Unbalance Between Working Memory Task-Activation and Task-Deactivation Networks in Epilepsy: Simultaneous EEG-fMRI Study
Working memory (WM) is one cognitive function, involving emergent properties of theta oscillation and large-scale network interactions. The synchronization of WM task-related networks in brain enhanced working memory performance. However, how these networks regulated WM processing was not well known, and the alteration of the interaction among these networks may play an important role in the patients with cognitive dysfunction. In this study, we used simultaneous EEG-fMRI to examine the
... of theta oscillation and the functional interactions among activation/deactivation networks during n-back WM task in patients with idiopathic generalized epilepsy (IGE). The results showed that there was more enhancement of frontal theta power along with WM load increasing in IGE, and the theta power was positively correlated with the accuracy of the WM tasks. Moreover, fMRI activations/deactivations correlated with n-back tasks were estimated, and we found that IGE group had increased and widespread activations in high-load WM task, including frontoparietal activation network, and the task-related deactivation areas, such as the default mode network, primary visual and auditory networks. In addition, the result of network connectivity demonstrated decreased counteraction between activation network and deactivation network, and the counteraction was correlated with the higher theta power in IGE. These results indicated the important role of the interactions between activation and deactivation networks during WM process, and the unbalance among them may imply the pathophysiological mechanism of cognitive dysfunction in generalized epilepsy.