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. 2012 Aug 6;7(8):e40233. doi: 10.1371/journal.pone.0040233

Figure 4. The error landscape for a neuron with two synapses and the descent on this landscape during learning.

Figure 4

The neuron receives several input spikes on each synapse, the same as in Figs. 1 and 2, and has to fire one spike at a predefined target timing, the same as in Fig. 2. (A), (B) A contour plot of the VP and E distances between the actual spike train and the target spike train as a function of the values of the synaptic efficacies. The thick lines correspond to discontinuities of the distances. (A) VP distance. (B) E distance. (C), (D), (E) The dynamics of the synaptic efficacies according to the learning rules. The black lines represent actual trajectories of the synaptic efficacies. The vectors represent synaptic changes. The green line corresponds to the values of the synaptic efficacies for which the output corresponds to the target spike train. (C) E-learning. (D) I-learning. (E) ReSuMe.