Figure 5.

Long linear sequences of orientation preference within an organization of the radial type. (A) The local preferred orientation and the magnitude of preference are shown in a format of short lines polar map (the area shown here is the same as that depicted by the angle map shown in Fig. 4B). In the background is the pattern of magnitude of the orientation gradient. The point-like bright regions indicate the pinwheel centers; the organization here is of the radial type. Blue and red lines represent the tracks along which sequences of orientation were sampled for presentation in B. The orientation singularities are distributed approximately along straight lines, parallel to the two marked lines. (B) Blue and red curves stand for the orientation preferences along the blue and red lines in A. Along these lines, the preferred orientation changes in an approximately linear manner, yet in opposite rotation direction within the space of orientation. (C) Cartoon of a crystal-like orientation preference map showing overlap between perfectly radial and perfectly linear organizations. The map is shown at a resolution of 45° (four colors). Orientation centers are distributed along rows and columns across the map. The chirality (clockwise or counter clockwise change of orientation) of pinwheels located in the same row is identical. Singularities located along adjacent rows are of opposite chirality. Linear sequences of orientation run parallel to and in between the horizontal lines formed by the orientation centers. The orientation preference along adjacent linear sequences changes in opposite rotation directions within the orientation space. This cartoon demonstrates that infinitely long linear sequences of orientation may be embedded within a crystal-like orientation map organized radially.