Final Report Summary - P-CYCLES (Perceptual Cycles: Exploring and controlling the perceptual consequences of brain rhythms)
Many current theories implicate brain oscillations in cognitive functions such as perception, attention, consciousness and memory. The involvement of brain oscillations, however, has one critical implication that is often overlooked in cognitive sciences: if a perceptual function relies on an oscillatory neural implementation, then it should operate periodically, i.e. as a sequence of successive episodes or 'snapshots', with more or less favourable moments recurring at a well-defined periodicity following the up-and-down fluctuations of neural activity. In other words, perception should be a rhythmic process. The P-CYCLES project aimed to explore the validity and the consequences of this groundbreaking notion of "rhythmic perception". Contrary to conventional contemporary research linking perceptual functions to relatively slow changes of oscillatory amplitude, we investigated the perceptual consequences of brain oscillations at the rapid time scale of the oscillatory cycle -hence, the notion of "perceptual cycles". In work-package (WP) 1, we demonstrated that a vast range of perceptual and cognitive operations in both the visual and the auditory domains display cyclic behaviour. In WP2, we related these perceptual and cognitive cycles to the underlying neural activities by means of brain imaging techniques (EEG, fMRI, TMS); we found that cycles originate in sensory cortices but can propagate as a travelling wave throughout the entire brain. In WP3, we utilized this knowledge to control the power, frequency and phase of perceptual rhythms and thereby dynamically manipulate, improve or prevent perception. In WP4, we used computational models of visual information multiplexing to explore the functional role of perceptual cycles, and found them to be related to information transmission, attention and predictive coding. The project as a whole brings us closer to understanding the rhythmic dynamics of perception, their neural basis and their functional implications. The idea that sensory perception and cognition follow a succession of snapshots rather than a continuous stream is sparking a transformation in several areas of cognitive sciences.