Adolescent development of the neural circuitry for thinking about intentions.

In this fMRI study, we investigated the development during adolescence of the neural network underlying thinking about intentions. A total of 19 adolescent participants (aged 12.1-18.1 years), and 11 adults (aged 22.4-37.8 years), were scanned using fMRI. A factorial design was employed with between-subjects factor age group and within-subjects factor causality (intentional or physical). In both adults and adolescents, answering questions about intentional causality vs physical causality activated the medial prefrontal cortex (PFC), superior temporal sulcus (STS), temporal poles and precuneus bordering with posterior cingulate cortex. In addition, there was a significant interaction between group and task in the medial PFC. During intentional relative to physical causality, adolescents activated part of the medial PFC more than did adults and adults activated part of the right STS more than did adolescents. These results suggest that the neural strategy for thinking about intentions changes between adolescence and adulthood. Although the same neural network is active, the relative roles of the different areas change, with activity moving from anterior (medial prefrontal) regions to posterior (temporal) regions with age.