Dynamic entrainment of low frequency phase appears puzzling from a viewpoint that focuses primarily on perception and considers action to be a secondary phenomenon evoked by percepts through conditioned associations. However, a case can be made for reversing this order and viewing action as the primary purpose of the brain – evolution works via survival selection, and survival depends on appropriate action taken by an organism. In this view of motor primacy, the purpose of the brain is to guide action, and perception and cognition arose as ‘error-correction’ mechanisms to adjust and optimize an actively ongoing process of action selection [60]. This purpose is best served if sensory organs are under direct and active motor control. Under ecologically valid conditions organisms will actively control the timing and targeting of their own sensory experience – contrast seeing vs. looking, hearing vs. listening, or smelling vs. sniffing. Importantly, the time course of motor actions – including the motor control of active sensing – will often exhibit rhythmic patterns [61]. Therefore, the arrival of neuronal spikes carrying information about stimuli to early sensory areas will occur in rhythmic volleys, introducing a volitionally-controlled rhythmicity to perception and multisensory integration.
