A Classification Mechanism of Brain Functional fMRI in Resting State

2014 ◽  
Vol 687-691 ◽  
pp. 1087-1090
Author(s):  
Hui Zhou ◽  
Zhen Cheng Chen ◽  
Jian Ming Zhu ◽  
Dong Cui Wang ◽  
Biao Xu
Keyword(s):  
Hierarchical Clustering ◽  
Default Mode Network ◽  
Resting State ◽  
Low Frequency ◽  
Brain Regions ◽  
Default Mode ◽  
Complex Network Theory ◽  
Healthy Young People ◽  
Comparative Results ◽  
The Brain

To investigate the brain default mode network (DMN) of healthy young people, a novel hierarchical clustering method was proposed to detect similarities of low-frequency fluctuations between any two out of 160 regions of interest (ROI) all over the brain. Feature of these ROIs were firstextractedand analyzed the feature using hierarchical clustering approach.Combining with the strongest connected network node identified by network centric criterion, the default mode network which presented the strongest connectivity in resting state was then determined. The results demonstrated that cingulate had the highest value of average degree, making it the most suspectof where the centrality indices of DMN lay.The comparative results between nodes included by DMN returned by our method and these given by Dosenbach’s research showed quite high coincidence rates,indicating the proposed method of combining complex network theory and hierarchical clustering analysis feasible method to parse brain regions.

scholarly journals Task-evoked Negative BOLD Response and Functional Connectivity in the Default Mode Network are Representative of Two Overlapping but Separate Neurophysiological Processes

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
David B. Parker ◽  
Qolamreza R. Razlighi
Keyword(s):  
Functional Connectivity ◽  
Default Mode Network ◽  
Resting State ◽  
Low Frequency ◽  
Brain Regions ◽  
Intrinsic Activity ◽  
Bold Response ◽  
Default Mode ◽  
Macro Scale ◽  
Negative Bold

Abstract The topography of the default mode network (DMN) can be obtained with one of two different functional magnetic resonance imaging (fMRI) methods: either from the spontaneous but organized synchrony of the low-frequency fluctuations in resting-state fMRI (rs-fMRI), known as “functional connectivity”, or from the consistent and robust deactivations in task-based fMRI (tb-fMRI), here referred to as the “negative BOLD response” (NBR). These two methods are fundamentally different, but their results are often used interchangeably to describe the brain’s resting-state, baseline, or intrinsic activity. While the DMN was initially defined by consistent task-based decreases in blood flow in a set of specific brain regions using PET imaging, recently nearly all studies on the DMN employ functional connectivity in rs-fMRI. In this study, we first show the high level of spatial overlap between NBR and functional connectivity of the DMN extracted from the same tb-fMRI scan; then, we demonstrate that the NBR in putative DMN regions can be significantly altered without causing any change in their overlapping functional connectivity. Furthermore, we present evidence that in the DMN, the NBR is more closely related to task performance than the functional connectivity. We conclude that the NBR and functional connectivity of the DMN reflect two separate but overlapping neurophysiological processes, and thus should be differentiated in studies investigating brain-behavior relationships in both healthy and diseased populations. Our findings further raise the possibility that the macro-scale networks of the human brain might internally exhibit a hierarchical functional architecture.

Revisiting default mode network function in major depression: evidence for disrupted subsystem connectivity

2013 ◽  
Vol 44 (10) ◽  
pp. 2041-2051 ◽  
Author(s):  
F. Sambataro ◽  
N. D. Wolf ◽  
M. Pennuto ◽  
N. Vasic ◽  
R. C. Wolf
Keyword(s):  
Default Mode Network ◽  
Resting State ◽  
Large Scale ◽  
Critical Role ◽  
Low Frequency ◽  
Network Connectivity ◽  
Brain Regions ◽  
Default Mode ◽  
Network Function ◽  
Functional Relevance

BackgroundMajor depressive disorder (MDD) is characterized by alterations in brain function that are identifiable also during the brain's ‘resting state’. One functional network that is disrupted in this disorder is the default mode network (DMN), a set of large-scale connected brain regions that oscillate with low-frequency fluctuations and are more active during rest relative to a goal-directed task. Recent studies support the idea that the DMN is not a unitary system, but rather is composed of smaller and distinct functional subsystems that interact with each other. The functional relevance of these subsystems in depression, however, is unclear.MethodHere, we investigated the functional connectivity of distinct DMN subsystems and their interplay in depression using resting-state functional magnetic resonance imaging.ResultsWe show that patients with MDD exhibit increased within-network connectivity in posterior, ventral and core DMN subsystems along with reduced interplay from the anterior to the ventral DMN subsystems.ConclusionsThese data suggest that MDD is characterized by alterations of subsystems within the DMN as well as of their interactions. Our findings highlight a critical role of DMN circuitry in the pathophysiology of MDD, thus suggesting these subsystems as potential therapeutic targets.

scholarly journals Multimodal Imaging of Alzheimer Pathophysiology in the Brain's Default Mode Network

