Default Mode Network Functional Connectivity Research Articles

Evaluating functional connectivity of executive control network and frontoparietal network in Alzheimer’s disease

Investigating the early Alzheimer’s disease (AD) more emphasizes sensitive and specific biomarkers, which can help the clinicians to monitor the progression and treatments of AD. Among these biomarkers, default mode network (DMN) functional connectivity is gaining more attention as a potential noninvasive biomarker to diagnose incipient Alzheimer's disease. However, besides changed functional connectivity of DMN, other functional networks haven’t yet been examined systematically. Recent brain imaging studies reported that a number of reproducible and robust functional networks, which were distributed in distant neuroanatomic areas. Inspired by these works, in this paper, we apply sparse representation to the whole brain signals to identify these reproducible networks and detect partly affected brain regions of Alzheimer’s disease, then adopt sparse inverse covariance estimation (SICE) approach to investigate the changed functional connectivity of intrinsic connectivity networks. Our experimental results show that besides DMN, AD is also affected by others large scale functional brain networks and regions, e.g., executive control network (ECN), frontoparietal network (FPN), where in the superior frontal gyrus (SFGmed) and middle frontal gyrus (MFG) of ECN and in the part paracentral Lobule (PCL) of FPN have an increased functional connectivity, as well as in the Superior Parietal Gyrus (SPG) regions of FPN has shown decreased connectivity. The results may suggest AD is associated with larger scale functional networks and causes the functional connectivity change of many different brain regions. It also proves that these networks may sometimes work together to perform tasks, and such changed functional connectivity may provide a useful baseline for early AD diagnosis.

Systemic Inflammation and Multimodal Biomarkers in Amnestic Mild Cognitive Impairment and Alzheimer's Disease.

There is increasing evidence suggesting that one of the most relevant pathophysiological features of Alzheimer's disease (AD) is neuroinflammation, which plays an important role in the production and regulation of AD-related proteins (amyloid beta (Aβ) and Tau) and exacerbates AD pathology. Neuroinflammation can also be induced by systemic influences (factors from outside the central nervous system). However, the role of systemic inflammation in AD pathophysiology is much less understood. Thus, our main objective in this study was to verify whether the presence of serum cytokines (IL-1β, IL-6, IL-10, IL-12, and TNF-α) affects different AD biomarkers: Aβ1-42 and Tau protein levels, hippocampal volumes (HV), and default mode network functional connectivity (DMN FC) in healthy elderly controls, amnestic mild cognitive impairment (aMCI) patients due to AD, and mild AD patients. To accomplish this, we acquired 3-T MRI, blood, and cerebrospinal fluid (CSF) samples from 42 healthy controls, 55 aMCI patients due to AD, and 33 mild AD patients. Comparing the groups, we found that the mild AD patients presented smaller HV, disrupted DMN FC, and proportionally less IL-1β than the controls. The aMCI patients only differed from the controls in DMN FC. In intra-group comparison, aMCI and mild AD with detectable levels of cytokines (TNF-α, IL-1β, IL-10, and IL-12) had decreased DMN FC. On the other hand, patients with detectable levels of IL-10 and IL-12 presented a more favorable AD biomarkers profile (larger HV, more CSF Aβ1-42, and less p-Tau), indicating a possible protective role of these ILs. Our findings indicate a possible relationship between systemic inflammation with DMN FC disruption, hippocampal atrophy, and CSF protein levels in the subjects with mild AD and aMCI.

Brain sexual differentiation and effects of cross-sex hormone therapy in transpeople: A resting-state functional magnetic resonance study

