The ordinate shows the mean Pearson correlation coefficient between the LFP responses to all 77 images at a given site and the average spiking activity within a circle of a given radius around the LFP recording site (indicated in the x-axis) as shown in Figure 6. The distances across penetrations were determined from the anterior/posterior and lateral/medial locations of the penetrations at the cortical surface (see text and Experimental Procedures for details). Since these distances are prone to errors, here we estimate how the plot would change after assuming different degrees of error in the distance measurements. A random amount of noise was added to the distance between sites. The noise was a zero-mean gaussian with either 0 (red), 1000 (green), 5000 (blue) or 10000 (yellow) microns for standard deviation.