Polar angle mapping with DOT Polar angle mapping with DOT. (a) Functional responses to an angularly swept grid (subject 5). Polar angle mapping with DOT. (a) Functional responses to an angularly swept grid (subject 5). The grid (60° polar angle, 0.5–10° radial angle, reversed at 10 Hz) was rotated in steps of 10° (polar angle) each second. The successive stimulus and activation images have a phase shift of 90° from the previous image. Color maps were normalized within each frame to plus or minus maximum contrast (0.34, 0.60, 0.45, and 0.32 μM, top to bottom respectively). (b) Half-maximum contours of the four activations show the left–right symmetry of the mapping for the angular sweep. Benjamin W. Zeff et al. PNAS 2007;104:29:12169-12174 ©2007 by National Academy of Sciences