It is hypothesized that transpeople show sex-atypical differentiation of the brain. Various structural neuroimaging studies provide support for this notion, but little is known about the sexual differentiation of functional resting-state networks in transpeople. In this study we therefore aimed to determine whether brain functional connectivity (FC) patterns in transpeople are sex-typical or sex-atypical, before and after the start of cross-sex hormone therapy (CHT). We acquired resting-state functional magnetic resonance data in 36 transpeople (22 with female sex assigned at birth), first during gonadal suppression, and again four months after start of CHT, and in 37 cisgender people (20 females), both sessions without any hormonal intervention. We used independent component analysis to identify the default mode network (DMN), salience network (SN), and left and right working memory network (WMN). These spatial maps were used for group comparisons. Within the DMN, SN, and left WMN similar FC patterns were found across groups. However, within the right WMN, cisgender males showed significantly greater FC in the right caudate nucleus than cisgender females. There was no such sex difference in FC among the transgender groups and they did not differ significantly from either of the cisgender groups. CHT (in transgender participants) and circulating sex steroids (in cisgender participants) did not affect FC. Our findings may suggest that cisgender males and females experience a dissimilar (early) differentiation of the right WMN and that such differentiation is less pronounced in transpeople.

Default Mode Network Connectivity and Related White Matter Disruption in Type 2 Diabetes Mellitus Patients Concurrent with Amnestic Mild Cognitive Impairment.

As a risk factor for Alzheimer's disease (AD), type 2 diabetes mellitus (T2DM) itself causes cognitive impairment and has higher prevalence of mild cognitive impairment (MCI). The aim of this study was to explore the cognition especially the episodic memory difference, the DMN functional connectivity and DMN-related white matter integrity in patients with both T2DM and amnestic MCI (T2DM-MCI) as compared to patients with T2DM only. Focusing especially on T2DM population, we investigated the default mode network (DMN) through resting-state functional magnetic resonance imaging among 22 elderly T2DM-MCI patients and 24 elderly T2DM patients. Including primarily the bilateral cingulum, hippocampus and uncinate fasciculus, these DMN white matter fibers were also closely associated with episodic memory and the integrity of them was also investigated using diffusion tensor imaging in 19 elderly T2DM-MCI patients and 23 elderly T2DM patients. Compared with the patients with T2DM, the T2DM-MCI patients performed worse in several areas of cognition besides episodic memory, and showed stronger DMN functional connectivity in the left precuneus and weaker functional connectivity in the left calcarine, as well as decreased integrity of the left cingulate bundle and bilateral uncinate fasciculus. Furthermore, a correlation analysis indicated that higher left calcarine connectivity was associated with better episodic memory performance among the overall group. Our results demonstrated that T2DM patients with comorbid amnestic MCI had abnormal functional connectivity patterns and decreased white matter integrity, which could potentially serve as AD or AD risk biomarkers for early detection of those elderly individuals with T2DM.

Influence of cerebrovascular disease on brain networks in prodromal and clinical Alzheimer's disease.

Network-sensitive neuroimaging methods have been used to characterize large-scale brain network degeneration in Alzheimer's disease and its prodrome. However, few studies have investigated the combined effect of Alzheimer's disease and cerebrovascular disease on brain network degeneration. Our study sought to examine the intrinsic functional connectivity and structural covariance network changes in 235 prodromal and clinical Alzheimer's disease patients with and without cerebrovascular disease. We focused particularly on two higher-order cognitive networks-the default mode network and the executive control network. We found divergent functional connectivity and structural covariance patterns in Alzheimer's disease patients with and without cerebrovascular disease. Alzheimer's disease patients without cerebrovascular disease, but not Alzheimer's disease patients with cerebrovascular disease, showed reductions in posterior default mode network functional connectivity. By comparison, while both groups exhibited parietal reductions in executive control network functional connectivity, only Alzheimer's disease patients with cerebrovascular disease showed increases in frontal executive control network connectivity. Importantly, these distinct executive control network changes were recapitulated in prodromal Alzheimer's disease patients with and without cerebrovascular disease. Across Alzheimer's disease patients with and without cerebrovascular disease, higher default mode network functional connectivity z-scores correlated with greater hippocampal volumes while higher executive control network functional connectivity z-scores correlated with greater white matter changes. In parallel, only Alzheimer's disease patients without cerebrovascular disease showed increased default mode network structural covariance, while only Alzheimer's disease patients with cerebrovascular disease showed increased executive control network structural covariance compared to controls. Our findings demonstrate the differential neural network structural and functional changes in Alzheimer's disease with and without cerebrovascular disease, suggesting that the underlying pathology of Alzheimer's disease patients with cerebrovascular disease might differ from those without cerebrovascular disease and reflect a combination of more severe cerebrovascular disease and less severe Alzheimer's disease network degeneration phenotype.

