ASSOCIATIVE LEARNING AND STIMULUS NOVELTY INFLUENCE THE SONG-INDUCED EXPRESSION OF AN IMMEDIATE-EARLY GENE IN THE CANARY FOREBRAIN

To identify variables that affect immediate early gene (IEG) expressio n in the auditory telencephalon of songbirds, we developed a condition ing paradigm that trained adult male canaries to associate song with a mild shock. Learning of the association was measured by a bird's fear and avoidance responses. Birds exposed to paired song and shock were compared to yoked controls exposed to each stimulus alone or to both u npaired. Additional groups examined the effects of attention and stres s, and of the novelty of the stimulus situation. In situ hybridization analysis of brain sections revealed an enhancement of ZENK expression in birds learning the association between song and shock above levels induced by song alone or yoked-unpaired song and shock. This effect w as specifically seen in the caudomedial auditory telencephalon (NCM-HV CM). A comparison of the several control groups indicated that novelty of the song stimulus or of its pairing with shock were the main varia bles that predicted ZENK levels in NCM-HVCM. These observations are co mpatible with ZENK playing a role in the formation of song perceptual memories.