Unbalance between working memory task-activation and task-deactivation networks in epilepsy: Simultaneous EEG-fMRI...

Area of Science:

• Neuroscience
• Cognitive Science
• Epilepsy Research

Background:

• Working memory (WM) relies on theta oscillations and large-scale brain network interactions.
• Synchronization of WM networks enhances cognitive performance.
• Dysfunctional network interactions are implicated in cognitive deficits, particularly in epilepsy.

Purpose of the Study:

• To investigate theta oscillations and functional interactions between activation/deactivation networks during n-back WM tasks in patients with idiopathic generalized epilepsy (IGE).
• To explore the relationship between these neural features and WM performance in IGE.

Main Methods:

• Simultaneous electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) were employed.
• Analysis focused on theta oscillations and functional connectivity during an n-back WM task.
• Participants included patients with IGE and controls.

Main Results:

• Patients with IGE showed enhanced frontal theta power with increasing WM load, positively correlating with task accuracy.
• The IGE group exhibited widespread brain activation increases in high-load WM tasks, including frontoparietal networks and task-related deactivation areas (default mode, visual, auditory networks).
• Decreased counteraction between activation and deactivation networks was observed in IGE, correlating with higher theta power.

Conclusions:

• Interactions between activation and deactivation networks are crucial for WM processing.
• An imbalance in these network interactions may represent a key pathophysiological mechanism for cognitive dysfunction in generalized epilepsy.
• Findings highlight the role of neural network dynamics in WM deficits in IGE.