Inflection Point in Course of Mild Cognitive Impairment: Increased Functional Connectivity of Default Mode Network.

The alteration of the default mode network (DMN) functional connectivity (FC) has been reported in patients with amnestic mild cognitive impairment (aMCI) as a predictor of Alzheimer's disease (AD). However, no studies exist that examined stage-dependent DMN FC changes throughout the course of aMCI. The present study aims to characterize patterns of DMN FC over three aMCI stages as first defined. Utilizing the extreme groups approach on the performance of memory tasks, aMCI subjects were divided into mild, moderate, and severe stages. Independent component analysis was used to assess DMN for individual patients in each of the three cross-sectionally defined stages. Instead of finding that continued monotonic decline was the case for the hippocampus volume, which we also investigated in this study, we observed an increase in DMN functional connectivity from mild aMCI to moderate aMCI and a decrease to severe aMCI, mainly in the left precuneus and superior parietal lobe. Moreover, the FC was significantly associated with cognitive performance. Though a longitudinal study is needed to confirm these results, our cross-sectional finding is that non-linear FC changes in DMN could be a characteristic of prodromal early disease development.

Inter-hemispherical asymmetry in default-mode functional connectivity and BAIAP2 gene are associated with anger expression in ADHD adults

Attention deficit hyperactivity disorder (ADHD) is accompanied by resting-state alterations, including abnormal activity, connectivity and asymmetry of the default-mode network (DMN). Concurrently, recent studies suggested a link between ADHD and the presence of polymorphisms within the gene BAIAP2 (i.e., brain-specific angiogenesis inhibitor 1-associated protein 2), known to be differentially expressed in brain hemispheres. The clinical and neuroimaging correlates of this polymorphism are still unknown. We investigated the association between BAIAP2 polymorphisms and DMN functional connectivity (FC) asymmetry as well as behavioral measures in ADHD adults. Resting-state fMRI was acquired from 30 ADHD and 15 healthy adults. For each subject, rs7210438 and rs8079626 within the gene BAIAP2 were genotyped. ADHD severity, impulsiveness and anger were assessed for the ADHD group. Using multivariate analysis of variance, we found that genetic features do have an impact on DMN FC asymmetry. In particular, polymorphism rs8079626 affects medial frontal gyrus and inferior parietal lobule connectivity asymmetry, lower for AA than AG/GG carriers. Further, when combining FC asymmetry and the presence of the rs8079626 variant, we successfully predicted increased externalization of anger in ADHD. In conclusion, a complex interplay between genetic vulnerability and inter-hemispherical DMN FC asymmetry plays a role in emotion regulation in adult ADHD.

Altered default mode network configuration in posttraumatic stress disorder after earthquake: A resting-stage functional magnetic resonance imaging study.

The neural substrates of posttraumatic stress disorder (PTSD) are still not fully elucidated. Hence, this study is to explore topological alterations of the default mode network (DMN) in victims with PTSD after a magnitude of 8.0 earthquake using resting-state functional magnetic resonance imaging (rs-fMRI).This study was approved by the local ethical review board, and all participants signed written informed consent. Sixty-two PTSD victims from the 2008 Sichuan earthquake and 62 matched exposed controls underwent rs-fMRI. PTSD was diagnosed by Clinician-Administered PTSD Scale, and underwent PTSD Checklist-Civilian Version for symptom scoring. The DMN was analyzed by using graph theoretical approaches. Further, Pearson correlation analysis was performed to correlate neuroimaging metrics to neuropsychological scores in victims with PTSD.Victims with PTSD showed decreased DMN functional connectivity strength between the right superior frontal gyrus and left inferior parietal lobule (IPL), and showed increased functional connectivity between the right IPL and precuneus or left posterior cingulate cortex. It was also found that victims with PTSD exhibited decreased nodal efficiency in right superior frontal gyrus and precuneus, and increased nodal efficiency in right hippocampus/parahippocampus. Apart from that, PTSD showed higher nodal degree in bilateral hippocampus/parahippocampus. In addition, the functional connectivity strength between the right IPL and precuneus correlated negatively to the avoid scores (r = -0.26, P = .04).This study implicates alteration of topological features on the DMN in PTSD victims after major earthquake, and provides new insights into DMN malfunction in PTSD based on graph theory.

