Anticipatory saccade target processing and the presaccadic transfer of visual features

As we shift our gaze to explore the visual world, information enters cortex in a sequence of successive snapshots, interrupted by phases of blur. Our experience, in contrast, appears like a movie of a continuous stream of objects embedded in a stable world. This perception of stability across eye movements has been linked to changes in spatial sensitivity of visual neurons anticipating the upcoming saccade, often referred to as shifting receptive fields (Duhamel et al., 1992; Walker et al., 1995; Umeno and Goldberg, 1997; Nakamura and Colby, 2002). How exactly these receptive field dynamics contribute to perceptual stability is currently not clear. Anticipatory receptive field shifts toward the future, postsaccadic position may bridge the transient perisaccadic epoch (Sommer and Wurtz, 2006; Wurtz, 2008; Melcher and Colby, 2008). Alternatively,apresaccadic shiftofreceptive fields toward the saccade target area (Toliasetal., 2001) may serve to focus visual resources onto the most relevant objects in the postsaccadic scene (Hamker et al., 2008). In this view, shifts of feature detectors serve to facilitate the processing of the peripheral visual content before it is foveated. While this conception is consistent with previous observations on receptive field dynamics and on perisaccadic compression (Ross et al., 1997; Morrone et al., 1997; Kaiser and Lappe, 2004), it predicts that receptive fields beyond the saccade target shift toward the saccade target rather than in the direction of the saccade. We have tested this prediction in human observers via the presaccadic transfer of the tilt-aftereffect (Melcher, 2007).