on Functional Connectivity in Adolescence.

J Am Acad Child Adolesc Psychiatry. 2019 Feb 13;:

Authors: Vaidya JG, Elmore AL, Wallace A, Langbehn DR, Kramer JR, Kuperman S, O'Leary DS

Abstract
OBJECTIVE: Youth with a family history of alcohol use disorder (family history positive; FHP) are at increased risk for developing maladaptive substance use relative to family history negative (FHN) peers. Building on earlier studies demonstrating morphological differences and distinct patterns of neural activation in FHP, the purpose of the present study was to investigate differential intrinsic functional connectivity among brain networks indexing premorbid risk of developing alcohol use disorder (AUD).
METHOD: The current study examined intrinsic functional connectivity using resting state functional magnetic resonance imaging (fMRI) in 191 adolescents 13 to 18 years with and without family history of alcohol use disorder (AUD) via independent component analysis (ICA), a method enabling data-driven investigation of internetwork and intranetwork connectivity among brain regions at rest.
RESULTS: Analyses revealed significantly lower intranetwork connectivity in FHP compared to FHN participants between dorsal premotor cortex and other sensorimotor network regions. Reduced intranetwork connectivity in this region was further correlated with the number of biological family members with AUD and mood disorders. Robust differences were also evident in internetwork connectivity as a function of age. However, there was no evidence for family history by age interactions.
CONCLUSION: Intra- but not inter-network connectivity appears to differentiate FHP and FHN adolescents whereas age differences within adolescence are marked by differences in internetwork connectivity.

PMID: 30768382 [PubMed - as supplied by publisher]

Anterior cingulate GABA and glutamate concentrations are associated with resting-state network connectivity.

Sat, 02/16/2019 - 13:20
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Anterior cingulate GABA and glutamate concentrations are associated with resting-state network connectivity.

Sci Rep. 2019 Feb 14;9(1):2116

Authors: Levar N, Van Doesum TJ, Denys D, Van Wingen GA

Abstract
In recent years, resting-state (RS) networks and RS function have received increased attention, highlighting their importance in both cognitive function and psychopathology. The neurochemical substrates underlying RS networks and their interactions, however, have not yet been well established. Even though prior research has provided first evidence for a negative association between brain GABA levels and RS connectivity, these findings have been limited to within network connectivity, and not network interactions. In this multi-modal imaging study, we investigated the role of the main inhibitory neurotransmitter У-aminobutyric acid (GABA) and the main excitatory neurotransmitter glutamate (Glx) on RS network function and network coupling of three core networks: the default-mode network (DMN), salience network (SN), and central executive network (CEN). Resting-state functional connectivity and GABA and Glx levels in the dorsal anterior cingulate cortex (dACC) were assessed in 64 healthy male participants using functional MRI and magnetic resonance spectroscopy (MRS). Analyses showed that dACC GABA levels were positively correlated with resting-state connectivity in the CEN, and negatively associated with functional coupling of the DMN and CEN. In contrast, GABA/Glx ratios were inversely correlated with the SN and DMN. These findings extend insights into the role of GABA and Glx in individual networks to interactions across networks, suggesting that GABA levels in the SN might play a role in RS functional connectivity within the central executive network, and network interactions with the default-mode network. Our results further suggest a potentially critical role of the relationship between GABA and Glx in RS network function.

PMID: 30765822 [PubMed - in process]

Manipulation of Subcortical and Deep Cortical Activity in the Primate Brain Using Transcranial Focused Ultrasound Stimulation.

Sat, 02/16/2019 - 13:20
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Manipulation of Subcortical and Deep Cortical Activity in the Primate Brain Using Transcranial Focused Ultrasound Stimulation.

