Pattern separation engages regions beyond the hippocampus among nondemented elderly subjects: a 7T task fMRI study

Motivation: Investigating the ability to differentiate similar representations is extensively focused on hippocampus. The roles of cortical regions and their interaction with the hippocampus largely remain unclear. Goal(s): We aim to address this issue with whole-brain high-resolution fMRI data collected during a mnemonic similarity task. Approach: Whole-brain and hippocampal ROI analysis were conducted to examine brain activity during the task. Results: The right frontoparietal network showed increased activity when a lure or the same object was presented compared to a new object. The left anterior CA3/DG and left frontoparietal network had higher activity when a lure was correctly identified as “similar” instead of “same”. Impact: Besides the CA3/DG, left frontoparietal regions were also involved in discriminating similar objects while right frontoparietal regions were mainly involved in successful retrieval, suggesting the functional lateralization of frontoparietal network.