Altered DMN functional connectivity and regional homogeneity in partial epilepsy patients: a seventy cases study.

PurposeClinically diagnosed partial epilepsy is hard to be functionally diagnosed by regular electroencephalograph (EEG) and conventional magnetic resonance imaging (MRI). By collecting transient brain regional signals, blood oxygenation level-dependent (BOLD) function MRI (BOLD-fMRI) can provide brain function change information with high accuracy. By using resting state BOLD-fMRI technique, we aim to investigate the changes of brain function in partial epilepsy patients.MethodsBOLD-fMRI scanning was performed in 70 partial epilepsy and 70 healthy people. BOLD-fMRI data was analyzed by using the Regional Homogeneity (ReHo) method and functional connectivity of Default Mode Network (DMN) methods. The abnormal brain functional connectivity in partial epilepsy patients was detected by Statistical Parametric Mapping 8 (SPM8) analysis.ResultsCompared to healthy group, epilepsy patients showed significant decreased ReHo in left inferior parietal lobule/pre- and post-central gyrus, right thalamus/paracentral lobule/Cerebellum anterior and posterior Lobe, bilateral insula. The DMN functional connectivity regions decreased significantly in right uncus, left Inferior parietal lobule, left supramarginal gyrus, left uncus, left parahippocampa gyrus, and left superior temporal gyrus, in epilepsy patients, compared to healthy controls.SignificanceThis study clarified that both ReHo and functional connectivity of DMN decreased in partial epilepsy patients compared to healthy controls. While left inferior parietal lobule was detected in both ReHo and DMN, many other identified regions were different by using these two BOLD-fMRI techniques. We propose that both ReHo and DMN patterns in BOLD-fMRI may suggest networks responsible for partial epilepsy genesis or progression.

Frequency-Dependent Altered Functional Connections of Default Mode Network in Alzheimer's Disease.

Alzheimer’s disease (AD) is a neurodegenerative disorder associated with the progressive dysfunction of cognitive ability. Previous research has indicated that the default mode network (DMN) is closely related to cognition and is impaired in Alzheimer’s disease. Because recent studies have shown that different frequency bands represent specific physiological functions, DMN functional connectivity studies of the different frequency bands based on resting state fMRI (RS-fMRI) data may provide new insight into AD pathophysiology. In this study, we explored the functional connectivity based on well-defined DMN regions of interest (ROIs) from the five frequency bands: slow-5 (0.01–0.027 Hz), slow-4 (0.027–0.073 Hz), slow-3 (0.073–0.198 Hz), slow-2 (0.198–0.25 Hzs) and standard low-frequency oscillations (LFO) (0.01–0.08 Hz). We found that the altered functional connectivity patterns are mainly in the frequency band of slow-5 and slow-4 and that the decreased connections are long distance, but some relatively short connections are increased. In addition, the altered functional connections of the DMN in AD are frequency dependent and differ between the slow-5 and slow-4 bands. Mini-Mental State Examination scores were significantly correlated with the altered functional connectivity patterns in the slow-5 and slow-4 bands. These results indicate that frequency-dependent functional connectivity changes might provide potential biomarkers for AD pathophysiology.

Shared atypical default mode and salience network functional connectivity between autism and schizophrenia.

Autism spectrum disorder (ASD) and schizophrenia are two common neurodevelopmental disorders which share several genetic and behavioral features. The present study identified common neural mechanisms contributing to ASD and schizophrenia using resting-state functional MRI data. The results may help to understand the pathology of these two neurodevelopmental disorders.

