Brain areas where the increase in activation associated with a more demanding memory task vs an easier task correlated positively with the NART (National Adult Reading Test) score, a proxy for Intelligence Quotient and cognitive reserve. Scatter graph below illustrates these positive correlation at a selected voxel. From: Stern Y, Zarahn E, Hilton HJ, Flynn J, DeLa Paz R, Rakitin B. Exploring the neural basis of cognitive reserve. Journal of Clinical and Experimental Neuropsychology 2003;5:691-701.