New resting-state fMRI related studies at PubMed

Organisational and neuromodulatory underpinnings of structural-functional connectivity decoupling in patients with Parkinson's disease.

Thu, 01/21/2021 - 11:40
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Organisational and neuromodulatory underpinnings of structural-functional connectivity decoupling in patients with Parkinson's disease.

Commun Biol. 2021 Jan 19;4(1):86

Authors: Zarkali A, McColgan P, Leyland LA, Lees AJ, Rees G, Weil RS

Abstract
Parkinson's dementia is characterised by changes in perception and thought, and preceded by visual dysfunction, making this a useful surrogate for dementia risk. Structural and functional connectivity changes are seen in humans with Parkinson's disease, but the organisational principles are not known. We used resting-state fMRI and diffusion-weighted imaging to examine changes in structural-functional connectivity coupling in patients with Parkinson's disease, and those at risk of dementia. We identified two organisational gradients to structural-functional connectivity decoupling: anterior-to-posterior and unimodal-to-transmodal, with stronger structural-functional connectivity coupling in anterior, unimodal areas and weakened towards posterior, transmodal regions. Next, we related spatial patterns of decoupling to expression of neurotransmitter receptors. We found that dopaminergic and serotonergic transmission relates to decoupling in Parkinson's overall, but instead, serotonergic, cholinergic and noradrenergic transmission relates to decoupling in patients with visual dysfunction. Our findings provide a framework to explain the specific disorders of consciousness in Parkinson's dementia, and the neurotransmitter systems that underlie these.

PMID: 33469150 [PubMed - in process]

Crosstalk between Depression and Dementia with Resting-State fMRI Studies and Its Relationship with Cognitive Functioning.

Thu, 01/21/2021 - 11:40
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Crosstalk between Depression and Dementia with Resting-State fMRI Studies and Its Relationship with Cognitive Functioning.

Biomedicines. 2021 Jan 16;9(1):

Authors: Kim J, Kim YK

Abstract
Alzheimer's disease (AD) is the most common type of dementia, and depression is a risk factor for developing AD. Epidemiological studies provide a clinical correlation between late-life depression (LLD) and AD. Depression patients generally remit with no residual symptoms, but LLD patients demonstrate residual cognitive impairment. Due to the lack of effective treatments, understanding how risk factors affect the course of AD is essential to manage AD. Advances in neuroimaging, including resting-state functional MRI (fMRI), have been used to address neural systems that contribute to clinical symptoms and functional changes across various psychiatric disorders. Resting-state fMRI studies have contributed to understanding each of the two diseases, but the link between LLD and AD has not been fully elucidated. This review focuses on three crucial and well-established networks in AD and LLD and discusses the impacts on cognitive decline, clinical symptoms, and prognosis. Three networks are the (1) default mode network, (2) executive control network, and (3) salience network. The multiple properties emphasized here, relevant for the hypothesis of the linkage between LLD and AD, will be further developed by ongoing future studies.

PMID: 33467174 [PubMed]

Identifying Diurnal Variability of Brain Connectivity Patterns Using Graph Theory.

Thu, 01/21/2021 - 11:40
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Identifying Diurnal Variability of Brain Connectivity Patterns Using Graph Theory.

Brain Sci. 2021 Jan 16;11(1):

Authors: Farahani FV, Fafrowicz M, Karwowski W, Bohaterewicz B, Sobczak AM, Ceglarek A, Zyrkowska A, Ostrogorska M, Sikora-Wachowicz B, Lewandowska K, Oginska H, Beres A, Hubalewska-Mazgaj M, Marek T

Abstract
Significant differences exist in human brain functions affected by time of day and by people's diurnal preferences (chronotypes) that are rarely considered in brain studies. In the current study, using network neuroscience and resting-state functional MRI (rs-fMRI) data, we examined the effect of both time of day and the individual's chronotype on whole-brain network organization. In this regard, 62 participants (39 women; mean age: 23.97 ± 3.26 years; half morning- versus half evening-type) were scanned about 1 and 10 h after wake-up time for morning and evening sessions, respectively. We found evidence for a time-of-day effect on connectivity profiles but not for the effect of chronotype. Compared with the morning session, we found relatively higher small-worldness (an index that represents more efficient network organization) in the evening session, which suggests the dominance of sleep inertia over the circadian and homeostatic processes in the first hours after waking. Furthermore, local graph measures were changed, predominantly across the left hemisphere, in areas such as the precentral gyrus, putamen, inferior frontal gyrus (orbital part), inferior temporal gyrus, as well as the bilateral cerebellum. These findings show the variability of the functional neural network architecture during the day and improve our understanding of the role of time of day in resting-state functional networks.

PMID: 33467070 [PubMed]

The benefit of high-performance gradients on echo planar imaging for BOLD-based resting-state functional MRI.

