Abstract
Eye movements induce visual spatial mislocalization of briefly flashed stimuli. The neural basis of this perceptual phenomenon is as yet unknown: physiological, behavioral and theoretical studies have suggested various neural mechanisms, from displacement of visual receptive fields during eye movements to erroneously decoded eye position. Here we utilized the mislocalization of briefly presented stimuli during different types of monocular eye movements (i.e. fixation, saccades and smooth pursuit eye-movements) to induce a perceptual localization shift into the area of the blind spot, a region of the retina that is physiologically blind due to the absence of photoreceptors. Our study confirmed previous findings on binocular mislocalization for monocular vision and showed that mislocalization induced by different types of eye movements is capable to shift the perceived location of targets to a position a subject should be blind for. Furthermore, the area for which each subject perceived the least amount of targets, forming a perceptual blind spot, shifted for each form of eye movement in a characteristic manner. The distinctive shapes of the perceptual blind spots for each subject were basically preserved during eye movements as compared to fixation. In all cases, perceived location of stimuli presented close to the blind spot were shifted towards its center, inducing a resetting of the typically observed increase of mislocalization for larger retinal eccentricities. Our findings imply a combination of two independent neural signals as the neural basis of stimulus localization: a visual map and an eye-position signal. Both signals might be combined at a rather late processing stage, in which visual space is already fully represented. This hypothesis predicts, at a neuronal level, visual receptive fields at identical retinal locations across eye movements and agrees well with previous studies suggesting the source of perceptual mislocalization during eye movements by an erroneous internal representation of eye-position.
Meeting abstract presented at VSS 2016