Intermittent Photic Stimulation Modulates the Epileptogenic Network: Preliminary Evidence from MEG
Abstract number :
2.189
Submission category :
3. Neurophysiology / 3D. MEG
Year :
2025
Submission ID :
1226
Source :
www.aesnet.org
Presentation date :
12/7/2025 12:00:00 AM
Published date :
Authors :
Presenting Author: Paul Ferrari, PhD – Corewell Health
Veikko Jousmaki, PhD – Aalto University
Jeremy Gurumendi, BS – Corewell Health
Erin Skrzypek, BS – Corewell Health
Bahram SarviZargar, MSEng – Corewell Health
Ammar Kheder, MD, MRCP – Michigan State University
Michael Bercu, MD – Corewell Health
David Burdette, MD – Corewell Health
Angel Hernandez, MD – Johns Hopkins All Children's Hospital
Rationale: Rhythmic auditory and visual stimulation modulates both local and distant cortical brain oscillations. In healthy individuals this propagation serves to bind multimodal functional networks. Patients with drug resistant epilepsy (DRE) demonstrate signatures of hypersynchrony in their spontaneous brain recordings, and research has described abnormalities in resting state connectivity across the epilepsy network. Additionally, recent evidence has shown that multisensory peripheral flicker stimulation can interact with distant cortical regions and interrupt ongoing interictal activity. We hypothesize that in patients with DRE, regions around the epilepsy network would show distinct frequency specific modulation in response to intermittent photic stimulation.
Methods: Patients undergoing non-invasive MEG recordings (MEGIN Triux Neo) for presurgical mapping underwent photic stimulation using an LED stimulation device. Patients lay supine with eyes closed as 15Hz stimulation was delivered for sixty trials (1.3s on, 2.5s off). An MEG beamformer was used to localize volumetric event-related modulations in the Alpha (7-14Hz), Beta (15-30Hz), and Low-Gamma (30-50Hz) frequency bands. Photic brain maps from forty patients were compared to their interictal MEG dipole localization clusters, and in four cases to localization of ictal events as well as seizure onset zones determined by SEEG recordings. A classification scale (0 – no overlap, 1-lobar overlap, 2-focal overlap) quantified the correspondence.
Results: Photic maps overlapped with MEG dipoles most prominently in the Beta band as a focal decrease in power. Sixty-three percent cases had concordance of one or higher. There were no concordant cases localized to the mesial/anterior temporal lobe, although selected cases show entrainment in region around the hippocampi. Of the four cases with ictal MEG and SEEG, three had concordance of two and the other was mesial onset. In one case MEG failed to correctly localize a right frontal seizure-onset zone, whereas the photic map did. There were two cases of generalized photo-paroxysmal responses to the stimuli. In both cases, these responses were mapped to the dominant MEG dipole cluster in the gamma frequency range.
Conclusions: These preliminary findings suggest that Beta-band mapping of intermittent photic stimulation has promise as a diagnostic tool in MEG. More detailed analytics and correlation to epilepsy and anatomical classifications may lead to a mechanistic understanding of oscillatory coupling in the epileptic brain and hold promise for potential diagnostic and or therapeutic applications.
Funding: NA
Neurophysiology