DELAY-LINE MODELS OF SOUND LOCALIZATION IN THE BARN OWL

The detection of interaural time differences underlies azimuthal sound localization in the barn owl. Sensitivity to these time differences arises in the brainstem nucleus laminaris. Auditory information reaches the nucleus laminaris via bilateral projections from the cochlear nucleus magnocellularis. The magnocellular inputs to the nucleus laminaris act as delay lines to create maps of interaural time differences. These delay lines are tapped by postsynaptic coincidence detectors that encode interaural time differences. The entire circuit, from the auditory nerve to the nucleus magnocellularis to the nucleus laminaris, is specialized for the encoding and preservation of temporal information. A mathematical model of this circuit (Grun et al., 1990) provides useful predictions.