QUALITY OF COINCIDENCE DETECTION AND ITD TUNING: A THEORETICAL FRAMEWORK

Coincidence detector neurons increase their firing rate significantly if the input changes from random to coherent. Similarly, neurons in the avian nucleus laminaris vary their firing rate as a function of the interaural time difference (ITD). In both cases, neurons transform temporally coded input into a rate-coded output. To characterize the quality of this transformation we define a new measure, which explicitly takes noisy spike output of neurons into account. As an application, we investigate the coincidence detection properties of an integrate-and-fire (I&F) neuron in dependence on internal parameters and input statistics. We show that there is an optimal threshold and, furthermore, that there is a broad range of near-optimal threshold values. The theoretical results are applied to ITD-tuning of neurons in the laminar nucleus of the barn owl.