December 30, 2013
Testosterone Study In Male Birds Offers Insight In Human Behaviors
Lee Rannals for redOrbit.com - Your Universe Online
Adding a little testosterone to a male canary’s brain influences the bird’s ability to successfully attract a mate through birdsong. Male canaries use their song to win over a female canary as a mate. The quality and frequency of the songs change along with the seasons.Researchers at The Johns Hopkins University wrote in the journal Proceedings of the National Academy of Sciences (PNAS) that adding testosterone into select areas of a male’s brain enhances song activity. The study’s findings could help provide more insight into how testosterone acts in the human brain to regulate speech or help explain how anabolic steroids affect human behaviors.
The team divided 20 canaries into two groups to receive a hormone implant, with one group receiving a testosterone injection in the medial pre-optic nucleus (POM) and the other receiving an injection that acted throughout the brain. The scientists artificially replicated a springtime environment to study the birdsong and mating habits that occur during mating season. The birds responded to the conditions with birdsong and mating behaviors as they normally would during this season.
Researchers discovered that when a male canary received testosterone in a specific area of the brain, the frequency of the song increased. However, they also discovered that the song quality did not change in comparison to birds that received testosterone treatment throughout the entire brain.
The team said that some of the birds that received treatment sang songs poorly. Birds that received injections in the POM region sang their songs at high rates, but were unable to produce the 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,” Beau Alward, lead author of the study and a graduate student, said in a statement. “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.”
Male canaries that received testosterone throughout the brain showed high-quality song behavior, showing that hormones act on several different brain areas to regulate how much as well as how well the birds can sing.
Scientists consider the canary brain a good model for brain study because of its ability to change its neural pathways and synapses in response to changes in behavior, the seasonal environment and injury. The team believes their study could have implications for research concerning how steroid use in humans affect sexual behaviors and how hormones regulate the difference components of human speech.
“The hormones in these birds are identical to those in humans and they can regulate brain changes in a similar manner,” senior author Gregory F Ball, vice dean for science and research infrastructure and professor in the Department of Psychological and Brain Sciences in the Zanvyl Krieger School of Arts and Sciences, said in a statement.