On the basis of the recent reports, immediate early gene (IEG) can be rapidly induced and expressed when a songbird is either stimulated by bird-song or in its vocal-behavior. The expression area and level in brain of IEG, such as zenk, c-fos and c-jun, are corresponding to where the neurons are related, as a songbird is stimulated, suggesting that IEG plays an important role in vocal learning and memory.