Thu, 01/21/2021 - 11:40
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The benefit of high-performance gradients on echo planar imaging for BOLD-based resting-state functional MRI.

Phys Med Biol. 2020 11 27;65(23):235024

Authors: Kang D, Jo HJ, In MH, Yarach U, Meyer NK, Bardwell Speltz LJ, Gray EM, Trzasko JD, Huston Iii J, Bernstein MA, Shu Y

Abstract
Improved gradient performance in an MRI system reduces distortion in echo planar imaging (EPI), which has been a key imaging method for functional studies. A lightweight, low-cryogen compact 3T MRI scanner (C3T) is capable of achieving 80 mT m-1 gradient amplitude with 700 T m-1 s-1 slew rate, in comparison with a conventional whole-body 3T MRI scanner (WB3T, 50 mT m-1 with 200 T m-1 s-1). We investigated benefits of the high-performance gradients in a high-spatial-resolution (1.5 mm isotropic) functional MRI study. Reduced echo spacing in the EPI pulse sequence inherently leads to less severe geometric distortion, which provided higher accuracy than with WB3T for registration between EPI and anatomical images. The cortical coverage of C3T datasets was improved by more accurate signal depiction (i.e. less dropout or pile-up). Resting-state functional analysis results showed that greater magnitude and extent in functional connectivity (FC) for the C3T than the WB3T when the selected seed region is susceptible to distortions, while the FC matrix for well-known brain networks showed little difference between the two scanners. This shows that the improved quality in EPI is particularly valuable for studying certain brain regions typically obscured by severe distortion.

PMID: 33245051 [PubMed - indexed for MEDLINE]

Epilepsy enhance global efficiency of language networks in right temporal lobe gliomas.

Wed, 01/20/2021 - 16:40
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Epilepsy enhance global efficiency of language networks in right temporal lobe gliomas.

CNS Neurosci Ther. 2021 Jan 19;:

Authors: Fang S, Wang Y, Jiang T

Abstract
AIMS: We analyzed the resting state functional magnetic resonance images to investigate the alterations of neural networks in patients with glioma-related epilepsy (GRE).
METHODS: Fifty-six patients with right temporal lower-grade glioma were divided into GRE (n = 28) and non-GRE groups. Twenty-eight healthy subjects were recruited after matching age, sex, and education level. Sensorimotor, visual, language, and left executive control networks were applied to generate functional connectivity matrices, and their topological properties were investigated.
RESULTS: No significant alterations in functional connectivity were found. The least significant discovery test revealed differences only in the language network. The shortest path length, clustering coefficient, local efficiency, and vulnerability were greater in the non-GRE group than in the other groups. The nodal efficiencies of two nodes (mirror areas to Broca and Wernicke) were weaker in the non-GRE group than in the other groups. The node of degree centrality (Broca), nodal local efficiency (Wernicke), and nodal clustering coefficient (temporal polar) were greater in the non-GRE group than in the healthy group.
CONCLUSION: Different tumor locations alter different neural networks. Temporal lobe gliomas in the right hemisphere altered the language network. Glioma itself and GRE altered the network in opposing ways in patients with right temporal glioma.

PMID: 33464718 [PubMed - as supplied by publisher]

Do intrinsic brain functional networks predict working memory from childhood to adulthood?

Wed, 01/20/2021 - 16:40
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Do intrinsic brain functional networks predict working memory from childhood to adulthood?

Hum Brain Mapp. 2020 Nov;41(16):4574-4586

Authors: Zhang H, Hao S, Lee A, Eickhoff SB, Pecheva D, Cai S, Meaney M, Chong YS, Broekman BFP, Fortier MV, Qiu A

Abstract
Working memory (WM) is defined as the ability to maintain a representation online to guide goal-directed behavior. Its capacity in early childhood predicts academic achievements in late childhood and its deficits are found in various neurodevelopmental disorders. We employed resting-state fMRI (rs-fMRI) of 468 participants aged from 4 to 55 years and connectome-based predictive modeling (CPM) to explore the potential predictive power of intrinsic functional networks to WM in preschoolers, early and late school-age children, adolescents, and adults. We defined intrinsic functional networks among brain regions identified by activation likelihood estimation (ALE) meta-analysis on existing WM functional studies (ALE-based intrinsic functional networks) and intrinsic functional networks generated based on the whole brain (whole-brain intrinsic functional networks). We employed the CPM on these networks to predict WM in each age group. The CPM using the ALE-based and whole-brain intrinsic functional networks predicted WM of individual adults, while the prediction power of the ALE-based intrinsic functional networks was superior to that of the whole-brain intrinsic functional networks. Nevertheless, the CPM using the whole-brain but not the ALE-based intrinsic functional networks predicted WM in adolescents. And, the CPM using neither the ALE-based nor whole-brain networks predicted WM in any of the children groups. Our findings showed the trend of the prediction power of the intrinsic functional networks to cognition in individuals from early childhood to adulthood.

