Functional Connectivity of the Corpus Callosum in Epilepsy Patients with Secondarily Generalized Seizures

Abstract

The corpus callosum (CC) plays an important role in generalization of seizure activity. We used resting-state function magnetic resonance imaging (rs-fMRI) to investigate the regional and interregional functional connectivity of CC in patients with magnetic resonance imaging (MRI)-negative and secondarily generalized seizures. We measured the multi-regional coherences of blood oxygen level-dependent (BOLD) signals via rs-fMRI, cortical thickness via high-resolution T1-weighted MRI, and white matter (WM) integrity via diffusion-tensor imaging in 16 epilepsy patients as well as in 16 age- and gender-matched healthy subjects. All patients had non-lesional MRI, medically well-controlled focal epilepsy and history of secondarily generalized convulsions. Individuals with epilepsy had significant differences in regional and interregional hypersynchronization of BOLD signals intrahemispherically and interhemispherically, but no difference in cortical thickness and WM integrity. The only area with increased regional hypersynchrony in WM was over the anterior CC, which also exhibited lower activation of neighboring resting-state networks. The present study revealed abnormal local and distant synchronization of spontaneous neural activities in epileptic patients with secondarily generalized seizures.

Keywords: corpus callosum; functional networks; regional homogeneity; resting-state function MRI; secondarily generalized seizures.

Figure 1

Statistic t-map illustrating high local synchronization of blood oxygen level-dependent signals in the genu of the corpus callosum of patients with secondarily generalized seizures, when compared to healthy controls.

Figure 2

(A) Increases and (B) decreases of interregional correlations in the patient group. The network density of (A) is higher than (B). The blue circuits represent anatomical regions of interest (ROI) from the automated anatomical labeling atlas across the prefrontal and premotor regions.

Figure 3

One-sample t-maps, illustrating activation of the default mode network (DMN), executive control network (ECN), and sensorimotor network (SMN) in control and patient groups.