Fig. 3.

Effects of blur on pinwheel center position. (a) Simulation of pinwheel movement and annihilation due to low-pass filtering with increasing FWHM to 1,000 in vivo pinwheel patterns with 350 × 550-μm spacing. As the Cauchy blurring kernel broadens, the average pinwheel movement increases nearly linearly, resulting in a bias in the observed singularity location relative to the true in vivo location of the singularity. At 240 μm FWHM, the orientation singularity position error is 116 μm on average. (b) Simulation of the experiment of Maldonado et al. (15). The offset of the tetrode recording site from the true orientation singularity location is demonstrated on a synthetic orientation tuning preference map. Here, the tetrode is illustrated by a spotlight of radius 65 μm offset from a orientation singularity by 116 μm. In this example, the tetrode observes an orientation range of ≈40°. The black ring marks the area of a CO blob with a 100-μm radius centered at the chosen orientation singularity, and the areas of the tetrode recording and the CO blob exhibit little overlap. (Scale bar, 500 μm.)