Topography of the motion aftereffect with and without eye movements

Abstract

Although a lot is known about various properties of the motion aftereffect (MAE), there is no systematic study of the topographic organization of MAE. In the current study, first we provided a topographic map of the MAE to investigate its spatial properties in detail. To provide a fine topographic map, we measured MAE with small test stimuli presented at different loci after adaptation to motion in a large region within the visual field. We found that strength of MAE is highest on the internal edge of the adapted area. Our results show a sharper aftereffect boundary for the shearing motion compared to compression and expansion boundaries. In the second experiment, using a similar paradigm, we investigated topographic deformation of the MAE area after a single saccadic eye movement. Surprisingly, we found that topographic map of MAE splits into two separate regions after the saccade: one corresponds to the retinal location of the adapted stimulus and the other matches the spatial location of the adapted region on the display screen. The effect was stronger at the retinotopic location. The third experiment is basically replication of the second experiment in a smaller zone that confirms the results of previous experiments in individual subjects. The eccentricity of spatiotopic area is different from retinotopic area in the second experiment; Experiment 3 controls the effect of eccentricity and confirms the major results of the second experiment.

Psychophysical Evidence for Spatiotopic Processing in Area MT in a Short-Term Memory for Motion Task

“…Our reason for this is that in studying the motion aftereffect in a dimly lit room, Knapen et al (2009) found the effect in the retinotopic location rather than a spatiotopic location, suggesting that the presence of light does not automatically set all motion processing to a spatiotopic reference frame. Conversely, using slightly different stimuli in a dark room, Ezzati et al (2008) found a weak motion aftereffect in the spatiotopic location in addition to that in the retinotopic location. This suggests that light is not necessary for spatiotopic processing.…”

“…Evidence for this comes from a psychophysical study that showed that the integration of motion information over time can be performed in spatiotopic coordinates (Melcher and Morrone 2003) and from a functional magnetic resonance imaging study that showed spatiotopic blood oxygenation level-dependent (BOLD) information in MT (d'Avossa et al 2007). However, a more recent study found no evidence for spatiotopic processing in the BOLD response (Gardner et al 2008) and results from psychophysical studies on motion or direction aftereffects, both thought to involve MT, have predominantly found evidence for retinotopic processing with weak if any evidence for spatiotopic processing (Ezzati et al 2008;Knapen et al 2009;Wenderoth and Wiese 2008). Interestingly, apart from the presence of gain fields (Bremmer et al 1997), there is no electrophysiological evidence to support the idea of MT as processing spatiotopic information, although one study, examining a codebook readout of a population of neurons, did not find evidence of pure spatiotopic processing (Krekelberg et al 2003).…”

Position specificity of adaptation-related face aftereffects

“…Currently adaptation experiments suggest that the aftereffects observed for tilt [66,67], motion [68,69], duration [70], binocular rivalry [71] and shapes [67] have components that cannot be explained on the basis of retinotopic adaptations. These results together suggest the existence of spatiotopic representations, where position of objects is determined in world-based coordinates, for several types of stimulus categories.…”

Remapping of the line motion illusion across eye movements

“…How do we successfully perceive motion in allocentric/spatiotopic coordinates? There is recent psychophysical and fMRI evidence both for (Melcher and Morrone 2003;d'Avossa et al 2007;Ezzati et al 2008;Ong et al 2009;Fracasso et al 2010;Zhang and Li 2010) and against (Boi et al 2011;Wenderoth and Wiese 2008;Knapen et al 2009, Gardner et al 2008) spatiotopic motion processing. It is well accepted that coding visual stimuli in spatiotopic coordinates requires a more complex process than retinotopic coding, since spatial updating mechanisms must take into account the metrics of the upcoming saccade in order to integrate subsequent frames into a coherent percept (Prime et al 2011).…”