Large-scale cortical displacement of a human retinotopic map

The aim of the current study was to determine the retinotopic organization of a patient with congenital cortical dysgenesis and normal visual function. Using functional magnetic resonance imaging (fMRI), detailed retinotopic maps corresponding to the four visual field quadrants were projected onto cortical surfaces. Similar to control subjects, the upper right visual field mapped onto ventral left hemisphere and was retinotopically organized. The lower right visual field's cortical representation was also retinotopically organized, yet was displaced many centimeters anteriomedially. Moreover, the entire left visual field was represented in nonretinotopically organized islands in both hemispheres. These results indicate retinotopic maps can shift in both location and topography illustrating cortical reorganization presumably due to either cortical dysgenesis or functional displacement.