Thalamic Gating of Auditory Responses in Telencephalic Song Control Nuclei

In songbirds, nucleus Uvaeformis (Uva) is the sole thalamic input to the telencephalic nucleus HVC (used as a proper name), a sensori-motor structure essential to learned song production that also exhibits state-dependent responses to auditory presentation of the bird’s own song (BOS). The role ofUva in influencingHVCauditory activity is unknown.Using in vivo extracellular and intracellular recordings in urethane-anesthetized zebra finches, we characterized the auditory properties of Uva and examined its influence on auditory activity in HVC and in the telencephalic nucleus interface (NIf), the main auditory afferent of HVC and a corecipient of Uva input. We found robust auditory activity in Uva and determined that Uva is innervated by the ventral nucleus of lateral lemniscus, an auditory brainstem component. Thus,Uvaprovides adirect linkagebetween the auditorybrainstemandHVC.Although low-frequency electrical stimulation in Uva elicited short-latency depolarizing postsynaptic potentials in HVC neurons, reversibly silencing Uva exerted little effect o