An interaural time difference map resulting from axonal selection through non-specific learning

Abstract An orderly spatial representation of the azimuthal position of a sound source has been observed in many animals. Barn owls, e.g., derive the azimuth from a neuronal map of interaural time differences (ITD) with a temporal precision of a few microseconds. We present a model of how an ITD map can develop in an array of spiking neurons in the barn owl's nucleus laminaris. We have combined homosynaptic spike-based Hebbian learning with presynaptic propagation of synaptic modifications. The latter is a feasible interaction mechanism between neurons and may be orders of magnitude weaker than the former. It is a key to explaining the widely assumed place code proposed by Jeffress (J. Comput. Physiol. Psychol. 41 (1948) 35).