Prolonged Visual Entrainment Induces Long-Lasting Alpha-Band Modulations

Neural oscillations are fundamental for encoding, filtering, and integrating sensory information, representing a core computational principle underlying perceptual experience. In particular, fluctuations in alpha (~7-13 Hz) and theta (~4-7 Hz) activity are associated with changes in cortical excitability and rhythmic modulations of perception. These oscillations are not static features but are highly plastic and can be shaped through neural entrainment, whereby brain rhythms synchronize with external rhythmic sensory stimulation. While short-duration (~0.5-5 s) stimulation induces transient (~500 ms), localized entrainment effects, it remains unclear whether prolonged entrainment can produce persistent and spatially widespread modulations in ongoing neural activity. Here, we recorded resting-state EEG before and after 1 min of visual rhythmic stimulation at individualized alpha (individual alpha frequency, IAF; IAF -2 Hz; IAF +2 Hz) and theta (4.5 Hz) frequencies. We assessed frequency-specific and topographic effects by comparing alpha (7-13 Hz) and theta (3-6 Hz) power, frequency, and phase coherence before and after stimulation. Our results show that prolonged visual entrainment induces sustained increases in alpha power and phase coherence, persisting throughout the 1-min post-stimulation period without changes in frequency. Stimulation at IAF induced stronger modulations of intrinsic alpha oscillations than other frequencies, extending bilaterally from posterior to central and anterior regions. In contrast, theta stimulation increased phase consistency but did not induce persistent changes in theta power, suggesting no sustained modulation of endogenous theta activity. Together, these findings provide evidence that prolonged visual entrainment can induce long-lasting and spatially distributed modulations of resting-state alpha oscillations, particularly when stimulation is tuned to the brain's intrinsic resonant frequency. This highlights the frequency-specific nature of neural responsiveness and the potential of rhythmic sensory stimulation to induce long-lasting changes in large-scale brain oscillatory networks.