Decreased regional activity and network homogeneity of the fronto-limbic network at rest in drug-naive major depressive disorder

Brain alterations in adolescents with first-episode depression who have experienced adverse events: evidence from resting-state functional magnetic resonance imaging

Introduction

Adverse life events constitute primary risk factors for major depressive disorder (MDD), influencing brain function and structure. Adolescents, with their brains undergoing continuous development, are particularly susceptible to enduring impacts of adverse events.

Methods

We investigated differences and correlations among childhood trauma, negative life events, and alterations of brain function in adolescents with first-episode MDD. The study included 23 patients with MDD and 19 healthy controls, aged 10-19 years. All participants underwent resting-state functional magnetic resonance imaging and were assessed using the beck depression inventory, childhood trauma questionnaire, and adolescent self-rating life events checklist.

Results

Compared with healthy controls, participants with first-episode MDD were more likely to have experienced emotional abuse, physical neglect, interpersonal relationship problems, and learning stress (all p' < 0.05). These adverse life events were significantly correlated with alterations in brain functions (all p < 0.05).

Discussion

This study contributes novel evidence on the underlying process between adverse life events, brain function, and depression, emphasizing the significant neurophysiological impact of environmental factors.

Structural and functional features of treatment-resistant depression: A systematic review and exploratory coordinate-based meta-analysis of neuroimaging studies

OBJECTIVES

A third of people suffering from major depressive disorder do not experience a significant improvement in their symptoms even after adequate treatment with two different antidepressant medications. This common condition, termed treatment-resistant depression (TRD), severely affects the quality of life of millions of people worldwide, causing long-lasting interpersonal problems and social costs. Given its epidemiological and clinical relevance and the little consensus on whether the neurobiological underpinnings of TRD differ from treatment-sensitive depression (TSD), we sought to highlight the convergent morphometric and functional neuroimaging correlates of TRD.

METHODS

We systematically reviewed the published literature on structural and resting-state functional neuroimaging of TRD compared to TSD and healthy controls (HC) and performed exploratory coordinate-based meta-analyses (CBMA) of significant results separately for each modality and multimodally ("all-effects"). CBMAs were also performed for each direction and combining both directions of group contrasts.

RESULTS

Out of the initial 1929 studies, only eight involving 555 participants (189 patients with TRD, 156 with TSD, and 210 HC) were included. In all-effects CBMA, precentral/superior frontal gyrus showed a significant difference between TRD and HC. Functional and structural imaging meta-analyses did not yield statistically significant results. A marginally significant cluster of altered intrinsic activity was found between TRD and HC in the cerebellum/pons.

CONCLUSIONS

Frontal, cerebellar, and brainstem functions can be involved in the pathophysiology of TRD. However, the design and heterogeneity of the (scarce) published literature hinder the generalizability of the findings.

Win and Loss Responses in the Monetary Incentive Delay Task Mediate the Link between Depression and Problem Drinking

Depression and alcohol misuse, frequently comorbid, are associated with altered reward processing. However, no study has examined whether and how the neural markers of reward processing are shared between depression and alcohol misuse. We studied 43 otherwise-healthy drinking adults in a monetary incentive delay task (MIDT) during fMRI. All participants were evaluated with the Alcohol Use Disorders Identification Test (AUDIT) and Beck's Depression Inventory (BDI-II) to assess the severity of drinking and depression. We performed whole brain regressions against each AUDIT and BDI-II score to investigate the neural correlates and evaluated the findings at a corrected threshold. We performed mediation analyses to examine the inter-relationships between win/loss responses, alcohol misuse, and depression. AUDIT and BDI-II scores were positively correlated across subjects. Alcohol misuse and depression shared win-related activations in frontoparietal regions and parahippocampal gyri (PHG), and right superior temporal gyri (STG), as well as loss-related activations in the right PHG and STG, and midline cerebellum. These regional activities (β's) completely mediated the correlations between BDI-II and AUDIT scores. The findings suggest shared neural correlates interlinking depression and problem drinking both during win and loss processing and provide evidence for co-morbid etiological processes of depressive and alcohol use disorders.

Altered Regional Activity and Network Homogeneity within the Fronto-Limbic Network at Rest in Medicine-Free Obsessive–Compulsive Disorder

Functional abnormalities in brain areas within the fronto-limbic network have been widely reported in obsessive–compulsive disorder (OCD). However, region- and network-level brain activities of the fronto-limbic network at rest have not been simultaneously investigated in OCD. In this study, 40 medicine-free and non-comorbidity patients with OCD and 38 age-, education-, and gender-matched healthy controls (HCs) underwent a resting-state functional magnetic-resonance-imaging scan. Fractional amplitude of low-frequency fluctuations (fALFF), network homogeneity (NH), and support vector machine were used to analyze the data. Patients with OCD showed increased fALFF in the right orbital frontal cortex (OFC), increased NH in the left OFC, and decreased NH in the right putamen. Decreased NH of the right putamen was negatively correlated with the Y-BOCS total and compulsive behavior scores. Furthermore, a combination of NH in the left OFC and right putamen could be applied to differentiate OCD from HCs with optimum specificity and sensitivity. The current findings emphasize the crucial role of the fronto-limbic network in the etiology of OCD.

The Bilateral Precuneus as a Potential Neuroimaging Biomarker for Right Temporal Lobe Epilepsy: A Support Vector Machine Analysis

Background and Objective

While evidence has demonstrated that the default-mode network (DMN) plays a key role in the broad-scale cognitive problems that occur in right temporal lobe epilepsy (rTLE), little is known about alterations in the network homogeneity (NH) of the DMN in TLE. In this study, we used the NH method to investigate the NH of the DMN in TLE at rest, and an support vector machine (SVM) method for the diagnosis of rTLE.

Methods

A total of 43 rTLE cases and 42 healthy controls (HCs) underwent resting-state functional magnetic resonance imaging (rs-fMRI). Imaging data were analyzed with the NH and SVM methods.

Results

rTLE patients have a decreased NH in the right inferior temporal gyrus (ITG) and left middle temporal gyrus (MTG), but increased NH in the bilateral precuneus (PCu) and right inferior parietal lobe (IPL), compared with HCs. We found that rTLE had a longer performance reaction time (RT). No significant correlation was found between abnormal NH values and clinical variables of the patients. The SVM results showed that increased NH in the bilateral PCu as a diagnostic biomarker distinguished rTLE from HCs with an accuracy of 74.12% (63/85), a sensitivity 72.01% (31/43), and a specificity 72.81% (31/42).

