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Fred H. Hamker, Marc Zirnsak, Dirk Calow, Markus Lappe; The perisacadic compression of visual space - what may it have to do with spatial attention?. Journal of Vision 2006;6(6):105. doi: https://doi.org/10.1167/6.6.105.
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© ARVO (1962-2015); The Authors (2016-present)
Several experiments have shown that the plan of making an eye movement affects visual processing. Under certain conditions briefly flashed stimuli are mislocalized towards the saccade target (Ross et al 1997, Kaiser and Lappe 2004). The physiological mechanism that causes the percept of a ‘compressed’ visual space is not known, but perisaccadic remapping has been suggested as one possible candidate.
Based on a previous model (Hamker 2005), we have developed a quantitative model of perisaccadic perception to evaluate if the phenomenon of ‘compression’ is linked to attention. We assume a spatially selective corollary discharge signal. It is directed towards the saccade target in cortical space and increases the gain of cells in extrastriate areas, e.g. MT and V4. Such a spatial gradient is often found in cell recordings and typically referred to as attention related.
Based on these assumptions, the model reproduces the temporal course and the 1D spatial pattern of mislocalization as measured by Morrone et al (1997) and the 2D mislocalization data of Kaiser & Lappe (2004). It further inherently predicts RF dynamics. For the selected parameters we observe a perisaccadic shrinkage and shift of RFs towards the saccade target similar as reported for V4 (Tolias et al 2004). This prediction has been experimentally verified in a discrimination task in which objects and flankers were presented at the saccade target.
Concluding, our results predict that perisaccadic spatial attention and the phenomenon of a ‘compressed’ visual space, both originate from the same oculomotor feedback signal.
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