INCREASED FUNCTIONAL CONNECTIVITY OF DEFAULT MODE NETWORK IN PATIENTS WITH MODERATE AMNESTIC MILD COGNITIVE IMPAIRMENT: INFLECTION POINT IN COURSE OF DISEASE

The neuroimaging biomarkers model of the progression from MCI to AD indicated there is first increased brain functional activation at early MCI, followed by reduced activation at the late stage. Such a functional inflection point of “increase followed by decrease” could serve as a marker of the onset of abnormal cognitive behavior. The alteration of functional connectivity (FC) of default mode network (DMN) has been reported in patients with amnestic mild cognitive impairment (aMCI). However, due to the lack of a finer MCI stage, no studies exist that examined stage-dependent DMN-FC changes throughout the course of aMCI. Utilizing the extreme groups approach on the performance of episodic memory tasks, 45 aMCI subjects were divided into mild (10, age = 61.60 ± 7.53), moderate (19, age = 64.94 ± 6.30) and severe (16, age = 66.06 ± 8.49) stages. All subjects underwent an extensive neuropsychological assessment. Both T1-weighted structure images and resting-state functional images were acquired. Independent component analysis was used to assess DMN for individual patients in each of the three stages. Partial correlation analysis was performed to examine the relationship between the ROI-based FC in DMN and the neuropsychological performances with gender, age and years of education as covariates. Instead of finding that continued monotonic decline as the case for the hippocampus volume (p = 0.030, p = 0.029, p = 0.024 for left, right and total hippocampus volumes respectively in a trend analysis), we observed an increase in DMN functional connectivity from mild aMCI to moderate aMCI and a decrease to severe aMCI [p (FDR-corrected for multiple comparisons) < 0.05], mainly in the left precuneus and superior parietal lobe. Moreover, the FC of the left precuneus is significantly correlated with backward (r = -0.338, p = 0.029) and digit span (r = -0.328, p = 0.034).

Self-regulation of primary motor cortex activity with motor imagery induces functional connectivity modulation: A real-time fMRI neurofeedback study.

Recent developments in data acquisition of functional magnetic resonance imaging (fMRI) have led to rapid preprocessing and analysis of brain activity in a quasireal-time basis, what so called real-time fMRI neurofeedback (rtfMRI-NFB). This information is fed back to subjects allowing them to gain a voluntary control over their own region-specific brain activity. Forty-one healthy participants were randomized into an experimental (NFB) group, who received a feedback directly proportional to their brain activity from the primary motor cortex (M1), and a control (CTRL) group who received a sham feedback. The M1 ROI was functionally localized during motor execution and imagery tasks. A resting-state functional run was performed before and after the neurofeedback training to investigate the default mode network (DMN) modulation after training. The NFB group revealed increased DMN functional connectivity after training to the cortical and subcortical sensory/motor areas (M1/S1 and caudate nucleus, respectively), which may be associated with sensorimotor processing of learning in the resting state. These results show that motor imagery training through rtfMRI-NFB could modulate the DMN functional connectivity to motor-related areas, suggesting that this modulation potentially subserved the establishment of motor learning in the NFB group.

RELATIONSHIPS BETWEEN MEMORY FUNCTION, TAU PATHOLOGY AND FUNCTIONAL CONNECTIVITY IN THE DEFAULT MODE NETWORK IN AUTOSOMAL-DOMINANT ALZHEIMER’S DISEASE: A PRELIMINARY REPORT

