Early Spatial Attentional Modulation of Inputs to the Fovea

Abstract

Attending to a specific spatial location modulates responsivity of neurons with receptive fields processing that part of the environment. A major outstanding question is whether attentional modulation operates differently for the foveal (central) representation of the visual field than it does for the periphery. Indeed, recent animal electrophysiological recordings suggest that attention differentially affects spatial integration for central and peripheral receptive fields in primary visual cortex. In human electroencephalographic recordings, spatial attention to peripheral locations robustly modulates activity in early visual regions, but it has been claimed that this mechanism does not operate in foveal vision. Here, however, we show clear early attentional modulation of foveal stimulation with the same timing and cortical sources as seen for peripheral stimuli, demonstrating that attentional gain control operates similarly across the entire field of view. These results imply that covertly attending away from the center of gaze, which is a common paradigm in behavioral and electrophysiological studies of attention, results in a precisely timed push-pull mechanism. While the amplitude of the initial response to stimulation at attended peripheral locations is significantly increased beginning at 80 ms, the amplitude of the response to foveal stimulation begins to be attenuated.