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 Default Mode Network in Temporal Lobe epilepsy: interactions with memory performance

2017 ◽  
Author(s):  
Tamires Araujo Zanão ◽  
Tátila Martins Lopes ◽  
Brunno Machado de Campos ◽  
Mateus Henrique Nogueira ◽  
Clarissa Lin Yasuda ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Temporal Lobe Epilepsy ◽  
Left Hemisphere ◽  
Temporal Lobe ◽  
Default Mode Network ◽  
Verbal Memory ◽  
Resting State ◽  
Visual Memory ◽  
Hippocampal Sclerosis ◽  
Default Mode

ABSTRACTObjectiveto investigate abnormal functional connectivity in the resting-state default mode network (DMN) and its relation to memory impairments in patients with temporal lobe epilepsy with and without hippocampal sclerosis (HS)Methodwe enrolled 122 MTLE patients divided into right-HS (n=42), left-HS (n=49), MRI-negative MTLE (n=31) and controls (n=69). All underwent resting-state seed-based connectivity fMRI, with a seed placed at the posterior cingulate cortex, an essential node for the DMN. In addition, patients and 41 controls were tested for verbal and visual memory, estimated intelligence coefficient and delayed recall.ResultsBoth right-HS and MRI-negative group presented the poorest visual memory scores, and right-HS and left-HS had a worse performance in verbal memory compared to controls and MRI-negative groups. As expected, hippocampus was less connected than controls in all groups of patients. Although EEGs indicated that 64.5% of MRI-negative patients were lateralized to the left, this group showed activations similar to the right-HS.ConclusionOur data suggest that there is a disruption of the normal pattern of DMN in MTLE. Patients with left and right-HS presented similar, increased and decreased connectivity in the ipsilateral hemisphere; however, left-HS had abnormal decreased connectivity in the contralateral hemisphere. Per neuropsychological examination, the presence of HS in the left hemisphere had more impact on verbal memory, which was not found when the seizure focus is in the left hemisphere in the absence of HS. The absence of hippocampal atrophy seems to yield a less prominent disruption in both functional connectivity and neuropsychological performance.

scholarly journals The Relationship between Glucose Metabolism, Resting-State fMRI BOLD Signal, and GABAA-Binding Potential: A Preliminary Study in Healthy Subjects and Those with Temporal Lobe Epilepsy

2015 ◽  
Vol 35 (4) ◽  
pp. 583-591 ◽  
Author(s):  
Allison C Nugent ◽  
Ashley Martinez ◽  
Alana D'Alfonso ◽  
Carlos A Zarate ◽  
William H Theodore
Keyword(s):  
Glucose Metabolism ◽  
Temporal Lobe Epilepsy ◽  
Human Brain ◽  
Temporal Lobe ◽  
Resting State ◽  
Healthy Subjects ◽  
Binding Potential ◽  
Bold Signal ◽  
Healthy Human ◽  
The Brain

Glucose metabolism has been associated with magnitude of blood oxygen level-dependent (BOLD) signal and connectivity across subjects within the default mode and dorsal attention networks. Similar correlations within subjects across the entire brain remain unexplored. [18F]-fluorodeoxyglucose positron emission tomography ([18F]-FDG PET), [11C]-flumazenil PET, and resting-state functional magnetic resonance imaging (fMRI) scans were acquired in eight healthy individuals and nine with temporal lobe epilepsy (TLE). Regional metabolic rate of glucose (rMRGlu) was correlated with amplitude of low frequency fluctuations (ALFFs) in the fMRI signal, global fMRI connectivity (GC), regional homogeneity (ReHo), and gamma-aminobutyric acid A—binding potential (GABAA BPND) across the brain. Partial correlations for ALFFs, GC, and ReHo with GABAA BPND were calculated, controlling for rMRGlu. In healthy subjects, significant positive correlations were observed across the brain between rMRGlu and ALFF, ReHo and GABAA BPND, and between ALFFs and GABAA BPND, controlling for rMRGlu. Brain-wide correlations between rMRGlu and ALFFs were significantly lower in TLE patients, and correlations between rMRGlu and GC were significantly greater in TLE than healthy subjects. These results indicate that the glutamatergic and GABAergic systems are coupled across the healthy human brain, and that ALFF is related to glutamate use throughout the healthy human brain. TLE may be a disorder of altered long-range connectivity in association with glutamate function.

scholarly journals Diminished default mode network recruitment of the hippocampus and parahippocampus in temporal lobe epilepsy

2013 ◽  
Vol 119 (2) ◽  
pp. 288-300 ◽  
Author(s):  
G. Andrew James ◽  
Shanti Prakash Tripathi ◽  
Jeffrey G. Ojemann ◽  
Robert E. Gross ◽  
Daniel L. Drane
Keyword(s):  
Functional Connectivity ◽  
Temporal Lobe Epilepsy ◽  
Temporal Lobe ◽  
Default Mode Network ◽  
Resting State ◽  
Functional Neuroimaging ◽  
Parahippocampal Gyrus ◽  
Epileptogenic Focus ◽  
Data Set ◽  
Default Mode