Conclusion

These findings suggest that abnormal NH of the DMN exists in rTLE, and highlights the significance of the DMN in the pathophysiology of cognitive problems occurring in rTLE, and the bilateral PCu as a neuroimaging diagnostic biomarker for rTLE.

Global Functional Connectivity Analysis Indicating Dysconnectivity of the Hate Circuit in Major Depressive Disorder

Background

Abnormalities of functional connectivity (FC) in certain brain regions are closely related to the pathophysiology of major depressive disorder (MDD). Findings are inconsistent with different presuppositions in regions of interest. Our research focused on voxel-wise brain-wide FC changes in patients with MDD in an unbiased manner.

Method

We examined resting-state functional MRI in 23 patients with MDD and 26 healthy controls. Imaging data were analyzed by using global-brain FC (GFC) and used to explore the correlation of abnormal GFC values with clinical variables.

Results

Increased GFC values in the left medial superior frontal gyrus (SFGmed) and decreased GFC values in the right supplementary motor area (SMA) were observed in the patients with MDD compared with the controls. The decreased GFC values in the right SMA had a positive correlation with vitamin D and Hamilton Anxiety Scale (HAM-A) scores.

Conclusion

Abnormal GFC in the hate circuit, particularly increased GFC in the left SFGmed and decreased GFC in the right SMA, appears to be a new sight for comprehending the pathological alterations in MDD.

Regulatory Effects of Acupuncture on Emotional Disorders in Patients With Menstrual Migraine Without Aura: A Resting-State fMRI Study

Background: Menstrual migraine without aura (MMoA) refers to a specific type of migraine that is associated with the female ovarian cycle. It is particularly serious and has brought huge life pressure and mental burden to female patients. Acupuncture has been commonly used to prevent migraines and relieve concomitant emotional disorders; however, the physiological mechanism underlying this intervention remains unclear. This study aimed to use resting-state functional magnetic resonance imaging (rsfMRI) to investigate whether acupuncture can modulate brain function and if the potential influence on brain activity correlates with improving emotional symptoms in MMoA patients. Methods: Overall, 44 patients were randomly divided into a true acupuncture (TA) group and the sham acupuncture (SA) group. Patients underwent rsfMRI before and after 3-month treatment, the amplitude of low-frequency fuctuations (ALFF) and regional homogeneity (ReHo) in rsfMRI were calculated. Zung self-rating anxiety scale (SAS), Zung self-rating depression scale (SDS), frequency of migraine attacks, visual analog scale, and intensity of the migraine were used for evaluate the clinical effect. The clinical changes of variables were also used to further assess the correlation with brain activity in MMoA patients. Results: After acupuncture treatment, the emotional symptoms of both groups of patients improved, and the clinical symptoms of migraine were alleviated. The major finding of our study was that patients with MMoA showed lower ALFF value in the left anterior cingulate and the value was positively correlated with the decreases in the SAS and SDS scores. In the SA group, common brain regions responded both in ALFF and regional homogeneity values mainly in the insula, and no significant correlations were observed between brain regions and clinical variables. Conclusions: These results indicated that both two acupuncture treatments were helpful in treating migraine and could improve emotion symptoms. TA had a relatively better effect in reducing the frequency of migraine attack than SA. The two therapies have different modulation effects as TA regulates emotional disorders by modulating the frontal-limbic regions, and SA may modulate pain perception through the placebo effect on insula and by indirectly regulating emotional disorders. These findings provided evidence that acupuncture is a complementary and alternative therapy to relieve clinical symptoms in female patients with migraines and could help enhance clinical diagnosis and treatment. Clinical Trial Registration: [http://www.chictr.org.cn/index.aspx], identifier [ChiCTR-IOR-15006648. Registered 23 June 2015].

Anomalous functional connectivity within the default-mode network in treatment-naive patients possessing first-episode major depressive disorder

BACKGROUND AND OBJECTIVE

Previous studies have shown that the default-mode network (DMN) has a substantial role in patients with major depressive disorder (MDD). However, there is a shortage of information regarding variations in the functional connectivity (FC) of the DMN of treatment-naive patients with first-episode MDD. The present study aims to explore the FC of the DMN in such patients.

METHODS

The study population consisted of 33 patients and 35 controls, paired regarding age, gender, education level, and health condition. Depression severity was assessed through the Hamilton Depression Scale (HAM-D), and subjects underwent evaluation during the resting-state through functional magnetic resonance imaging (rs-fMRI). To assess the result, we used FC and ICA. We used Spearman's correlation test to detect potential correlations between anomalous FC and severity of HAM-D scores.

RESULTS

We have found a decreased FC in the left medial orbitofrontal gyrus (MOFG) and right marginal gyrus (SMG) in depressive patients compared to controls. There was a negative correlation between abnormal FC in the right SMG and HAM-D scores. We have not found any increase in FC of the DMN in treatment-naive, first-episode of MDD patients.

CONCLUSIONS

Our study provided evidence of a negative correlation between abnormal FC in the DMN and severity of depression symptoms measured by HAM-D in treatment-naive MDD patients. This finding could shed some light on the relevance of DMN for understanding the pathophysiology of cognitive impairment in MDD.

Differentiating Melancholic and Non-melancholic Major Depressive Disorder Using Fractional Amplitude of Low-Frequency Fluctuations

BACKGROUND

Melancholic major depressive disorder (MDD) is a network-based brain disorder. However, whether or not network-based changes can be applied to differentiate melancholic (MEL) from non-melancholic (NMEL) MDD remains unclear.

METHODS

Thirty-one MEL patients, 28 NMEL patients, and 32 matched healthy controls (HCs) were scanned using resting-state functional magnetic resonance imaging. Patients were assessed by the Chinese version of Snaith-Hamilton Pleasure Scale (SHAPS-C) and Temporal Experience of Pleasure Scale (TEPS). Fractional amplitude of low-frequency fluctuations (fALFF) and correlation analysis were used to analyze the data.

