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Fig. 12.3. Effect of excitatory connection range on synchronization. A network of 30 neurons with varying extent of lateral excitatory connections was simulated for 500 iterations. Synchronization occurs through the excitatory connections even though the connections did not cover the whole network. From (a) to (e), the lateral excitatory connection radius r_E was reduced from 30 (i.e. full connectivity) to 10, 5, 2, and 0 (the bars at right depict the connections of the neuron in row 15). All other parameters were the same as before. Synchronization starts to break once the radius reaches 2, but for a fairly local connection radius (e.g. 5), global synchronization is maintained. As expected, with no excitatory connections (e), the initial random order of spikes is maintained throughout the simulation. Global synchrony can therefore be established with local connections.