Figure 3.

A schematic description of a reference-cell method for obtaining RF position disparities. (a) Reference-cell method. (i) Left and right RF maps are superimposed and are rotated so that the left and right eye RFs of cell-A (a reference cell) are at the same location and orientation. (ii) The position disparity of cell-B is defined as the distance between the centers of the left and right eye RFs (X: the distance perpendicular to RF orientation, Y: the distance parallel to RF orientation). (b) Hypothetical distributions of true and relative position disparities for a cell population. The position disparity measured in this study is actually the relative position disparity of one cell to that of a reference cell, i.e., it is the difference between the true position disparities of cell-B and cell-A. Assuming that true position disparities of individual cells are independent of each other, the SD of the distribution for true position disparity is expected to be smaller than that of the distribution for relative position disparity by a factor of . In other words, the distribution of true position disparity can be estimated by measuring relative position disparities for a population of cells. In addition, if the true position disparity of cell-B (d_B) is estimated as the relative position disparity (d_B-d_A), there will be an error in the estimate equal to the amount of the true position disparity for cell-A (d_A). Therefore, the distribution of true position disparity also represents the distribution of the error.