Perisaccadic vision

Humans and other primates constantly redirect their gaze in order to scan their environment. This behavior is necessary to overcome the lack of high acuity vision in the visual periphery, and is largely achieved via saccades, quick jerk-like eye movements. Saccades ultimately lead to the foveation of important visual stimuli, and thus allow the brain to process fine spatial details contained within those targets. Even before the eyes start to move, saccade related changes in vision can be observed. While vision seems enhanced at saccade targets, it appears to be suppressed at non-target locations. Furthermore, several perisaccadic perceptual distortions have been reported. For example, briefly presented stimuli are grossly mislocalized towards the targets of saccades, resembling a compression of visual space. However, the substantial displacements of the retinal image caused by saccades go unnoticed. This perceptual stability is entirely an illusion, and it is one that has puzzled scientists at least since the time of Helmholtz in the 19th century. Seemingly convergent evidence has led to a widespread notion that an anticipatory updating of visual receptive fields, or predictive remapping, mediates the perception of stability across saccades. In particular, RFs have been reported to shift from their current, presaccadic, locations to their future, postsaccadic, locations in anticipation of an upcoming saccade. Thus, in principle, these anticipatory shifts could contribute to the integration of visual information across eye movements by generating transient non-retinocentric representations around the time of saccades. However, the concept of an anticipatory shift of receptive fields to their future postsaccadic locations has been challenged recently. In one line of research it has been argued that presaccadic shifts of receptive fields reflect a preemptive deployment of visuospatial attention at saccade targets. According to this notion receptive fields do not shift to their postsaccadic locations, but converge towards the saccade target. This convergence of receptive fields mirrors the special role of the saccade target in perisaccadic vision and has been linked to the compression of perceptual space. However, other researchers have abandoned the conception of shifting receptive fields completely. In their view, the existing evidence of predictive remapping should rather be interpreted as a predictive updating of saliency or priority maps, which point attention to relevant parts of visual space. While this notion has been supported by some evidence others have argued that attention lingers in retinocentric coordinates and is only slowly updated postsaccadically. Finally, the debate of whether explicit higher order non-retinocentric representations exist has been started again lately by a number of studies attempting to explain previous conflicting reports. According to those studies, explicit higher order representations may exist but take time and attentional resources to build up.


To summarize, much research on perisaccadic vision has been conducted recently using a variety of approaches including extracellular recordings in non-human primates, electrophysiological recordings in humans, fMRI experiments, psychophysics, and modeling studies. Many of these studies have pushed forward interesting new views, causing an ongoing discussion on the mechanisms and principles of perisaccadic vision. This research topic aims to bring together scientists from various disciplines to present their research and communicate their ideas.