De Lange, F. P. | Search bioRxiv

bioRxiv2025

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.

neuroscience↗

bioRxiv2017

Prior expectations induce pre-stimulus sensory templates

Perception can be described as a process of inference, integrating bottom-up sensory inputs and top-down expectations. However, it is unclear how this process is neurally implemented. It has been proposed that expectations lead to pre-stimulus baseline increases in sensory neurons tuned to the expected stimulus, which in turn affects the processing of subsequent stimuli. Recent fMRI studies have revealed stimulus-specific patterns of activation in sensory cortex as a result of expectation, but this method lacks the temporal resolution necessary to distinguish pre- from post-stimulus processes. Here, we combined human MEG with multivariate decoding techniques to probe the representational content of neural signals in a time-resolved manner. We observed a representation of expected stimuli in the neural signal well before they were presented, demonstrating that expectations indeed induce a pre-activation of stimulus templates. These results suggest a mechanism for how predictive perception can be neurally implemented.

neuroscience↗