Attention modulates spatial priority maps in the human occipital, parietal and frontal cortices

Attention alters neural responses that encode different aspects of visual stimuli, but exactly how these changes together modulate the encoded spatial representation of a scene remains unclear. Here the authors look at spatial priority maps of attended to and ignored stimuli and find that attention increases the gain but not the size of stimulus representations. Computational theories propose that attention modulates the topographical landscape of spatial 'priority' maps in regions of the visual cortex so that the location of an important object is associated with higher activation levels. Although studies of single-unit recordings have demonstrated attention-related increases in the gain of neural responses and changes in the size of spatial receptive fields, the net effect of these modulations on the topography of region-level priority maps has not been investigated. Here we used functional magnetic resonance imaging and a multivariate encoding model to reconstruct spatial representations of attended and ignored stimuli using activation patterns across entire visual areas. These reconstructed spatial representations reveal the influence of attention on the amplitude and size of stimulus representations within putative priority maps across the visual hierarchy. Our results suggest that attention increases the amplitude of stimulus representations in these spatial maps, particularly in higher visual areas, but does not substantively change their size.