PMID: 33463860 [PubMed - in process]

DREZotomy in the management of post brachial plexus root avulsion neuropathic pain: fMRI correlates for pain relief.

Wed, 01/20/2021 - 16:40
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DREZotomy in the management of post brachial plexus root avulsion neuropathic pain: fMRI correlates for pain relief.

Br J Neurosurg. 2021 Jan 19;:1-10

Authors: Baruah S, Bhat DI, Devi BI, Uppar AM, Bharti K, Ramalingaiah AH

Abstract
BACKGROUND: Deafferentiation pain following brachial plexus root avulsion has been documented to be severe enough to affect activities of daily living in patients. Microsurgical DREZotomy is known to alleviate the symptoms by decreasing the afferent signals transmitted from the spinal cord to sensory cortex.
OBJECTIVES: To document and analyse the effectiveness of DREZotomy and to evaluate the role of 'sensory cortex' in the cause and relief of dysesthetic pain, using fMRI.
MATERIALS AND METHODS: This was a prospective study conducted between 2010 and 2016 and included all patients who underwent DREZotomy for dysesthetic pain following traumatic brachial plexus injury (TBPI). Patients were evaluated both preoperatively and postoperatively with Visual Analogue Scale(VAS), Hospital Anxiety and Depression score (HADS) and SF36 questionnaire and effectiveness of surgery was assessed. Functional magnetic resonance imaging (fMRI) of the brain in resting state was performed before and after surgery and was also compared with controls. Patients underwent standard microsurgical DREZotomy from C5 to D1. Postoperative assessment was done at 6 weeks and 6 months following surgery.
RESULTS: Our series had 18 patients aged between 22 and 63 years. RTA was the most common cause of injury. There was significant decrease in pain at 6 months follow up compared to pre-operative values as assessed by VAS, HADS, SF36 questionnaire. fMRI analysis revealed cluster activations in the sensory, motor cortex and in the right cingulate gyrus in the preoperative group which was higher than in normal controls. In the postoperative group, the size of the resting state activation was significantly reduced.
CONCLUSION: DREZotomy is an effective procedure for TBPI patients. We hypothesize that these fMRI findings reflect the cortical reorganization that occurs not only after injury but also following successful surgery which explains the cause and relief of dyesthetic pain.

PMID: 33463389 [PubMed - as supplied by publisher]

Excitatory-inhibitory balance within EEG microstates and resting-state fMRI networks: assessed via simultaneous trimodal PET-MR-EEG imaging.

Wed, 01/20/2021 - 16:40
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Excitatory-inhibitory balance within EEG microstates and resting-state fMRI networks: assessed via simultaneous trimodal PET-MR-EEG imaging.

Transl Psychiatry. 2021 Jan 18;11(1):60

Authors: Rajkumar R, Régio Brambilla C, Veselinović T, Bierbrier J, Wyss C, Ramkiran S, Orth L, Lang M, Rota Kops E, Mauler J, Scheins J, Neumaier B, Ermert J, Herzog H, Langen KJ, Binkofski FC, Lerche C, Shah NJ, Neuner I

Abstract
The symbiosis of neuronal activities and glucose energy metabolism is reflected in the generation of functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) signals. However, their association with the balance between neuronal excitation and inhibition (E/I-B), which is closely related to the activities of glutamate and γ-aminobutyric acid (GABA) and the receptor availability (RA) of GABAA and mGluR5, remains unexplored. This research investigates these associations during the resting state (RS) condition using simultaneously recorded PET/MR/EEG (trimodal) data. The trimodal data were acquired from three studies using different radio-tracers such as, [11C]ABP688 (ABP) (N = 9), [11C]Flumazenil (FMZ) (N = 10) and 2-[18F]fluoro-2-deoxy-D-glucose (FDG) (N = 10) targeted to study the mGluR5, GABAA receptors and glucose metabolism respectively. Glucose metabolism and neuroreceptor binding availability (non-displaceable binding potential (BPND)) of GABAA and mGluR5 were found to be significantly higher and closely linked within core resting-state networks (RSNs). The neuronal generators of EEG microstates and the fMRI measures were most tightly associated with the BPND of GABAA relative to mGluR5 BPND and the glucose metabolism, emphasising a predominance of inhibitory processes within in the core RSNs at rest. Changes in the neuroreceptors leading to an altered coupling with glucose metabolism may render the RSNs vulnerable to psychiatric conditions. The paradigm employed here will likely help identify the precise neurobiological mechanisms behind these alterations in fMRI functional connectivity and EEG oscillations, potentially benefitting individualised healthcare treatment measures.

PMID: 33462192 [PubMed - in process]

Neurovascular coupling alterations in type 2 diabetes: a 5-year longitudinal MRI study.

