Rostral prefrontal cortex (rPFC) is a brain area that is significantly larger in humans than in other primates and is one of the last areas to achieve maturation. Cellular studies have suggested that significant synaptic proliferation occurs in the PFC at the onset of puberty, followed by a period of synaptic pruning and continued axonal myelination, which continues throughout adolescence.Similarly, recent magnetic resonance imaging (MRI) studies have demonstrated continued development in terms of the volume of grey matter and white matter in the adolescent human brain. Behavioural studies have demonstrated a development of executive functions abilities during this time period. Some studies demonstrated linear improvements, other non linear changes, e.g. Mc Givern et al. observed a significant rise in reaction time on an executive function task involving emotionally related stimuli around the age of puberty onset, possibly associated with these neural alterations.In this project, we propose to investigate the development of rPFC during puberty and adolescence, focusing on two functions of rPFC. It has been proposed that posterior medial rPFC is involved in interpreting others mental states (Theory of Mind: ToM), while anterior medial rPFC and lateral rPFC are differentially involved in allocating attention to ones thought or towards the environment. Behaviourally, we would first aim to study differences in performance in a task combining the social (ToM) and attention aspects of rPFC function. Functional MRI would be used to investigate the different involvement of lateral, medial, and posterior rPFC in these two functions.Finally an anatomical study, using voxel-based morphometry, would add quantitative observation of the structural development of the brain. We predict a decrement in performance on mentalising/social tasks and attention switching tasks around the age of puberty onset, associated with developmental changes in posterior and lateral rPFC.