Dendritic spine loss and enlargement during maturation of the speech control system in the mynah bird (Gracula religiosa).

Three types of neurons were identified in Golgi-Cox preparations of the telencephalic nucleus HVc of the mynah bird with the Sholl method. In a comparison of birds of 10 weeks and speech-trained birds of one year of age a reduction of dendritic spine density and an enlargement of the remaining spines was found in a large isopolar cell type. These findings are interpreted in terms of the mynah's shrinking potential with age to imitate new sounds and the stabilization of the acquired repertoire.