Entrainment of neuronal oscillations as a mechanism of attentional selection

Whereas gamma- band neuronal oscillations clearly appear integral to visual attention, the role of lower- frequency oscillations is still being debated. Mounting evidence indicates that a key functional property of these oscillations is the rhythmic shifting of excitability in local neuronal ensembles. Here, we show that when attended stimuli are in a rhythmic stream, delta- band oscillations in the primary visual cortex entrain to the rhythm of the stream, resulting in increased response gain for task- relevant events and decreased reaction times. Because of hierarchical cross- frequency coupling, delta phase also determines momentary power in higher- frequency activity. These instrumental functions of low- frequency oscillations support a conceptual framework that integrates numerous earlier findings.