Abstract
What is the neural locus of visual attention? In this study, we provide evidence that attention does not always operate in the same set of visual areas; instead, the neural locus of attention changes rapidly to provide a match between the spatial scale of task-relevant information in the current scene and the sizes of neural receptive fields. To examine this hypothesis, we obtained electrical (ERP), magnetic (MEG), and hemodynamic (fMRI) measures of attention from human subjects while they detected large-scale or small-scale targets within multi-scale stimulus patterns. Subjects did not know the scale of the target prior to stimulus onset, and yet the neural locus of attention-related activity between 250 and 300 ms reflected the scale of the target. Specifically, attention-related activity was confined to a high-level, relatively anterior visual area (the lateral occipital complex) for large-scale targets; for small-scale targets, attention-related activity was observed in both this relatively anterior visual area and a lower-level, more posterior area (V4). This rapid change indicates that the neural locus of attention in visual cortex is not static, but can change rapidly depending on the nature of the task-relevant information in the current visual input. This suggests that the operation of attention within a given visual area is not tonically controlled by top-down executive systems, but is instead determined on a moment-by-moment basis as a function of interactions between top-down control signals and local information about the current visual input.