Behavior of the simulated spiking network for the MNIST dataset.

a: Behavior of the network during a typical image presentation; compare with Fig 1b. Time period of external stimulation shown by grey bar. Raster plot includes all neurons which fired at least one spike during the presentation. The spikes of the visible neurons are in the bottom row and those of the hidden neurons are directly above. The top two rows, in grey, show the spikes for the inhibitory pools at each layer. Although the each training presentation ran for 65ms, all spikes occurred before 30ms so the raster plot was ended there. b: Reconstruction loss function, black dots, (defined in text) decreases over time, as does sparsity loss function (red, note log scale on y axis). c: The trained networks’ attempted reconstruction of representative training images. Each image shows the ON cell values minus the OFF cells. The first row shows the inputs to the network. The second row shows the attempted reconstruction .