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Jonghan Shin ◽  
Vladimir Kepe ◽  
Gary W. Small ◽  
Michael E. Phelps ◽  
Jorge R. Barrio
Keyword(s):  
Default Mode Network ◽  
Multimodal Imaging ◽  
Temporal Cortex ◽  
Brain Regions ◽  
Default Network ◽  
Spatial Correlations ◽  
Tau Pathology ◽  
Significant Discrepancy ◽  
Default Mode ◽  
The Brain

The spatial correlations between the brain's default mode network (DMN) and the brain regions known to develop pathophysiology in Alzheimer's disease (AD) have recently attracted much attention. In this paper, we compare results of different functional and structural imaging modalities, including MRI and PET, and highlight different patterns of anomalies observed within the DMN. Multitracer PET imaging in subjects with and without dementia has demonstrated that [C-11]PIB- and [F-18]FDDNP-binding patterns in patients with AD overlap within nodes of the brain's default network including the prefrontal, lateral parietal, lateral temporal, and posterior cingulate cortices, with the exception of the medial temporal cortex (especially, the hippocampus) where significant discrepancy between increased [F-18]FDDNP binding and negligible [C-11]PIB-binding was observed. [F-18]FDDNP binding in the medial temporal cortex—a key constituent of the DMN—coincides with both the presence of amyloid and tau pathology, and also with cortical areas with maximal atrophy as demonstrated by T1-weighted MR imaging of AD patients.

scholarly journals The Default Mode Network In Patient with Temporal Lobe Epilepsy (TLE): A Resting State fMRI Study

2020 ◽  
Vol 4 (1) ◽  
pp. 23-30
Author(s):  
Shuhada J.M ◽  
Husbani M.A.R ◽  
A I A Hamid ◽  
Muhammad
Keyword(s):  
Temporal Lobe Epilepsy ◽  
Temporal Lobe ◽  
Default Mode Network ◽  
Resting State ◽  
Healthy Subjects ◽  
Brain Activation ◽  
Resting State Fmri ◽  
Default Mode ◽  
Parietal Lobes ◽  
The Brain

The default mode network (DMN) is involved in conscious, resting state cognition and is thought to be affected in TLE where seizures cause impairment of consciousness. The study aimed to evaluate the brain activation of the DMN regions in both temporal lobe epilepsy (TLE) patients  and healthy subjects by using resting-state functional Magnetic Resonance Imaging (rsfMRI) technique. A same number of fourteen participants with age and gender matched for the healthy subjects and TLE patients were selected with the average age is 36.9 and 37.0 years old, respectively. The rsfMRI imaging protocol was executed using a 3-T Phillips Achieva MRI scanner at the Radiology Department, Hospital Universiti Sains Malaysia (HUSM). For healthy subjects, the brain activation cluster in bilateral superior parietal lobes (SPL),precuneus (PRE), supramarginal gyrus (SMG) and inferior parietal lobes (IPL) were found higher than TLE patients. While for TLE patients displays higher activation clusters in bilateral MFG, STG, and ANG. The result from  random effects (RFX) on  two-sample t-tests thresholded at p = 0.001 revealed that the TLE patients display significantly higher activations on the bilateral superior frontal gyrus (SFG), left SMG, left middle frontal gyrus (MFG) and right IPL. However for the core-region of DMN such as  bilateral precuneus, left MFG, bilateral STG and bilateral IPL were significantly activated but the number of voxels survives are substantially smaller than other regions such as bilateral SFG. The findings suggested that TLE patients may suffer from an impairment in some DMN region, which may cause certain neuropsychological and cognitive degradation.       Keywords: resting-state fMRI, temporal lobe epilepsy, brain activation, two-sample t-tests

scholarly journals Modulatory interactions between the default mode network and task positive networks in resting-state

2014 ◽  
Author(s):  
Xin Di ◽  
Bharat B. Biswal
Keyword(s):  
Basal Ganglia ◽  
Default Mode Network ◽  
Resting State ◽  
Brain Structures ◽  
Brain Regions ◽  
Salience Network ◽  
Imaging Data ◽  
Default Mode ◽  
Task Positive Network ◽  
And Task

The two major brain networks, i.e. the default mode network (DMN) and the task positive network, typically reveal negative and variable connectivity in resting-state. In the present study, we examined whether the connectivity between the DMN and different components of the task positive network were modulated by other brain regions by using physiophysiological interaction (PPI) on resting-state functional magnetic resonance imaging data. Spatial independent component analysis was first conducted to identify components that represented networks of interest, including the anterior and posterior DMNs, salience, dorsal attention, left and right executive networks. PPI analysis was conducted between pairs of these networks to identify networks or regions that showed modulatory interactions with the two networks. Both network-wise and voxel-wise analyses revealed reciprocal positive modulatory interactions between the DMN, salience, and executive networks. Together with the anatomical properties of the salience network regions, the results suggest that the salience network may modulate the relationship between the DMN and executive networks. In addition, voxel-wise analysis demonstrated that the basal ganglia and thalamus positively interacted with the salience network and the dorsal attention network, and negatively interacted with the salience network and the DMN. The results demonstrated complex modulatory interactions among the DMNs and task positive networks in resting-state, and suggested that communications between these networks may be modulated by some critical brain structures such as the salience network, basal ganglia, and thalamus.

