Shared and disorder-specific prenatal and perinatal risk factors for neurodevelopmental disorders: a nationwide cohort study.

Regular infra-slow (<0.02 Hz) oscillations in neuro-physiological activity have been found throughout the mammalian visual system, including the retina (), optic chiasm (), the dorsal lateral geniculate nucleus (dLGN) (; ), ventral lateral geniculate nucleus (vLGN) (), olivary pretectal nucleus (OPN) (, ), suprachiasmatic nucleus (SCN) (), intergeniculate leaflet (IGL) (, ) and primary visual cortex (). Infra-slow oscillatory rhythm features such as frequency and amplitude are modulated by light and depend on retinal activity (; ; ; ; ). Nevertheless, despite its ubiquity, the contribution of such rhythmicity, if any, to visual processing is still a matter of debate. Oscillations at a quite different frequency range (20–100 Hz, termed beta/gamma) are also a feature of the early visual system. Such oscillations have been implicated in different aspects of visual processing ranging from inter-area communication () to feature binding (). Recently, we and others also reported that the power of fast beta/gamma oscillations encodes for ambient light intensity and spatially structured changes in luminance (; ). Decades of research have highlighted a general organizing principle by which the brain orchestrates oscillations expressed at different timescales. Namely, faster oscillations are ‘nested’ within slower oscillations so that the power of faster oscillations is controlled by the phase of the slower ones. A remarkable example of this phenomenon is the theta-gamma coupling in the hippocampus that has been shown to underlie spatial navigation and object memory recollection (; ). Electroencephalographic recordings in humans indicate that infra-slow oscillations can also modulate faster rhythms (; ). Thus one possible impact of infra-slow oscillations in vision is to guide visual processing by interacting with fast narrowband oscillations.