Most recent paper
Evid Based Complement Alternat Med. 2021 Mar 23;2021:6616060. doi: 10.1155/2021/6616060. eCollection 2021.
Research exploring the mechanism of acupuncture has been a hot topic in medicine. Resting-state functional magnetic resonance imaging (rs-fMRI) research is a noninvasive and extensive method, which is aimed at the research of the mechanism of acupuncture. Researchers use fMRI technologies to inspect the acupuncture process. The authors reviewed the application of rs-fMRI in acupuncture research in recent 10 years from the aspects of studying acupoints, subjects, acupuncture methods, and intensities. The results found that the application of rs-fMRI in acupuncture research mainly includes research on the onset mechanism of acupuncture treatment; visual evidence of diagnosis and treatment of dominant diseases; efficacy assessments; physiological mechanism of acupoint stimulation; and specific visualization of acupoints.
Sci Rep. 2021 Apr 15;11(1):8322. doi: 10.1038/s41598-021-87088-z.
In cervical dystonia, functional MRI (fMRI) evidence indicates changes in several resting state networks, which revert in part following the botulinum neurotoxin A (BoNT) therapy. Recently, the involvement of the cerebellum in dystonia has gained attention. The aim of our study was to compare connectivity between cerebellar subdivisions and the rest of the brain before and after BoNT treatment. Seventeen patients with cervical dystonia indicated for treatment with BoNT were enrolled (14 female, aged 50.2 ± 8.5 years, range 38-63 years). Clinical and fMRI examinations were carried out before and 4 weeks after BoNT injection. Clinical severity was evaluated using TWSTRS. Functional MRI data were acquired on a 1.5 T scanner during 8 min rest. Seed-based functional connectivity analysis was performed using data extracted from atlas-defined cerebellar areas in both datasets. Clinical scores demonstrated satisfactory BoNT effect. After treatment, connectivity decreased between the vermis lobule VIIIa and the left dorsal mesial frontal cortex. Positive correlations between the connectivity differences and the clinical improvement were detected for the right lobule VI, right crus II, vermis VIIIb and the right lobule IX. Our data provide evidence for modulation of cerebello-cortical connectivity resulting from successful treatment by botulinum neurotoxin.
Neuroimage Clin. 2021 Mar 1:102598. doi: 10.1016/j.nicl.2021.102598. Online ahead of print.
Development of a task-free method for presurgical mapping of language function is important for use in young or cognitively impaired patients. Resting state connectivity fMRI (RS-fMRI) is a task-free method that may be used to identify cognitive networks. We developed a voxelwise RS-fMRI metric, Functional Connectivity Hemispheric Contrast (FC-HC), to map the language network and determine language laterality through comparison of within-hemispheric language network connections (Integration) to cross-hemispheric connections (Segregation). For the first time, we demonstrated robustness and efficacy of a RS-fMRI metric to map language networks across five groups (total N = 243) that differed in MRI scanning parameters, fMRI scanning protocols, age, and development (typical vs pediatric epilepsy). The resting state FC-HC maps for the healthy pediatric and adult groups showed higher values in the left hemisphere, and had high agreement with standard task language fMRI; in contrast, the epilepsy patient group map was bilateral. FC-HC has strong but not perfect agreement with task fMRI and thus, may reflect related and complementary information about language plasticity and compensation.
Altered amygdala effective connectivity in migraine without aura: evidence from resting-state fMRI with Granger causality analysis
J Headache Pain. 2021 Apr 15;22(1):25. doi: 10.1186/s10194-021-01240-8.
BACKGROUND: Granger causality analysis (GCA) has been used to investigate the pathophysiology of migraine. Amygdala plays a key role in pain modulation of migraine attack. However, the detailed neuromechanism remained to be elucidated. We applied GCA to explore the amygdala-based directional effective connectivity in migraine without aura (MwoA) and to determine the relation with clinical characteristics.
METHODS: Forty-five MwoA patients and forty age-, sex-, and years of education-matched healthy controls(HCs) underwent resting-state functional magnetic resonance imaging (fMRI). Bilateral amygdala were used as seed regions in GCA to investigate directional effective connectivity and relation with migraine duration or attack frequency.
