The acetylcholine and catecholamine contents in song control nuclei of zebra finch during song ontogeny.

The acetylcholine (ACh), dopamine (DA) and noradrenaline (NA) concentrations in the song control nuclei, the magnocellular nucleus of the anterior neostriatum (MAN), the caudal nucleus of the ventral hyperstriatum (HVc) and the robust nucleus of the archistriatum (RA) were measured using high performance liquid chromatography (HPLC) at 5 different ages (30, 40, 50, 60 and 90 days after hatching). ACh concentration of these nuclei increased markedly during the critical period for learning and decreased gradually toward adult age. The change either in the HVc or the MAN preceded that in the RA. The developmental changes of catecholamine concentration of each nucleus were different from those of ACh. DA concentrations in the HVc increased at the same time (between 30 and 40 days after hatching) as ACh increased, whereas concentrations of DA and NA in the other two nuclei did not increase. Combined increment of both ACh and DA occurred only in the HVc and this may contribute to plastic change by dual synaptic modification during the critical period of song learning.