Wed, 01/20/2021 - 16:40
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Neurovascular coupling alterations in type 2 diabetes: a 5-year longitudinal MRI study.

BMJ Open Diabetes Res Care. 2021 Jan;9(1):

Authors: Zhang Y, Zhang X, Ma G, Qin W, Yang J, Lin J, Zhang Q

Abstract
INTRODUCTION: Respective alterations in resting-state brain neural activity and cerebral blood flow (CBF) in type 2 diabetes mellitus (T2DM) have been reported. However, their coupling alteration in T2DM remains largely unknown.
RESEARCH DESIGN AND METHODS: Twenty-seven patients with T2DM aged 40-67 years and 36 well-matched healthy controls (HCs) underwent resting-state functional MRI (rs-fMRI) and arterial spin labeling (ASL) scans at two time points with a 5-year interval. Regional homogeneity (ReHo) and CBF were calculated from rs-fMRI and ASL, respectively. The standardized ReHo:CBF ratio (mReHo:mCBF ratio), the spontaneous neuronal activity per unit CBF supply, was compared between the two time points. Relationships between the mReHo:mCBF ratio and memory performance were analyzed.
RESULTS: Over 5 years, decreased mReHo:mCBF ratios in patients with T2DM were mainly distributed in four regions, among which the left insula exhibited more severely decreased mReHo:mCBF ratio in patients with T2DM than in HCs, while the left postcentral gyrus, the right Rolandic operculum, and the right precentral gyrus showed no significant intergroup difference. Correlations between the mReHo:mCBF ratio and memory performance were also found in patients with T2DM.
CONCLUSIONS: This study suggests that T2DM may accelerate neurovascular coupling impairment in specific brain regions (the left insula), contributing to memory decline. This study implies that the mReHo:mCBF ratio is a potential imaging marker for detecting neurovascular changes.

PMID: 33462074 [PubMed - in process]

Longitudinal changes in blood-based biomarkers in chronic moderate to severe traumatic brain injury: preliminary findings.

Wed, 01/20/2021 - 16:40
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Longitudinal changes in blood-based biomarkers in chronic moderate to severe traumatic brain injury: preliminary findings.

Brain Inj. 2021 Jan 18;:1-7

Authors: Schnakers C, Divine J, Johnson MA, Lutkenhoff E, Monti MM, Keil KM, Guthrie J, Pouratian N, Patterson D, Jensen G, Morales VC, Weaver KF, Rosario ER

Abstract
Objectives: This longitudinal study aims at 1) providing preliminary evidence of changes in blood-based biomarkers across time in chronic TBI and 2) relating these changes to outcome measures and cerebral structure and activity. Methods: Eight patients with moderate-to-severe TBI (7 males, 35 ± 7.6 years old, 5 severe TBI, 17.52 ± 3.84 months post-injury) were evaluated at monthly intervals across 6 time-points using: a) Blood-based biomarkers (GFAP, NSE, S100A12, SDBP145, UCH-L1, T-tau, P-tau, P-tau/T-tau ratio); b) Magnetic Resonance Imaging to evaluate changes in brain structure; c) Resting-state electroencephalograms to evaluate changes in brain function; and d) Outcome measures to assess cognition, emotion, and functional recovery (MOCA, RBANS, BDI-II, and DRS). Results: Changes in P-tau levels were found across time [p = .007]. P-tau was positively related to functional [p < .001] and cognitive [p = .006] outcomes, and negatively related to the severity of depression, 6 months later [R = -0.901; p =.006]. P-tau and P-tau/T-tau ratio were also positively correlated to shape change in subcortical areas such as brainstem [T(7) = 4.71, p = .008] and putamen [T(7) = 3.25, p = .012]. Conclusions: Our study provides preliminary findings that suggest a positive relationship between P-tau and the recovery of patients with chronic TBI.

PMID: 33461331 [PubMed - as supplied by publisher]

Corticocortical and Thalamocortical Changes in Functional Connectivity and White Matter Structural Integrity after Reward-Guided Learning of Visuospatial Discriminations in Rhesus Monkeys.

Wed, 01/20/2021 - 16:40
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Corticocortical and Thalamocortical Changes in Functional Connectivity and White Matter Structural Integrity after Reward-Guided Learning of Visuospatial Discriminations in Rhesus Monkeys.

