Short-Term Modulation of Epileptic Network with Low-Frequency Thalamic Stimulation

Area of Science:

• Neuroscience
• Neurology
• Medical Engineering

Background:

• Thalamic neuromodulation is a promising therapy for epilepsy when surgical resection is not possible.
• The precise mechanisms by which thalamic stimulation affects epileptic network dynamics are not fully understood.

Purpose of the Study:

• To investigate if brief thalamic stimulation can transiently alter cortico-cortical activity and coupling within patient-specific epileptic networks.
• To identify sub-second electrophysiological markers of thalamic stimulation's effects on seizure propagation.

Main Methods:

• Studied 10 epilepsy patients undergoing stereo-EEG targeting anterior or centromedian thalamic nuclei.
• Delivered low-frequency (1 Hz) single-pulse thalamic stimulations during wakefulness.
• Analyzed changes in spectral power and Granger causality in cortical contacts post-stimulation (15-900 ms) compared to baseline.

Main Results:

• Thalamic stimulation rapidly decreased power in early-propagating regions and seizure onset zones.
• Directed interactions (Granger causality) showed a modest increase, particularly toward the seizure onset zone.
• Nucleus-specific effects were observed, with anterior thalamic stimulation showing prominent effects in limbic epilepsy.

Conclusions:

• Thalamic stimulation induces rapid, nucleus-specific network modulation, rebalancing cortico-cortical coupling.
• Findings support a model where thalamic input limits seizure propagation by altering cortico-cortical interactions.
• Identified sub-second markers for network-informed neuromodulation, guiding treatment parameter selection.