Precise Timing Of Sensory Modulations Coupled To Eye Movements During Active Vision

Abstract

Perception is the result of ongoing brain activity combined with sensory stimuli. In natural vision, changes in the visual input typically occur as the result of self-initiated eye movements. Nonetheless, in most studies, stimuli are flashed, and natural eye movements are avoided or restricted. As a consequence, the neural sensory processing associated with active vision is poorly understood. Here, we show that occipital event-related potentials (ERP) to eye movements during free exploration of natural images exhibited different amplitudes, time course and motor dependency than that from the same flashed stimuli. We found that the ERP to visual fixations doubles in P1 magnitude and does not show a late component, which is classically seen with flashed stimuli1,2. In addition, we discovered that the ERP to the saccade onset was as large as the ERP to fixations onset, with an early component that preceded the visual input, suggesting that a motor modulation was associated with the saccades3. Furthermore, the use of different visual scenes revealed that both the ERP amplitude and time course were dependent on the type of image explored. Our results demonstrated that during active vision, the nervous system engages a mechanism of sensory modulation that is precisely timed to the self-initiated stimulus changes. This mechanism could help coordinate neural activity across different cortical areas and, by extension, serve as a general mechanism for the global coordination of neural networks.