RESULTS

Compared with HCs, the MEL group had significantly higher fALFF values in the bilateral inferior frontal gyrus and right supplementary motor area (SMA) and significantly lower fALFF values in the right inferior occipital gyrus (IOG), right middle temporal gyrus (MTG)/left IOG, and bilateral superior occipital gyrus (SOG)/MTG. On the other hand, the NMEL group showed significantly higher fALFF values in the bilateral SMA and significantly lower fALFF values in the bilateral posterior cingulate cortex/precuneus relative to HCs. Compared with the NMEL group, the MEL group showed significantly lower fALFF values in the left anterior cingulate cortex (ACC). A correlation was found between the fALFF values of the right SMA and the SHAPS-C in the MEL group. In addition, correlations were observed between the fALFF values of the left ACC and the TEPS contextual consummatory and total scores in all patients.

CONCLUSION

Our study uncovered that MDD exhibited altered brain activity in extensive brain networks, including the default-mode network, frontal-striatal network, reward system, and frontal-limbic network. Decreased fALFF in the left ACC might be applied to differentiate the two subtypes of MDD.

Disrupted Regional Homogeneity in Melancholic and Non-melancholic Major Depressive Disorder at Rest

Background: Melancholic depression has been viewed as one severe subtype of major depressive disorder (MDD). However, it is unclear whether melancholic depression has distinct changes in brain imaging. We aimed to explore specific or distinctive alterations in melancholic MDD and whether the alterations could be used to separate melancholic MDD from non-melancholic MDD or healthy controls. Materials and Methods: Thirty-one outpatients with melancholic MDD and thirty-three outpatients with non-melancholic MDD and thirty-two age- and gender-matched healthy controls were recruited. All participants were scanned by resting-state functional magnetic resonance imaging (fMRI). Imaging data were analyzed with the regional homogeneity (ReHo) and support vector machine (SVM) methods. Results: Melancholic MDD patients exhibited lower ReHo in the right superior occipital gyrus/middle occipital gyrus than non-melancholic MDD patients and healthy controls. Merely for non-melancholic MDD patients, decreased ReHo in the right middle frontal gyrus was negatively correlated with the total HRSD-17 scores. SVM analysis results showed that a combination of abnormal ReHo in the right fusiform gyrus/cerebellum Crus I and the right superior occipital gyrus/middle occipital gyrus exhibited the highest accuracy of 83.05% (49/59), with a sensitivity of 90.32% (28/31), and a specificity of 75.00% (21/28) for discriminating patients with melancholic MDD from patients with non-melancholic MDD. And a combination of abnormal ReHo in the right fusiform gyrus/cerebellum VI and left postcentral gyrus/precentral gyrus exhibited the highest accuracy of 98.41% (62/63), with a sensitivity of 96.77% (30/31), and a specificity of 100.00%(32/32) for separating patients with melancholic MDD from healthy controls. Conclusion: Our findings showed the distinctive ReHo pattern in patients with melancholic MDD and found brain area that may be associated with the pathophysiology of non-melancholic MDD. Potential imaging markers for discriminating melancholic MDD from non-melancholic MDD or healthy controls were reported.

Anterior cingulate cortex, insula and amygdala seed-based whole brain resting-state functional connectivity differentiates bipolar from unipolar depression

OBJECTIVE

The frontal-limbic circuit is hypothesized as sub-serving emotional regulation. We performed whole brain resting-state functional connectivity (rs-FC) analysis by studying the key hubs of frontal-limbic circuit: anterior cingulate cortex (ACC), bilateral insula subregions, bilateral amygdala (Amy) as seeds, separately, to discriminate bipolar depression (BipD) from unipolar depression (UniD).

METHODS

We compared seed-based rs-FC of the frontal-limbic seeds with whole brain among 23 BipD participants; 23 age, gender, and depression severity matched patients with UniD, and 23 healthy controls (HCs). We also used support vector machine learning to study classification based on the rs-FC of ACC, bilateral insula subregions, and bilateral Amy seeds with whole brain.

RESULTS

BipD showed increased rs-FC between the left ventral anterior insula (vAI) seed and the left anterior supramarginal gyrus (aSMG) and left postcentral gyrus, as well as increased rs-FC between left amygdala seed and the left aSMG when compared to HCs and UniD. Compared to UniD, BipD was associated with increased rs-FC between right dorsal anterior insula seed and right superior frontal gyrus, as well as increased rs-FC between left posterior insula seed and right precentral gyrus and right thalamus. Combined rs-FC of ACC, bilateral insula subregions and bilateral Amy seeds with the whole brain discriminated BipD from UniD with an accuracy of 91.30%.

CONCLUSIONS

Rs-FC of the emotional regulation circuit is more widely disturbed in BipD than UniD. Using rs-FC with this circuit may lead to further developments in diagnostic decision-making.

Chinese Taoist Cognitive Therapy for Symptoms of Depression and Anxiety in Adults in China: A Systematic Review and Meta-Analysis

Background: Chinese Taoist cognitive therapy (CTCT), a culture-oriented psychological therapy for Chinese mental well-being, has been proposed for decades. However, the evidence for its effects is unclear. This study aimed to systematically assess the effect of this therapy on symptoms of depression and anxiety in Chinese adults. Methods: Relevant studies were searched from major electronic databases through November 2018 without language limits. Several search terms used include "anxiety" OR "depression" AND "Taoism" OR "Daoism" OR "Chinese Taoist Cognitive Therapy." A total of 11 clinical trials focusing on CTCT were included in this meta-analysis. Random-effects meta-analytical models were conducted. Heterogeneity and publication bias were also explored. Results: Eight clinical trials for 580 subjects were included. The majority of these studies explored samples with depressive symptoms. Overall, CTCT significantly reduced depressive symptoms with a small positive effect (SMD = 0.16, 95% CI: -0.36-0.68). Medium-to-large effect sizes were observed across individuals with clinical or non-clinical depression and chronic physical diseases (SMD = 0.70, 95%CI: 0.27-1.13 and SMD = 0.72, 95%CI: 0.09-1.35, respectively). However, the effectiveness for anxiety symptoms remains debatable. Conclusions: Our findings hold promise that CTCT can help reduce depressive symptoms in Chinese adults, including patients with chronic physical diseases and clinical or non-clinical depression. Our findings may be generalized to Chinese communities in other countries.

