Telencephalic nuclei control late but not early nestling calls in the budgerigar

Bilateral lesions targeting the central nucleus of the anterior archistriatum (AAc) were placed in nestling budgerigars (Melopsittacus undulatus) aged 5, 9, 13, 22, 26, and 33 days post-hatch in order to evaluate the role of the telencephalon in producing nestling vocalizations in this species. In budgerigars, AAc is the final common pathway from telencephalic vocal control nuclei to brainstem respiratory and syringeal motorneuron pools. The results show that lesions destroying AAc bilaterally in addition to surrounding archistriatum and neostriatum do not alter the production of early simple patterned foodbegging calls but do prevent both the normal transition at 3-4 weeks post-hatch to more complex begging calls as well as the emergence of individually-distinctive contact calls around the time of fledging. These vocal results are strikingly similar to those obtained in previous studies in which early deafening of nestlings (Heaton and Brauth, 1999) and early lesioning of auditory areas in the anterior telencephalon (Hall WS, Brauth SE, Heaton JT. Comparison of the effects of lesions in nucleus basalis and field 'L' on vocal control learning and performance in the budgerigar (M. undulatus), Brain Behav. Evol., 1994;44:133-148) did not affect call production until 3-4 weeks post-hatch. These data combined support the idea that neither auditory feedback nor telencephalic sensorimotor circuits are necessary for the production of nestling calls before 3 weeks post-hatch.