At what eccentricity positive BOLD turns to negative BOLD.

Spatial spread of positive BOLD signal for center, near surround, and far surround in V1, V2 and V3. The angles indicate the average (95% CI) eccentricity representation where the positive BOLD signal turns to negative BOLD signal. For central direction, the value at the title row indicates the inner edge eccentricity of the stimulus ring. For peripheral direction, the value indicates the outer edge, correspondingly.