Unvealing Early-Stage Memory Deficits: Pattern Separation Impairments and Neural Dysfunction in Subjective Cognitive Decline

Poster Session F - Tuesday, April 16, 2024, 8:00 – 10:00 am EDT, Sheraton Hall ABC

Juan Li¹ (lijuan@psych.ac.cn), Qinghe Zeng¹, Wei Tang¹, Xiaoyu Cui¹; ¹Institute of Psychology, Chinese Academy of Sciences

Pattern separation, the process that establishes distinguishable memory representations of similar episodes, is typically examined through the Mnemonic Discrimination Task (MST). Previous literature has unveiled correlations between deficits in pattern separation and alterations in neural mechanisms attributed to cognitive impairment. However, the alterations in pattern separation performance and whole-brain activation remain unclear in individuals experiencing Subjective Cognitive Decline (SCD), a pre-clinical stage of cognitive impairment. In the present study, 51 older adults aged over 60 years were recruited and divided into two groups based on SCD-Q9 (25 NC, 26 SCD). Participants underwent functional magnetic resonance imaging (fMRI) scanning while engaging in MST. In this task, they were required to make judgments of "new," "similar," or "old" in response to novel items, similar but not identical items (i.e., lure), or repetition items. The analyses revealed that the SCD group exhibited lower Lure Discrimination Indexes (LDI) than NC group. The fMRI analyses demonstrated that individuals with SCD exhibited lower activation in the hippocampus and dysfunction in the frontal lobes compared to those without SCD when they successfully responded to lure stimuli. These findings suggest that individuals with SCD may display detectable pattern separation deficits compared to healthy older adults. These deficits are associated with functional hypoactivation in the hippocampus and dysfunction in the control network, indicating an impaired memory mechanism in a very early stage of cognitive impairment.

Topic Area: LONG-TERM MEMORY: Development & aging