Neuron. 2019 Feb 07;:

Authors: Folloni D, Verhagen L, Mars RB, Fouragnan E, Constans C, Aubry JF, Rushworth MFS, Sallet J

Abstract
The causal role of an area within a neural network can be determined by interfering with its activity and measuring the impact. Many current reversible manipulation techniques have limitations preventing their application, particularly in deep areas of the primate brain. Here, we demonstrate that a focused transcranial ultrasound stimulation (TUS) protocol impacts activity even in deep brain areas: a subcortical brain structure, the amygdala (experiment 1), and a deep cortical region, the anterior cingulate cortex (ACC, experiment 2), in macaques. TUS neuromodulatory effects were measured by examining relationships between activity in each area and the rest of the brain using functional magnetic resonance imaging (fMRI). In control conditions without sonication, activity in a given area is related to activity in interconnected regions, but such relationships are reduced after sonication, specifically for the targeted areas. Dissociable and focal effects on neural activity could not be explained by auditory confounds.

PMID: 30765166 [PubMed - as supplied by publisher]

Altered connectivity of the right anterior insula drives the pain connectome changes in chronic knee osteoarthritis.

Sat, 02/16/2019 - 13:20
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Altered connectivity of the right anterior insula drives the pain connectome changes in chronic knee osteoarthritis.

Pain. 2018 May;159(5):929-938

Authors: Cottam WJ, Iwabuchi SJ, Drabek MM, Reckziegel D, Auer DP

Abstract
Resting-state functional connectivity (FC) has proven a powerful approach to understand the neural underpinnings of chronic pain, reporting altered connectivity in 3 main networks: the default mode network (DMN), central executive network, and the salience network (SN). The interrelation and possible mechanisms of these changes are less well understood in chronic pain. Based on emerging evidence of its role to drive switches between network states, the right anterior insula (rAI, an SN hub) may play a dominant role in network connectivity changes underpinning chronic pain. To test this hypothesis, we used seed-based resting-state FC analysis including dynamic and effective connectivity metrics in 25 people with chronic osteoarthritis (OA) pain and 19 matched healthy volunteers. Compared with controls, participants with painful knee OA presented with increased anticorrelation between the rAI (SN) and DMN regions. Also, the left dorsal prefrontal cortex (central executive network hub) showed more negative FC with the right temporal gyrus. Granger causality analysis revealed increased negative influence of the rAI on the posterior cingulate (DMN) in patients with OA in line with the observed enhanced anticorrelation. Moreover, dynamic FC was lower in the DMN of patients and thus more similar to temporal dynamics of the SN. Together, these findings evidence a widespread network disruption in patients with persistent OA pain and point toward a driving role of the rAI.

PMID: 29557928 [PubMed - indexed for MEDLINE]

Circadian phenotype impacts the brain's resting state functional connectivity, attentional performance and sleepiness.

Fri, 02/15/2019 - 12:00

Circadian phenotype impacts the brain's resting state functional connectivity, attentional performance and sleepiness.

Sleep. 2019 Feb 15;:

Authors: Facer-Childs ER, Campos BM, Middleton B, Skene DJ, Bagshaw AP

Abstract
INTRODUCTION: Functional connectivity (FC) of the human brain's intrinsically connected networks underpins cognitive functioning and disruptions of FC are associated with sleep and neurological disorders. However, there is limited research on the impact of circadian phenotype and time of day on FC.
STUDY OBJECTIVES: The aim of this study was to investigate resting state FC of the default mode network (DMN) in Early and Late circadian phenotypes over a socially constrained day.
METHODS: 38 healthy individuals (14 male, 22.7 ± 4.2 years) categorised as Early (n =16) or Late (n = 22) using the Munich ChronoType Questionnaire took part. Following a two week baseline of actigraphy coupled with saliva samples for melatonin and cortisol rhythms, participants underwent testing at 14.00 h, 20.00 h and 08.00 h the following morning. Testing consisted of resting state functional MRI, a structural T1 scan, attentional cognitive performance tasks and self-reported daytime sleepiness. Seed based FC analysis from the medial prefrontal and posterior cingulate cortices of the DMN was performed, compared between groups and linked with behavioural data.
RESULTS: Fundamental differences in the DMN were observed between Early and Late circadian phenotypes. Resting state FC of the DMN predicted individual differences in attention and subjective ratings of sleepiness.
CONCLUSION: Differences in FC of the DMN may underlie the compromised attentional performance and increased sleepiness commonly associated with Late types when they conform to a societally constrained day that does not match their intrinsic circadian phenotype.

