Thesis defense Rik van Dinteren (Donders series 241)
19 October 2016
Promotor: prof. dr. R. Kessels, copromotors: dr. M. Arns, dr. M. Jongsma
Finding a new balance: change in cortical activations during the lifespan
The aim of the present thesis was to examine the validity of an ERP index that is suitable for quantifying and indexing cognitive aging in both healthy and clinical populations. In the first part we demonstrated that the P3 develops across the lifespan in a specific way in healthy participants. Furthermore, the developmental models differ depending on the location of P3 measurement, frontal versus parietal. It was hypothesised that the frontal P3 could be an indicator of frontal compensatory cortical activation. In the second part the use of the ERP P3 component in treatment prediction was investigated. This was done within the international Study to Predict Optimized Treatment in Depression (SPOT-D) project that provided 1008 MDD patients. Unfortunately, the P3 could not dissociate the responders from non-responders to antidepressants in this study. Therefore, in the final part the P3 signal was decomposed into separate independent components using independent component analysis to capture a more accurate and localizable reflection of frontal compensatory brain activation. The decomposed P3s were compared between young and old participants and localized to a cortical region. It was observed that one of the independent components reflected a different mix of cortical activity in old and young participants. Older participants use their available brain capacity differently from younger participants when performing the same behavioral task. By doing so, they are able to achieve a similar behavioral performance. There is a limitation to this compensatory process, however. As cognitive tasks get more complex, older participants might reach their capacity limits earlier than younger participants. This may not occur that often in many day-to-day tasks, making frontal compensation an effective and successful strategy in everyday life.