Alward said both groups of birds that received testosterone treatment sang but the researchers noticed in some cases the canaries' songs were sung poorly. The birds that only received testosterone to the POM sang at high rates, but could not produce high quality song that is most attractive to females.
"Our data suggests that testosterone needs to act in different areas of the brain to regulate the specific components of this complex social phenomenon," said Alward. "It appears that, like in so many other species, testosterone in the POM can regulate an animal's motivation, in this case, the motivation to sing. However, singing and courting a female is more than just motivation. There is the quality of the song that is required to successfully attract a mate and then the process of attending to the female, or singing to her, when she is there which requires the coordination of multiple brain regions."
Meanwhile, the canaries that received testosterone throughout the brain displayed high-quality typical canary vocalization behavior, consistent with the idea that the hormone acts on several different brain areas to regulate how much as well as how well the birds can sing.
The canary brain is considered a good model for brain study due to its ability to change its neural pathways and synapses in response to changes in behavior, the seasonal environment and injury. For the birds used in the study, the researchers artificially replicated a springtime environment to study the birdsong and mating habits that occur during the appropriate season. The birds responded to the spring-like conditions with birdsong and mating behaviors as they normally would at that time of the year.
The researchers say these results have broad implications for research concerning how steroid use in humans affects sexual behaviors and how hormones regulate the difference components of speech in humans.
"The hormones in these birds are ide
|Contact: Latarsha Gatlin|
Johns Hopkins University