Evolution of weights and reconstructions in the spiking model.

a–b: Evolution of weights in the spiking model. Weights as learned after different numbers of stimulus presentations are shown for 10 example hidden units. c–d: Attempted reconstructions at different points in training for the two spiking model experiments, for the stimuli shown in the bottom rows. Early in training, the same few hidden units whose incoming weights happened to be strongest were often activated regardless of the stimulus, leading to similar reconstruction attempts for different stimuli (first rows). Over time, the attempted reconstructions came to resemble the input stimuli.