[babulus]

In general the contribution of an action potential from one neuron is not enough to make the neurons it's connected to also fire. Neurons require relatively synchronized excitatory inputs from a large number of neurons to induce an action potential. There will also be inhibitory inputs from other neurons as well.

Another phenomenon that counters recurrent excitation is lateral inhibition. An excitatory neuron firing will synapse with an inhibitory interneuron nearby. If the interneuron fires it inhibits a great number of neurons in the local vicinity, including the excitatory neurons that just made it fire. It can act to reduce local excitability.