Abstract
In this human fMRI study we describe the complete topography of attention-related cortical activation throughout the visual field and compare it with previous models. We cataloged separate fMRI-based maps of attentional topography in V1 when subjects covertly attended to each target location in an array (22 degrees max radius) of 3 concentric rings of 6 targets each. On each run, auditory cues directed the subject to attend to one specific target or to a central segment in a randomized block design. We combined the attentional maps for each of the 18 target locations for each subject into a unique composite display to identify common principles of attentional organization for different target locations. In general, attention modulated cortical activity throughout the visual field, not just at the cued location. Attentional activation was highest at the attended target but spread to other segments in a manner depending on eccentricity. For targets in the inner (1–5 degrees) and middle (5–12 degrees) rings, attention spread mainly outward to other segments along the same clock angle. For targets in the outer ring, attentional gradient was more diffuse, spreading to nearby segments of the same eccentricity and inward to the middle ring segments. We propose an “Attentional Landscape” model that is more complex than a ‘spotlight’ or simple ‘gradient’ model but includes aspects of both and accounts for some seemingly conflicting reports in the literature. The model suggests that peripheral and central attention may differ in spatial precision, perhaps reflecting distinct functional roles (monitoring vs. scrutiny).
Supported by NIH EB00843,EY13801,RR00058