Fig. 3. (A) Left striatum (peak x = −20, y = 4, and z = 14) was activated before training and showed a training-related increase for both letter memory and 3-back in younger adults. The bar graph shows the activation profiles across tasks and sessions. The red line indicates mean baseline bold values for the striatal region (mean of trained before, controls before, and controls after). (B) Left striatum (peak x = −24,y = 10, and z = −2) showed a training-related increase for letter memory in older adults. Error bars are SEM. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)