Abnormal functional connectivity strength in first-episode, drug-naïve adult patients with major depressive disorder

BACKGROUND

The pathogenesis of major depressive disorder (MDD) is complicated and equivocal. Previous studies have found an incidence of abnormal changes of neural networks, with plentiful evidence pointing the finger of suspicion firmly at the default mode network (DMN) and cortico-limbic networks. The aim of the present study was to use the approach of functional connectivity strength (FCS) to directly investigate the features of spontaneous brain activity in the case of first-episode, drug-naïve adult patients with MDD at rest.

METHODS

Resting-state functional magnetic resonance imaging (MRI) scans were performed on 23 first-episode drug-naïve major depressive disorder (MDD) patients and 20 healthy controls (HCs). In this study, using graph-theory approaches(FCS), we computed the characteristics of brain connectivity. Simultaneously, we used a series of validated test procedures to evaluate the patients' cognitive function. Subsequently, the results were compared with the peak of FCS value and a correlation analysis was conducted.

RESULTS

Compared with the HCs group, MDD patients showed significantly decreased FCS in bilateral posterior cingulate cortex (PCC)/precuneus and bilateral prefrontal cortex(PFC) and increased FCS in right posterior central gyrus, left thalamus and left temporal lobe. These brain regions belongs to the default-mode network and cortico-limbic networks. Finally, the correlation analyses showed the negative correlation of the FCS values in the left posterior cingulate cortex (PCC)/precuneus and Hamilton Anxiety Rating Scale (HAMA, r = -0.472, p = .023), Stroop Color Word Test-A(SCWT-A, r = -0.451, p = .031), Stroop Color Word Test-B(SCWT-B, r = -0.588, p = .003).Meanwhile, there was negative correlation between the FCS values in the left thalamus and SCWT-A(r = -0.473, p = .023), SCWT-B(r = -0.465, p = .025), SCWTC(r = -0.524, p = .010).In addition, the FCS values in the right PCC has negative correlation with Montgomery Asberg Depression Rating Scale (MADRS) (r = -0.433, p = .039).

CONCLUSIONS

DMN is an important node of MDD. FCS within the default mode network and cortico-limbic networks in patients with major depressive disorder has been changed in the early stage of MDD. FCS can provide favourable and additional evidence in the investigation of brain pathophysiology and therapy in depression.

Altered gray matter volumes in post-stroke depressive patients after subcortical stroke

Stroke survivors are known to suffer from post-stroke depression (PSD). However, the likelihood of structural changes in the brains of PSD patients has not been explored. This study aims to extract changes in the gray matter of these patients and test how these changes account for the PSD symptoms. High-resolution T1 weighted images were collected from 23 PSD patients diagnosed with subcortical stroke. Voxel-based morphometry and support vector machine analyses were used to analyze the data. The results were compared with those collected from 33 non-PSD patients. PSD group showed decreased gray matter volume (GMV) in the left middle frontal gyrus (MFG) when compared to the non-PSD patients. Together with the clinical and demographic variables, the MFG's GMV predictive model was able to distinguish PSD from the non-PSD patients (0•70 sensitivity and 0•88 specificity). The changes in the left inferior frontal gyrus (61%) and dorsolateral prefrontal cortex (39%) suggest that the somatic/affective symptoms in PSD is likely to be due to patients' problems with understanding and appraising negative emotional stimuli. The impact brought by the reduced prefrontal to limbic system connectivity needs further exploration. These findings indicate possible systemic involvement of the frontolimbic network resulting in PSD after brain lesions which is likely to be independent from the location of the lesion. The results inform specific clinical interventions to be provided for treating depressive symptoms in post-stroke patients.

The neural markers of MRI to differentiate depression and panic disorder

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

Reduced Brain Activity in the Right Putamen as an Early Predictor for Treatment Response in Drug-Naive, First-Episode Schizophrenia

Antipsychotic medications can have a significant effect on brain function after only several days of treatment. It is unclear whether such an acute effect can serve as an early predictor for treatment response in schizophrenia. Thirty-two patients with drug-naive, first-episode schizophrenia and 32 healthy controls underwent resting-state functional magnetic resonance imaging. Patients were treated with olanzapine and were scanned at baseline and 1 week of treatment. Healthy controls were scanned once at baseline. Symptom severity was assessed within the patient group using the Positive and Negative Syndrome Scale (PANSS) at three time points (baseline, 1 week of treatment, and 8 weeks of treatment). The fractional amplitude of low frequency fluctuation (fALFF) and support vector regression (SVR) methods were used to analyze the data. Compared with the control group, the patient group showed increased levels of fALFF in the bilateral putamen at baseline. After 1week of olanzapine treatment, the patient group showed decreased levels of fALFF in the right putamen relative to those at baseline. The SVR analysis found a significantly positive relationship between the reduction in fALFF after 1 week of treatment and the improvement in positive symptoms after 8 weeks of treatment (r = 0.431, p = 0.014). The present study provides evidence that early reduction and normalization of fALFF in the right putamen may serve as a predictor for treatment response in patients with schizophrenia.

Reduced Resting State Neural Activity in the Right Orbital Part of Middle Frontal Gyrus in Anxious Depression

BACKGROUND

Anxious depression (AD), which is generally recognized as a common clinical subtype of major depressive disorder (MDD), holds distinctive features compared with unanxious depression (UAD). However, the neural mechanism of AD still remains unrevealed. To give insight to it, we compared resting-state functional magnetic resonance amplitude of low-frequency fluctuation (ALFF) and functional connectivity (FC) between AD and UAD patients.

METHOD

The data were collected from 60 AD patients, 38 UAD patients, and 60 matched healthy controls. The ALFF and seed-based FC were examined. Pearson correlations were computed between ALFF/FC and clinical measures.

RESULTS

In Comparison with the UAD group, the ALFF value of the right orbital part of middle frontal gyrus (RO-MFG) decreased in AD group. Specifically, the ALFF values of the RO-MFG were negatively correlated with retardation factor scores in AD group (r = -0.376, p = 0.003).

CONCLUSIONS

AD patients exhibited disturbed intrinsic brain function compared with UAD patients. The decreased activity of the RO-MFG is indicative of the alterations involved in the neural basis of AD.

