Abstract
Control over visual selection has long been framed in terms of a dichotomy between "source" and "site", with frontoparietal cortical areas serving as the source of control signals and posterior sensory regions serving as the site for visual processing. This distinction is motivated in part by studies suggesting that frontoparietal cortical areas encode abstract or categorical representations of task goals while posterior sensory areas encode detailed representations of stimuli. Here, we present evidence that challenges this distinction. We used fMRI, a roving searchlight analysis, and an inverted encoding model to examine representations of an elementary feature property (orientation) across the entire human cortical sheet while participants attended either the orientation or luminance of a peripheral grating. We observed robust, continuous representations of orientation in many sensory and frontoparietal cortical areas, including medial and lateral visual cortex, medial and lateral parietal cortex, the superior precentral sulcus, lateral prefrontal cortex, and posterior cingulate cortex. Additionally, we found that attention modulated the amplitudes of orientation-selective representations in several frontoparietal regions, including bilateral posterior parietal cortex and the superior precentral sulcus. Collectively, these findings challenge models that posit a dissociation between the source and site of attentional modulations by demonstrating that feature-based attention enhances the strength of continuous feature-selective representations across the visual processing hierarchy.
Meeting abstract presented at VSS 2016