RESULTS: MwoA patients showed significantly decreased effective connectivity from right amygdala to right superior temporal gyrus, left superior temporal gyrus and right precentral gyrus compared with HCs. Furthermore, MwoA patients demonstrated significantly decreased effective connectivity from the left amygdala to the ipsilateral superior temporal gyrus. Also, MwoA patients showed enhanced effective connectivity from left inferior frontal gyrus to left amygdala. Effective connectivity outflow from right amygdala to right precentral gyrus was negatively correlated to disease duration.
CONCLUSIONS: Altered directional effective connectivity of amygdala demonstrated that neurolimbic pain networks contribute to multisensory integration abnormalities and deficits in pain modulation of MwoA patients.
Brain Connect. 2021 Apr 15. doi: 10.1089/brain.2020.0982. Online ahead of print.
Background: Brain interdependencies can be studied from either a structural/anatomical perspective ("structural connectivity"-SC) or by considering statistical interdependencies ("functional connectivity"-FC). Interestingly, while SC is by definition pairwise (white-matter fibers project from one region to another), FC is not. However, most FC analyses only focus on pairwise statistics and they neglect higher-order interactions. A promising tool to study high-order interdependencies is the recently proposed O-Information, which can quantify the intrinsic statistical synergy and the redundancy in groups of three or more interacting variables. Methods: We analyzed functional magnetic resonance imaging (fMRI) data obtained at rest from 164 healthy subjects with ages ranging in 10 to 80 years and used O-Information to investigate how high-order statistical interdependencies are affected by age. Results: Older participants (from 60 to 80 years old) exhibited a higher predominance of redundant dependencies as compared to younger participants, an effect that seems to be pervasive as it is evident for all orders of interaction. In addition, while there is strong heterogeneity across brain regions, we found a 'redundancy core' constituted by the prefrontal and motor cortices in which redundancy was evident at all the interaction orders studied. Discussion: High-order interdependencies in fMRI data reveals a dominant redundancy in functions such as working memory, executive and motor functions. Our methodology can be used for a broad range of applications, and the corresponding code is freely available.
Curr Alzheimer Res. 2021 Apr 13. doi: 10.2174/1567205018666210414111536. Online ahead of print.
BACKGROUND: Little is known so far about the brain phenotype and the spatial interplay of different Alzheimer's disease (AD) biomarkers with structural and functional brain connectivity in the early phase of autosomal-dominant AD (ADAD). Multimodal PET/MRI might be suitable to fill this gap.
MATERIAL AND METHODS: We presented a 31-year-old male patient without a family history of de- mentia with progressive worsening of memory and motor function. Two separate sessions of 3T PET/MRI acquisitions were arranged with the ß-amyloid tracer [18F]Florbetaben and the second-- generation tau tracer [18F]PI-2620. Simultaneously acquired MRI consisted of high-resolution 3D T1, diffusion-tensor imaging (DTI), and resting-state fMRI. PET/MRI data were compared with ten age-matched healthy controls.
RESULTS: Widespread β-amyloid depositions were found in cortical regions, and striatum (Thal stage III) along with tau pathology restricted to the mesial-temporal structures (Braak stage III/IV). Volumetric/shape analysis of subcortical structures revealed atrophy of the hippocampal-amygdala complex. In addition, cortical thinning was detected in the right middle temporal pole. Alterations of multiple DTI indices were noted in the major white matter fiber bundles, together with disrup- tion of default mode and sensory-motor network functional connectivity. Molecular genetic analy- sis by next-generation sequencing revealed a heterozygote missense pathogenic variant of the PSEN1 (Met233Val).
CONCLUSION: Multimodal PET/MR imaging is able to deliver, in a one-stop-shop approach, an ar- ray of molecular, structural and functional brain information in AD due to de novo pathogenic variant, which can be studied for spatial interplay and might provide a rationale for initiating an- ti-amyloid/tau therapeutic approaches.
Repetitive deep TMS for the reduction of body weight: Bimodal effect on the functional brain connectivity in "diabesity"
Nutr Metab Cardiovasc Dis. 2021 Feb 25:S0939-4753(21)00084-3. doi: 10.1016/j.numecd.2021.02.015. Online ahead of print.
