Age-related shifts in hippocampal subregion activation during recall

Poster Session B - Sunday, March 30, 2025, 8:00 – 10:00 am EDT, Back Bay Ballroom/Republic Ballroom

Nathan Chabin^1,4,5 (natechabaz@gmail.com), Molly Booth^2,4,5, Susan Bookheimer^3,4,5, Jesse Rissman^3,4,5, Dara Ghahremani^4,5; ¹Pitzer College, ²Scripps College, ³UCLA Department of Psychology, ⁴UCLA Department of Psychiatry & Biobehavioral Sciences, ⁵UCLA Semel Institute for Neuroscience & Human Behavior

Neuroimaging studies have shown subregional differences in hippocampal activation with respect to memory encoding and retrieval. These dissociations may change with age, with potential consequences for memory performance. We examined fMRI activation during encoding and recall during a paired-associates task in 684 participants (age: 36-90 y/o, M=59.9, SD=15.4; 383 female) who participated in the Human Connectome Project Aging study. Encoding- and recall-related activation and recall performance were assessed using the FACENAME fMRI task (Zeineh et al., 2003), which includes face-name encoding blocks alternating with name recall blocks. Recall performance was verified post-scan. Hippocampal subregional segmentations (head, body, tail) were determined using Freesurfer. FMRI data were analyzed using FSL’s FEAT. Parameter estimates for encoding and recall blocks were extracted from the 3 subregions from each hemisphere. Linear mixed models were used to determine subregional relationships between memory condition (i.e., encoding or recall) and age, as well as recall performance. We found a memory condition-by-age interaction [p=0.0084] in the left hippocampal body (Bonferroni corrected p-threshold = 0.008). Recall activation in this region reduced with age while encoding activation remained constant. No relationships between recall performance and fMRI activation were found. In conclusion, activation of the left hippocampal body is sensitive to age-related changes during recall. This decline in activation may underlie age-related memory performance deficits captured by other testing procedures.

Topic Area: LONG-TERM MEMORY: Development & aging