Daselaar et. al. have used MRI to observe memory retrieval accompanied by specific contextual details (recollection) or on the feeling that an item is old (familiarity) or new (novelty) in the absence of contextual details. There have been indications that recollection, familiarity, and novelty involve different medial temporal lobe subregions, but available evidence is scarce and inconclusive. Within the medial temporal lobes (MTLs), they found a triple dissociation among the posterior half of the hippocampus, which was associated with recollection, the posterior parahippocampal gyrus, which was associated with familiarity, and anterior half of the hippocampus and rhinal regions, which were associated with novelty. Furthermore, multiple regression analyses based on individual trial activity showed that all three memory signals, i.e., recollection, familiarity, and novelty, make significant and independent contributions to recognition memory performance.
FIG. 1. A triple dissociation within the medial temporal lobe (MTL) regarding recollection, familiarity, and novelty.
Functional dissociations among recollection, familiarity, and novelty were also found in posterior midline, left parietal cortex, and prefrontal cortex regions.
FIG. 2. Brain regions outside MTL showing recollection-, familiarity, and novelty-related activity.
There has been debate in the behavioral memory literature over whether recollection and familiarity/novelty processes are independent, given reports of correlations between behavioral measures of recollection and familiarity. The anatomical dissociations shown by the present fMRI evidence fit better with the assumption of independence.