BACKGROUND AND AIMS: Deep repetitive Transcranial Magnetic Stimulation (deep rTMS) over the bilateral insula and prefrontal cortex (PFC) can promote weight-loss in obesity, preventing cardiometabolic complications as Type 2 Diabetes (T2D). To investigate the changes in the functional brain integration after dTMS, we conducted a resting-state functional connectivity (rsFC) study in obesity.
METHODS AND RESULTS: This preliminary study was designed as a randomized, double-blind, sham-controlled study: 9 participants were treated with high-frequency stimulation (realTMS group), 8 were sham-treated (shamTMS group). Out of the 17 enrolled patients, 6 were affected by T2D. Resting-state fMRI scans were acquired at baseline (T0) and after the 5-week intervention (T1). Body weight was measured at three time points [T0, T1, 1-month follow-up visit (FU1)]. A mixed-model analysis showed a significant group-by-time interaction for body weight (p = .04), with a significant decrease (p < .001) in the realTMS group. The rsFC data revealed a significant increase of degree centrality for the realTMS group in the medial orbitofrontal cortex (mOFC) and a significant decrease in the occipital pole.
CONCLUSION: An increase of whole-brain functional connections of the mOFC, together with the decrease of whole-brain functional connections with the occipital pole, may reflect a brain mechanism behind weight-loss through a diminished reactivity to bottom-up visual-sensory processes in favor of increased reliance on top-down decision-making processes.
TRIAL REGISTRATION NUMBER: ClinicalTrials.gov NCT03009695.
Intranasal vasopressin modulates resting state brain activity across multiple neural systems: evidence from a brain imaging machine learning study
Neuropharmacology. 2021 Apr 11:108561. doi: 10.1016/j.neuropharm.2021.108561. Online ahead of print.
Arginine vasopressin (AVP), a neuropeptide with widespread receptors in brain regions important for socioemotional processing, is critical in regulating various mammalian social behavior and emotion. Although a growing body of task-based brain imaging studies have revealed the effects of AVP on brain activity associated with emotion processing, social cognition and behaviors, the potential modulations of AVP on resting-state brain activity remain largely unknown. Here, the current study addressed this issue by adopting a machine learning approach to distinguish administration of AVP and placebo, employing the amplitude of low-frequency fluctuation (ALFF) as a measure of resting-state brain activity. The brain regions contributing to the classification were then subjected to functional connectivity and decoding analyses, allowing for a data-driven quantitative inference on psychophysiological functions. Our results indicated that ALFF across multiple neural systems were sufficient to distinguish between AVP and placebo at individual level, with the contributing regions distributed across the social cognition network, sensorimotor regions and emotional processing network. These findings suggest that the role of AVP in socioemotional functioning recruits multiple brain networks distributed across the whole brain rather than specific localized neural pathways. Beyond these findings, the current data-driven approach also opens a novel avenue to delineate neural underpinnings of various neuropeptides or hormones.
Cortico-subcortical functional connectivity modifications in fatigued ms patients treated with fampridine and amantadine
Eur J Neurol. 2021 Apr 14. doi: 10.1111/ene.14867. Online ahead of print.
BACKGROUND: Fatigue in multiple sclerosis (MS) is common and disabling; medication efficacy is still not fully proven. Aim of this study was to investigate four-week modifications of fatigue severity in 45 relapsing-remitting MS patients following different symptomatic treatments, and concomitant resting state (RS) functional connectivity (FC) changes.
METHODS: Patients were randomly, blindly assigned to treatment with fampridine (n=15), amantadine (n=15) or placebo (n=15), and underwent clinical/3T RS fMRI at baseline (t0) and after four weeks (w4) of treatment. Fifteen healthy controls (HC) were also studied. Changes of modified fatigue impact scale (MFIS) and network RS FC were assessed.
RESULTS: In MS, abnormalities of network RS FC at t0 did not differ between treatment groups and correlated with fatigue severity. At w4, global and subscore MFISs decreased in all groups, with no time-by-treatment interaction. At w4, all patient groups had changes of RS FC in several networks, with significant time-by-treatment interactions in basal ganglia, sensorimotor and default-mode networks in fampridine patients vs the other groups, and in fronto-parietal network in amantadine patients. In fampridine-group, RS FC changes correlated with concurrently decreased MFIS (r range=-0.75 to 0.74, p range=0.003-0.05).
