Localizing objects in physical space requires integrating information about head position, eye position and location of stimulation on the retina. The first cortical stages of visual processing contain retinotopic maps that maintain the relative locations of retinal stimulation along the surface of the cortex, providing an obvious basis for space perception. While it has been long assumed that these maps are fixed and determined by the anatomy of the retino-cortical projection, recent neuroimaging and electrophysiological studies have challenged this view by suggesting that contextual effects such as depth information and attention can distort these maps.
We propose to use a combination of behavioral and neuroimaging techniques to investigate the neural substrates of space perception. Brief flashes presented during shifts of attention or gaze direction are known to be systematically mislocalized. Using fMRI and Multi-Voxel Pattern analysis, we will locate the representation of these stimuli within retinotopic maps to determine if it corresponds to the real or the perceived location of the stimuli. In this way, we will quantify the effects that attention and eye movements induce on the neural representations of visual space, and how do they correspond to the distortions of visual perception. We will test the novel hypothesis that the pattern of neural activation reflects the perceived stimulus position since the earliest stages of visual processing, with visual maps adapting flexibly and dynamically in response to the behavioral demands.
The proposal involves two of the best international laboratories for the study of the human vision, attention and eye movements, and makes use of the most advanced neuroimaging tools and analysis techniques. The skills that will be acquired through this fellowship define a professional profile ideally suited to acquire an independent research position in vision science.
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