Abnormal default-mode network homogeneity in patients with temporal lobe epilepsy

Default-mode network (DMN) plays a key role in a broad-scale cognitive problem, which occurs in temporal lobe epilepsy (TLE). However, little is known about the alterations of the network homogeneity (NH) of DMN in TLE. In the present study, we employed NH method to investigate the NH of DMN in TLE at rest.A total of 47 patients with TLE (right TLE [rTLE] 29, and left TLE [lTLE] 18) and 35 healthy controls who underwent resting-state functional magnetic resonance imaging were enrolled. NH approach was used to analyze the data.rTLE exhibited decreased NH in the right middle temporal pole gyrus and increased NH in the bilateral posterior cingulate cortex compared to the control group. In lTLE, decreased NH was observed in left inferior temporal gyrus and left hippocampus. Meanwhile, we found that lTLE had a longer performance reaction time. No significant correlation was found between abnormal NH values and clinical variables in the patients.These findings suggested that abnormal NH of the DMN exists in rTLE and lTLE, and highlighted the significance of DMN in the pathophysiology of cognitive problems occurring in TLE and also found the existence of abnormality of executive function in lTLE.

Voxel-wise brain-wide functional connectivity abnormalities in first-episode, drug-naive patients with major depressive disorder

Due to different foci and single sample across studies, abnormal functional connectivity (FC) has been implicated in the pathophysiology of major depressive disorder (MDD) with inconsistent results. The inconsistency may reflect a combination of clinical and methodological variability, which leads to limited reproducibility of these findings. The samples included 59 patients with MDD and 31 controls from Sample 1, 29 patients with MDD and 24 controls from Sample 2, and 31 patients with schizophrenia and 37 controls from Sample 3. Global-brain FC (GFC) and an overlapping technique were applied to analyze the imaging data. Compared with healthy controls, patients with MDD in Samples 1 and 2 showed increased GFC in the overlapped brain areas, including the bilateral insula, right inferior parietal lobule (IPL), and right supramarginal gyrus/IPL. By contrast, decreased GFC in the overlapped brain areas, including the bilateral posterior cingulate cortex/presuneus and left calcarine cortex, was found in patients with MDD. In addition, patients with schizophrenia in Sample 3 did not show any GFC abnormalities in the overlapped areas from the results of Samples 1 and 2. The present study is the first to examine voxel-wise brain-wide FC in MDD with two independent samples by using an overlapping technique. The results indicate that aberrant FC patterns of insula-centered sensorimotor circuit may account for the pathophysiology of MDD.

The regional homogeneity of cingulate-precuneus regions: The putative biomarker for depression and anxiety

OBJECTIVES

In addition to clinical interview, the modern putative biomarker to differentiate depression and anxiety would be warranted. The translational medicine characteristics of neuroimaging, such as the regional homogeneity (ReHo), is an option for depression and anxiety. Therefore we designed this study trying to identify the biomarker pattern for depression and anxiety.

METHODS

Resting-state functional magnetic resonance imaging was acquired for 53 patients with first-episode medicine-naïve major depressive disorder (MDD), 53 first-episode medicine-naïve patients with panic disorder (PD) and 54 controls. The calculation of ReHo was performed. The ANOVA repeated measures were applied for the 3 groups to investigate the putative differences between MDD and PD (FDR corrected p < 0.05).

RESULTS

After multiple comparisons, the major findings of ReHo were found in the bilateral anterior cingulate cortex and bilateral precuneus. MDD group had lower ReHo values than PD group in the left anterior cingulate cortex. MDD group had significant alterations of ReHo in the left anterior cingulate cortex and bilateral precuneus when compared to controls. PD group had alterations in the bilateral precuneus when compared to controls.

CONCLUSION

The specific cingulate alterations might be a putative ReHo biomarker to differentiate MDD from PD in cingulate-precuneus background for ReHo alterations.

Task-related changes in degree centrality and local coherence of the posterior cingulate cortex after major cardiac surgery in older adults

OBJECTIVES

Older adults often display postoperative cognitive decline (POCD) after surgery, yet it is unclear to what extent functional connectivity (FC) alterations may underlie these deficits. We examined for postoperative voxel-wise FC changes in response to increased working memory load demands in cardiac surgery patients and nonsurgical controls.

EXPERIMENTAL DESIGN

Older cardiac surgery patients (n = 25) completed a verbal N-back working memory task during MRI scanning and cognitive testing before and 6 weeks after surgery; nonsurgical controls with cardiac disease (n = 26) underwent these assessments at identical time intervals. We measured postoperative changes in degree centrality, the number of edges attached to a brain node, and local coherence, the temporal homogeneity of regional functional correlations, using voxel-wise graph theory-based FC metrics. Group × time differences were evaluated in these FC metrics associated with increased N-back working memory load (2-back > 1-back), using a two-stage partitioned variance, mixed ANCOVA.

PRINCIPAL OBSERVATIONS

Cardiac surgery patients demonstrated postoperative working memory load-related degree centrality increases in the left dorsal posterior cingulate cortex (dPCC; p < .001, cluster p-FWE < .05). The dPCC also showed a postoperative increase in working memory load-associated local coherence (p < .001, cluster p-FWE < .05). dPCC degree centrality and local coherence increases were inversely associated with global cognitive change in surgery patients (p < .01), but not in controls.

CONCLUSIONS

Cardiac surgery patients showed postoperative increases in working memory load-associated degree centrality and local coherence of the dPCC that were inversely associated with postoperative global cognitive outcomes and independent of perioperative cerebrovascular damage.

Increased Salience Network Activity in Patients With Insomnia Complaints in Major Depressive Disorder

BACKGROUND

Insomnia is one of the main symptom correlates of major depressive disorder (MDD), but the neural mechanisms underlying the multifaceted interplay between insomnia and depression are not fully understood.

MATERIALS AND METHODS

Patients with MDD and high insomnia (MDD-HI, n = 24), patients with MDD and low insomnia (MDD-LI, n = 37), and healthy controls (HCs, n = 51) were recruited to participate in the present study. The amplitude of low-frequency fluctuations (ALFF) during the resting state were compared among the three groups.

