A relationship between behavior, neurotrophin expression, and new neuron survival

The high vocal center (HVC) controls song production in songbirds and sends a projection to the robust nucleus of the archistriatum (RA) of the descen ding vocal pathway. HVC receives new neurons in adulthood. Most of the new neurons project to RA and replace other neurons of the same kind. We show h ere that singing enhances mRNA and protein expression of brain-derived neur otrophic factor (BDNF) in the HVC of adult male canaries, Serinus canaria. The increased BDNF expression is proportional to the number of songs produc ed per unit time. Singing-induced BDNF expression in HVC occurs mainly in t he RA-projecting neurons. Neuronal survival was compared among birds that d id or did not sing during days 31-38 after BrdUrd injection. Survival of ne w HVC neurons is greater in the singing birds than in the nonsinging birds. A positive causal link between pathway use, neurotrophin expression, and n ew neuron survival may be common among systems that recruit new neurons in adulthood.