Behaviorally Regulated mRNA and Protein Expression in the Songbird Brain

Excerpt

Most biological processes are the result of the regulated expression of genes into their protein products in a defined temporal and spatial manner. The study of these dynamic protein changes in the brain is called neuroproteomics. A class of proteins expressed in the brain that have generated significant interests are those regulated by neural activity, called activity-dependent genes. The activity of neurons in the brain is important for normal brain function and expression of behavior. One system where the study of these features has been brought together is that of the songbird vocal learning system. Songbirds, and a limited number of animals (i.e., parrots, hummingbirds, bats, cetaceans, seals, elephants, and humans) are capable of vocal learning, the ability to produced imitative and improvisational sounds. Most animals do not have vocal learning but produce species-specific innate sounds used for alarm (e.g., predator) or other communication functions (e.g., alert for food or attracting a mate). The production of learned vocalizations requires the animal to process what it hears in the auditory pathway of the brain and then to produce the sounds heard, as song in songbirds or speech in humans, through specialized motor learning pathways. In songbirds and other vocal learning birds, this song learning motor pathway is organized into anatomically discrete nuclei that are not found in vocal non-learning birds. In this regard, songbirds represent a relatively unique animal model suited to the study of molecular mechanisms of a learned behavior with parallels to human speech. In recent years, a number of genes and their protein products have been identified that are regulated by neural activity during hearing and singing in the auditory and vocal brain pathways of songbirds. This chapter focuses on proteins regulated in the vocal pathway of songbirds performing learned vocalization. A discussion of proteins regulated in the auditory pathway by hearing is presented by Pinaud et al. in Chapter 14.