Object Functional neuroimaging has shown that the brain organizes into several independent networks of spontaneously coactivated regions during wakeful rest (resting state). Previous research has suggested that 1 such network, the default mode network (DMN), shows diminished recruitment of the hippocampus with temporal lobe epilepsy (TLE). This work seeks to elucidate how hippocampal recruitment into the DMN varies by hemisphere of epileptogenic focus. Methods The authors addressed this issue using functional MRI to assess resting-state DMN connectivity in 38 participants (23 control participants, 7 patients with TLE and left-sided epileptogenic foci, and 8 patients with TLE and right-sided foci). Independent component analysis was conducted to identify resting-state brain networks from control participants' data. The DMN was identified and deconstructed into its individual regions of interest (ROIs). The functional connectivity of these ROIs was analyzed both by hemisphere (left vs right) and by laterality to the epileptogenic focus (ipsilateral vs contralateral). Results This attempt to replicate previously published methods with this data set showed that patients with left-sided TLE had reduced connectivity between the posterior cingulate (PCC) and both the left (p = 0.012) and right (p < 0.002) hippocampus, while patients with right-sided TLE showed reduced connectivity between the PCC and right hippocampus (p < 0.004). After recoding ROIs by laterality, significantly diminished functional connectivity was observed between the PCC and hippocampus of both hemispheres (ipsilateral hippocampus, p < 0.001; contralateral hippocampus, p = 0.017) in patients with TLE compared with control participants. Regression analyses showed the reduced DMN recruitment of the ipsilateral hippocampus and parahippocampal gyrus (PHG) to be independent of clinical variables including hippocampal sclerosis, seizure frequency, and duration of illness. The graph theory metric of strength (or mean absolute correlation) showed significantly reduced connectivity of the ipsilateral hippocampus and ipsilateral PHG in patients with TLE compared with controls (hippocampus: p = 0.028; PHG: p = 0.021, after correction for false discovery rate). Finally, these hemispheric asymmetries in strength were observed in patients with TLE that corresponded to hemisphere of epileptogenic focus; 87% of patients with TLE had weaker ipsilateral hippocampus strength (compared with the contralateral hippocampus), and 80% of patients had weaker ipsilateral PHG strength. Conclusions This study demonstrated that recoding brain regions by the laterality to their epileptogenic focus increases the power of statistical approaches for finding interhemispheric differences in brain function. Using this approach, the authors showed TLE to selectively diminish connectivity of the hippocampus and parahippocampus in the hemisphere of the epileptogenic focus. This approach may prove to be a useful method for determining the seizure onset zone with TLE, and could be broadly applied to other neurological disorders with a lateralized onset.

scholarly journals Increased Intrinsic Connectivity of the Default Mode Network in Temporal Lobe Epilepsy: Evidence from Resting-State MEG Recordings

PLoS ONE ◽  
2015 ◽  
Vol 10 (6) ◽  
pp. e0128787 ◽  
Author(s):  
Fu-Jung Hsiao ◽  
Hsiang-Yu Yu ◽  
Wei-Ta Chen ◽  
Shang-Yeong Kwan ◽  
Chien Chen ◽  
...  
Keyword(s):  
Temporal Lobe Epilepsy ◽  
Temporal Lobe ◽  
Default Mode Network ◽  
Resting State ◽  
Default Mode ◽  
Intrinsic Connectivity

scholarly journals Development of the default-mode network during childhood and adolescence: A longitudinal resting-state fMRI study

NeuroImage ◽  
2021 ◽  
Vol 226 ◽  
pp. 117581
Author(s):  
Fengmei Fan ◽  
Xuhong Liao ◽  
Tianyuan Lei ◽  
Tengda Zhao ◽  
Mingrui Xia ◽  
...  
Keyword(s):  
Default Mode Network ◽  
Resting State ◽  
Resting State Fmri ◽  
Childhood And Adolescence ◽  
Default Mode ◽  
Fmri Study

scholarly journals Comparison of EEG microstates with resting state fMRI and FDG-PET measures in the default mode network via simultaneously recorded trimodal (PET/MR/EEG) data

2018 ◽  
Author(s):  
Ravichandran Rajkumar ◽  
Ezequiel Farrher ◽  
Jörg Mauler ◽  
Praveen Sripad ◽  
Cláudia Régio Brambilla ◽  
...  
Keyword(s):  
Default Mode Network ◽  
Resting State ◽  
Fdg Pet ◽  
Resting State Fmri ◽  
Default Mode ◽  
Eeg Data

scholarly journals Neurophysiology (fMRI)

2015 ◽  
Vol 42 (S1) ◽  
pp. S38-S38
Author(s):  
ST Lang ◽  
B Goodyear ◽  
J Kelly ◽  
P Federico
Keyword(s):  
Cognitive Functioning ◽  
Default Mode Network ◽  
Resting State ◽  
Attentional Control ◽  
Brain Tumours ◽  
Resting State Fmri ◽  
Fmri Data ◽  
Resting State Networks ◽  
Default Mode ◽  
Eloquent Cortex

Background: Resting state functional MRI (rs-fMRI) provides many advantages to task-based fMRI in neurosurgical populations, foremost of which is the lack of the need to perform a task. Many networks can be identified by rs-fMRI in a single period of scanning. Despite the advantages, there is a paucity of literature on rs-fMRI in neurosurgical populations. Methods: Eight patients with tumours near areas traditionally considered as eloquent cortex participated in a five minute rs-fMRI scan. Resting-state fMRI data underwent Independent Component Analysis (ICA) using the Multivariate Exploratory Linear Optimized Decomposition into Independent Components (MELODIC) toolbox in FSL. Resting state networks (RSNs) were identified on a visual basis. Results: Several RSNs, including language (N=7), sensorimotor (N=7), visual (N=7), default mode network (N=8) and frontoparietal attentional control (n=7) networks were readily identifiable using ICA of rs-fMRI data. Conclusion: These pilot data suggest that ICA applied to rs-fMRI data can be used to identify motor and language networks in patients with brain tumours. We have also shown that RSNs associated with cognitive functioning, including the default mode network and the frontoparietal attentional control network can be identified in individual subjects with brain tumours. While preliminary, this suggests that rs-fMRI may be used pre-operatively to localize areas of cortex important for higher order cognitive functioning.

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