New vistas for α-frequency band oscillations

The amplitude of α-frequency band (8–14 Hz) activity in the human electroencephalogram is suppressed by eye opening, visual stimuli and visual scanning, whereas it is enhanced during internal tasks, such as mental calculation and working memory. α-Frequency band oscillations have hence been thought to reflect idling or inhibition of task-irrelevant cortical areas. However, recent data on α-amplitude and, in particular, α-phase dynamics posit a direct and active role for α-frequency band rhythmicity in the mechanisms of attention and consciousness. We propose that simultaneous α-, β- (14–30 Hz) and γ- (30–70 Hz) frequency band oscillations are required for unified cognitive operations, and hypothesize that cross-frequency phase synchrony between α, β and γ oscillations coordinates the selection and maintenance of neuronal object representations during working memory, perception and consciousness.