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Updated: May 15, 2026
Network Analysis of the Default Mode Network Using Functional Connectivity MRI in Temporal Lobe Epilepsy
Published on: August 5, 2014
Alterations in regional homogeneity of resting-state brain activity in mesial temporal lobe epilepsy
Hongwu Zeng1, Ricardo Pizarro, Veena A Nair
1Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, WI 53792, USA.
Purpose:
The purpose of the present study was to identify abnormal areas of regional synchronization in patients with mesial temporal lobe epilepsy and hippocampus sclerosis (mTLE-HS) compared to healthy controls, by applying a relatively novel method, the Regional Homogeneity (ReHo) method to resting state fMRI (RS-fMRI) data.
Methods:
Eyes closed RS-fMRI data were acquired from 10 mTLE-HS patients (four right-side, six left-side) and 15 age- and gender-matched healthy subjects, and were analyzed by using ReHo. For group analysis, four right-side MTLE-HS patients' functional images were flipped, in order to make a homogeneous left MTLE-HS group (10 cases) and increase the sample size.
Key Findings:
Compared to the healthy control group, patients showed significantly increased ReHo in ipsilateral parahippocampal gyrus, midbrain, insula, corpus callosum, bilateral sensorimotor cortex, and frontoparietal subcortical structures, whereas decreased ReHo was observed mainly in default mode network (DMN) (including precuneus and posterior cingulate gyrus, bilateral inferior lateral parietal, and mesial prefrontal cortex) and cerebellum in patients relative to the control group.
Significance:
This study identified that ReHo pattern in mTLE-HS patients was altered compared to healthy controls. We consider decreased ReHo in DMN to be responsible for wide functional impairments in cognitive processes. We propose that the increased ReHo in specific regions may form a network that might be responsible for seizure genesis and propagation.
Insights
Mesial temporal lobe epilepsy with hippocampus sclerosis (mTLE-HS) patients exhibit altered brain synchronization patterns, with decreased activity in the default mode network and increased activity in other regions. These changes may explain cognitive impairments and seizure activity.
Area of Science:
- Neuroscience
- Epilepsy Research
- Functional Neuroimaging
Background:
- Mesial temporal lobe epilepsy with hippocampus sclerosis (mTLE-HS) is a common form of epilepsy.
- Understanding the underlying functional brain alterations is crucial for diagnosis and treatment.
- Resting-state functional magnetic resonance imaging (RS-fMRI) offers insights into intrinsic brain activity.
Purpose of the Study:
- To investigate regional synchronization abnormalities in mTLE-HS patients using the Regional Homogeneity (ReHo) method.
- To compare ReHo patterns between mTLE-HS patients and healthy controls.
- To identify potential neural correlates of cognitive deficits and seizure propagation in mTLE-HS.
Main Methods:
- Acquired eyes-closed RS-fMRI data from 10 mTLE-HS patients and 15 healthy controls.
- Analyzed brain synchronization using the Regional Homogeneity (ReHo) method.
- Applied image processing techniques to ensure group homogeneity for analysis.
Main Results:
- mTLE-HS patients showed significantly increased ReHo in the parahippocampal gyrus, midbrain, insula, corpus callosum, sensorimotor cortex, and frontoparietal subcortical structures.
- Decreased ReHo was observed in the default mode network (DMN), including the precuneus, posterior cingulate gyrus, and medial prefrontal cortex.
- Cerebellar ReHo was also reduced in mTLE-HS patients compared to controls.
Conclusions:
- ReHo patterns are significantly altered in mTLE-HS patients compared to healthy individuals.
- Reduced ReHo in the DMN is associated with widespread cognitive functional impairments.
- Increased ReHo in specific brain regions may contribute to seizure generation and spread.
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