Attention selectively enhances stimulus information for surround over foveal stimulus representations in occipital cortex

Abstract

By attending to part of a visual scene, we can prioritizeprocessing of the most relevant visual information andso use our limited resources effectively. Previousfunctional magnetic resonance imaging (fMRI) work hasshown that attention can increase overallblood-oxygen-level-dependent (BOLD) signalresponsiveness but also enhances the stimulusinformation in terms of classifier performance. Here, weinvestigate how these effects vary across the visual field.We compare attention-enhanced fMRI–BOLD amplituderesponses and classifier accuracy in fovea andsurrounding stimulus regions using a set of four simplestimuli subdivided into a foveal region (1.4° diameter)and a surround region (15° diameter).We founddissociations between the effects of attention onaverage response and in enhancing stimulusinformation. In early visual cortex, we found thatattention increased the amplitude of responses to bothfoveal and surround parts of the stimuli and increasedclassifier performance only for the surround stimulus.Conversely, ventral visual areas showed less change inaverage response but greater changes in decoding.Unlike for early visual cortex, in the ventral visual cortexattention produced similar changes in decoding forcenter and surround stimuli.