Fig. 12.

Averaged retinotopic organization of human visual cortex revealed by fMRI of thin phase-encoded stimuli and field sign analysis. The diagrams have a format comparable to the corresponding macaque retinotopy in Figure 3. A reveals the averaged polar angle retinotopy, and B reveals the averaged eccentricity data, from the same six hemispheres, averaged in right hemisphere format. The steps involved in the geometric averaging are described in the text. In A, each of thered, blue, and greenpseudocolor ranges represents retinotopically differentiable activation within a 60° subdivision of polar angle in the contralateral visual field (see logo, A). In B, the red, blue, and greenranges correspond to fMRI activation within logarithmically equal subdivisions of the eccentricity range from 0.75 through ∼15° in the visual field, centered at ∼1.5° (red), 3.8° (blue), and 10.3° (green) (seelogo, B). The representation of eccentricities beyond 15° was not activated by our stimuli, so the diagrams are correspondingly limited to the central two-thirds of the surface area in each of retinotopic areas shown here. Although techniques used to study the macaque and human retinotopy differ significantly, the macaque and human retinotopic maps are quite similar. The most significant difference here is inV3/VP, in which the polar angle representation is expanded proportionately in humans.