Figure 3.

Tau-related differences in MTL activation for repetition suppression, novel stimuli, and repeated stimuli. A, Repetition suppression was quantified by contrasting activity between novel and repeated stimuli, and compared across the YA, low tau (Tau– OA), and high tau (Tau+ OA) groups with ANOVAs and follow-up pairwise comparisons. Tau– OA demonstrated a significant reduction in repetition suppression (vs YA) in bilateral hippocampus and alEC-R (independent samples t test, ps < 0.05). Tau+ OA demonstrated additional reductions in repetition suppression across the MTL (vs YA and Tau– OA; ps < 0.05). B, C, To determine whether activity changes to novel and/or repeated stimuli were driving reduced repetition suppression, we next investigated each subcomponent of the contrast separately. B, Activity to novel stimuli was compared to the perceptual baseline condition. There were minimal group differences in activity to novel stimuli, including both increases and decreases in activity. C, Activity to repeated stimuli was compared to the perceptual baseline condition. Hyperactivity in the Tau– OA group (vs YA) was found in bilateral hippocampus and alEC-R, and hyperactivity in the Tau+ OA group (vs Tau– OA and YA) was found throughout the MTL. This hyperactivity to repeated stimuli can be inferred to drive the reduction in repetition suppression seen in A. Significance above each bar reflects one sample t tests within each group, while lines across bars represent significant group differences with independent samples t tests. Error bars represent SEM; ***p < 0.001, **p < 0.01, *p < 0.05.