Perceptual Cycles

Brain function involves oscillations at various frequencies. This could imply that perception and cognition operate periodically, as a succession of cycles mirroring the underlying oscillations. This age-old notion of discrete perception has resurfaced in recent years, fueled by advances in neuroscientific techniques. Contrary to earlier views of discrete perception as a unitary sampling rhythm, contemporary evidence points not to one but several rhythms of perception that may depend on sensory modality, task, stimulus properties, or brain region. In vision, for example, a sensory alpha rhythm (∼10 Hz) may coexist with at least one more rhythm performing attentional sampling at around 7 Hz. How these multiple periodic functions are orchestrated, and how internal sampling rhythms coordinate with overt sampling behavior, remain open questions.