  We investigated the influence of efficacy of synaptic interaction on firing
synchronization in excitatory neuronal networks. We found spike death
phenomena, namely, the state of neurons transits from limit cycle to fixed
point or transient state. The phenomena occur under the perturbation of
excitatory synaptic interaction that has a high efficacy. We showed that the
decrease of synaptic current results in spike death through depressing the
feedback of sodium ionic current. In the networks with spike death property the
degree of synchronization is lower and unsensitive to the heterogeneity of
neurons. The mechanism of the influence is that the transition of neuron state
disrupts the adjustment of the rhythm of neuron oscillation and prevents
further increase of firing synchronization.
