The zebra finch (Taeniopygia guttata) is an oscine bird established as a model for studying the neural mechanisms involved in vocal production. As every oscine it has a telencephalic nucleus called HVC involved in the song learning, production and maintenance. One major characteristic is it’s selective auditory responses to the bird’s own song (BOS) in anesthetized or sleeping birds.
Zebra finches’ songs have harmonics that can reach 20 kHz. A previous study showed BOS and low frequency enhanced BOS (increased relative power of frequencies below 1 kHz) evoke similar spike-count responses in HVC. However, an analysis of spike patterns demonstrated temporal coding information that discriminated between both stimuli, suggesting low frequencies are relevant for this nucleus.
There are no studies that evaluate which frequencies of BOS are necessary to elicit the auditory response in HVC. We recorded extracellular neural activity while the bird was asleep and used the BOS and filtered versions of it (f-BOS) as stimuli. We found HVC selective auditory response depends on the frequency range of the stimuli. Frequencies below 1.5 kHz are not enough for eliciting the same spike count as the original BOS. Contrarily, we found no differences in the spike-count elicited by BOS and f-BOS with frequencies above 5.5 kHz filtered (suppressed). These results suggest that frequencies below 5.5 kHz are relevant in auditory feedback and may be important for speech development and maintenance.