The neurodevelopmental changes in cognitive control during childhood and adolescence. Evidence from Event-Related Potential research

Salient maturational changes in cognitive functioning not only characterize the first years of a child’s life, but continue to take place through late childhood and adolescence up into early adulthood. One of the most striking changes seen in cognitive functioning in school-aged children and adolescents is the improvement of cognitive control. Children get better and better at engaging in complex behaviours aimed at reaching often long-term goals, thereby overriding the distraction by irrelevant information and the engagement in impulsive reactions. These developmental changes in cognitive control are enabled by structural and functional changes in the child’s and adolescent’s brain, in particular by developmental changes of the prefrontal cortex. Only recently brain imaging studies have begun to unravel these neural changes and their relationship with cognitive development; however both are still far from fully understood. This doctoral project is aimed at a better understanding of the developmental changes in cognitive control seen during childhood and adolescence and their relation to developmental changes in the underlying brain processes. To this end an extensive battery of cognitive tasks was administered to a large group of normally developing children ranging in age from 6 to 15 years of age. This battery included several tasks typically used to assess different cognitive control functions, such as response control, response inhibition, attentional set shifting, dual task performance, decision making and working memory. The age-related changes evident in task performance will be investigated. Because hormonal changes related to puberty are also known to influence cognitive functioning during the age period under study, a puberty rating scale was administered to the entire group of children. This will allow us to disentangle developmental changes in cognitive control related to age from changes related to puberty stage. The inclusion of several tasks that are standard for the assessment of cognitive control will provide insight into the differential developmental trajectories followed by the different cognitive control functions. Based on a review of the imaging literature on the neural processing involved during performance of such commonly used cognitive control tasks, a model of the prefrontal cortex could be established. This model indicated both commonly and task-specific activated regions and enabled us to relate the patterns of development seen in the behavioural performance on the neurocognitive tasks to the differential development of functional organization of the prefrontal cortex. Furthermore, to gain more direct insight into the neurodevelopmental changes in cognitive control during childhood and adolescence, actual brain processing was measured within the same group of children during electrophysiological research. During four of the typically used cognitive control tasks, event-related potentials (ERPs) were measured. Due to their excellent temporal resolution, ERPs can provide an insight into the real-time neural correlates of task performance. This allows investigating the developmental changes in the different stages of information processing involved. We investigated the validity of the ERP technique for research with the established cognitive control tasks in a study with nine adults in whom ERPs were measured during administration of the same cognitive tasks. The results of the visual cued attention task illustrate that ERP research could confirm the present-day knowledge about the brain areas involved in such tasks. Moreover, due to its excellent temporal resolution, the ERP technique could provide support for the hypothesis that different neural processes are involved in different mechanisms of attentional orienting, which could not be verified previously with fMRI. Within a final part of this research project the same battery of cognitive tasks used in our study on the development of cognitive control was administered to a group of children, ranging in age from 6 to 16 years, who had sustained a mild traumatic brain injury (mild TBI). Mild TBI is known to result in, mostly subtle, dysfunctions in cognitive control in adults, however the impact on these functions during the period of important developmental changes, i.e. childhood and adolescence, remains largely unclear. Task performance of children who had sustained a mild TBI was assessed at the acute moment of hospitalization and again six months post-injury. Additionally, at both moments neural processing of cognitive control tasks was measured using ERPs. By comparing the results of this group of children with these from a group of normally developing children, we will gain insight into the cognitive functions that are most vulnerable after mild TBI in childhood and into whether any long-term deficits can be found. Moreover, by comparing the ERP patterns of both groups, the existence of possible deficits in actual brain processing will be investigated.status: publishe