PMID: 30763951 [PubMed - as supplied by publisher]

Functional and neurochemical disruptions of brain hub topology in chronic pain.

Fri, 02/15/2019 - 12:00

Functional and neurochemical disruptions of brain hub topology in chronic pain.

Pain. 2019 Jan 16;:

Authors: Kaplan CM, Schrepf A, Vatansever D, Larkin TE, Mawla I, Ichesco E, Kochlefl L, Harte SE, Clauw DJ, Mashour GA, Harris RE

Abstract
A critical component of brain network architecture is a robust hub structure, wherein hub regions facilitate efficient information integration by occupying highly connected and functionally central roles in the network. Across a wide range of neurological disorders, hub brain regions seem to be disrupted, and the character of this disruption can yield insights into the pathophysiology of these disorders. We applied a brain network-based approach to examine hub topology in fibromyalgia, a chronic pain condition with prominent central nervous system involvement. Resting state functional magnetic resonance imaging data from 40 fibromyalgia patients and 46 healthy volunteers, and a small validation cohort of 11 fibromyalgia patients, were analyzed using graph theoretical techniques to model connections between 264 brain regions. In fibromyalgia, the anterior insulae functioned as hubs and were members of the rich club, a highly interconnected nexus of hubs. In fibromyalgia, rich-club membership varied with the intensity of clinical pain: the posterior insula, primary somatosensory, and motor cortices belonged to the rich club only in patients with the highest pain intensity. Furthermore, the eigenvector centrality (a measure of how connected a region is to other highly connected regions) of the posterior insula positively correlated with clinical pain and mediated the relationship between glutamate + glutamine (assessed by proton magnetic resonance spectroscopy) within this structure and the patient's clinical pain report. Together, these findings reveal altered hub topology in fibromyalgia and demonstrate, for the first time to our knowledge, a neurochemical basis for altered hub strength and its relationship to the perception of pain.This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal.

PMID: 30763287 [PubMed - as supplied by publisher]

Abnormal intrinsic functional network hubs and connectivity following peripheral visual loss because of inherited retinal degeneration.

Fri, 02/15/2019 - 12:00

Abnormal intrinsic functional network hubs and connectivity following peripheral visual loss because of inherited retinal degeneration.

Neuroreport. 2019 Mar 06;30(4):295-304

Authors: Huang X, Dan HD, Zhou FQ, Deng QQ, Shen Y

Abstract
Previous neuroimaging studies have shown that the long-term effects of peripheral vision loss lead to functional and morphological reorganization in visual cortices. However, it has not been determined whether whole-brain functional network centrality changes occur during peripheral vision loss. This study aimed to investigate functional network centrality and connectivity changes in individuals with peripheral vision loss because of retinitis pigmentosa (RP) by using voxel-wise degree centrality (DC) and seed-based resting-state functional connectivity (rsFC) methods. In total, 30 RP patients (18 men and 12 women, mean age: 38.77±14.44 years) and 30 healthy controls (HCs) (18 men and 12 women, mean age: 34.57±10.70 years) matched for age, sex, cognition, education, and visual expertise underwent resting-state magnetic resonance imaging scans. Graph theory-based network analysis was carried out to investigate DC between the two groups. A seed-based rsFC analysis was then carried out to further reveal the abnormal functional connectivity of the altered DC brain region. Pearson's correlation was used to analyze the relationships of DC and rsFC index with the clinical variables in RP patients: visual function (best-corrected visual acuity and visual field, VF) and optical coherence tomography testing (mean retinal nerve fiber layer). Compared with HCs, RP patients had significantly lower DC values in the bilateral cuneus/calcarine/precuneus (CUN/CAL/PreCUN) [Brodmann's area (BA) 17/18/19/30/31]. In addition, RP patients showed decreased rsFC index, relative to that of HCs, from bilateral CUN/CAL/PreCUN to bilateral lingual/cuneus/calcarine (LIG/CUN/CAL) (BA 18/19/30) and the bilateral postcentral gyrus/superior parietal lobule (BA 3/5/7/40). In contrast, RP patients showed increased rsFC index, relative to that of HCs, from bilateral CUN/CAL/PreCUN to bilateral thalamus/caudate (voxel-level P<0.01; Gaussian random-field correction, cluster-level P<0.05). Moreover, the course of RP showed a negative correlation with the mean DC values of the bilateral CUN/CAL/PreCUN (r=-0.480; P=0.007) and the mean FC values of the bilateral LIG/CUN/CAL (r=-0.484; P=0.007); the mean DC values of the bilateral CUN/CAL/PreCUN in RP showed a negative correlation with the right eye VF (r=-0.411; P=0.024) and left eye VF (r=-0.426; P=0.019). Our results showed that RP patients showed abnormal function network hubs in various brain regions related to visual, thalamocortical, and sensorimotor networks; these might reflect impaired top-down modulations, visual imagery, and visuomotor coordination in RP patients. Moreover, the DC index can be used as a biomarker to indicate the severity of visual loss in RP patients.

