In 1970, Marler set the idea of a parallel between human speech and birdsong, emphasizing the many common properties in vocal

In 1970, Marler set the idea of a parallel between human speech and birdsong, emphasizingthe many common properties in vocal development of both infants and songbirds. One of thebest-known features of human speech is the hemispheric specialization of the brain for itsperception and production. The lateralization for the production of song that has beenobserved in a number of passerine birds is reminiscent of this hemispheric asymmetry.However, although evidence exists for a lateralization of song production, very few studieshave focused on the perceptual aspect of lateralization in songbirds. In the present study, weinvestigated the central processing of communicative and artificial signals at different level ofthe song system in male starlings. Neuronal responses to a variety of species-specific andartificial nonspecific stimuli were recorded in both hemispheres of awake and anesthetizedbirds. Recordings were made in the primary auditory area of the songbird brain, namely theField L Complex, which is the main auditory input of the song system, and in the vocalcontrol nucleus HVC, which is a highly integrative part of this system. In both cases, the righthemisphere exhibited significantly more responsive units than the left one when the birdswere awake, and this difference was reduced or even suppressed under anesthesia. Mostimportantly, our results showed a complex and state-dependent hemispheric specializationtowards behaviorally-relevant classes of stimuli. These results are in agreement with thesuggestion that the two hemispheres exhibit different general functions in terms of attentionor the nature of the cognitive task performed, and add to the many parallels between the avianand human systems that have become paradigmatic of vocal communication. Hemisphericspecialization may therefore have been a general feature in the evolution of vocalcommunication. ReferencesMarler P., (1970). A comparative approach to vocal learning: song development in white-crowned sparrow. J. Comp. Physiol. Psychol.(Monogr.), 71, 1-25.