Active vision modulates early cortical stages of visual processing: Evidence from MEG and eye-tracking

It has been hypothesized that the visual system anticipates upcoming visual input contingent on the execution of saccadic eye movements. In line with this idea, it has been shown that changes in visual input across saccades elicit stronger post-saccadic fixation-locked neural responses compared to no-change conditions; an effect known as the preview effect . In the present study, we demonstrate that this preview effect depends on active vision and cannot be explained by either classical or spatiotopic adaptation. In a gaze-contingent experiment, in which participants were cued to make saccades to object stimuli, we concurrently recorded magnetoencephalography (MEG) and eye-tracking data. The source-localized MEG signal was deconvolved with stimulus onset and eye movement events in order to account for systematic variation in gaze behavior related to the no-change (valid preview) and change (invalid preview) conditions. Crucially, preview effects in the primary visual and in ventral-occipital cortices were markedly larger when participants made saccades compared to replay blocks in which we simulated the visual consequences of saccades absent saccade execution, demonstrating that the preview effect cannot be simply explained by classic adaptation. A further control condition ruled out spatiotopic adaptation. Our results show that early visual cortical areas which are not known to exhibit saccadic remapping neurons still show signs of sequential neural history effects across saccades. Previous research might have overlooked this influence of active vision because of the lack of an invalid preview condition which breaks the correspondence between pre-saccadic extrafoveal and post-saccadic foveal stimulation.