Twitter thread on the latest paper from Katie Schroeder @katieschro8. Illustrations by Katie Schroeder
Baby songbirds already have a surprisingly well-developed auditory processing system!
@HealeyLab and I are excited to share the first paper from my dissertation.
Songbirds, like other altricial animals, are not fully developed at hatching. Hearing sensitivity is not fully mature until ~3 weeks of age, right around the time that the sensitive period for tutor song acquisition begins.
Nevertheless, behavioral evidence suggests that embryos and nestlings can discriminate songs and learn call elements before hearing sensitivity matures. How is that accomplished in the brain of a still-developing bird?
I conducted extracellular recordings in the auditory forebrain region NCM (analogous to mammalian A2) of young zebrafinches to assess neural properties and responses to species-specific songs before the sensitive period of song motor learning opens.
Remarkably, all birds were highly responsive to songs. Nestlings even showed the same putative cell types and stimulus-specific adaptation that is characteristic of NCM in adults!
Fidelity of temporal coding also showed the same pattern in response to different species’ songs across all ages, suggesting that species recognition is either innate or learned very early.
This study provides the first evidence that electrophysiological properties of higher-order auditory neurons are already mature in nestling songbirds.