Neural Mechanisms of Visual Stability

We examined the mechanisms that support processes of transsaccadic visual stability by measuring hemodynamic activity across cortical areas associated with spatial working memory and saccade updating during a transsasccadic change detection task. Participants were presented with a saccade target and instructed to execute a saccade to the target. In some trials, the color of the saccade target would change during the saccade, and participants were asked to report whether they detected a change in a two-alternative forced choice task. Further, we used the postsaccadic blanking paradigm, where the saccade target briefly disappears upon saccade onset and reappears after 250ms, to manipulate stability in half of the trials. To examine how stability processes generalize to non-target information, we further included a session where the item probed for report was a peripheral target, rather than the target of the saccade. The results demonstrated that blanking significantly improved sensitivity to changes of the target object during the saccade, both for the saccade target object and the peripheral target object. Neuroimaging data further demonstrated that both spatial memory mechanisms and saccade updating mechanisms were recruited across the task, however the saccade updating mechanisms were particularly recruited for disruptions of visual stability of the saccade target object and maintained stability for a peripheral target. Thus, while disruptions to visual stability result in similar behavioral results for the saccade target and a peripheral target item, the mechanisms of stability appear to differ, possibly due to differences in storage of information across the saccade or different attentional mechanisms.