Much of my work has been directed to studying human behavioral effects of prenatal hormones in children and adults who were exposed to high levels of androgens early in life because of congenital adrenal hyperplasia (CAH). Results from that work suggest that early androgens differentially affect different aspects of behavior. Exposure to moderate levels of androgen early in development (as is typical of girls with CAH) is associated with increases in some male-typical behaviors, including play with boys' toys, aggression, and spatial ability, and reductions in some female-typical behaviors, such as play with girls' toys and interest in infants. Nevertheless, some behaviors appear to be only weakly affected by moderate levels of androgen: most CAH girls have female-typical gender identity and prefer girl playmates. Of course, individuals with CAH do not provide a perfect test of hormonal influences on behavior, and I have attempted to rule out alternative explanations of the behavioral changes seen in CAH girls, such as parent treatment in response to the girls' virilized genitalia, and postnatal androgen excess, although definitive studies remain to be done. In addition to providing evidence about behavioral effects of prenatal androgens, these studies also provide information that can be used in the medical management of children with CAH and other intersex conditions.

My research efforts are now focused on understanding more about the nature and mechanisms of hormonal influences on behavior.

I am studying behaviors that have not been well-studied in representative samples of people with unusual hormone exposure. In my longitudinal sample of females with CAH, I am studying sexual orientation and romantic experiences, and examining whether these behaviors are related to earlier (measured) childhood behavior. I am also studying whether early androgens inhibit behaviors that are more characteristic or higher in females than in males, such as decoding of emotions (nonverbal sensitivity) and verbal memory.

Because it is likely that early gonadal hormones affect behavior by acting directly on the brain, I am in the process of planning a collaborative fMRI study of the children with CAH whose behavior I have carefully detailed.

As a developmentalist, I am particularly interested in knowing more about the ways that those brain changes result in behavioral changes. It seems likely that hormonally-influenced predispositions affect an individual's selection of and response to the social environment. Girls with CAH provide a unique opportunity to investigate the factors that account for children's learning. For example, are girls with CAH -- most of whom play with boys' toys, but identify as girls -- more likely to imitate girls and women or boys and men? does this depend on the behavior that is being imitated (a sex-typed activity vs. a neutral activity)?

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Uniting my interests in individual differences in behavior and in the biological origins of those differences, I have studied the neural substrates of individual differences in cognition, in both normal and clinical samples. For example, data from a study of people with temporal lobe epilepsy (in collaboration with Michael Seidenberg and Leslie Baxter at Finch University of Health Science/Chicago Medical School and Bruce Hermann at the University of Wisconsin, Madison) indicate that, although the hippocampus clearly plays a role in verbal memory, sex differences in the presence or integrity of the hippocampus do not seem to be responsible for the sex difference in memory.

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