Disruption of the default-mode network (DMN) has been associated with memory dysfunction and beta-amyloid deposition in preclinical Alzheimer's disease (AD). However, the role of tau accumulation in the integrity of the DMN in AD is not well understood. In this study we investigated the relationship between DMN integrity, as measured by resting-state functional connectivity, AD pathology (amyloid burden and tau), and memory function in individuals from a Colombian kindred with autosomal-dominant AD, up to fifteen years before the kindred's estimated median age 44 of mild cognitive impairment (MCI). Twenty-two family members of the Colombian kindred with ADAD due to the Presenilin-1 E280A mutation (8 cognitively-unimpaired carriers, 2 MCI patients, and 12 non-carriers), aged 29–56 years, were included. All participants underwent a comprehensive neuropsychological assessment, PET imaging and resting-state fMRI. Amyloid burden was measured using PiB PET cerebral-to cerebellar DVR, and tau was measured using Flortaucipir (a.k.a AV-1451AV1451) PET cerebral-to-cerebellar SUVR. PET images were analyzed using structural ROIs as defined by Freesurfer. Seed-based functional connectivity analyses of the posterior cingulate cortex and DMN regions were performed. Compared to non-carriers, carriers had elevated levels of cortical β-amyloid (t (20)=-3.78, p=0.004). No statistically significant differences were seen between groups in levels of tau accumulation or DMN functional connectivity. Among mutation carriers, greater DMN functional connectivity was associated with higher mean scores on memory measures (e.g. Logical Memory II: r=0.76, p=0.03), and lower SUVR tau levels in the inferior temporal lobe (r=-0.63, p=0.05). Cortical β-Amyloid was not associated with functional connectivity in the DMN regions (r=-0.61, p=0.06). Preliminary findings support a relationship between disruption of the DMN, memory dysfunction and tau accumulation among carriers of autosomal-dominant AD, years before their estimated clinical onset. Future studies with larger samples are needed to confirm these findings and better understand the relationship between AD pathology and memory networks in preclinical and prodromal AD.

Aberrant Intra- and Internetwork Functional Connectivity in Depressed Parkinson\u2019s Disease

Much is known concerning the underlying mechanisms of Parkinson’s disease (PD) with depression, but our understanding of this disease at the neural-system level remains incomplete. This study used resting-state functional MRI (rs-fMRI) and independent component analysis (ICA) to investigate intrinsic functional connectivity (FC) within and between large-scale neural networks in 20 depressed PD (dPD) patients, 35 non-depressed PD (ndPD) patients, and 34 healthy controls (HC). To alleviate the influence caused by ICA model order selection, this work reported results from analyses at 2 levels (low and high model order). Within these two analyses, similar results were obtained: 1) dPD and ndPD patients relative to HC had reduced FC in basal ganglia network (BGN); 2) dPD compared with ndPD patients exhibited increased FC in left frontoparietal network (LFPN) and salience network (SN), and decreased FC in default-mode network (DMN); 3) dPD patients compared to HC showed increased FC between DMN and LFPN. Additionally, connectivity anomalies in the DMN, LFPN and SN correlated with the depression severity in patients with PD. Our findings confirm the involvement of BGN, DMN, LFPN and SN in depression in PD, facilitating the development of more detailed and integrative neural models of PD with depression.

Effect of PICALM rs3851179 polymorphism on the default mode network function in mild cognitive impairment

Alterations in default mode network (DMN) functional connectivity (FC) might accompany the dysfunction of Alzheimer’s disease (AD). Indeed, episodic memory impairment is a hallmark of AD, and mild cognitive impairment (MCI) has been associated with a high risk for AD. Phosphatidylinositol-binding clathrin assembly protein (PICALM) (rs3851179) has been associated with AD; in particular, the A allele may serve a protective role, while the G allele serves as a strong genetic risk factor. Therefore, the identification of genetic polymorphisms associated with the DMN is required in MCI subjects. In all, 32 MCI subjects and 32 healthy controls (HCs) underwent resting-state functional magnetic resonance imaging (rs-fMRI) and a genetic imaging approach. Subjects were divided into four groups according to the diagnosis (i.e., MCI and HCs) and the PICALM rs3851179 polymorphism (i.e., AA/AG genotype and GG genotype). The differences in FC within the DMN between the four subgroups were explored. Furthermore, we examined the relationship between our neuroimaging measures and cognitive performance. The regions associated with the genotype-by-disease interaction were in the left middle temporal gyrus (LMTG) and left middle frontal gyrus (LMFG). These changes in LMFG FC were generally manifested as an “inverse U-shaped curve”, while a “U-shaped curve” was associated with the LMTG FC between these four subgroups (all P<0.05). Furthermore, higher FC within the LMFG was related to better episodic memory performance (i.e., AVLT 20min DR, rho=0.72, P=0.044) for the MCI subgroups with the GG genotype. The PICALM rs3851179 polymorphism significantly affects the DMN network in MCI. The LMFG and LMTG may be associated with opposite patterns. However, the altered LMFG FC in MCI patients with the GG genotype was more sensitive to episodic memory impairment, which is more likely to lead to a high risk of AD.

