Inducible gene expression analysis has been successfully used to identify and characterize areas involved in the auditory processing of song in songbirds. When songbirds hear song, zenk, a gene encoding a transcriptional regulator linked to synaptic plasticity, is rapidly and transiently induced in several discrete areas of the telencephalon. This phenomenon is most marked in the caudomedial neostriatum (NCM), a major auditory processing area. zenk induction by song has proven very useful to investigate the functional organization of NCM as well as to characterize song-responding neurons in this brain area. Combined with data from anatomical and electrophysiological studies, the results of gene expression analysis suggest that NCM is involved in the auditory processing of complex sounds such as song and possibly in the formation and/or storage of song auditory memories. Thus, NCM appears to play a prominent role in perceptual aspects of vocal communication, and potentially in the process of vocal learning in songbirds and other vocal learning avian orders, i.e. parrots and hummingbirds.