RESULTS

We observed ALFF differences between the three groups in the right inferior frontal gyrus/anterior insula (IFG/AI), right middle temporal gyrus, left calcarine, and bilateral dorsolateral prefrontal cortex (dlPFC). Further region of interest (ROI) comparisons showed that the increases in the right IFG/AI reflected an abnormality specific to insomnia in MDD, while increases in the bilateral dlPFC reflected an abnormality specific to MDD generally. Increased ALFF in the right IFG/AI was also found to be correlated with sleep disturbance scores when regressing out the influence of the severity of anxiety and depression.

CONCLUSION

Our findings suggest that increased resting state ALLF in IFG/AI may be specifically related to hyperarousal state of insomnia in patients with MDD, independently of the effects of anxiety and depression.

Abnormal Default Mode Network Homogeneity in Treatment-Naive Patients With First-Episode Depression

Background and Objective: The default mode network (DMN) may be an important component involved in the broad-scale cognitive problems seen in patients with first-episode treatment-naive depression. Nevertheless, information is scarce regarding the changes in network homogeneity (NH) found in the DMN of these patients. Therefore, in this study, we explored the NH of the DMN in patients with first-episode treatment-naive depression. Methods: The study included 66 patients and 74 control participants matched by age, gender, educational level and health status who underwent resting-state functional magnetic resonance imaging (rs-fMRI) and the attentional network test (ANT). To assess data, the study utilizes NH and independent component analysis (ICA). Additionally, Spearman's rank correlation analysis is performed among significantly abnormal NH in depression patients and clinical measurements and executive control reaction time (ECRT). Results: In comparison with the control group, patients with first-episode treatment-naive depression showed lower NH in the bilateral angular gyrus (AG), as well as increased NH in the bilateral precuneus (PCu) and posterior cingulate cortex (PCC). Likewise, patients with first-episode treatment-naive depression had longer ECRT. No significant relation was found between abnormal NH values and the measured clinical variables. Conclusions: Our results suggest patients with first-episode treatment-naive depression have abnormal NH values in the DMN. This highlights the significance of DMN in the pathophysiology of cognitive problems in depression. Our study also found alterations in executive functions in patients with first-episode treatment-naive depression.

Increased anterior default-mode network homogeneity in first-episode, drug-naive major depressive disorder: A replication study

BACKGROUND

Abnormal default-mode network (DMN) homogeneity has been involved in the neurophysiology of major depressive disorder (MDD) with inconsistent findings. The inconsistency may be due to clinical and methodological variability, and the reproducibility of the findings is limited. The present study aimed to examine alterations of the DMN homogeneity in two independent samples of patients with first-episode, drug-naive MDD.

METHODS

The samples included 59 patients with MDD and 31 comparison subjects from Sample 1 and 29 patients with MDD and 24 comparison subjects from Sample 2. Network homogeneity (NH) was computed with an overlapping technique, which was employed to define brain regions with abnormal NH common to the MDD samples.

RESULTS

Compared with comparison subjects, patients with MDD exhibited increased NH in an overlapped brain region of the left superior medial prefrontal cortex (MPFC). No correlations were found between abnormal NH and HAMD total/subscale scores in the patients of each sample and in the combined patients from both samples.

CONCLUSIONS

This study is the first to examine alterations of DMN homogeneity in first-episode, drug-naive patients with MDD in two independent samples by using an overlapping technique. Patients with MDD exhibit increased NH in an overlapped region in the anterior DMN. The present study thus highlights the importance of the DMN in the neurophysiology of MDD.

Aberrant patterns of brain cerebral blood flow in Chinese han first-episode drug-naïve depressive patients with and without a family history of depression

A positive family history plays a key role in the brain pathology of depression patients and previous research has confirmed that disturbed mood maintenance may be related to abnormal regional cerebral blood flow (rCBF). However, little is known about whether the rCBF is different between depression patients with and without family histories. To address this question, we examined the rCBF in drug-naïve, first-episode depression patients with and without family histories of depression using a 3D pseudo-continuous arterial spin-labelling technique. We found that decreased rCBF was predominantly observed in the patients without family histories, while decreased and increased rCBF co-existed in patients with family histories. The observed brain regions with altered rCBF were associated with affection processing, such as the prefrontal, occipital and insular areas. However the patterns of rCBF alteration observed in the present study were different from those found in previous studies where patients were compared with healthy controls. Our present findings, together with the findings from previous studies have prompted the need of a long-term follow-up study to characterize the brain features of the developmental trajectory of depression and investigate the targets for precise, personalized treatments.

Olanzapine modulates the default-mode network homogeneity in recurrent drug-free schizophrenia at rest

BACKGROUND

Previous studies on brain function alterations associated with antipsychotic treatment for schizophrenia have produced conflicting results because they used short treatment periods and different designs.

METHODS

Resting-state functional magnetic resonance imaging scans were obtained from 17 drug-free patients with recurrent schizophrenia and 24 healthy controls. The patients were treated with olanzapine for 6 months and were scanned at three time points (baseline, 6 weeks of treatment and 6 months of treatment). Network homogeneity was used to analyze the imaging data to examine default-mode network homogeneity alterations associated with antipsychotic treatment.

RESULTS

Compared with the controls, the patients at baseline showed increased network homogeneity in the bilateral precuneus and decreased network homogeneity in the bilateral middle temporal gyrus. Network homogeneity values in the bilateral precuneus decreased, and network homogeneity values in the left superior medial prefrontal cortex and the right middle temporal gyrus increased in patients administered olanzapine as antipsychotic treatment. By contrast, network homogeneity values in the left middle temporal gyrus remained unchanged in patients after treatment.

CONCLUSION

This study provides evidence that antipsychotic treatment with olanzapine modulates the default-mode network homogeneity in schizophrenia. These findings contribute to the understanding of antipsychotic treatment effects on brain functions.

A Combined Study of SLC6A15 Gene Polymorphism and the Resting-State Functional Magnetic Resonance Imaging in First-Episode Drug-Naive Major Depressive Disorder

AIMS

The SLC6A15 gene has been identified as a novel candidate gene for major depressive disorder (MDD). However, the mechanism underlying the effects of how the SLC6A15 gene affects functional brain activity of patients with MDD remains unknown.

