The Developmental Cognitive Neuroscience Group focuses on neurocognitive development in typically developing adolescents. We are particularly interested in the development of the social brain - that is, the network of brain regions involved in understanding other people.

The social brain

Humans are inherently social. A large proportion of the human brain is involved in social interaction and understanding other people. The social brain is defined as the

complex network of areas that enable us to recognise others and evaluate their mental states (intentions, desires, beliefs), feelings and actions. Over the past two decades, research has shed light on how the brain enables the diverse set of functions that allow humans to understand and interact with each other. Brain areas involved in social cognitive processes include medial prefrontal cortex (mPFC), anterior cingulate cortex (ACC), inferior frontal gyrus, superior temporal sulcus (STS), the amygdala and anterior insula (see Figure below). 

Our current research focuses mostly on the development of the social brain during adolescence.

Social brain development during adolescence

There is a rich literature on the development of social cognition in infancy and childhood, pointing to multiple changes in social cognitive abilities during the first five years of life. In the past decade or so, behavioural and neuroimaging studies have started to investigate the development of the social brain beyond childhood.

Several fMRI studies of social cognition have shown that medial prefrontal cortex activity decreases between adolescence and adulthood. For example, the dorsal medial prefrontal cortex (dmPFC) was found to be more active in adolescents than in adults in an fMRI study that involved thinking about one's own intentions (Blakemore et al. 2007). Adolescents (aged 12-18) and adults (aged 22-38) were presented with scenarios about intentional causality (involving intentions and consequential actions) or physical causality (involving natural events and their consequences). In both groups, intentional causality relative to physical causality activated the classic mentalising network including the dmPFC, temporal poles and pSTS/TPJ. However, the dmPFC was more active in adolescents than in adults during intentional causality relative to physical causality. Conversely, a region in the right STS was more active in adults than in adolescents when they were thinking about intentional causality compared with physical causality.

In another fMRI study, volunteers had their brain scanned when thinking about social situations that would cause many people to experience social emotions such as guilt and embarrassment. For example, in the Embarrassment condition, volunteers read sentences like, "Your dad started doing rock 'n' roll dances in the supermarket". Thinking about guilt and embarrassment situations activated the social brain in both adolescents and adults. However, the dmPFC was more active in adolescents than in adults while the temporal pole was more active in adults than in adolescents (Burnett et al. 2008).

These results might suggest that the neural strategy for thinking about intentions changes from adolescence to adulthood. Although the same neural network is active, the relative roles of the different areas change with age, with activity moving from anterior (mPFC) regions to posterior (temporal) regions of the social brain.

Several recent fMRI studies have shown that activity in the mPFC during social cognitive tasks decreases between adolescence and adulthood (see Blakemore, 2008 for meta-analysis and figure).

Executive functions and cognitive control in adolescence

As well as social functions, we are interested in how the brain matures to enable cognitive control, a collection of brain processes that guide thought and behaviour in accordance with internally generated goals or plans. Inhibitory control, task switching and working memory have been investigated in children by various groups; it has been found that performance on executive function tasks continues to improve as late as adolescence and early adulthood.

One study focused on the control of the selection and manipulation of self-generated thoughts. This ability is involved when one's mind is wandering and reflecting about future or past events, or when one's is trying to solve a problem's that require multiple steps of reasoning. The lateral parts of rostral prefrontal cortex, or Brodmann area 10 (shown in the figure on the left), are recruited during these types of cognitive processing (Dumontheil et al., QJEP, 2010). The rostral prefrontal cortex is of particular interest because it is a region where the density of connections between neurons is greater in humans than in other primates, where the development continues during adolescence, and which is involved both in social cognition and in cognitive control.

We collected behavioural and neuroimaging data on two tasks that recruit the rostrolateral prefrontal cortex in adults. We were interested in how performance and brain activation during these tasks change during development, as well as how brain activation changes relate to structural changes in grey and white matter. Behavioural results showed that the ability to focus on self-generated thoughts and to reason about multiple relationships between stimuli (relational reasoning) continued to improve during adolescence. Neuroimaging data suggested that although overall adolescents and adults recruited a very similar network of brain regions (see figure on the right), there were significant differences in how much the two groups activated prefrontal regions. In one task, which requires switching between focusing on self-generated thoughts and focusing on information derived from the environment, we found that there were linear decreases in activations with age, and that they occurred independently of the developmental changes in grey and white matter (Dumontheil et al., JoN, 2010). 

In another task, which requires relational reasoning, the developmental trajectory was different (Dumontheil et al., Dev Sci, 2010). The behavioural and brain activity changes were not always linear, or gradual, from early adolescence to adulthood. Participants age 9-11 were as accurate as the adults and more accurate than the older adolescent participants (see graph on the left). The oldest adolescents in our neuroimaging sample (14-18 years old) recruited the rostrolateral prefrontal cortex more than the younger adolescents and adults, and in this case this increased activation was related to differences in performance and brain structure between the age groups. 

Thus depending on the task, the developmental changes in brain activity in the prefrontal cortex may relate to developmental changes in performance or brain structure, or may be independent from these and instead reflect, for example, greater functioning and integration of information across brain networks.