Alpha Frequency Entrainment Reduces the Effect of Visual Distractors.

Numerous studies have linked alpha frequency (∼10 Hz) visual entrainment to the inhibition of incoming visual information. However, although these studies have provided key evidence for the intrinsic sensitivity of the human brain to incoming alpha frequency signals, they have only examined the negative impact of alpha entrainment on target stimuli. Thus, it remains uncertain whether the perception of distracting or nonimperative stimuli can also be affected by alpha frequency entrainment. In the current study, we address this question using an adapted version of the arrow-based Erikson "flanker" paradigm that incorporates stimuli flickering at two distinct frequencies: 10 Hz (alpha) and 30 Hz. By presenting flickering stimuli in the portions of the visual field where the flanking arrows would soon appear, we aimed to determine whether the frequency of visual entrainment (i.e., 10 Hz vs. 30 Hz) significantly interacted with the congruency of the flanking arrows (representing selective attention processing) using behavioral task performance and neural oscillations as the outcome metrics. Twenty-three healthy adult participants underwent magnetoencephalography during performance of the task. Our results indicated a reduced congruency effect (i.e., a smaller difference between congruent and incongruent trials) in the alpha flicker condition, as compared with the 30-Hz flicker condition, which suggests a robust relationship between alpha entrainment and the active inhibition of distractor stimuli appearing in that portion of the visual field. Supporting this, alpha frequency (but not 30 Hz) entrainment responses in the primary visual cortex also covaried significantly with the behavioral congruency effect.