Chapter IV Immediate-early gene (IEG) expression mapping of vocal communication areas in the avian brain

Publisher Summary This chapter describes the way the analysis of immediate-early gene (IEG) expression has been used to map vocal communication areas in the brain of songbirds and other avian groups. IEGs are genes that are rapidly and transiently induced in neuronal cells when these undergo depolarization. While some IEGs code for proteins that exert direct effects on neuronal cell function, several others encode transcription factors thought to modulate neuronal function indirectly by triggering gene regulatory cascades. Although the function of the IEG response is not yet fully understood, the analysis of induced IEG expression can be used to identify patterns of brain activation associated with specific stimuli or behaviors. The chapter focuses on zenk , the IEG for which most data in birds are currently available. The comparative zenk expression analysis has revealed several striking similarities in the organization of brain systems for vocal communication in independent avian vocal learning orders.