RETINOTOPIC ORGANIZATION OF HUMAN VISUAL-CORTEX - DEPARTURES FROM THECLASSICAL-MODEL

Retinotopic mapping strategies similar to those used for invasive elec trophysiological studies to identify multiple visual areas in monkeys have been adapted for noninvasive studies in humans, using magnetic re cordings of brain activity in conjunction with anatomical magnetic res onance imaging. The retinotopic organization of the primary visual are a (V1) in the left hemisphere of human subjects was examined by presen ting small patterned stimuli near the vertical and horizontal meridian s in the lower right visual field. In contrast with the classical mode l of V1 retinotopy, our results suggest that the representation of the horizontal meridian does not necessarily correspond in a one-to-one m anner with the base of the calcarine fissure and that some lower field stimuli can activate regions in the lower bank of the fissure. The re sults also indicate significant individual variability in the details of how V1 maps around the calcarine fissure.