scholarly journals Modulatory interactions between the default mode network and task positive networks in resting-state

2014 ◽  
Author(s):  
Xin Di ◽  
Bharat B. Biswal
Keyword(s):  
Basal Ganglia ◽  
Default Mode Network ◽  
Resting State ◽  
Brain Structures ◽  
Brain Regions ◽  
Salience Network ◽  
Imaging Data ◽  
Default Mode ◽  
Task Positive Network ◽  
And Task

The two major brain networks, i.e. the default mode network (DMN) and the task positive network, typically reveal negative and variable connectivity in resting-state. In the present study, we examined whether the connectivity between the DMN and different components of the task positive network were modulated by other brain regions by using physiophysiological interaction (PPI) on resting-state functional magnetic resonance imaging data. Spatial independent component analysis was first conducted to identify components that represented networks of interest, including the anterior and posterior DMNs, salience, dorsal attention, left and right executive networks. PPI analysis was conducted between pairs of these networks to identify networks or regions that showed modulatory interactions with the two networks. Both network-wise and voxel-wise analyses revealed reciprocal positive modulatory interactions between the DMN, salience, and executive networks. Together with the anatomical properties of the salience network regions, the results suggest that the salience network may modulate the relationship between the DMN and executive networks. In addition, voxel-wise analysis demonstrated that the basal ganglia and thalamus positively interacted with the salience network and the dorsal attention network, and negatively interacted with the salience network and the DMN. The results demonstrated complex modulatory interactions among the DMNs and task positive networks in resting-state, and suggested that communications between these networks may be modulated by some critical brain structures such as the salience network, basal ganglia, and thalamus.

scholarly journals Topographic connectivity reveals task-dependent retinotopic processing throughout the human brain

2020 ◽  
Vol 118 (2) ◽  
pp. e2017032118
Author(s):  
Tomas Knapen
Keyword(s):  
Visual System ◽  
Default Mode Network ◽  
Spatial Organization ◽  
Brain Regions ◽  
Cognitive State ◽  
Default Mode ◽  
Visual Spatial ◽  
Retinotopic Maps ◽  
Visual Organization ◽  
The Brain

The human visual system is organized as a hierarchy of maps that share the topography of the retina. Known retinotopic maps have been identified using simple visual stimuli under strict fixation, conditions different from everyday vision which is active, dynamic, and complex. This means that it remains unknown how much of the brain is truly visually organized. Here I demonstrate widespread stable visual organization beyond the traditional visual system, in default-mode network and hippocampus. Detailed topographic connectivity with primary visual cortex during movie-watching, resting-state, and retinotopic-mapping experiments revealed that visual–spatial representations throughout the brain are warped by cognitive state. Specifically, traditionally visual regions alternate with default-mode network and hippocampus in preferentially representing the center of the visual field. This visual role of default-mode network and hippocampus would allow these regions to interface between abstract memories and concrete sensory impressions. Together, these results indicate that visual–spatial organization is a fundamental coding principle that structures the communication between distant brain regions.

scholarly journals Rest-fMRI Based Comparison Study between Autism Spectrum Disorder and Typically Control Using Graph Frequency Bands

2021 ◽  
Author(s):  
Alireza Talesh Jafadideh ◽  
Babak Mohammadzadeh Asl
Keyword(s):  
Autism Spectrum Disorder ◽  
Signal Processing ◽  
Default Mode Network ◽  
High Frequency ◽  
Low Frequency ◽  
Autism Spectrum ◽  
Spectrum Disorder ◽  
Default Mode ◽  
Frequency Bands ◽  
The Brain

AbstractGraph signal processing is a subset of signal processing enabling the analysis of functional magnetic resonance imaging (fMRI) data in brain topological domain. One of the most important and highly interested tool of GSP is graph Fourier transform (GFT) by which brain signals can be analyzed in different graph frequency bands. In this paper, the resting-state fMRI (rfMRI) data is analyzed using GFT tool in order to discover new knowledge about the autism spectrum disorder (ASD) and find features discriminating between ASD and typically control (TC) subjects. For ASD group, the signal concentration in both low and high frequency bands is decreased by increasing the age in most of the brain well-known networks. The ASD in comparison to TC shows less intention for changing the signal concentration level when the level is very low or very high. In graph low frequency band, increasing the age is along with increasing the segregation and integration of brain ROIs respectively for ASD and TC. Also, in this band, the brain ROIs integration of ASD is more than TC. By increasing the age, the auditory network of ASD subjects shows increasing segregation and integration in graph low and high frequency bands, respectively. The reduced segregation of default mode network in ASD is happened in graph middle and higher frequency bands. The functional connectivity analysis between low and high frequency signals shows that some of the high frequency ROIs have connections with all low frequency ROIs so that the most of these connections are dramatically and significantly different between ASD and TC. By analyzing the local vertex frequency spectrum (LVFS) of ASD and TC at different states, it is seen these groups show contradictory behaviors with respect to each other in brain default mode network in two states. The results of different scenarios at different graph frequency bands demonstrate that using functional and structural data together can provide powerful tool for recognizing the ASD or even other brain disorders.

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