Final answer:
Zhou et al. discovered that the volume of the BSTc in the brain was smaller in male-to-female transgender individuals, aligning more closely with cisgender females than cisgender males, suggesting a biological component to gender identity.
Step-by-step explanation:
The student's question asks about research by Zhou et al., which focused on the differences in brain structure between individuals with male to female gender dysphoria and cisgender individuals. One pivotal study by Zhou et al. in 1995 found that the volume of the central subdivision of the bed nucleus of the stria terminalis (BSTc), a region in the brain associated with sexual behavior, was smaller in male-to-female transgender individuals compared to cisgender males and more akin to cisgender females. This study was significant because it suggested that certain neural structures in the brain may reflect an individual's sense of gender identity, rather than just their biological sex, indicating a biological underpinning to gender identity and dysphoria. However, interpreting these findings must be done with caution as many factors, including social, environmental, and cultural influences, can impact brain development and structure.