CONCLUSIONS: Fatigue improved in all MS groups, independently from treatment. Concomitant RS FC modifications were located in sensorimotor, inferior frontal and subcortical regions for fampridine and amantadine patients, and in associative sensory cortices for placebo patients.
Conduct disorder symptomatology is associated with an altered functional connectome in a large national youth sample
Dev Psychopathol. 2021 Apr 14:1-12. doi: 10.1017/S0954579421000237. Online ahead of print.
Conduct disorder (CD), characterized by youth antisocial behavior, is associated with a variety of neurocognitive impairments. However, questions remain regarding the neural underpinnings of these impairments. To investigate novel neural mechanisms that may support these neurocognitive abnormalities, the present study applied a graph analysis to resting-state functional magnetic resonance imaging (fMRI) data collected from a national sample of 4,781 youth, ages 9-10, who participated in the baseline session of the Adolescent Brain Cognitive DevelopmentSM Study (ABCD Study®). Analyses were then conducted to examine the relationships among levels of CD symptomatology, metrics of global topology, node-level metrics for subcortical structures, and performance on neurocognitive assessments. Youth higher on CD displayed higher global clustering (β = .039, 95% CIcorrected [.0027 .0771]), but lower Degreesubcortical (β = -.052, 95% CIcorrected [-.0916 -.0152]). Youth higher on CD had worse performance on a general neurocognitive assessment (β = -.104, 95% CI [-.1328 -.0763]) and an emotion recognition memory assessment (β = -.061, 95% CI [-.0919 -.0290]). Finally, global clustering mediated the relationship between CD and general neurocognitive functioning (indirect β = -.002, 95% CI [-.0044 -.0002]), and Degreesubcortical mediated the relationship between CD and emotion recognition memory performance (indirect β = -.002, 95% CI [-.0046 -.0005]). CD appears associated with neuro-topological abnormalities and these abnormalities may represent neural mechanisms supporting CD-related neurocognitive disruptions.
Comparing activated brain regions between noisy and conventional galvanic vestibular stimulation using functional magnetic resonance imaging
Neuroreport. 2021 May 5;32(7):583-587. doi: 10.1097/WNR.0000000000001629.
OBJECTIVE: Galvanic vestibular stimulation (GVS) enhances vestibular sensory inputs in vestibular afferents. However, it is unclear whether noisy and conventional GVS activate different regions of the brain. The purpose of this study was to investigate the differences in activated brain regions between those two interventions using functional MRI (fMRI).
METHODS: Twenty-four healthy volunteers who met the inclusion/exclusion criteria were randomly assigned to the noisy GVS or conventional GVS groups. Brain activity was measured during stimulation and compared with that during resting fMRI. This study used a blocked design comprising four task-rest blocks, each consisting of a 30-s period of vestibular stimulation followed by a 30-s period of rest. We evaluated the differences in contrast images between the noisy and conventional GVS groups.
RESULTS: The noisy GVS group showed significantly increased activation in the vestibular system-related brain regions, including the insula and central operculum. The conventional GVS group showed significant activity in multisensory areas, including the supramarginal gyrus, central operculum and opercular part of the inferior frontal gyrus. Thus, the noisy GVS group showed significantly increased activity in the insula, putamen and central operculum compared with the conventional GVS group.
CONCLUSIONS: Noisy GVS could increase brain activity in the insular peripheral region compared to conventional GVS. Our results extend the literature about the importance of the stochastic resonance of noise addition for the vestibular system.
Small-world network of patients with primary insomnia: a resting-state functional magnetic resonance imaging study
Nan Fang Yi Ke Da Xue Xue Bao. 2021 Mar 25;41(3):424-429. doi: 10.12122/j.issn.1673-4254.2021.03.16.
OBJECTIVE: To explore the changes of small-world network properties in patients with primary insomnia based on resting-state functional magnetic resonance imaging (rs-fMRI).
OBJECTIVE: The rs-MRI data and neurological scale data of 65 patients and 60 matched healthy controls were collected. The brain network was constructed using GRENTA software. SPSS software and network-based statistical analysis methods were used for statistical analysis.
OBJECTIVE: There was no significant difference between the two groups in terms of age, gender or education level (P > 0.05), but PSQI, HAMA and HAMD scale scores differed significantly between the two groups (P < 0.05). Both of the groups showed attributes of the small-world network. Compared with the control group, the patients with insomnia showed lower Cp, γ, Eloc, λ, connectivity, and σ of the small world network (P < 0.05).
