Top-down modulation of visual cortical processing after transient congenital blindness

Abstract

Early visual experience has been shown to be critical for the development of visual and multisensory functions; however, its impact on functional brain organization remains largely unexplored. Here, we therefore investigated the effect of early visual deprivation on top-down attentional modulation of visual cortical processing within the occipito-temporal cortex. Furthermore, we explored whether early visual deprivation may affect the extent to which typically visual, motion-selective area hMT responds to moving visual stimuli. Using functional magnetic resonance imaging, we compared cortical responses in area hMT and in the fusiform face area (FFA) to moving face stimuli - which were either task relevant or task irrelevant - relative to stationary face stimuli between cataract-reversal participants and normally sighted controls. Although both groups exhibited significantly stronger visual cortical responses in area hMT to moving stimuli than during the stationary baseline, the magnitude of this effect was significantly lower in the cataract-reversal group. In contrast, both groups exhibited significantly enhanced visual cortical responses in area hMT and in the FFA when moving face stimuli were task relevant compared to when they were task irrelevant, with no significant differences between groups in the magnitude of these effects. These results indicate that top-down attentional modulation of visual cortical processing in area hMT and FFA does not depend on early visual experience. Furthermore, the present results suggest that the functional specialization of area hMT for visual motion processing may be partially disrupted by early visual deprivation.

Keywords: Congenital blindness; Sight restoration; Top-down modulation; Visual processing; fMRI.