The Developmental Cognitive Neuroscience Group mostly focuses on neurocognitive development in typically developing children and 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, enduring dispositions and actions. 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). Over the past two decades, research has begun to shed light on how the brain enables the diverse set of functions that allow humans to understand and interact with each other. These functions range from the recognition of faces and bodily gestures to the evaluation of what another person is thinking or feeling, predicting what they are about to do next and communicating with them.
Our current research focuses mostly on the development of the social brain during adolescence.
In the past decade or so, a number of structural magnetic resonance imaging (MRI) studies have shown that several cortical regions, in particular the PFC, parts of the temporal cortex and parietal cortex, as well as a number of subcortical structures, undergo substantial changes in white matter and grey matter density during the first two decades of life. In several brain regions, white matter volume tends to increase linearly during the first two decades and beyond while grey matter volume tends to decrease during adolescence. Some of the brain regions that are late-maturing include parts of the social brain.
Social brain development during adolescence
There is a rich literature on the development of social cognition in infancy and childhood, pointing to step-wise changes in social cognitive abilities during the first five years of life. However, there has been surprisingly little empirical research on social cognitive development beyond childhood. Only recently have studies focussed on development of the social brain beyond childhood.
Although there is no strong evidence that performance in mentalising tasks changes during adolescence, several fMRI studies of social cognition have shown that medial prefrontal cortex activity decreases between adolescence and adulthood. For example, the dorsal mPFC 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 mPFC, temporal poles and pSTS/TPJ. However, the dorsal mPFC was more active in adolescents than in adults during intentional causality relative to physical causality. A different activity cluster within the same region was negatively correlated with age over the whole group of participants. 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.
These results 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.
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.
Our research focuses 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), have been shown to be recruited during these types of cognitive processing (Dumontheil et al., QJEP, 2010). Iroise Dumontheil is running a research project on how rostral prefrontal cortex develops during late childhood and adolescence, and how it might be divided in functionally dissociated sub-regions (Dumontheil et al., DCMN 2008). 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 recently collected both 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).
Thus depending on the task, the developmental changes in brain activity we observe in the prefrontal cortex may relate to developmental changes in performance, in brain structure, or may be independent from these and instead reflect, for example, a better functioning and integration of information across brain networks.
In future research, we will aim to further explore these varying developmental patterns, and study the impact of common genetic polymorphisms on behaviour and brain function. In addition, we aim to develop tasks that combine social cognition and cognitive control to better understand the interplay between these cognitives functions during development.