Auditory responses in the HVC of anesthetized starlings

The present study, using a systematic recording method that we recently developed, describes the behavior of the neurons of the vocal control nucleus HVC in response to a variety of acoustic stimuli in a songbird species with multiple song types, the European starling. Most neurons did not respond to any of the stimuli that were presented, and those neurons that did respond responded to a different number of stimuli and showed distinct response features. The latter were thus classified into 3 categories, according to the number of stimuli to which they responded. Although only intracellular data could unambiguously determine to which population the neurons we recorded belonged, these 3 categories might correspond to the 3 populations of neurons that have been previously described in the HVC. Interestingly, responsive neurons of the 3 categories appeared to mainly respond to stimuli that were not the bird's own song. However, most of the stimuli to which the HVC neurons responded correspond to sounds that are important in the everyday social life of the starlings. We thus discuss our results in relation to the social life of these birds, to possible species differences in the processing of communicative signals, and to methodological issues.