Sound delay lines in the nucleus laminaris of the chicken

Delays of neurophonic potentials (NP) induced by monaural sound stimuli were measured across the three dimensions in the nucleus laminaris (NL) of the anesthetized chicken. Peak latencies and delays in cross-correlograms changed with recording distance. An orderly delay line was observed across the NL thickness, that is, along dendritic trees of individual fusiform cells (FC), where phase lags increased dorso-ventrally during ipsi- and in the opposite direction during contralateral stimuli. Delays along isofrequency FC arrays were variable, with delay ranges being smaller for ipsilateral than for contralateral sound stimuli. Net delays for contralateral sounds were directed medio-laterally and differences between ipsi- and contralateral delays covered, roughly, intercochlear time differences (ITD). The observed delays are thought to contribute to sound localization and frequency analysis.