The role of feedback from the vocal organ. I. Maintenance of stereotypical vocalizations by adult zebra finches.

The stereotypical vocal patterns of adult male zebra finches (Poephila guttata) were examined before and after elimination of auditory feedback and/or feedback from the vocal organ (the syrinx). Elimination of auditory feedback was accomplished via bilateral removal of the cochleae, whereas feedback from the syrinx was eliminated by cutting hypoglossal afferent fibers while leaving hypoglossal efferents intact. Very little or no disruption of song was observed in birds which underwent deafening as well as unilateral deafferentation of the syrinx. Control experiments showed that the minor deficits observed were not attributable to lesion of pulmonary fibers in the descending branch of the vagus. There was also little deficit in song behavior of birds that were deafened and subjected to bilateral deafferentation of the syrinx. These results are consistent with the hypothesis that stable song patterns in adult passerine birds are not dependent on peripheral sources of feedback, but may be governed by a learned central control program.