The neural bases of vocal behaviour in relation to its communicative/social aspects: Differential representation of sounds with distinct biological significance in an avian associative auditory area
Résumé
Categorization is essential to all cognitive processes, but identifying the neural substrates underlying categorization processes is a real challenge. Among animals that have been shown to be able of categorization, songbirds are particularly interesting because they provide researchers with clear examples of categories of acoustic signals allowing different levels of recognition, and they possess a system of specialized brain structures found only in birds that learn to sing: the song system.In this study, we demonstrate that the activity of a songbird's non-primary, associative auditory area can indicate or represent classes of sounds corresponding to behaviourally-defined recognition processes. This auditory area has been compared to the superficial layers of auditory cortex or to secondary mammalian auditory regions such as the lateral belt in primates or Wernicke's area in humans. By showing differential representation of sounds with distinct biological significance (as observed in the field), as seen in higher-order fields of the auditory cortex of mammals, including humans, our study actually reinforce the parallel between these structures, and contribute to widen the impact of studies on songbirds. Moreover, given the many parallels that exist between birdsong and speech, we believe our results may contribute to a better understanding of the neural bases of speech.