Figure 2. Auditory spectrotemporal and visual spatiotemporal RFs of real neurons and temporal prediction model units.

(a), Example spectrotemporal RFs of real A1 neurons (Willmore et al., 2016). Red – excitation, blue – inhibition. Most recent two time steps (10 ms) were removed to account for conduction delay. (b), Example spectrotemporal RFs of model units when model is trained to predict the future of natural sound inputs. Note that the overall sign of a receptive field learned by the model is arbitrary. Hence, in all figures and analyses we multiplied each model receptive field by −1 where appropriate to obtain receptive fields which all have positive leading excitation (see Materials and methods). (c), Example spatiotemporal (I, space-time separable, and II, space-time inseparable) RFs of real V1 neurons (Ohzawa et al., 1996). Left, grayscale: 3D (space-space-time) spatiotemporal RFs showing the spatial RF at each of the most recent six time steps. Most recent time step (40 ms) was removed to account for conduction delay. White – excitation, black – inhibition. Right: corresponding 2D (space-time) spatiotemporal RFs obtained by summing along the unit’s axis of orientation for each time step. Red – excitation, blue – inhibition. (d), Example 3D and corresponding 2D spatiotemporal (I-III, space-time separable, and IV-VI, space-time inseparable) RFs of model units when model is trained to predict the future of natural visual inputs.