J Neurosci. 2020 10 07;40(41):7887-7901

Authors: Pelekanos V, Premereur E, Mitchell DJ, Chakraborty S, Mason S, Lee ACH, Mitchell AS

Abstract
The frontal cortex and temporal lobes together regulate complex learning and memory capabilities. Here, we collected resting-state functional and diffusion-weighted MRI data before and after male rhesus macaque monkeys received extensive training to learn novel visuospatial discriminations (reward-guided learning). We found functional connectivity changes in orbitofrontal, ventromedial prefrontal, inferotemporal, entorhinal, retrosplenial, and anterior cingulate cortices, the subicular complex, and the dorsal, medial thalamus. These corticocortical and thalamocortical changes in functional connectivity were accompanied by related white matter structural alterations in the uncinate fasciculus, fornix, and ventral prefrontal tract: tracts that connect (sub)cortical networks and are implicated in learning and memory processes in monkeys and humans. After the well-trained monkeys received fornix transection, they were impaired in learning new visuospatial discriminations. In addition, the functional connectivity profile that was observed after the training was altered. These changes were accompanied by white matter changes in the ventral prefrontal tract, although the integrity of the uncinate fasciculus remained unchanged. Our experiments highlight the importance of different communication relayed among corticocortical and thalamocortical circuitry for the ability to learn new visuospatial associations (learning-to-learn) and to make reward-guided decisions.SIGNIFICANCE STATEMENT Frontal neural networks and the temporal lobes contribute to reward-guided learning in mammals. Here, we provide novel insight by showing that specific corticocortical and thalamocortical functional connectivity is altered after rhesus monkeys received extensive training to learn novel visuospatial discriminations. Contiguous white matter fiber pathways linking these gray matter structures, namely, the uncinate fasciculus, fornix, and ventral prefrontal tract, showed structural changes after completing training in the visuospatial task. Additionally, different patterns of functional and structural connectivity are reported after removal of subcortical connections within the extended hippocampal system, via fornix transection. These results highlight the importance of both corticocortical and thalamocortical interactions in reward-guided learning in the normal brain and identify brain structures important for memory capabilities after injury.

PMID: 32900835 [PubMed - indexed for MEDLINE]

Effects of TPH2 gene variation and childhood trauma on the clinical and circuit-level phenotype of functional movement disorders.

Wed, 01/20/2021 - 16:40
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Effects of TPH2 gene variation and childhood trauma on the clinical and circuit-level phenotype of functional movement disorders.

J Neurol Neurosurg Psychiatry. 2020 08;91(8):814-821

Authors: Spagnolo PA, Norato G, Maurer CW, Goldman D, Hodgkinson C, Horovitz S, Hallett M

Abstract
BACKGROUND: Functional movement disorders (FMDs), part of the wide spectrum of functional neurological disorders (conversion disorders), are common and often associated with a poor prognosis. Nevertheless, little is known about their neurobiological underpinnings, particularly with regard to the contribution of genetic factors. Because FMD and stress-related disorders share a common core of biobehavioural manifestations, we investigated whether variants in stress-related genes also contributed, directly and interactively with childhood trauma, to the clinical and circuit-level phenotypes of FMD.
METHODS: Sixty-nine patients with a 'clinically defined' diagnosis of FMD were genotyped for 18 single-nucleotide polymorphisms (SNPs) from 14 candidate genes. FMD clinical characteristics, psychiatric comorbidity and symptomatology, and childhood trauma exposure were assessed. Resting-state functional connectivity data were obtained in a subgroup of 38 patients with FMD and 38 age-matched and sex-matched healthy controls. Amygdala-frontal connectivity was analysed using a whole-brain seed-based approach.
RESULTS: Among the SNPs analysed, a tryptophan hydroxylase 2 (TPH2) gene polymorphism-G703T-significantly predicted clinical and neurocircuitry manifestations of FMD. Relative to GG homozygotes, T carriers were characterised by earlier FMD age of onset and decreased connectivity between the right amygdala and the middle frontal gyrus. Furthermore, the TPH2 genotype showed a significant interaction with childhood trauma in predicting worse symptom severity.
CONCLUSIONS: This is, to our knowledge, the first study showing that the TPH2 genotype may modulate FMD both directly and interactively with childhood trauma. Because both this polymorphism and early-life stress alter serotonin levels, our findings support a potential molecular mechanism modulating FMD phenotype.

PMID: 32576619 [PubMed - indexed for MEDLINE]

Blunted medial prefrontal cortico-limbic reward-related effective connectivity and depression.

Wed, 01/20/2021 - 16:40
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Blunted medial prefrontal cortico-limbic reward-related effective connectivity and depression.

Brain. 2020 06 01;143(6):1946-1956

Authors: Rupprechter S, Romaniuk L, Series P, Hirose Y, Hawkins E, Sandu AL, Waiter GD, McNeil CJ, Shen X, Harris MA, Campbell A, Porteous D, Macfarlane JA, Lawrie SM, Murray AD, Delgado MR, McIntosh AM, Whalley HC, Steele JD