PMID: 30763285 [PubMed - in process]

Increased ventromedial prefrontal cortex activity and connectivity predict poor sertraline treatment outcome in late-life depression.

Fri, 02/15/2019 - 12:00
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Increased ventromedial prefrontal cortex activity and connectivity predict poor sertraline treatment outcome in late-life depression.

Int J Geriatr Psychiatry. 2019 Feb 13;:

Authors: Emam H, Steffens DC, Pearlson G, Wang L

Abstract
OBJECTIVE: Previous studies of imaging predictors on acute treatment response in late life depression (LLD) demonstrated that poor response to selective serotonin reuptake inhibitors (SSRI) is associated with pre-treatment low functional connectivity (FC) within executive control network and high FC within default-mode network including the ventromedial prefrontal cortex (vmPFC). However, there is less research in regional resting-state functional activity that explains FC changes related to SSRI response.
METHODS: Thirty-six older MDD patients not currently on antidepressant treatment had a baseline, pre-treatment resting state functional magnetic resonance imaging scan, followed by sertraline treatment for 12 weeks. Depression severity was assessed using the Montgomery-Åsberg Depression Rating Scale (MADRS). Subjects whose MADRS score decreased < 50% from baseline or who discontinued sertraline for any reason were classified as non-responders (n=21). Subjects whose 12-week MADRS score dropped ≥ 50% from baseline were defined as responders (n=15). We conducted the amplitude of low-frequency fluctuation (ALFF) and region of interest (ROI)-to-ROI FC analyses independently. Significance threshold was set at p<0.05 with FDR correction for multiple comparisons.
RESULTS: Relative to the responder group, the non-responder group showed significantly less ALFF in the dorsomedial prefrontal cortex (dmPFC), and greater ALFF in the vmPFC/subgenual cingulate area. For ROI-to-ROI connectivity, there was significantly greater connectivity between the vmPFC and the cerebellar vermis in the non-responder group. ​ CONCLUSION: Our study highlighted the association of vmPFC resting state activity and connectivity with SSRI response. Future studies are warranted for understanding the role of vmPFC-vermis connectivity in late-life depression.

PMID: 30761621 [PubMed - as supplied by publisher]

Functional Network-Based Statistics Reveal Abnormal Resting-State Functional Connectivity in Minimal Hepatic Encephalopathy.

Fri, 02/15/2019 - 12:00
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Functional Network-Based Statistics Reveal Abnormal Resting-State Functional Connectivity in Minimal Hepatic Encephalopathy.

