Female canaries sing sexily with testosterone

The influence of hormones on the brain, and on learning and memory processes, is complex and difficult to measure, but canary song is a good model for analysing these types of process. Hartog analysed which substances played a part in the singing behaviour of female canaries and how these substances altered the anatomy of the brain.

Multifunctional testosterone Previous research had already shown that testosterone influenced singing behaviour. It gave rise to new neurones (nerve cells) in the area of the brain that controls singing. However, the extent to which other proteins, such as BDNF, also played a part remained unclear. Hartog established that BDNF could get the females to sing, even if the female birds had not been treated with testosterone. Moreover, combining BDNF and testosterone allowed the females to master the art of 'sexy' song structures, normally reserved for virile male birds.

Interestingly, testosterone has two completely independent effects. It stimulates the production and fusion of new neurones in existing networks in the brain and also results in a widening of the blood vessels and a changed anatomical structure in the area of the brain responsible for singing. The first effect depends on the protein BDNF, but the second appears to be independent of BDNF.

With her results, Hartog has shown that changes in the nerve cells not only produce a physical change, but also a change in behaviour patterns. Tessa Hartog's research throws new light on the influence of hormones on the brain and on learning and memory processes.

Tessa Hartog's research was funded by NWO, and was part of the Open Programme Solid Earth.