Abstract
Major depressive disorder is a leading cause of disability and significant mortality, yet mechanistic understanding remains limited. Over the past decade evidence has accumulated from case-control studies that depressive illness is associated with blunted reward activation in the basal ganglia and other regions such as the medial prefrontal cortex. However it is unclear whether this finding can be replicated in a large number of subjects. The functional anatomy of the medial prefrontal cortex and basal ganglia has been extensively studied and the former has excitatory glutamatergic projections to the latter. Reduced effect of glutamatergic projections from the prefrontal cortex to the nucleus accumbens has been argued to underlie motivational disorders such as depression, and many prominent theories of major depressive disorder propose a role for abnormal cortico-limbic connectivity. However, it is unclear whether there is abnormal reward-linked effective connectivity between the medial prefrontal cortex and basal ganglia related to depression. While resting state connectivity abnormalities have been frequently reported in depression, it has not been possible to directly link these findings to reward-learning studies. Here, we tested two main hypotheses. First, mood symptoms are associated with blunted striatal reward prediction error signals in a large community-based sample of recovered and currently ill patients, similar to reports from a number of studies. Second, event-related directed medial prefrontal cortex to basal ganglia effective connectivity is abnormally increased or decreased related to the severity of mood symptoms. Using a Research Domain Criteria approach, data were acquired from a large community-based sample of subjects who participated in a probabilistic reward learning task during event-related functional MRI. Computational modelling of behaviour, model-free and model-based functional MRI, and effective connectivity dynamic causal modelling analyses were used to test hypotheses. Increased depressive symptom severity was related to decreased reward signals in areas which included the nucleus accumbens in 475 participants. Decreased reward-related effective connectivity from the medial prefrontal cortex to striatum was associated with increased depressive symptom severity in 165 participants. Decreased striatal activity may have been due to decreased cortical to striatal connectivity consistent with glutamatergic and cortical-limbic related theories of depression and resulted in reduced direct pathway basal ganglia output. Further study of basal ganglia pathophysiology is required to better understand these abnormalities in patients with depressive symptoms and syndromes.

PMID: 32385498 [PubMed - indexed for MEDLINE]

Asymmetry of amygdala resting-state functional connectivity in healthy human brain.

Wed, 01/20/2021 - 16:40
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Asymmetry of amygdala resting-state functional connectivity in healthy human brain.

Neuroreport. 2020 01 08;31(1):17-21

Authors: Tetereva AO, Balaev VV, Kartashov SI, Ushakov VL, Ivanitsky AM, Martynova OV

Abstract
Lateral asymmetry is one of the fundamental properties of the functional anatomy of the human brain. Amygdala (AMYG) asymmetry was also reported in clinical studies of resting-state functional connectivity (rsFC) but rarely in healthy groups. To explore this issue, we investigated the reproducibility of the data on rsFC of the left and right AMYG using functional MRI twice a week in 20 healthy volunteers with mild-to-moderate anxiety. We found a resting-state network of the AMYG, which included regions involved in emotional processing and several other brain areas associated with memory and motor inhibition. The AMYG network was stable in time and within subjects, but the right AMYG had more significant connections with anatomical brain regions. The rsFC values of the right AMYG were also more sustained across the week than the left AMYG rsFC. Subjective ratings of anxiety did not correlate significantly with the patterns of seed-based AMYG connectivity. Our findings indicate that, for healthy subjects, rsFC may differ for the right and left AMYG. Moreover, the AMYG functional connectivity is variable in short-term observations, which may also influence the results of longitude studies.

PMID: 31651703 [PubMed - indexed for MEDLINE]

Characterizing functional regional homogeneity (ReHo) as a B-SNIP psychosis biomarker using traditional and machine learning approaches.

Wed, 01/20/2021 - 16:40
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Characterizing functional regional homogeneity (ReHo) as a B-SNIP psychosis biomarker using traditional and machine learning approaches.

Schizophr Res. 2020 01;215:430-438

Authors: Ji L, Meda SA, Tamminga CA, Clementz BA, Keshavan MS, Sweeney JA, Gershon ES, Pearlson GD

Abstract
BACKGROUND: Recently, a biologically-driven psychosis classification (B-SNIP Biotypes) was derived using brain-based cognitive and electrophysiological markers. Here, we characterized a local functional-connectivity measure, regional homogeneity (ReHo), as a biomarker across Biotypes and conventional DSM diagnoses.
METHODS: Whole-brain ReHo measures of resting-state functional MRI were examined in psychosis patients and healthy controls organized by Biotype and by DSM-IV-TR diagnosis (n = 737). Group-level ANOVA and individual-level prediction models using support vector machines (SVM) were employed to evaluate the discriminative characteristics in comparisons of 1) DSM diagnostic groups, 2) Biotypes, to controls, and 3) within-proband subgroups with each other.
RESULTS: Probands grouped by Biotype versus controls showed a unique abnormality pattern: Biotype-1 displayed bidirectional ReHo differences in more widespread areas, with higher ReHo in para-hippocampus, fusiform, inferior temporal, cerebellum, thalamus and caudate, plus lower ReHo in the postcentral gyrus, middle temporal, cuneus, and middle occipital cortex; Biotype-2 and Biotype-3 showed lesser and unidirectional ReHo changes. Among diagnostic groups, only schizophrenia showed higher ReHo versus control values in the inferior/middle temporal area and fusiform gyrus. For within-patient comparisons, Biotype-1 showed characteristic ReHo when compared to Biotype-2 and Biotype-3. SVM results more accurately identified Biotypes than DSM diagnoses.
CONCLUSION: We characterized patterns of ReHo abnormalities across both Biotypes and DSM sub-groups. Both group-level statistical and machine-learning methods were more sensitive in capturing ReHo deficits in Biotypes than DSM. Overall ReHo is a robust psychosis biomarker.

