Investigating the influence of proximity on unitization within the associative memory network

Poster Session B - Sunday, April 14, 2024, 8:00 – 10:00 am EDT, Sheraton Hall ABC

Nancy A. Dennis¹, Alexa Becker¹, Catherine M. Carpenter¹, Spencer Chase¹, John West¹, Amy A. Overman²; ¹Penn State University, ²Elon University

Although associative memory has been shown to decline in aging, memory for single items remains relatively intact in older adults. Unitization is a cognitive process that has been demonstrated to enhance associative memory by creating a single ensemble from discrete items, thereby ameliorating age-related deficits in associative memory. Although it has been suggested that unitization enhances associative memory by allowing item pairs to be processed as a single item, the neural basis of this hypothesis has yet to be tested empirically. The current study aimed to test this claim by comparing memory for item pairs encoded using a unitization-based presentation to both item pairs in a non-unitized condition and single items. Results showed that a presentation intended to promote unitization, which entailed presenting item pairs in close proximity to one another (proximal condition), enhanced associative memory in both younger and older adults compared to item pairs presented at a distance (distal condition). Pattern similarity analyses (PSA) for both encoding and retrieval showed greater overlap in patterns of neural activity underlying the single item and proximal configurations compared to the proximal and distal configurations in frontal-parietal regions and in subsets of voxels within the hippocampus. However, the opposite pattern was found in the parahippocampal cortex. Results suggest that although proximity aids in associative memory by creating neural representations of item pairs that are more similar to single items than two separate items, this shift in processing is nuanced, and there is a need for additional investigation, particularly within the MTL.

Topic Area: LONG-TERM MEMORY: Episodic