Measuring compensation and its plasticity across the lifespan.

PURPOSE The present paper integrates two important aspects when studying compensation: (1) the knowledge about specific compensational mechanisms and (2) the consideration of lifelong changes in these mechanisms (i.e., plasticity of compensation). Hence, the paper addresses the questions (a) which neural networks are supporting successful cognitive performance across development, (b) what are the associated compensational mechanisms and (c) are these compensational mechanisms plastic across the lifespan. METHODS To answer these questions, we suggest to integrate behavioural and neuroimaging methods and present specific methods and their advantages and disadvantages. RESULTS We will illustrate the relevance of this integration by presenting data using ERPs and (s)LORETA to study compensational processes across the lifespan in a higher order cognitive function, i.e., delayed intentional behaviour. A higher activation in old adults or adolescents in successful trials compared to young adults is considered compensatory as specialized cortical regions are selectively recruited in response to task demands. CONCLUSIONS Findings show that whereas the performance outcome might be the same across age groups, underlying processes and activations might be fundamentally different. We conclude with a discussion about specific implications of this integrative approach when studying the adaptive potentials and limits of human cognition.