Spatial summation in the human fovea: Do normal optical aberrations and fixational eye movements have an effect? J Vis 2018 Aug 01;18(8):6
Date
08/15/2018Pubmed ID
30105385Pubmed Central ID
PMC6091889DOI
10.1167/18.8.6Scopus ID
2-s2.0-85052645209 (requires institutional sign-in at Scopus site) 15 CitationsAbstract
Psychophysical inferences about the neural mechanisms supporting spatial vision can be undermined by uncertainties introduced by optical aberrations and fixational eye movements, particularly in fovea where the neuronal grain of the visual system is fine. We examined the effect of these preneural factors on photopic spatial summation in the human fovea using a custom adaptive optics scanning light ophthalmoscope that provided control over optical aberrations and retinal stimulus motion. Consistent with previous results, Ricco's area of complete summation encompassed multiple photoreceptors when measured with ordinary amounts of ocular aberrations and retinal stimulus motion. When both factors were minimized experimentally, summation areas were essentially unchanged, suggesting that foveal spatial summation is limited by postreceptoral neural pooling. We compared our behavioral data to predictions generated with a physiologically-inspired front-end model of the visual system, and were able to capture the shape of the summation curves obtained with and without pre-retinal factors using a single postreceptoral summing filter of fixed spatial extent. Given our data and modeling, neurons in the magnocellular visual pathway, such as parasol ganglion cells, provide a candidate neural correlate of Ricco's area in the central fovea.
Author List
Tuten WS, Cooper RF, Tiruveedhula P, Dubra A, Roorda A, Cottaris NP, Brainard DH, Morgan JIWAuthor
Robert F. Cooper Ph.D Assistant Professor in the Biomedical Engineering department at Marquette UniversityMESH terms used to index this publication - Major topics in bold
AdultEye Movements
Female
Fixation, Ocular
Fovea Centralis
Humans
Male
Middle Aged
Psychophysics
Sensory Thresholds
Spatial Processing
Visual Pathways