Differences in Default Mode Network Connectivity in Meditators and Non-meditators During an Attention Task

Activity in the default mode network (DMN) is reduced during non-self-referential goal-directed tasks in healthy individuals. In this study, we investigated differences in DMN functional connectivity between regular meditators and non-meditators during an attention paradigm. Non-meditators and regular meditators, matched by age, years of education, and gender were instructed to name the color of single words visually presented in a Stroop Word-Color Task (SWCT) adapted for functional magnetic resonance imaging (fMRI). The task was performed when the participants were not formally meditating. Logistic analysis based on imaging data indicated that the connectivity between the PCC (precuneus/posterior cingulate cortex) and the right and left parietal lobules helps differentiating regular meditators from non-meditators. Granger causality results showed that the activity in the PCC contains information to predict the activity in the right lateral parietal cortex and that the accuracy in this prediction is higher in regular meditators when compared to non-meditators. This suggests a stronger link between these two regions in regular meditators. In contrast to regular meditators, the PCC is more influenced by the left parietal region (related to the process of reading—which is the interference in the SWCT), and this region is more influenced by the PCC in non-meditators. These functional connectivity differences in the DMN between groups possibly reflect a higher degree of interference and probably more distraction during the SWCT in non-meditators compared with meditators.

Spontaneous migraine attack causes alterations in default mode network connectivity: a resting-state fMRI case report

BackgroundAlthough migraine is one of the most investigated neurologic disorders, we do not have a perfect neuroimaging biomarker for its pathophysiology. One option to improve our knowledge is to study resting-state functional connectivity in and out of headache pain. However, our understanding of the functional connectivity changes during spontaneous migraine attack is partial and incomplete.Case presentationUsing resting-state functional magnetic resonance imaging we assessed a 24-year old woman affected by migraine without aura at two different times: during a spontaneous migraine attack and in interictal phase. Seed-to-voxel whole brain analysis was carried out using the posterior cingulate cortex as a seed, representing the default mode network (DMN). Our results showed decreased intrinsic connectivity within core regions of the DMN with an exception of a subsystem including the dorsal medial and superior frontal gyri, and the mid-temporal gyrus which is responsible for pain interpretation and control. In addition, increased connectivity between the DMN and pain and specific migraine-related areas, such as the pons and hypothalamus, developed during the spontaneous migraine attack.ConclusionOur preliminary results provide further support for the hypothesis that alterations of the DMN functional connectivity during migraine headache may lead to maladaptive top-down modulation of migraine pain-related areas which might be a specific biomarker for migraine.

Shared effects of the clusterin gene on the default mode network among individuals at risk for Alzheimer's disease.

To explore the common effects of the clusterin (CLU) rs11136000 variant on the default mode network (DMN) in amnestic mild cognitive impairment (aMCI) subjects and remitted geriatric depression (RGD) subjects. Fifty-one aMCI subjects, 38 RGD subjects, and 64 cognitively normal elderly subjects underwent resting-state fMRI scans and neuropsychological tests at both baseline and a 35-month follow-up. Posterior cingulate cortex seed-based functional connectivity (FC) analysis was used to obtain the DMN patterns. A CLU gene×disease×time interaction for aMCI subjects was mainly detected in the core cortical midline structures of the DMN, and the interaction for RGD subjects was mainly detected in the limbic system. However, they overlapped in two frontal regions, where consistent effects of the CLU gene on FC alterations were found between aMCI and RGD groups. Furthermore, the alterations of FC with frontal, parietal, and limbic regions compensated for episodic memory impairments in CLU-CT/TT carriers, while no such compensation was found in CLU-CC carriers. The CLU gene could consistently affect the DMN FC with frontal regions among individuals at risk for Alzheimer's disease, and the CLU-T allele was associated with more compensatory neural processes in DMN changes.

Psilocybin in long-term meditators: Effects on default mode network functional connectivity and retrospective ratings of qualitative experience

Psilocybin in long-term meditators: Effects on default mode network functional connectivity and retrospective ratings of qualitative experience