Aims Adolescence is the transitional stage of physical, psychological and social development between childhood and adulthood. The social brain, the network of brain regions involved in understanding other people's mental states and emotions, undergoes structural and functional changes during adolescence. This network includes the dorsomedial prefrontal cortex (DMPFC), the anterior temporal cortex (ATC), the temporoparietal junction (TPJ) and the posterior superior temporal sulcus (pSTS). The timing of this development coincides with puberty, and it is hypothesised that pubertal hormones may contribute to the observed changes. We used functional MRI (fMRI) to investigate how pubertal development relates to both brain activity during a social emotion task, and functional connectivity between social brain network regions.

Method 42 females aged 11.0 to 13.7 years underwent fMRI scanning while reading scenarios pertaining to either social or basic emotions. Social emotions (e.g. guilt, embarrassment) require the representation of another person's mental state, while basic emotions (e.g. fear, disgust) do not. Puberty measures taken for each participant included: visual physician Tanner stage assessment; self-assessment questionnaire; and salivary hormone levels for testosterone, oestradiol and DHEA. The functional images were analysed and differences in mean brain activity as well as psychophysiological interactions were explored. Results are significant at p<0.001 (uncorrected), and survive small volume correction (SVC) at p<0.05.

Results

1. Increased testosterone levels (independent of age) were associated with higher activity in the left ATC, during social relative to basic emotion processing. Both oestradiol and DHEA were positively correlated with left ATC activity (but did not survive SVC).

2. More advanced age (independent of pubertal hormone levels) was associated with reduced activity in the DMPFC during social relative to basic emotion processing.

3. Participants in later stages of puberty had increased functional connectivity between the DMPFC and other social brain network regions.

Conclusion We have shown that changing patterns of functional brain activity in the female adolescent social brain correlate with increasing pubertal hormones, independent of age. The increased functional connectivity seen with advancing puberty suggests developing integration of the social brain network. These findings imply a role for pubertal hormones in the development of the social brain network.