Fig. 5: Generalization of low-dimensional hippocampal representations from learning to creating.

A Trial-wise activity patterns were extracted from the left hippocampus for both higher (HSC, red) or lower (LSC, blue) subsequent creation conditions during the learning and creating phases. These patterns were projected into a shared principal component analysis (PCA) space, and cross-phase pattern similarity was computed based on PCs to quantify the transfer of low-dimensional neural representations between conditions. B Cross-phase similarity as a function of variance explained by retained PCs (70–90%). HSC trials (red) consistently showed higher similarity than LSC trials (blue), reflecting more effective transfer of low-dimensional hippocampal representations. The inset boxplots display average similarity across the 70–90% range, confirming a significant HSC > LSC effect (n = 39 independent participants; two-tailed paired t-test: t₍₃₈₎ = 2.12, p = 0.04, R² = 0.34, 95% CI [0.002, 0.08]). Curves indicate mean similarity, with shaded areas representing ±s.e.m. Box plots show the median (center), 25th–75th percentiles (bounds of box), and minima and maxima (whiskers). C Trial-wise hippocampal activity patterns from HSC and LSC conditions were separately projected into condition-specific PCA spaces. Within each condition, cross-phase similarity was computed between learning and creating patterns, and the resulting similarity indices were then compared across conditions at the group level. D HSC trials (red) again exhibited higher cross-phase similarity of low-dimensional representations than LSC trials (blue) across the 70–90% explained variance range (n = 39 independent participants; two-tailed paired t-test: t₍₃₈₎ = 2.41, p = 0.02, R² = 0.39, 95% CI [0.06, 0.71]), plot features as in (B). *p <  0.05. Source data are provided as a Source Data file.