Emergence of Oriented Cell Assemblies Associated with Spike-Timing-Dependent Plasticity
We studied the emergence of cell assemblies out of a locally connected random network of 10,000 integrate-and-fire units distributed on a 100×100 2D lattice. The network was composed of 80% excitatory and 20% inhibitory units with balanced excitatory/inhibitory synaptic weights. Excitatory–excitatory synapses were modified according to a spike-timing-dependent synaptic plasticity (STDP) rule associated with synaptic pruning. In presence of a stimulus and with independent random background noise (5 spikes/s), we observed that after 5·105 ms of simulated time, about 8% of the exc–exc connections remained active and were reinforced with respect to the initial strength. The projections that remained active after pruning tended to be oriented following a feed-forward converging–diverging pattern. This result suggests that topologies compatible with synfire chains may appear during unsupervised pruning processes.
KeywordsInput Unit Time Domain Analysis Discrete Time Step Spike Neural Network Synaptic Pruning
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