The existence of midline retinal nasotemporal overlap in humans is controversial. Here we used the Poffenberger paradigm and monocular vision to assess the existence of a midline retinal area projecting to both hemispheres and of a possible differential contribution of the two hemiretinae. When brief visual stimuli were presented at 1 degrees eccentricity they were responded to equally quickly with either hand while at 6 degrees the hand on the same side as the stimulated hemifield was consistently faster than the contralateral hand. This pattern of results is consistent with a nasotemporal overlap at 1 degrees and a complete lateralization at 6 degrees . Both hemiretinae contribute to the overlap area which can be considered as responsible for foveal sparing in hemianopic patients.
Evidence of midline retinal nasotemporal overlap in healthy humans: A model for foveal sparing in hemianopia?
MARZI, Carlo Alberto;MANCINI, Francesca;SPERANDIO, Irene;SAVAZZI, Silvia
2009-01-01
Abstract
The existence of midline retinal nasotemporal overlap in humans is controversial. Here we used the Poffenberger paradigm and monocular vision to assess the existence of a midline retinal area projecting to both hemispheres and of a possible differential contribution of the two hemiretinae. When brief visual stimuli were presented at 1 degrees eccentricity they were responded to equally quickly with either hand while at 6 degrees the hand on the same side as the stimulated hemifield was consistently faster than the contralateral hand. This pattern of results is consistent with a nasotemporal overlap at 1 degrees and a complete lateralization at 6 degrees . Both hemiretinae contribute to the overlap area which can be considered as responsible for foveal sparing in hemianopic patients.
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