Superposition models of the discharge patterns of units in the lower auditory system

Superposition of point processes has often been suggested as an abstract model for the generation of neural discharge patterns due to its simplicity (input spike trains are simply merged and then retransmitted by the model neuron). The properties of the superposition of two renewal processes are examined in relation to the properties of its components. A satisfactory condition is found so that the superposition of two renewal processes possesses negative serial dependence of interevent intervals. However, the imposition of a dead time of approximately the same duration as that of the components on their superposition process is shown to remove much of this dependence. Thus, the adequacy of the simple superposition of renewal processes as a model for discharge patterns from regions that are typified by negative serial dependence (such as the lateral superior olive) may be limited, but may suffice for the discharges of primary-like units.