Friday, April 4, 2025
4/4/2025
Vision, Attention and Eye Movements at the Scale of the Foveola - PROJECT SUMMARY The foveola, the 1-deg retinal region where cones are most densely packed, is of paramount importance for vision. Damage to this tiny portion of the retina has devastating consequences for many daily activities as humans use it to resolve fine details in the visual scene. Yet, primarily as a consequence of technical challenges, little is known about the mechanisms of foveal vision. A major difficulty in studying foveal functions comes from the need to finely control retinal stimulation. At this scale, both placing and maintaining a stimulus at a desired eccentricity is difficult, because of uncertainty in localizing the center of gaze, and because of the continual retinal motion caused by fixational eye movements, the slow eye drifts and small saccades (microsccades) that humans continually perform. Recent technical developments offer complementary strengths for overcoming these challenges: high- resolution retinal imaging allows for high-precision eye-tracking and gaze-contingent retinal stimulation while at the same time imaging the central fovea, yet it poses limitations in how psychophysical testing is conducted and makes it challenging to run high volume of subjects/trials. On the other hand, high-precision video eye-tracking coupled with gaze-contingent display control provides a flexible way for testing vision at the fine grain of the foveola and acquire large volume of data, but it does not provide information on foveal anatomy. To overcome these limitations this research uses a unique blend of these cutting-edge techniques for flexibly mapping visual functions and attention at the fine scale and linking oculomotor behavior, visual perception and anatomy in the foveola. The overarching goal of this research is to determine the limits and constraints of foveal vision and the mechanisms the visuomotor system relies on to compensate for these limitations, and to optimize fine spatial vision. Foveal vision will be investigated from three different perspectives: how eye movements and retinal anatomy jointly shape fine spatial vision in the foveola (Aim 1), how oculomotor plasticity and attention contribute to fine spatial vision in the foveola (Aim 2), how attention and the interplay with peripheral vision constrain the temporal dynamics of foveal processing (Aim 3). By bridging anatomy, oculomotor behavior and visual acuity, the research in Aim 1 will examine the fine modulations of visual acuity and cone density across the central fovea, how ocular drift varies in relation to cone density and whether the location chosen as the preferred retinal locus has an impact on acuity. Research in Aim 2 will examine the plasticity of microsaccades and how fine control of attention acts at spatial frequencies near the resolution limit and to compensate for anisotropies in sensitivity in the central fovea. Research in Aim 3 will elucidate how the temporal dynamics of vision and attention change foveally and extrafoveally and how sensitivity to co-occurring foveal and extrafoveal stimuli is modulated during fixation. The outcomes of this research may raise the possibility that fine control of attention and fixational eye movements can counteract vision loss within the central fovea in the early stages of certain diseases, and they may open the way for visual rehabilitation procedures acting on the fine control of eye movements and attention.
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