Predicting the Anisotropy of Lateral Connections in the Visual Cortex from the Distribution of Singular Points in the Pattern of Orientation Columns Laboratory for Visual Neurocomputing It is known that neurons in the visual cortex selectively respond to the inclination (orientation) of the contour lines of visual images, and that the optimally responsive orientation changes continuously along the cortical surface, indicating a pattern of orientation columns. The pattern of orientation columns is also characterized by the presence of singular points around which the optimal orientation changes by 180 degrees. So far, it has been shown by the optical recordings from area 17 in monkeys and cats that clockwise and counterclockwise singular points tend to be collocated alternately. In this study, we carefully examined the distribution of singular points for optimal orientations near the areas 17/18 border of cats, using the intrinsic optical recording technique. As a result, near the interareal boundary singular points of the same type tend to be arranged parallel to the boundary (Fig. A), and it was confirmed that this tendency is statistically significant. It is thought that the observed pattern is formed to maximize the orthogonality of the orientation columns and the area 17/18 border. We also conducted computer simulation based on a simple model of orientation column formation assuming anisotropic lateral connections in the cortex. We could reproduce the same tendency of arrangement of singular points as observed in our experiment. This suggests that there are anisotropic lateral connections near the interareal boundary. 　 Fig. A Pattern of orientation columns obtained from the optical recording. The area sandwiched by the two dashed lines indicates the transition zone between areas 17 and 18. The optimal orientations are represented by the colors. Fig. B Pattern of orientation columns obtained from the simulation when the excitatory lateral connections are elongated in the vertical direction on paper. We can see the tendency that singular points of the same type are arranged horizontally. Ohki, K., Matsuda, Y., Ajima, A., Kim, D.-S., Tanaka, S. Arrangement of Orientation Pinwheel Centers around Area 17/18 Transition Zone in Cat Visual Cortex Cerebral Cortex 10, pp593-601, Jun (2000)