Figure 4.

Topography of hippocampal activation as a function of relative familiarity. Activation in the left hippocampus spreads posteriorly as meaningful items (exemplars) become increasingly familiar. Three voxels within the left hippocampus, each separated by 12 mm along the transverse plane, were identified by an SPM constructed to detect any change in activation relative to baseline across the 14 subjects. (a) The BOLD response of the principal component within a 4-mm radius of each chosen voxel is plotted relative to baseline. (b) The coordinate of each chosen voxel is shown below each plot along with the region from which the principal component was selected (superimposed on a transverse section of the T1-weighted anatomical image). Note that the left anterior hippocampal activation displayed in Fig. 3b peaks at the second/third presentation of the exemplar set. This activation is situated at y = −16, which in the anterior–posterior axis is midway between the first and second chosen voxels displayed.