Decoding object-based attention signals in the human brain

Abstract

Visual attention can be directed to spatial locations and various features, as well as to a unitary object independently of spatial and feature variations. Previous work has shown object-based attention can modulate neural activity in category-selective areas in the ventral visual cortex. However, whether earlier visual areas can be modulated by object-based attention and how higher-order areas control and represent the deployment of object-based attention is not clear. To investigate the neural mechanism of object-based attention, we presented two superimposed objects with similar shape that occupied the same spatial location, and asked participants to perform an attention-demanding task on one of the objects. We observed enhanced fMRI response for object-attended condition compared to a neutral condition in a network of occipital-parietal-frontal areas. There was no difference in overall sustained fMRI response between attending to different objects in any attention task regions. Using multivariate pattern analysis (MVPA), however, we successfully “read out” the attended object from activity patterns in both early visual areas (V1 to MT+), object-selective areas (lateral occipital complex, LOC), and some parietal and frontal areas (e.g., IPS, MFG, and SFG). These results indicate that neural activity in multiple visual areas can be modulated by object-based attention. Furthermore, parietal and frontal cortical regions contain neural signals related to priority of attended object.