Localization of the Berger effect in human posterior brain regions with simultaneous electroencephalogram (EEG) and stereo-EEG (SEEG) recordings

The Berger effect, characterized by a marked increase in alpha power (8-13 Hz) upon eye closure, is a fundamental neurophysiological phenomenon whose underlying neural networks and generating mechanism is not fully understood. To delineate this network, we simultaneously recorded Stereo-EEG (SEEG) across 36 brain regions alongside scalp EEG. Spectral analysis revealed significant state-dependent alpha power differences in nine distinct regions. Critically, we identified a robust Berger effect at the population level in five posterior cortical regions: the calcarine cortex, Cuneus, Lingual Gyrus, Precuneus, and Supramarginal Gyrus. At site level, certain subcortical region, such as the pulvinar, was also found to contribute partially to the effect. Furthermore, our decomposition analysis indicated that the Berger effect is predominantly driven by periodic alpha activity. A direct comparison of the SEEG and scalp EEG based on alpha-band spectra and alpha peak frequency consistency confirmed that the classic scalp-level effect primarily contributed from a posterior cortical source (specifically the calcarine cortex/Area 17). Our findings suggest the while the Berger effect arises from distributed cortical-subcortical networks, it is ultimately anchored in the visual cortex. This work provides a anatomically constrained understanding of the neural dynamics underlying posterior dominant rhythm and offers new insights for the clinical application of scalp EEG in resting state.