Front Neurol. 2019;10:33

Authors: Zhan C, Chen HJ, Gao YQ, Zou TX

Abstract
Purpose: Whole-brain functional network analysis is an emerging methodology for exploring the mechanisms underlying hepatic encephalopathy (HE). This study aimed to identify the brain subnetwork that is significantly altered within the functional connectome in minimal HE (MHE), the earliest stage of HE. Materials and Methods: The study enrolled 19 cirrhotic patients with MHE and 19 controls who underwent the resting-state functional magnetic resonance imaging and cognitive assessment based on the Psychometric Hepatic Encephalopathy Score (PHES). A whole-brain functional connectivity (FC) matrix was calculated for each subject. Then, network-based statistical analyses of the functional connectome were used to perform group comparisons, and correlation analyses were conducted to identify the relationships between FC alterations and cognitive performance. Results: MHE patients showed significant reduction of positive FC within a subnetwork that predominantly involved the regions of the default-mode network, such as the bilateral posterior cingulate gyrus, bilateral medial prefrontal cortex, bilateral hippocampus and parahippocampal gyrus, bilateral angular gyrus, and left lateral temporal cortex. Meanwhile, MHE patients showed significant reduction of negative FC between default-mode network regions (such as the bilateral posterior cingulate gyrus, medial prefrontal cortex, and angular gyrus) and the regions involved in the somatosensory network (i.e., bilateral precentral and postcentral gyri) and the language network (i.e., the bilateral Rolandic operculum). The correlations of FC within the default-mode subnetwork and PHES results were noted. Conclusion: Default-mode network dysfunction may be one of the core issues in the pathophysiology of MHE. Our findings support the notion that HE is a neurological disease related to intrinsic brain network disruption.

PMID: 30761070 [PubMed]

Resting State Functional Connectivity of Dorsal Raphe Nucleus and Ventral Tegmental Area in Medication-Free Young Adults With Major Depression.

Fri, 02/15/2019 - 12:00
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Resting State Functional Connectivity of Dorsal Raphe Nucleus and Ventral Tegmental Area in Medication-Free Young Adults With Major Depression.

Front Psychiatry. 2018;9:765

Authors: Anand A, Jones SE, Lowe M, Karne H, Koirala P

Abstract
Background: This study has, for the first time, investigated the dorsal raphe nucleus (DRN) and ventral tegmental area (VTA) resting state whole-brain functional connectivity in medication-free young adults with major depression (MDD), at baseline and in relationship to treatment response. Method: A total of 119 subjects: 78 MDD (24 ± 4 years.) and 41 Healthy Controls (HC) (24 ± 3 years) were included in the analysis. DRN and VTA ROIs anatomical templates were used to extract resting state fluctuations and used to derive whole-brain functional connectivity. Differences between MDD and HCs were examined, as well as the correlation of baseline Hamilton Depression and Anxiety scale scores to the baseline DRN and VTA connectivity. The relationship to treatment response was examined by investigating the correlation of the percentage decrease in depression and anxiety scale scores with baseline connectivity measures. Results: There was a significant decrease (p = 0.05; cluster-wise corrected) in DRN connectivity with the prefrontal and mid-cingulate cortex in the MDD group, compared with the HC group. DRN connectivity with temporal areas, including the hippocampus and amygdala, positively correlated with baseline depression scores (p = 0.05; cluster-wise corrected). VTA connectivity with the cuneus-occipital areas correlated with a change in depression scores (p = 0.05; cluster-wise corrected). Conclusion: Our results indicate the presence of DRN-prefrontal and DRN-cingulate cortex connectivity abnormalities in young medication-free depressed subjects when compared to HCs and that the severity of depressive symptoms correlates with DRN-amygdala/hippocampus connectivity. VTA connectivity with the parietal and occipital areas is related to antidepressant treatment associated with a decrease in depressive symptoms. Future studies need to be carried out in larger and different age group populations to confirm the findings of the study.

PMID: 30761028 [PubMed]

Diffuse optical tomography for the detection of perinatal stroke at the cot side: a pilot study.

Thu, 02/14/2019 - 17:00
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Diffuse optical tomography for the detection of perinatal stroke at the cot side: a pilot study.

Pediatr Res. 2019 Feb 13;:

