Synaptic facilitation: long-term neuromuscular facilitation in crustaceans.

Continuous stimulation at frequencies equal to or greater than 5 hertz for 20 to 30 minutes results in a two- to fivefold increase in the amplitudes of excitatory postsynaptic potential recorded from certain stretcher and opener muscles of decapod crustaceans. This long-term facilitation appears to result from an accumulation of sodium ions within the nerve terminals. It persists for at least 1 hour after stimulation has stopped.