Model units are drawn from Figure 4—figure supplement 6; Figure 4—figure supplement 7 (a), Example spatial RFs of randomly selected units at their best time step. (b–c), Example 3D and corresponding 2D spatiotemporal RFs at most recent six time steps of (I, space-time separable, and II, space-time inseparable) real (Rao and Ballard, 1999) V1 neurons and (c) (I-III, space-time separable, and IV-VI, space-time inseparable) sparse coding model units. (d), Proportion of power (sum of squared weights over space and averaged across units) in each time step, for real and model populations. (e), Joint distribution of spatial frequency and orientation tuning for population of model units. (f), Distribution of orientation tuning for population of model units. (g), Distribution of RF shapes for real neurons (cat, Jones and Palmer, 1987, mouse, Niell and Stryker, 2008 and monkey, Ringach, 2002) and model units. For (e–g), only units that could be well approximated by Gabor functions (n = 1246 units; see Materials and methods) were included in the analysis. Of these, only model units that were space-time separable (n = 569) are shown in (g) to be comparable with the neuronal data (Ringach, 2002). The addition of noise only leads to subtle changes in the RFs; most apparently, there are more units with RFs comprising multiple short subfields (forming an increased number of points towards the lower right quadrant of (g) than is seen in the case when noise is used.