Making waves in the stream of consciousness: entraining oscillations in EEG alpha and fluctuations in visual awareness with rhythmic visual stimulation.
Journal of cognitive neuroscience December 1, 2012 Kyle E Mathewson, Christopher Prudhomme, Monica Fabiani et al.
Rhythmic visual stimuli can entrain ongoing neural oscillations in the human brain, locking the timing of excitability cycles and enhancing processing of predictable stimuli. The study shows that the phase of existing brain oscillations can be modified by rhythmic visual stimulation in the alpha frequency band, leading to phase-locked fluctuations in excitability that produce concomitant fluctuations in visual awareness. This entrainment effect depended on the amount of spontaneous alpha power before the experiment and the level of 12-Hz oscillation before each trial, and could not be explained by evoked activity. The findings support a role for alpha oscillations as pulsed inhibition of cortical activity and provide evidence for the quantized nature of conscious experience.