Authors: Chalia M, Dempsey LA, Cooper RJ, Lee CW, Gibson AP, Hebden JC, Austin T

Abstract
BACKGROUND: Perinatal stroke is a potentially debilitating injury, often under-diagnosed in the neonatal period. We conducted a pilot study investigating the role of the portable, non-invasive brain monitoring technique, diffuse optical tomography (DOT), as an early detection tool for infants with perinatal stroke.
METHODS: Four stroke-affected infants were scanned with a DOT system within the first 3 days of life and compared to four healthy control subjects. Spectral power, correlation, and phase lag between interhemispheric low frequency (0.0055-0.3 Hz) hemoglobin signals were assessed. Optical data analyses were conducted with and without magnetic resonance imaging (MRI)-guided stroke localization to assess the efficacy of DOT when used without stroke anatomical information.
RESULTS: Interhemispheric correlations of both oxyhemoglobin and deoxyhemoglobin concentration were significantly reduced in the stroke-affected group within the very low (0.0055-0.0095 Hz) and resting state (0.01-0.08 Hz) frequencies (p < 0.003). There were no interhemispheric differences for spectral power. These results were observed even without MRI stroke localization.
CONCLUSION: This suggests that DOT and correlation-based analyses in the low-frequency range can potentially aid the early detection of perinatal stroke, prior to MRI acquisition. Additional methodological advances are required to increase the sensitivity and specificity of this technique.

PMID: 30759451 [PubMed - as supplied by publisher]

GridLoc: An automatic and unsupervised localization method for high-density ECoG grids.

Thu, 02/14/2019 - 17:00
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GridLoc: An automatic and unsupervised localization method for high-density ECoG grids.

Neuroimage. 2018 10 01;179:225-234

Authors: Branco MP, Leibbrand M, Vansteensel MJ, Freudenburg ZV, Ramsey NF

Abstract
Precise localization of electrodes is essential in the field of high-density (HD) electrocorticography (ECoG) brain signal analysis in order to accurately interpret the recorded activity in relation to functional anatomy. Current localization methods for subchronically implanted HD electrode grids involve post-operative imaging. However, for situations where post-operative imaging is not available, such as during acute measurements in awake surgery, electrode localization is complicated. Intra-operative photographs may be informative, but not for electrode grids positioned partially or fully under the skull. Here we present an automatic and unsupervised method to localize HD electrode grids that does not require post-operative imaging. The localization method, named GridLoc, is based on the hypothesis that the anatomical and vascular brain structures under the ECoG electrodes have an effect on the amplitude of the recorded ECoG signal. More specifically, we hypothesize that the spatial match between resting-state high-frequency band power (45-120 Hz) patterns over the grid and the anatomical features of the brain under the electrodes, such as the presence of sulci and larger blood vessels, can be used for adequate HD grid localization. We validate this hypothesis and compare the GridLoc results with electrode locations determined with post-operative imaging and/or photographs in 8 patients implanted with HD-ECoG grids. Locations agreed with an average difference of 1.94 ± 0.11 mm, which is comparable to differences reported earlier between post-operative imaging and photograph methods. The results suggest that resting-state high-frequency band activity can be used for accurate localization of HD grid electrodes on a pre-operative MRI scan and that GridLoc provides a convenient alternative to methods that rely on post-operative imaging or intra-operative photographs.

PMID: 29920373 [PubMed - indexed for MEDLINE]

A common polymorphism on the oxytocin receptor gene (rs2268498) and resting-state functional connectivity of amygdala subregions - A genetic imaging study.

Thu, 02/14/2019 - 17:00
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A common polymorphism on the oxytocin receptor gene (rs2268498) and resting-state functional connectivity of amygdala subregions - A genetic imaging study.

Neuroimage. 2018 10 01;179:1-10

Authors: Zimmermann J, Deris N, Montag C, Reuter M, Felten A, Becker B, Weber B, Markett S

Abstract
Across species, the neuropeptide oxytocin has been associated with affiliative and social approach behavior. It has been suggested to exert its effects by modulating neural circuitry underlying anxiety, affiliative motivation, and social salience. The present study aims to investigate differences in subregional amygdala resting-state connectivity in healthy adult carriers of different genotypes of the oxytocin receptor (OXTR) gene polymorphism rs2268498. Previous studies have associated this polymorphic locus with social cognitive and affiliative phenotypes. The amygdala qualifies as a reasonable target due to its broad implication in emotional and social cognitive processing as well as its key role in mediating the behavioral effects of oxytocin. Whole brain seed-based functional connectivity analyses for the basolateral, centromedial and superficial amygdala revealed stronger resting-state connectivity of all amygdala subregions to the fusiform and inferior occipital gyrus in TT-carriers compared to C-allele carriers. Additional modulations were found for the centromedial amygdala which showed stronger resting-state connectivity to inferior frontal regions and the insula in C-allele carriers and to brainstem regions in TT-carriers. Our findings not only show the importance of oxytocin functioning in amygdalar neuronal signaling but also emphasize the need to investigate the amygdalar subregions individually instead of the amygdala as a whole. In summary, the present study is the first to characterize the impact of genetic variation of the OXTR gene with known functional consequences on widespread changes in a functional brain network originating from the amygdala.

