Fig. 5: Receptive field plasticity.
a, External stimulus (for example, sound) activates a set of correlated excitatory and inhibitory afferents (simulated as inhomogeneous Poisson point processes) that feed forward onto a postsynaptic neuron with plastic synapses (*). Eight group pathways, consisting of 100 excitatory and 25 inhibitory afferents each, have correlated spike trains. The responsiveness of inhibitory afferents can be modulated by an additional learning signal. b, Timecourse of the mean excitatory (top) and inhibitory (bottom) weights of each group (color coded by groups). During a ‘learning window’, indicated by the shaded area (*), all inhibitory afferents are downregulated. The activation of excitatory input groups (Extended Data Fig. 4a) in the absence of inhibition establishes a receptive field profile. c, Continued simulation from b. Weights are stable until inhibition is downregulated for a 200-ms window (*), during which the green pathway (4) has the strongest activation (Extended Data Fig. 4b). Consequently, the preferred input pathway switches from 6 (pink) to 4 (green). d, Snapshots of the average synaptic weights for the different pathways before (top), immediately after plasticity induction (middle) and at the end of the simulation as indicated by the ⋆ symbols in b and c. e, Experimental data21 show receptive field profiles of excitatory and inhibitory inputs before (top) as well as 30 minutes (middle) and 180 minutes (bottom) after pairing of non-preferred tone and nucleus basalis activation. Error bars indicate s.e.m. Experimental data were adapted from ref. 21 with permission (we refer to ref. 21 for information about sample sizes and statistical analysis).
