Poster C56, Sunday, March 25, 1:00-3:00 pm, Exhibit Hall C
Age differences in memory retrieval: The role of regulatory downregulation of medial temporal lobe activity by the prefrontal cortex
Jaclyn Ford1, Elizabeth Kensinger1; 1Boston College
We have recently argued (e.g., Ford & Kensinger, 2017) that age differences in memory retrieval are partially due to an affective process by which older adults (OAs) recruit dorsomedial prefrontal (dmPFC) regions to decrease richness of negative memories via downregulation of the hippocampus (HC). The current analysis examined this claim by testing two predictions. First, if dmPFC serves to downregulate hippocampus, then OAs should show a dip in HC activity during negative event retrieval following recruitment of the dmPFC. Second, based on evidence that regulatory processes require cognitive control (e.g., Mather & Knight, 2005), this dmPFC-HC pattern should be strongest in OAs with greater cognitive control. In a memory task, participants (ages 18-85) encoded images paired with verbal titles. During an fMRI scan, they were presented with titles and asked whether each had been seen with an image during encoding. Participants provided vividness ratings following retrieval of each image. Consistent with our hypotheses, OAs initially recruited hippocampal regions equally for positive and negative events, but exhibited a significant decrease in activation for negative events following dmPFC recruitment. This pattern was related to connectivity estimates between these two regions. DmPFC-HC connectivity in OAs was also related to scores on a test of cognitive control, mental arithmetic. OAs with better scores had more negative dmPFC-HC connectivity estimates, suggesting that this connectivity reflects a controlled process. These findings are consistent with studies suggesting that OAs will reallocate cognitive control resources to regulate emotions during cognitive tasks if they are able to do so.
Topic Area: LONG-TERM MEMORY: Development & aging