PMID: 31439419 [PubMed - indexed for MEDLINE]

Neural functional connectivity in patients with periventricular nodular heterotopia-mediated epilepsy.

Wed, 01/20/2021 - 10:20
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Neural functional connectivity in patients with periventricular nodular heterotopia-mediated epilepsy.

Epilepsy Res. 2021 Jan 05;170:106548

Authors: Liu W, Yue Q, Tian Y, Gong Q, Zhou D, Wu X

Abstract
Periventricular nodular heterotopia (PNH) is characterized by disabled neural migration and is usually associated with epilepsy. Despite awareness of PNH-related epilepsy, little is known about the brain-level underlying functional neural bases. Thus, we used functional magnetic resonance imaging (MRI) to examine the neurobiology of 42 subjects with PNH-related epilepsy and 42 sex- and age-matched healthy controls. Measurements of functional connectivity (FC) and whole-brain graph theory analysis of data in the resting state were performed to assess neurological organization and topology. PNH patients exhibited significantly higher FC in the parietal lobe, cingulum and thalamus, as well as significantly lower FC in frontoparietal, hippocampal, and precentral regions. Graph theory analysis identified no significant differences between patients and controls, while patients showed lower network global efficiency in the limbic and cerebellum network and occipital cortex. Seed-based FC analysis confirmed disruption of activities and interregional connectivity in remote epileptic networks of patients, which may point to underlying pathological mechanisms. The cerebellum and limbic system of patients showed altered topology, suggesting that these regions or hubs may contribute to whole-brain circuits in PNH and epilepsy.

PMID: 33454660 [PubMed - as supplied by publisher]

Sex-related human brain asymmetry in hemispheric functional gradients.

Wed, 01/20/2021 - 10:20
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Sex-related human brain asymmetry in hemispheric functional gradients.

Neuroimage. 2021 Jan 14;:117761

Authors: Liang X, Zhao C, Jin X, Jiang Y, Yang L, Chen Y, Gong G

Abstract
The left and right hemispheres of the human brain are two connected but relatively independent functional modules; they show multidimensional asymmetries ranging from particular local brain unit properties to entire hemispheric connectome topology. To date, however, it remains largely unknown whether and how hemispheric functional hierarchical structures differ between hemispheres. In the present study, we adopted a newly developed resting-state (rs) functional connectivity (FC)-based gradient approach to evaluate hemispheric functional hierarchical structures and their asymmetries in right-handed healthy young adults. Our results showed an overall mirrored principal functional gradient between hemispheres, with the sensory cortex and the default-mode network (DMN) anchored at the two opposite ends of the gradient. Interestingly, the left hemisphere showed a significantly larger full range of the principal gradient in both males and females, with males exhibiting greater leftward asymmetry. Similarly, the principal gradient component scores of two regions around the middle temporal gyrus and posterior orbitofrontal cortex exhibited similar hemisphere × sex interaction effects: a greater degree of leftward asymmetry in males than in females. Moreover, we observed significant main hemisphere and sex effects in distributed regions across the entire hemisphere. All these results are reproducible and robust between test-retest rs-fMRI sessions. Our findings provide evidence of functional gradients that enhance the present understanding of human brain asymmetries in functional organization and highlight the impact of sex on hemispheric functional gradients and their asymmetries.

PMID: 33454413 [PubMed - as supplied by publisher]

Network variants are similar between task and rest states.

Wed, 01/20/2021 - 10:20
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Network variants are similar between task and rest states.

Neuroimage. 2021 Jan 14;:117743

Authors: Kraus BT, Perez D, Ladwig Z, Seitzman BA, Dworetsky A, Petersen SE, Gratton C

Abstract
Recent work has demonstrated that individual-specific variations in functional networks (that we call "network variants") can be identified in individuals using functional magnetic resonance imaging (fMRI). These network variants exhibit reliability over time with resting-state fMRI data. These properties have suggested that network variants may be trait-like markers of individual differences in brain organization. Another test of this conclusion would be to examine if network variants are stable between task and rest states. Here, we use precision data from the Midnight Scan Club (MSC) to demonstrate that (1) task data can be used to identify network variants reliably, (2) these network variants show substantial spatial overlap with those observed in rest, although state-specific effects are present, (3) network variants assign to similar canonical functional networks in different states, and (4) single tasks or a combination of multiple tasks produce similar network variants to rest. Together, these findings further reinforce the trait-like nature of network variants and demonstrate the utility of using task data to define network variants.

