What can functional imaging reveal about the role of attention in visual awareness?

Abstract

This review focuses on neuroimaging studies that address the relationship between selective attention, neural activity and visual awareness. Withdrawing attention from particular visual stimuli reduces modality-specific processing in posterior visual cortex, and when attention is fully engaged elsewhere, even highly salient but task-irrelevant stimuli can fail to evoke activity and reach awareness. However, the link between visual attention and awareness extends beyond posterior visual cortex to also encompass regions of parietal and prefrontal cortex. Activity in the posterior visual cortex may be necessary but not sufficient for awareness, without a contribution from frontal and parietal cortex. Consistent with this, enhanced interactions between parietal, frontal and posterior visual cortex are observed as a function of both visual attention and visual awareness; and lesions of parietal cortex disrupt both visual attention and awareness. Taken together, these data suggest that distributed interactions between modality-specific posterior visual cortex and frontoparietal areas subserve both visual attention and visual awareness.