PMID: 29885487 [PubMed - indexed for MEDLINE]

Concentric radiofrequency arrays to increase the statistical power of resting-state maps in monkeys.

Thu, 02/14/2019 - 17:00
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Concentric radiofrequency arrays to increase the statistical power of resting-state maps in monkeys.

Neuroimage. 2018 09;178:287-294

Authors: Gilbert KM, Schaeffer DJ, Zeman P, Diedrichsen J, Everling S, Martinez-Trujillo JC, Pruszynski JA, Menon RS

Abstract
The close homology of monkeys and humans has increased the prevalence of non-human-primate models in functional MRI studies of brain connectivity. To improve upon the attainable resolution in functional MRI studies, a commensurate increase in the sensitivity of the radiofrequency receiver coil is required to avoid a reduction in the statistical power of the analysis. Most receive coils are comprised of multiple loops distributed equidistantly over a surface to produce spatially independent sensitivity profiles. A larger number of smaller elements will in turn provide a higher signal-to-noise ratio (SNR) over the same field of view. As the loops become physically smaller, noise originating from the sample is reduced relative to noise originating from the coil. In this coil-noise-dominated regime, coil elements can have overlapping sensitivity profiles, yet still possess only mildly correlated noise. In this manuscript, we demonstrate that inductively decoupled, concentric coil arrays can improve temporal SNR when operating in the coil-noise-dominated regime-in contrast to what is expected for the more ubiquitous sample-noise-dominated array. A small, thin, 7-channel flexible coil is developed and operated in conjunction with an existing whole-head monkey coil. The mean and maximum noise correlation between the two arrays was 5% and 23%, respectively. When the flex coil was placed over the sensorimotor cortex, the temporal SNR improved by up to 2.3-fold in the peripheral cortex and up to 1.3-fold at a 2- to 3-cm depth within the brain. When the flex coil was placed over the frontal eye fields, resting-state maps showed substantially elevated sensitivity to correlations in the prefrontal cortex (54%), supplementary eye fields (39%), and anterior cingulate cortex (41%). The concentric-coil topology provided a pragmatic and robust means to significantly improve local temporal SNR and the statistical power of functional connectivity maps.

PMID: 29852280 [PubMed - indexed for MEDLINE]

Improved state change estimation in dynamic functional connectivity using hidden semi-Markov models.

Wed, 02/13/2019 - 16:00
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Improved state change estimation in dynamic functional connectivity using hidden semi-Markov models.

Neuroimage. 2019 Feb 09;:

Authors: Shappell H, Caffo BS, Pekar JJ, Lindquist MA

Abstract
The study of functional brain networks has grown rapidly over the past decade. While most functional connectivity (FC) analyses estimate one static network structure for the entire length of the functional magnetic resonance imaging (fMRI) time series, recently there has been increased interest in studying time-varying changes in FC. Hidden Markov models (HMMs) have proven to be a useful modeling approach for discovering repeating graphs of interacting brain regions (brain states). However, a limitation lies in HMMs assuming that the sojourn time, the number of consecutive time points in a state, is geometrically distributed. This may encourage inaccurate estimation of the time spent in a state before switching to another state. We propose a hidden semi-Markov model (HSMM) approach for inferring time-varying brain networks from fMRI data, which explicitly models the sojourn distribution. Specifically, we propose using HSMMs to find each subject's most probable series of network states and the graphs associated with each state, while properly estimating and modeling the sojourn distribution for each state. We perform a simulation study, as well as an analysis on both task-based fMRI data from an anxiety-inducing experiment and resting-state fMRI data from the Human Connectome Project. Our results demonstrate the importance of model choice when estimating sojourn times and reveal their potential for understanding healthy and diseased brain mechanisms.

PMID: 30753927 [PubMed - as supplied by publisher]

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