OBJECTIVE: Patients with primary insomnia have lower global and local efficiencies than healthy individuals, and their ability to transmit information on the surface topology is impaired. Our data provide objective imaging evidences for the neuropathological mechanism of patients with primary insomnia.
Elucidating the complementarity of resting-state networks derived from dynamic [(18)F]FDG and hemodynamic fluctuations using simultaneous small-animal PET/MRI
Neuroimage. 2021 Apr 10:118045. doi: 10.1016/j.neuroimage.2021.118045. Online ahead of print.
Functional connectivity (FC) and resting-state network (RSN) analyses using functional magnetic resonance imaging (fMRI) have evolved into a growing field of research and have provided useful biomarkers for the assessment of brain function in neurological disorders. However, the underlying mechanisms of the blood oxygen level-dependent (BOLD) signal are not fully resolved due to its inherent complexity. In contrast, [18F]fluorodeoxyglucose positron emission tomography ([18F]FDG-PET) has been shown to provide a more direct measure of local synaptic activity and may have additional value for the readout and interpretation of brain connectivity. We performed an RSN analysis from simultaneously acquired PET/fMRI data on a single-subject level to directly compare fMRI and [18F]FDG-PET-derived networks during the resting state. Simultaneous [18F]FDG-PET/fMRI scans were performed in 30 rats. Pairwise correlation analysis, as well as independent component analysis (ICA), were used to compare the readouts of both methods. We identified three RSNs with a high degree of similarity between PET and fMRI-derived readouts: the default-mode-like network (DMN), the basal ganglia network and the cerebellar-midbrain network. Overall, [18F]FDG connectivity indicated increased integration between different, often distant, brain areas compared to the results indicated by the more segregated fMRI-derived FC. Additionally, several networks exclusive to either modality were observed using ICA. These networks included mainly bilateral cortical networks of a limited spatial extent for fMRI and more spatially widespread networks for [18F]FDG-PET, often involving several subcortical areas. This is the first study using simultaneous PET/fMRI to report RSNs subject-wise from dynamic [18F]FDG tracer delivery and BOLD fluctuations with both independent component analysis (ICA) and pairwise correlation analysis in small animals. Our findings support previous studies, which show a close link between local synaptic glucose consumption and BOLD-fMRI-derived FC. However, several brain regions were exclusively attributed to either [18F]FDG or BOLD-derived networks underlining the complementarity of this hybrid imaging approach, which may contribute to the understanding of brain functional organization and could be of interest for future clinical applications.
Investigating the sub-regions of the superior parietal cortex using functional magnetic resonance imaging connectivity
Insights Imaging. 2021 Apr 13;12(1):47. doi: 10.1186/s13244-021-00993-9.
OBJECTIVES: Traditionally, the superior parietal lobule (SPL) is usually investigated as one region of interest, particularly in functional magnetic resonance imaging (fMRI) studies. However, cytoarchitectonic analysis has shown that the SPL has a complex, heterogeneous topology that comprises more than seven sub-regions. Since previous studies have shown how the SPL is significantly involved in different neurological functions-such as visuomotor, cognitive, sensory, higher order, working memory and attention-this study aims to investigate whether these cytoarchitecturally different sub-regions have different functional connectivity to different functional brain networks.
METHODS: This study examined 198 healthy subjects using resting-state fMRI and investigated the functional connectivity of seven sub-regions of the SPL to eight regional functional networks.
RESULTS: The findings showed that most of the seven sub-regions were functionally connected to these targeted networks and that there are differences between these sub-regions and their functional connectivity patterns. The most consistent functional connectivity was observed with the visual and attention networks. There were also clear functional differences between Brodmann area (BA) 5 and BA7. BA5, with its three sub-regions, had strong functional connectivity to both the sensorimotor and salience networks.
CONCLUSION: These findings have enhanced our understanding of the functional organisations of the complexity of the SPL and its varied topology and also provide clear evidence of the functional patterns and involvements of the SPL in major brain functions.