METHODS

In the present study, we investigated the effect of the SLC6A15 gene polymorphism, rs1545843, on resting-state brain function in MDD with the imaging genomic technology and the regional homogeneity (ReHo) method. Sixty-seven MDD patients and 44 healthy controls underwent functional magnetic resonance imaging scans and genotyping. The differences in ReHo between genotypes were initially tested using the student's t test. We then performed a 2 × 2 (genotypes × disease status) analysis of variance to identify the main effects of genotypes, disease status, and their interactions in MDD.

RESULTS

MDD patients with A+ genotypes showed decreased ReHo in the medial cingulum compared with MDD patients with the GG genotype. This was in contrast to normal controls with A+ genotypes who showed increased ReHo in the posterior cingulum and the frontal, temporal, and parietal lobes and decreased ReHo in the left corpus callosum, compared with controls with the GG genotypes. The main effect of disease was found in the frontal, parietal, and temporal lobes. The main effect of genotypes was found in the left corpus callosum and the frontal lobe. There was no interaction between rs1545843 genotypes and disease status. We found that the left corpus callosum ReHo was positively correlated with total scores of the Hamilton Depression Scale (HAMD) (p = 0.021), so as was the left inferior parietal gyrus ReHo with cognitive disorder (p = 0.02). In addition, the right middle temporal gyrus had a negative correlation with retardation (p = 0.049).

CONCLUSION

We observed an association between the SLC6A15 rs1545843 and resting-state brain function of the corpus callosum, cingulum and the frontal, parietal, and temporal lobes in MDD patients, which may be involved in the pathogenesis of MDD.

Weaker Functional Connectivity Strength in Patients with Type 2 Diabetes Mellitus

Type 2 diabetes mellitus (T2DM) is related to cognitive impairments and increased risk for dementia. Neuroimaging studies have demonstrated T2DM-related brain structural and functional changes which are partly associated to the cognitive decline. However, few studies focused on the early neuroimaging findingsin T2DM patients. In this study, a data-driven whole-brain resting state functional connectivity strength (rsFCS) methodwas used to evaluate resting functional changes in 53 T2DM patients compared with 55 matched healthy controls (HCs), and to detect the associations between the rsFCSchanges and cognitive functions in T2DM patients. The T2DM patients exhibited weaker long-range rsFCS in the right insula and weaker short-range rsFCS in the right supramarginalgyrus (SG) compared with the HCs. Additionally, seed-based functional connectivity (FC) analysis revealed weaker FC between the right insula and the bilateral superior parietal lobule (SPL), and between the right SG and the bilateral supplementary motor area (SMA)/right SPL in T2DM patientscompared with the HCs. In T2DM patients, negative correlation was found between the long-range rsFCS in the right insula and HbA1c levels; and the FC between the right SG and the bilateral SMA negatively correlated with TMT-A scores. Our results indicated that the rsFCS alteration occurredbefore obvious cognitive deficits in T2DM patients, which might be helpful for understanding the neuromechanism of cognitive declines in T2DM patients.

Probabilistic Entity-Relationship Diagram: A correlation between functional connectivity and spontaneous brain activity during resting state in major depressive disorder

BACKGROUND

Alterations of functional connectivity (FC) and spontaneous brain activity (SBA) during the resting state has been observed in subjects with major depressive disorder (MDD). Although there are many studies separately describing on the alterations of FC and SBA in major depressive disorder, their correlation are still have not been performed.

METHODS

A literature search based on Pubmed and Embase was conducted until 20 April 2016 to identify studies evaluating the correlation for the alterations between functional connectivity and spontaneous brain activity during resting-state in MDD. Meta-analyses were performed using the Probabilistic Entity-Relationship Diagram (PERD) approach to summarize the relationships among multiple factors in an intuitive manner.

RESULTS

A total of 30 studies (747 individuals with MDD and 757 healthy controls) met the inclusion criteria. In this study, we demonstrated that the functional connectivity and spontaneous brain activity, which was quantitatively measured by the primary analysis methods, was decreased in the parahippocampal gyrus, orbitofrontal cortex (OFC) and postcentral gyrus (PCG), and increased in insula and left dorsal medial prefrontal cortex (DMPFC) in MDD patients. Furthermore, we found that MDD patients presented negative correlation alterations both FC and SBA in the default mode network and the dorsal attention network, but positive correlation alterations both FC and SBA in the insular network, executive control network, the salience network and the other network.

CONCLUSIONS

Our results first suggested that there were correlation alterations between functional connectivity and spontaneous brain activity during resting-state in patients with MDD. Besides, we applied a recent meta-analysis approach (PERD) to summarize and integrate the inconsistence of the existing findings regarding the network dysfunction of MDD.

Intrinsic cerebral activity at resting state in adults with major depressive disorder: A meta-analysis

Numerous neuroimaging studies have been undertaken to detect cerebral intrinsic activity in major depressive disorder (MDD) with resting state fMRI (rs-fMRI). However, the inconsistent results have hindered our understanding of the exact neuropathology related to MDD. The current meta-analysis used state-of-the-art conjunction analysis techniques to systematically review and summarize all available neuroimaging studies using rs-fMRI with amplitude of low frequency fluctuation (ALFF) and/or fractional ALFF (fALFF) on MDD patients and further explored the effect of antidepressants on the intrinsic activity of the brain. The anisotropic effect size version of signed differential mapping (AES-SDM) was applied to investigate changes in ALFF/fALFF in depression. We performed a subgroup analysis and group comparison on medicated and drug naïve patients to detect drug effect on MDD patients and conjunction analysis to identify congruent results between the two methods. Meta-regression was used to explore the effects of demographics and clinical characteristics. Adult MDD patients showed a robust increase in intrinsic activity in the resting state in the anterior cingulate cortex (ACC) in both ALFF (P<0.001) and fALFF (P<0.01) studies. The subgroup analysis demonstrated that the increased activity in the ACC was prominent in medicated patients only and not seen in drug-naïve MDD patients, while medication-naïve patients showed a specific decreased activity in the cerebellum (P<0.01). Group comparison showed that the intrinsic ACC activity is elevated in medicated MDD patients compared with drug naïve MDD patients. Meta-regression analysis demonstrated that the increased ACC activation was positively correlated with illness duration (P<0.001). Our findings suggest that increased activity of the ACC is more likely to be associated with antidepressant treatment, while decreased intrinsic activity of the cerebellum might be a specific biomarker for current MDD.

