(A) Significant activations for the interaction effect of Condition × Age Group in an F-test are shown at a threshold of p < 0.005, voxel-level uncorrected, and p < 0.05, cluster-level corrected. (B) Mean activity in the significant cluster in left inferior frontal gyrus was extracted and plotted across the four conditions and age combinations. (C) The relation between neural activity in the left IFG and behavioral performance was numerically positive but non-significant for both younger and older adults in the rhyme judgment and (D) was significant in younger, but not older adults, for the semantic judgment. Spearman’s rho values are provided for each group in each analysis.