Neurocognitive disorders in the elderly: altered functional resting-state hyperconnectivities in postoperative delirium patients
Transl Psychiatry. 2021 Apr 12;11(1):213. doi: 10.1038/s41398-021-01304-y.
Postoperative delirium (POD) represents a confusional state during days/weeks after surgery and is particularly frequent in elderly patients. Hardly any fMRI studies were conducted to understand the underlying pathophysiology of POD patients. This prospective observational cohort study aims to examine changes of specific resting-state functional connectivity networks across different time points (pre- and 3-5 months postoperatively) in delirious patients compared to no-POD patients. Two-hundred eighty-three elderly surgical patients underwent preoperative resting-state fMRI (46 POD). One-hundred seventy-eight patients completed postoperative scans (19 POD). For functional connectivity analyses, three functional connectivity networks with seeds located in the orbitofrontal cortex (OFC), nucleus accumbens (NAcc), and hippocampus were investigated. The relationship of POD and connectivity changes between both time points (course connectivity) were examined (ANOVA). Preoperatively, delirious patients displayed hyperconnectivities across the examined functional connectivity networks. In POD patients, connectivities within NAcc and OFC networks demonstrated a decrease in course connectivity [max. F = 9.03, p = 0.003; F = 4.47, p = 0.036, resp.]. The preoperative hyperconnectivity in the three networks in the patients at risk for developing POD could possibly indicate existing compensation mechanisms for subtle brain dysfunction. The observed pathophysiology of network function in POD patients at least partially involves dopaminergic pathways.
Distinct impaired patterns of intrinsic functional network centrality in patients with early- and late-onset Alzheimer's disease
Brain Imaging Behav. 2021 Apr 12. doi: 10.1007/s11682-021-00470-3. Online ahead of print.
Early-onset Alzheimer's disease (EOAD) involves multiple cognitive domains and shows more rapid progression than late-onset Alzheimer's disease (LOAD). However, the difference in pathogenesis between EOAD and LOAD is still unclear. Accordingly, we applied intrinsic network analysis to explore the potential neuropathological mechanism underlying distinct clinical phenotypes. According to the cut-off age of 65, we included 20 EOAD patients, 20 LOAD patients, and 36 age-matched controls (19 young and 17 old controls). We employed resting-state functional MRI and network centrality analysis to explore the local (degree centrality (DC)) and global (eigenvector centrality (EC)) functional integrity. Two-sample t-test analysis was performed, with gray matter volume, age, gender, and education as covariates. Furthermore, we performed a correlation analysis between network metrics and cognition. Compared to young controls, EOAD patients exhibited lower DC in the middle temporal gyrus (MTG), parahippocampal gyrus (PHG), superior temporal gyrus (STG), and lower EC in the MTG, PHG, and postcentral gyrus. In contrast, LOAD patients exhibited lower DC in the STG and anterior cingulum gyrus and higher DC in the middle frontal gyrus compared to old controls. No significant difference in EC was observed in LOAD patients. Furthermore, both DC and EC correlated with cognitive performance. Our study demonstrated divergent functional network impairments in EOAD and LOAD patients. EOAD patients showed more complex network damage involving both local and global centrality properties, while LOAD patients mainly featured local functional connectivity changes. Such centrality impairments are related to poor cognition, especially regarding memory performance.
Decreased Functional Connectivity of the Primary Visual Cortex and the Correlation With Clinical Features in Patients With Intermittent Exotropia
Front Neurol. 2021 Mar 26;12:638402. doi: 10.3389/fneur.2021.638402. eCollection 2021.
The purpose of this study is to investigate characteristic alterations of functional connectivity (FC) patterns in the primary visual area (V1) in patients with intermittent exotropia (IXT) using resting-state functional magnetic resonance imaging (rs-fMRI) and how they relate to clinical features. Twenty-six IXT patients and 21 age-, sex-, handedness-, and education-matched healthy controls (HCs) underwent rs-fMRI. We performed FC analyses between bilateral V1 and other brain areas and compared FC strength between two groups. A Pearson correlation analysis was used to evaluate the correlation between the FC differences and clinical features. Compared with HCs, patients with IXT showed significantly lower FC of the right V1 with the right calcarine sulcus and right superior occipital gyrus, and the left V1 with right cuneus and right postcentral gyrus. The Newcastle Control Test score was positively correlated with mean FC values between the left inferior parietal lobule and bilateral V1, and between the left supramarginal gyrus and left V1. The duration of IXT was positively correlated with mean FC values between the right inferior occipital gyrus and right V1. Reduced FC between the V1 and various brain regions involved in vision and eye movement processes may be associated with the underlying neural mechanisms of impaired visual function in patients with IXT.
