The Auditory Brainstem Response of the Chicken Hatchling

Abstract

The auditory brainstem response (ABR) is a useful approach for evaluating hearing function. It is easily acquired in vertebrate animal models like reptiles, birds, and mammals, and routinely utilized in clinical audiology with human patients. The ABR is complementary in animal models with existing developmental and in vitro research. However, despite the domestic white leghorn chicken (gallus gallus domesticus) being studied extensively at the molecular, cellular, and system levels for decades, there exists no modern characterization of the chicken hatchling ABR. To address this gap, we used click- and tone-burst stimuli to elicit the ABR in 43 wild type chicken hatchlings one- and two-days post hatch (P1 and P2). Click-evoked ABRs presented with three to four positive going microvolt (µV) peaks within 6 milliseconds (ms) post stimulus onset. Tone-evoked ABRs resembled findings in other avian species; thresholds from 100–4000 Hertz (Hz) exhibited a range of best sensitivity between 750–2000 Hz. Population latency/intensity functions revealed an increase in peak latency of roughly 300 microseconds (µs) per a decrease of 20 decibels sound pressure level (dB SPL) for both click- and tone-evoked ABRs. The chicken hatchling ABR not only complements existing molecular, cellular, and systems level research, but also resembles the ABR waveform of altricial avian species, highlighting the precocious development of the chicken.