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

Medicine ◽  
2018 ◽  
Vol 97 (26) ◽  
pp. e11239 ◽  
Author(s):  
Yujun Gao ◽  
Jinou Zheng ◽  
Yaping Li ◽  
Danni Guo ◽  
Mingli Wang ◽  
...  
Keyword(s):  
Temporal Lobe Epilepsy ◽  
Temporal Lobe ◽  
Default Mode Network ◽  
Default Mode

Default mode network connectivity indicates episodic memory capacity in mesial temporal lobe epilepsy

Epilepsia ◽  
2013 ◽  
Vol 54 (5) ◽  
pp. 809-818 ◽  
Author(s):  
Cornelia McCormick ◽  
Maher Quraan ◽  
Melanie Cohn ◽  
Taufik A. Valiante ◽  
Mary Pat McAndrews
Keyword(s):  
Episodic Memory ◽  
Temporal Lobe Epilepsy ◽  
Temporal Lobe ◽  
Default Mode Network ◽  
Network Connectivity ◽  
Memory Capacity ◽  
Mesial Temporal Lobe Epilepsy ◽  
Default Mode ◽  
Mesial Temporal Lobe

scholarly journals Effect of lateralized temporal lobe epilepsy on the default mode network

2012 ◽  
Vol 25 (3) ◽  
pp. 350-357 ◽  
Author(s):  
Zulfi Haneef ◽  
Agatha Lenartowicz ◽  
Hsiang J. Yeh ◽  
Jerome Engel ◽  
John M. Stern
Keyword(s):  
Temporal Lobe Epilepsy ◽  
Temporal Lobe ◽  
Default Mode Network ◽  
Default Mode

scholarly journals Temporal Lobe Epilepsy and Surgery Selectively Alter the Dorsal, Not the Ventral, Default-Mode Network

2014 ◽  
Vol 5 ◽  
Author(s):  
Gaelle Eve Doucet ◽  
Christopher Skidmore ◽  
James Evans ◽  
Ashwini Sharan ◽  
Michael R. Sperling ◽  
...  
Keyword(s):  
Temporal Lobe Epilepsy ◽  
Temporal Lobe ◽  
Default Mode Network ◽  
Default Mode

scholarly journals Default Mode Network Ventral Hub Connectivity Associated with Memory Impairment in Temporal Lobe Epilepsy Surgery

2020 ◽  
Author(s):  
Elliot G. Neal ◽  
Long Di ◽  
You Jeong Park ◽  
Austin Finch ◽  
Ferdinand Korneli ◽  
...  
Keyword(s):  
Temporal Lobe Epilepsy ◽  
Temporal Lobe ◽  
Epilepsy Surgery ◽  
Default Mode Network ◽  
Memory Task ◽  
Network Connectivity ◽  
Default Mode ◽  
Non Invasive ◽  
Before And After ◽  
The Relationship

AbstractIn patients undergoing surgery for intractable temporal lobe epilepsy, the relationship between the default mode network and patients’ neurocognitive outcome remains unclear. The objective of this study is to employ non-invasive network mapping to identify the relationship between subdivisions of the default mode network and neurocognitive function before and after epilepsy surgery in patients with temporal lobe epilepsy.Twenty-seven medically patients with medically refractory temporal lobe epilepsy were prospectively enrolled and received resting state functional MRI and neuropsychological testing both pre- and post-operatively. Connectivity within the default mode network was modeled and average connectivity within the networks was calculated.Higher pre-operative connectivity in the ventral default mode network hub correlated with impaired baseline performance in a visual memory task. Post-operatively, a decrease in ventral but not dorsal default mode network connectivity was correlated with a deterioration of verbal and logical memory after surgery.Overall, higher connectivity in the ventral default mode network hub was associated with poor memory function in patients with temporal lobe epilepsy both before and after temporal lobe surgery. Pre-operatively, higher ventral connectivity was associated with worse visual function. Post-operatively, decreased connectivity of the ventral and dorsal default mode network was correlated with a greater decrease in logical and verbal memory when compared with the pre-operation baseline. An imbalance in default mode network connectivity towards the ventral stream and more widespread epilepsy networks may be used to predict memory impairments following surgical intervention and may lead to more tailored surgical decision making based on this non-invasive network modeling.

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