Then, researchers flipped a key genetic switch in the hermaphrodites, effectively making a few of their neurons think that they were actually part of a male worm. Immediately, they began behaving like males, crawling toward the scent of pyrazine. With a single genetic modification, the hermaphrodites began acting like males. Even though most of these worms looked like regular hermaphrodites, they behaved according to the sexual identity of a just a few of their neurons.
This work reveals an unexpected way that sex can influence the function of the brain, said Portman, who is also a member of the Center for Neural Development and Disease and the Department of Biology. It would be logical to think that all differences in the behavior of the sexes would result from neurons that are in one sex but not the other. We did not find that. Instead, we found that the behavior of nerve cells that are present in both sexes can be modified by the sexual status of the organism. That tells us that theres a surprising, unexpected dimension of sex differences in brain function.
Its far too soon to say what results like this might mean for our understanding of the human brain, said Portman. But autism is a perfect example of a disorder where we know very little about what is actually happening in the brain. The incidence of the disorder is increasing, and its clear that boys are affected more often than girls. At the same time, its unknown how or why a difference in sex chromosomes translates to differences in how brain cells function or to our susceptibility to different disorders. Thats what we hope to learn, ultimately for the benefit of people.
|Contact: Tom Rickey|
University of Rochester Medical Center