Our experimental approach will be based on the skills and expertise of the teams in the network. Plasticity in a variety of contexts will first be identified by in vivo brain imaging techniques and this approach will allow us to determine where and when plasticity takes places. Studies will then follow by a variety of tools ranging from molecular biology, transcriptomics, epigenomics, in situ hybridization, immunohistochemistry and tract tracing to define more precisely the cellular and biochemical events underlying and mediating the observed plasticity.

Specifically, 16 tasks (T) organized in 4 independent but nevertheless related work packages (WP) are outlined in this grant proposal.

In WP1, we shall investigate the genetic and epigenetic mechanisms that control the development of the connections between HVC and RA in the caudal motor pathway of the song control system in zebra finches.

WP2 will analyze the effects of steroid and thyroid hormones on genetic and epigenetic controls of axonal outgrowth during ontogeny in zebra finches.

WP3 will be modeled on WP2 but will analyze the genetic and epigenetic control of seasonal plasticity of the HVC to RA connection in adult starlings.

Finally in WP4, we will initiate investigations of the brain changes that take place during song learning in adult starlings. As in WP3 photoperiodic manipulations will be used to place male birds in a physiological stage corresponding to the fall when they will be exposed to defined song learning programs.

Together these studies will lead to major advances in our understanding of molecular (genetic and epigenetic) mechanisms underlying brain plasticity as it occurs spontaneously during ontogeny or during the annual cycle under the influence of steroid and thyroid hormones. This knowledge is important for the understanding of brain functioning in general (control of behavior, learning, effects of hormones, …) but it should also have an impact on the understanding of the mechanisms that could promote brain repair in pathological conditions such as brain trauma or neurodegenerative diseases.