biostudies-literatureHu LThe Natural Science Foundation of Zhejiang ProvinceThe National Natural Science Foundation of China115https://www.ebi.ac.uk/biostudies/studies/S-EPMC12924499biostudies-literatureUnknown24(1)<h4>Background</h4>Localization of the epileptogenic zone (EZ) requires further refinement. We identified a unique ictal spectral structure, the "harmonic pattern" (H pattern), which potentially serves as a novel biomarker for localizing the EZ. This study aimed to analyze the clinical significance of the H pattern and to explore its underlying waveform features.<h4>Methods</h4>Seventy patients with drug-resistant focal epilepsy, undergoing stereo-EEG (SEEG) evaluation and surgery, were included. Time-frequency maps (TFM) were generated using Morlet wavelet transform analysis. The H pattern was defined as multiple equidistant, high-density bands with varying frequencies on TFM. The upper quartile was employed to confirm contacts expressing dominant H pattern (dH pattern). Bispectral analysBMC medicineHarmonic patterns embedded in ictal EEG signals in focal epilepsy: new insight into the epileptogenic zone.PMC1292449982171437LD24H090003Zheng ZXiong KJiang HShen CHuang KChen CYang DDing MLiu XYe LZhu JChen ZZhang YWang SHu LWeiss SYe HWang ZWu YZhou JfalseHarmonic patterns embedded in ictal EEG signals in focal epilepsy: new insight into the epileptogenic zone.<h4>Background</h4>Localization of the epileptogenic zone (EZ) requires further refinement. We identified a unique ictal spectral structure, the "harmonic pattern" (H pattern), which potentially serves as a novel biomarker for localizing the EZ. This study aimed to analyze the clinical significance of the H pattern and to explore its underlying waveform features.<h4>Methods</h4>Seventy patients with drug-resistant focal epilepsy, undergoing stereo-EEG (SEEG) evaluation and surgery, were included. Time-frequency maps (TFM) were generated using Morlet wavelet transform analysis. The H pattern was defined as multiple equidistant, high-density bands with varying frequencies on TFM. The upper quartile was employed to confirm contacts expressing dominant H pattern (dH pattern). Bispectral analys2026-01-01T00:00:00Z2026 Jan2026-07-16T17:39:56.454Z2026-07-09T11:08:27.378ZS-EPMC129244994160673210.1186/s12916-026-04665-7