PMID: 33454409 [PubMed - as supplied by publisher]

Children with attention-deficit/hyperactivity disorder spend more time in hyperconnected network states and less time in segregated network states as revealed by dynamic connectivity analysis.

Wed, 01/20/2021 - 10:20
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Children with attention-deficit/hyperactivity disorder spend more time in hyperconnected network states and less time in segregated network states as revealed by dynamic connectivity analysis.

Neuroimage. 2021 Jan 14;:117753

Authors: Shappell HM, Duffy KA, Rosch KS, Pekar JJ, Mostofsky SH, Lindquist MA, Cohen JR

Abstract
Previous studies in children with attention-deficit/hyperactivity disorder (ADHD) have observed functional brain network disruption on a whole-brain level, as well as on a sub-network level, particularly as related to the default mode network, attention-related networks, and cognitive control-related networks. Given behavioral findings that children with ADHD have more difficulty sustaining attention and more extreme moment-to-moment fluctuations in behavior than typically developing (TD) children, recently developed methods to assess changes in connectivity over shorter time periods (i.e., "dynamic functional connectivity"), may provide unique insight into dysfunctional network organization in ADHD. Thus, we performed a dynamic functional connectivity (FC) analysis on resting state fMRI data from 38 children with ADHD and 79 TD children. We used Hidden semi-Markov models (HSMMs) to estimate six network states, as well as the most probable sequence of states for each participant. We quantified the dwell time, sojourn time, and transition probabilities across states. We found that children with ADHD spent less total time in, and switched more quickly out of, anticorrelated states involving the default mode network and task-relevant networks as compared to TD children. Moreover, children with ADHD spent more time in a hyperconnected state as compared to TD children. These results provide novel evidence that underlying dynamics may drive the differences in static FC patterns that have been observed in ADHD and imply that disrupted FC dynamics may be a mechanism underlying the behavioral symptoms and cognitive deficits commonly observed in children with ADHD.

PMID: 33454408 [PubMed - as supplied by publisher]

Association between emotional intelligence and effective brain connectome: a large-scale spectral DCM study.

Wed, 01/20/2021 - 10:20
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Association between emotional intelligence and effective brain connectome: a large-scale spectral DCM study.

Neuroimage. 2021 Jan 14;:117750

Authors: Bajaj S, Killgore WDS

Abstract
INTRODUCTION: Emotional Intelligence (EI) is a well-documented aspect of social and interpersonal functioning, but the underlying neural mechanisms for this capacity remain poorly understood. Here we used advanced brain connectivity techniques to explore the associations between EI and effective connectivity (EC) within four functional brain networks.
METHODS: The Mayer-Salovey-Caruso Emotional Intelligence Test (MSCEIT) was used to collect EI data from 55 healthy individuals (mean age = 30.56±8.3 years, 26 males). The MSCEIT comprises two area cores - experiential EI (T1) and strategic EI (T2). The T1 core included two sub-scales - perception of emotions (S1) and using emotions to facilitate thinking (S2), and the T2 core included two sub-scales - understanding of emotions (S3) and management of emotions (S4). All participants underwent structural and resting-state functional magnetic resonance imaging (rsfMRI) scans. The spectral dynamic causal modeling approach was implemented to estimate EC within four networks of interest - the default-mode network (DMN), dorsal attention network (DAN), control-execution network (CEN) and salience network (SN). The strength of EC within each network was correlated with the measures of EI, with correlations at pFDR < 0.05 considered as significant.
RESULTS: There was no significant association between any of the measures of EI and EC strength within the DMN and DAN. For CEN, however, we found that there were significant negative associations between EC strength from the right anterior prefrontal cortex (RAPFC) to the left anterior prefrontal cortex (LAPFC) and both S2 and T1, and significant positive associations between EC strength from LAPFC to RAPFC and S2. EC strength from the right superior parietal cortex (SPC) to RAPFC also showed significant negative association with S4 and T2. For the SN, S3 showed significant negative association with EC strength from the right insula to RAPFC and significant positive association with EC strength from the left insula to dorsal anterior cingulate cortex (DACC).
CONCLUSIONS: We provide evidence that the negative ECs within the right hemisphere, and from the right to left hemisphere, and positive ECs within the left hemisphere and from the left to right hemisphere of CEN (involving bilateral frontal and right parietal region) and SN (involving right frontal, anterior cingulate and bilateral insula) play a significant role in regulating and processing emotions. These findings also suggest that measures of EC can be utilized as important biomarkers to better understand the underlying neural mechanisms of EI.

PMID: 33454407 [PubMed - as supplied by publisher]

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