Steroids, not songs, spur growth of brain regions i...( Neuroscientists are attempting to und...)

Neuroscientists are attempting to understand if structural changes in the brain are related to sensory experience or the performance of learned behavior, and now University of Washington researchers have found evidence that one species of songbird apparently has something in common with a few baseball sluggers. Both rely on steroids, birds to increase the size of song production areas of their brain and some players, apparently, to knock a fastball out of the park.

Writing last month in the Journal of Neuroscience, Eliot Brenowitz and his colleagues showed that the Gambels white-crowned sparrow uses testosterone, a naturally occurring steroid, to trigger the seasonal growth of these brain regions. Birds use song to attract mates and mark their territory. Their finding is counter to some previous work with other birds and rodents that indicated environmental factors can influence brain development and create more neuronal connections.

We would like to think that if we shape the environment we can guide the brains structure, said Brenowitz, a UW professor of psychology and biology. But the idea that experience can drive growth of the brain regions that control song behavior in birds was disproved by this study. You can change the experience and the behavior, but you dont change the structure of the brain.The UW scientists found that the three brain regions in white-crowned sparrows that had been deafened were just as large as those regions in normal sparrows. However, the deafened birds only sang one-eighth the number of songs that the hearing birds sang.

To show this, the researchers captured 19 adult male white-crowned sparrows during their fall migration and housed them in short-day light conditions to mimic winter for 12 weeks. Eleven of the birds then were surgically deafened. A week after the surgery, all of the birds were given testosterone implants and were shifted to long-day light conditions, similar to what they w
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Contact: Joel Schwarz
joels@u.washington.edu
206-543-2580
University of Washington
23-Jul-2007