Perceived Occupational Stress is associated with Decreased Cortical Activity of the Prefrontal Cortex: A Multichannel Near-infrared Spectroscopy Study

Despite an increasing number of reports on the associations between chronic occupational stress and structural and functional changes of the brain, the underlying neural correlates of perceived occupational stress is still not clear. Perceived stress reflects the extents to which situations are appraised as stressful at a given point in one’s life. Using near-infrared spectroscopy, we investigated the associations between perceived occupational stress and cortical activity over the bilateral frontotemporal regions during a verbal fluency test. Sixty-eight participants (17 men, 51 women), 20–62 years of age were recruited. Perceived occupational stress was measured using the Chinese version of Job Content Questionnaire, and the Chinese version of the Copenhagen Burnout Inventory. We found statistically significant negative associations between occupational burnout and brain cortical activity over the fronto-polar and dorsolateral prefrontal cortex during the VFT (r = −0.343 to −0.464). In conclusion, our research demonstrated a possible neural basis of perceived occupational stress that are distributed across the prefrontal cortex.

Functional alterations of fronto-limbic circuit and default mode network systems in first-episode, drug-naïve patients with major depressive disorder: A meta-analysis of resting-state fMRI data

BACKGROUND

The neurobiological mechanisms of depression are increasingly being explored through resting-state brain imaging studies. However, resting-state fMRI findings have varied, perhaps because of differences between study populations, which included the disorder course and medication use. The aim of our study was to integrate studies of resting-state fMRI and explore the alterations of abnormal brain activity in first-episode, drug-naïve patients with major depressive disorder.

METHODS

Relevant imaging reports in English were searched, retrieved, selected and subjected to analysis by activation likelihood estimation, a coordinate-based meta-analysis technique (final sample, 31 studies). Coordinates extracted from the original reports were assigned to two categories based on effect directionality.

RESULTS

Compared with healthy controls, the first-episode, medication-naïve major depressive disorder patients showed decreased brain activity in the dorsolateral prefrontal cortex, superior temporal gyrus, posterior precuneus, and posterior cingulate, as well as in visual areas within the occipital lobe, lingual gyrus, and fusiform gyrus, and increased activity in the putamen and anterior precuneus.

LIMITATIONS

Not every study that has reported relevant data met the inclusion criteria.

CONCLUSION

Resting-state functional alterations were located mainly in the fronto-limbic system, including the dorsolateral prefrontal cortex and putamen, and in the default mode network, namely the precuneus and superior/middle temporal gyrus. Abnormal functional alterations of the fronto-limbic circuit and default mode network may be characteristic of first-episode, drug-naïve major depressive disorder patients.

Decreased long- and short-range functional connectivity at rest in drug-naive major depressive disorder

BACKGROUND

Abnormal functional connectivity has been observed in major depressive disorder. Anatomical distance may affect functional connectivity in patients with major depressive disorder. However, whether and how anatomical distance affects functional connectivity at rest remains unclear in drug-naive patients with major depressive disorder.

METHODS

Forty-four patients with major depressive disorder, as well as 44 age-, sex- and education-matched healthy controls, underwent resting-state functional magnetic resonance imaging scanning. Regional functional connectivity strength was calculated for each voxel in the whole brain, which was further divided into short- and long-range functional connectivity strength.

RESULTS

The patients showed decreased long-range positive functional connectivity strength in the right inferior parietal lobule, as well as decreased short-range positive functional connectivity strength in the right insula and right superior temporal gyrus relative to those of the controls. No significant correlations existed between abnormal functional connectivity strength and the clinical variables of the patients.

CONCLUSION

The findings revealed that anatomical distance decreases long- and short-range functional connectivity strength in patients with major depressive disorder, which may underlie the neurobiology of major depressive disorder.

The Current Situation on Major Depressive Disorder in China: Research on Mechanisms and Clinical Practice

Depression is the most disabling disorder worldwide that accounts for the highest proportion of global burden attributable to mental disorders. Major depressive disorder (MDD) is characterized by deep sadness, reduced energy, vegetative nervous system dysregulation, cognitive dysfunction, and even a high suicidal tendency. Although other treatment choices are available, antidepressant medication is the front-line treatment option for MDD. Regarding clinical efficacy, only ~50% of patients respond to frontline antidepressants, and <33% obtain remission. Currently, objective indexes to guide clinical decisions are still lacking. Furthermore, knowledge about the neurobiological mechanisms underlying discrepant antidepressant outcomes is still also fragmentary. In the present review, we discuss the current research progress and clinical opinions on MDD in China.

Frequency-dependent changes in amplitude of low-frequency oscillations in depression: A resting-state fMRI study

OBJECTIVE

We conducted this fMRI study to examine whether the alterations in amplitudes of low-frequency oscillation (LFO) of major depressive disorder (MDD) patients were frequency dependent.

MATERIALS AND METHODS

The LFO amplitudes (as indexed by amplitude of low-frequency fluctuation [ALFF] and fractional ALFF [fALFF]) within 4 narrowly-defined frequency bands (slow-5: 0.01-0.027Hz, slow-4: 0.027-0.073Hz, slow-3: 0.073-0.198Hz, and slow-2: 0.198-0.25Hz) were computed using resting-state fMRI data of 35 MDD patients and 32 healthy subjects. Repeated-measures analysis of variance (ANOVA) was performed on ALFF and fALFF both within the low frequency bands of slow-4 and slow-5 and within all of the four bands.

RESULTS

We observed significant main effects of group and frequency on ALFF and fALFF in widely distributed brain regions. Importantly, significant group and frequency interaction effects were observed in the ventromedial prefrontal cortex, inferior frontal gyrus, precentral gyrus, in a left-sided fashion, the bilateral posterior cingulate and precuneus, during ANOVA both within slow-4 and slow-5 bands and within all the frequency bands.

CONCLUSIONS

The results suggest that the alterations of LFO amplitudes in specific brain regions in MDD patients could be more sensitively detected in the slow-5 rather than the slow-4 bands. The findings may provide guidance for the frequency choice of future resting-state fMRI studies of MDD.