The cortical mechanisms of visual stability
Chang, Erik Chihhung
Doctor of Philosophy
Visual stability refers to the apparent stability of the visual world given the displacement of retinal images induced by eye movements. Phenomenally visual stability involves both a stable representation of visual space and reduced sensitivities to perceptual changes at the temporal proximity of eye movements. While the psychophysics of the perisaccadic perceptual changes have been studied extensively, how visual stability is implemented in the human visual system remains to be explored. This dissertation examines the cortical mechanisms of perceptual stability in spatial vision with four series of experiments. Series 1 established a paradigm to induce saccadic suppression of displacement (SSD) and examined how the direction of saccades and displacements influence the strength of SSD. Series 2 examined the consequence of disrupting the posterior parietal cortex (PPC) with transcranial magnetic stimulation (TMS) in perceiving perisaccadic displacements. Series 3 examined psychophysical factors influencing perisaccadic mislocalization. Finally, series 4 explored how TMS on PPC impacts perisaccadic mislocalization. These experiments conjointly illustrate how the PPC contributes to a stable visuospatial perception during saccades.