The first (inverted U-shaped relationship between brain activity and neuronal loss) and second (relationship between brain activity and task demands) criteria of attempted compensation are depicted in A and B respectively. The first (positive correlation between brain activity and task performance) and second (altered relationship between brain activity and task performance following disruption or enhancement of the compensating brain region) criteria of successful compensation are depicted in C and D respectively. (A,B) are adapted from Figure 37-3, p. 635, Dennis and Cabeza. Figure originally published in Frontiers in Psychiatry, 2014: Scheller E et al., Attempted and successful compensation in preclinical and early manifest neurodegeneration - a review of task FMRI studies 2014. Ref 2.