Fig. 4.

Response properties of number neurons. (A and B) Comparison of different scaling schemes for the tuning curves. (A) R-squared, a measure of goodness of fit reflects symmetry of the tuning curves plotted on the four different scales. The tuning curves of number neurons become more symmetric when plotted on the nonlinear scale. (B) Sigma of the Gaussian fit for neurons preferring different numerosities. When plotted on the linear scale, the tuning curves become wider with increased numerosity. Error bars correspond to SEM. (C) Averaged normalized activity of all numerosity selective neurons compared to the random tuning curve (see Materials and Methods for details). The neural activity was normalized (0 = response to the least preferred numerosity, 1 = response to the most preferred numerosity) and then plotted as a function of absolute numerical distance from the most preferred numerosity. Neural response of numerosity selective neurons (black line) gradually decreased with the numerical distance. The slope of this tuning curve is notably different from the random tuning curve (gray line) of false-positive neurons obtained by random shuffling of trials. Error bars correspond to SEM.