Figure 1. Novelty processing and successful memory encoding elicit a distinct activity pattern in hippocampal and parahippocampal subregions.

Group activity for (a) novelty and (b) successful encoding (difference due to memory, ‘DM’), overlaid on the group-specific T1 template (with same resolution as functional images: 0.8 mm isotropic voxels) after ROI-based diffeomorphic registration with ANTS. Group activation is illustrated on five coronal sample slices for two different smoothing kernels. EPIs were initially smoothed with 1.5 mm (<2 × voxel size, bright colours: cyan and yellow), which allows for higher anatomical precision at the cost of lower sensitivity. Furthermore, the analyses were repeated with a 2.4 mm FWHM (=3 × voxel size, dark colours: blue and red) to increase sensitivity and demonstrate reliability of activation. For both contrasts, there was significant activation in the EC (mostly medial). In the hippocampus, novelty-related activation was most prominent in the head with peak activation in CA2/3-DG and presubiculum. For successful encoding, hippocampal activation was found in CA1 pyramidal layers (slice 4, cluster right to cross-hairs) and subiculum (head & body, see cross-hairs) and a small cluster in CA2/3-DG (posterior body). Activation maps were thresholded at P_{voxel level}<0.005≈T>2.9; k_1.5 mm≥15 voxels and k_2.4 mm≥25 voxels (N=19).