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Mary-Ellen Large, Anil Kuchinad, Adrian Aldcroft, Jody Culham, Tutis Vilis; Visual field representation in the lateral occipital complex. Journal of Vision 2006;6(6):539. doi: 10.1167/6.6.539.
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© ARVO (1962-2015); The Authors (2016-present)
A current debate concerns the topographic organization of object-sensitive cortical regions in the ventral visual cortex. Using high-resolution fMRI we found that, although the lateral occipital area (LO) showed a contralateral preference, the representation of the upper and lower visual fields largely overlapped. To determine whether neurons in LO code the entire contralateral hemifield, two fMRI adaptation experiments were performed. In the first experiment alternating blocks of identical or different faces were displaced either along the horizontal or vertical meridian. If the same LO neurons code upper and lower hemifields, we predicted more adaptation for vertical translations than horizontal translations (8 deg). Although adaptation occurred for all repetitions of the same face, more adaptation occurred for faces displaced along the vertical axis compared to the horizontal axis. These data were supported by a second slow-event related experiment in which we measured adaptation to a second identical face presented either to the left of or below the first face. Although both LO and FFA showed a preference for stimuli in the contralateral vs. ipsilateral field, only LO showed greater adaptation to within-hemifield than between-hemifield pairs. The results suggest that both LO and FFA have some degree of position invariance, however, the invariance in LO is greater within a hemifield than between hemifields. The implication is that both FFA and LO contain large receptive fields that are biased toward the contralateral hemifield, but within LO the receptive fields may be elliptical about the vertical axis.
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