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Comparison of mass univariate and trial-wise measures of neural selectivity and their relationships with memory performance

Poster Session D - Monday, March 9, 2026, 8:00 – 10:00 am PDT, Fairview/Kitsilano Ballroom

Ayse N. Z. Aktas¹ (), Marianne DeChastelaine¹, Amber Kidwai¹, Sarah Monier¹, Michael Rugg¹; ¹Center for Vital Longevity and Department of Behavioral and Brain Sciences, The University of Texas at Dallas

We compared three metrics of category-related neural selectivity: a GLM-based mass univariate metric, and two other metrics, one univariate (the difference in mean activity elicited by preferred vs. non-preferred categories, scaled by the pooled trial-wise standard deviation - ‘differentiation index’) and one multi-voxel (within vs. between-category pattern similarity). During fMRI scanning, young (N = 41; ages 18–27) and middle-aged participants (N = 45; ages 45–56) viewed a series of face and scene images paired with concrete words and generated a scenario linking the two pair members. At test, participants judged whether each test word had been studied and, if so, whether it had been paired with a face or a scene. Selectivity during encoding was examined in the face-selective fusiform face (FFA) and occipital face areas (OFA), and the scene-selective parahippocampal place (PPA) and medial place areas (MPA). In scene-selective regions, the three selectivity metrics were robustly correlated. In face-selective regions, the correlations were restricted to the FFA. The differentiation index derived from the MPA, PPA, and FFA, and the pattern similarity metric from the MPA, were each positively associated with source memory performance. The differentiation index derived from the MPA and PPA, and the pattern similarity metric from the FFA, correlated with item memory performance. By contrast, mass univariate selectivity metrics were uncorrelated with either behavioral measure. These findings highlight commonalities and differences among univariate and trial-wise measures of neural selectivity, with the univariate differentiation index emerging as the strongest predictor of memory performance.

Topic Area: LONG-TERM MEMORY: Episodic