Firing between two spike thresholds: implications for oscillating lobster interneurons.

An identified interneuron in the lobster commissural ganglia fires spikes only between membrane potential values of -60 and -30 millivolts. The membrane potential of this neuron can also oscillate, and interaction between these two properties has important implications in determining the firing pattern of the neuron itself and the modalities of driving of a distant postsynaptic neuron.