Figure 5. Distribution of 3D shape tuning.

(a) Comparison distribution of surface point positions in the y/z plane (relative to object center of mass) in random stimuli (1^st generation stimuli for all 95 neurons described here). The scale is in arbitrary units approximately corresponding to stimulus size (maximum span in any direction averaged across stimuli = 1.08). (b) Distribution of Gaussian tuning peaks in best-fit models for 95 neurons. The stimulus distribution peak is shown in the surface plot (asterisk) and the stimulus distributions are shown in the marginal histograms (red curves). The distribution is biased toward positive values in the z dimension, i.e. positions in front of object center. (c) Comparison distribution of surface curvatures across random (1^st generation) stimuli. The bias toward positive (convex) curvatures is characteristic of closed, topologically spherical surfaces. (d) Distribution of Gaussian tuning peaks in the curvature domain. The stimulus distribution peak is shown in the surface plot (asterisk) and the stimulus distributions are shown in the marginal histograms (red curves). Relative to the stimulus distribution, the tuning peaks are biased toward higher magnitude convexity in the maximum curvature dimension and higher magnitude concavity in the minimum curvature dimension.