Exposure to Blue Wavelength Light Is Associated With Increases in Bidirectional Amygdala-DLPFC Connectivity at Rest
Front Neurol. 2021 Mar 26;12:625443. doi: 10.3389/fneur.2021.625443. eCollection 2021.
Blue wavelength light has been used successfully as a treatment method for certain mood disorders, but, the underlying mechanisms behind the mood enhancing effects of light remain poorly understood. We investigated the effects of a single dose of 30 min of blue wavelength light (n = 17) vs. amber wavelength light (n = 12) exposure in a sample of healthy adults on subsequent resting-state functional and directed connectivity, and associations with changes in state affect. Individuals who received blue vs. amber wavelength light showed greater positive connectivity between the right amygdala and a region within the left dorsolateral prefrontal cortex (DLPFC). In addition, using granger causality, the findings showed that individuals who received blue wavelength light displayed greater bidirectional information flow between these two regions relative to amber light. Furthermore, the strength of amygdala-DLPFC functional connectivity was associated with greater decreases in negative mood for the blue, but not the amber light condition. Blue light exposure may positively influence mood by modulating greater information flow between the amygdala and the DLPFC, which may result in greater engagement of cognitive control strategies that are needed to perceive and regulate arousal and mood.
Abnormal Large-Scale Network Activation Present in Bipolar Mania and Bipolar Depression Under Resting State
Front Psychiatry. 2021 Mar 26;12:634299. doi: 10.3389/fpsyt.2021.634299. eCollection 2021.
Introduction: Previous studies have primarily focused on the neuropathological mechanisms of the emotional circuit present in bipolar mania and bipolar depression. Recent studies applying resting-state functional magnetic resonance imaging (fMRI) have raise the possibility of examining brain-wide networks abnormality between the two oppositional emotion states, thus this study aimed to characterize the different functional architecture represented in mania and depression by employing group-independent component analysis (gICA). Materials and Methods: Forty-one bipolar depressive patients, 20 bipolar manic patients, and 40 healthy controls (HCs) were recruited and received resting-state fMRI scans. Group-independent component analysis was applied to the brain network functional connectivity analysis. Then, we calculated the correlation between the value of between-group differences and clinical variables. Results: Group-independent component analysis identified 15 components in all subjects, and ANOVA showed that functional connectivity (FC) differed significantly in the default mode network, central executive network, and frontoparietal network across the three groups. Further post-hoc t-tests showed a gradient descent of activity-depression > HC > mania-in all three networks, with the differences between depression and HCs, as well as between depression and mania, surviving after family wise error (FWE) correction. Moreover, central executive network and frontoparietal network activities were positively correlated with Hamilton depression rating scale (HAMD) scores and negatively correlated with Young manic rating scale (YMRS) scores. Conclusions: Three brain networks heighten activity in depression, but not mania; and the discrepancy regions mainly located in prefrontal, which may imply that the differences in cognition and emotion between the two states is associated with top-down regulation in task-independent networks.
Front Psychiatry. 2021 Mar 26;12:565136. doi: 10.3389/fpsyt.2021.565136. eCollection 2021.
There are currently no validated treatment biomarkers in psychiatry. Resting State Functional Connectivity (RSFC) is a popular method for investigating the neural correlates of mood disorders, but the breadth of the field makes it difficult to assess progress toward treatment response biomarkers. In this review, we followed general PRISMA guidelines to evaluate the evidence base for mood disorder treatment biomarkers across diagnoses, brain network models, and treatment modalities. We hypothesized that no treatment biomarker would be validated across these domains or with independent datasets. Results are organized, interpreted, and discussed in the context of four popular analytic techniques: (1) reference region (seed-based) analysis, (2) independent component analysis, (3) graph theory analysis, and (4) other methods. Cortico-limbic connectivity is implicated across studies, but there is no single biomarker that spans analyses or that has been replicated in multiple independent datasets. We discuss RSFC limitations and future directions in biomarker development.